- Διορθώσεις στα model της εφαρμογής

- Ολοκλήρωση των unit tests των models που χρησιμοποιούνται στη περίπτωση χρήσης 'Κράτηση Ραντεβού'

src/application/libraries/Unit_tests/Unit_tests.php

@@ -20,7 +20,10 @@ class Unit_tests extends CI_Driver_Library {
         // the unit testing classes.
         $this->valid_drivers = array(
             'Unit_tests_appointments_model',
-            'Unit_tests_customers_model'
+            'Unit_tests_customers_model',
+            'Unit_tests_providers_model',
+            'Unit_tests_services_model',
+            'Unit_tests_settings_model'
         );
     }
     
@@ -49,6 +52,9 @@ class Unit_tests extends CI_Driver_Library {
     public function run_model_tests($output_report = true) {
         $this->appointments_model->run_all();
         $this->customers_model->run_all();
+        $this->settings_model->run_all();
+        $this->providers_model->run_all();
+        $this->services_model->run_all();
         
         if ($output_report) {
             $this->CI->output->append_output($this->CI->unit->report());

src/application/libraries/Unit_tests/drivers/Unit_tests_appointments_model.php

@@ -125,14 +125,14 @@ class Unit_tests_appointments_model extends CI_Driver {
                                 'id_services' => $this->service_id
                              );
         
-        $hasThrownException = FALSE; // This method must throw a validation exception.
+        $has_thrown_exception = FALSE; // This method must throw a validation exception.
         try {
             $this->CI->Appointments_Model->add($appointment_data);
         } catch(ValidationException $valExc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test add() appointment with wrong date format.', 'A validation exception must be thrown.');
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test add() appointment with wrong date format.', 'A validation exception must be thrown.');
     }
     
     /**
@@ -140,7 +140,7 @@ class Unit_tests_appointments_model extends CI_Driver {
      * 
      * Insert a new appointment and test if it exists.
      */
-    private function test_appointment_exists() {
+    private function test_exists() {
         // Insert new appointment (this row will be checked later).
         $appointment_data = array(
                                'start_datetime' => '2013-05-01 12:30:00',
@@ -160,7 +160,7 @@ class Unit_tests_appointments_model extends CI_Driver {
         $this->CI->db->delete('ea_appointments', array('id' => $appointment_data['id']));
     }
     
-    private function test_appointment_does_not_exist() {
+    private function test_exists_record_does_not_exist() {
         // Create random appointmnet data that doesn't exist in the database.
         $appointment_data = array(
                                'start_datetime' => '2013-05-01 08:33:45',
@@ -174,7 +174,7 @@ class Unit_tests_appointments_model extends CI_Driver {
         $this->CI->unit->run($this->CI->Appointments_Model->exists($appointment_data), FALSE, 'Test exists() method with an appointment that does not exist');
     }
     
-    private function test_appointment_exists_wrong_data() {
+    private function test_exists_with_wrong_data() {
         // Create random appointmnet data that doesn't exist in the database.
         $appointment_data = array(
                                'start_datetime' => '2WRONG013-05-01 0WRONG8:33:45',
@@ -232,15 +232,15 @@ class Unit_tests_appointments_model extends CI_Driver {
                            );
         
         // Load the appointments model and execute the find record id method.
-        $hasThrownException = FALSE;
+        $has_thrown_exception = FALSE;
         
         try {
             $this->CI->Appointments_Model->find_record_id($appointment_data);
-        } catch(DatabaseException $dbExc) {
+        } catch(DatabaseException $db_exc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test find_record_id() with appointment ' 
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test find_record_id() with appointment ' 
                 . 'data that does not exist in the database.', 'A database exception is expected '
                 . 'to be raised.');
     }
@@ -264,15 +264,15 @@ class Unit_tests_appointments_model extends CI_Driver {
         
         // Try to find the appointmet's record id. A database 
         // exception should be raised.
-        $hasThrownException = FALSE;
+        $has_thrown_exception = FALSE;
         
         try {
             $this->CI->Appointments_Model->find_record_id($appointment_data);
-        } catch(DatabaseException $dbExc) {
+        } catch(DatabaseException $db_exc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test find_record_id() with appointment ' 
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test find_record_id() with appointment ' 
                 . 'data array with wrong values.', 'A database exception is expected to be raised.');
     } 
     
@@ -321,10 +321,15 @@ class Unit_tests_appointments_model extends CI_Driver {
     private function test_delete_record_wrong_parameter_given() {
         $wrong_record_id = 'not_an_integer';
         
-        $delete_result = $this->CI->Appointments_Model->delete($wrong_record_id);
+        $has_thrown_exception = FALSE;
-        echo $delete_result;
+        
-        $this->CI->unit->run($delete_result, FALSE, 'Test delete() method with a record id' 
+        try {
-                . ' that is not an integer');
+            $this->CI->Appointments_Model->delete($wrong_record_id);
+        } catch (InvalidArgumentException $ia_exc) {
+            $has_thrown_exception = TRUE;
+        }
+
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test delete() method with argument that is not an integer.');
     }
     
     /**
@@ -381,15 +386,15 @@ class Unit_tests_appointments_model extends CI_Driver {
      * igniter handles itself wrong queries.
      */
     private function unabled_test_get_batch_wrong_where_clause() {
-        $hasThrownException = FALSE;
+        $has_thrown_exception = FALSE;
         
         try {
             $this->CI->Appointments_Model->get_batch('WRONG QUERY HERE');
-        } catch(DatabaseException $dbExc) {
+        } catch(DatabaseException $db_exc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_batch() with wrong where clause.',
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_batch() with wrong where clause.',
                 'A database excpetion is expected to be thrown.');
     }
     
@@ -436,17 +441,17 @@ class Unit_tests_appointments_model extends CI_Driver {
      * 
      * A database exception is expected.
      */
-    private function test_get_row_wrong_argument_given() {
+    private function test_get_row_with_invalid_argument() {
-        $wrong_arguement_id = 'THIS IS NOT AN INTEGER';
+        $invalid_id = 'THIS IS NOT AN INTEGER';
         
-        $hasThrownException = FALSE;
+        $has_thrown_exception = FALSE;
         try {
-            $this->CI->Appointments_Model->get_row($wrong_arguement_id);        
+            $this->CI->Appointments_Model->get_row($invalid_id);        
-        } catch (DatabaseException $dbExc) {
+        } catch (InvalidArgumentException $db_exc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_row() with wrong arguement.');
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_row() with wrong argument.');
     }
     
     /**
@@ -466,7 +471,6 @@ class Unit_tests_appointments_model extends CI_Driver {
         $appointment_data['id'] = $this->CI->db->insert_id();
         
         // Get a specific value from the database.
-        
         $db_value = $this->CI->Appointments_Model->get_value('start_datetime', $appointment_data['id']);
         
         // Check if the value was correctly fetched from the database.
@@ -485,15 +489,15 @@ class Unit_tests_appointments_model extends CI_Driver {
     private function test_get_value_record_does_not_exist() {
         $random_record_id = 843521368768;
         
-        $hasThrownException = FALSE;
+        $has_thrown_exception = FALSE;
         
         try {
             $this->CI->Appointments_Model->get_value('start_datetime', $random_record_id);
-        } catch (DatabaseException $dbExc) {
+        } catch (InvalidArgumentException $db_exc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_value() with record id that does not exist.');
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that does not exist.');
     }
     
     /**
@@ -517,15 +521,15 @@ class Unit_tests_appointments_model extends CI_Driver {
         
         // Try to get record value with wrong field name.
         $wrong_field_name = 'THIS IS WRONG';
-        $hasThrownException = FALSE;
+        $has_thrown_exception = FALSE;
         
         try {
             $this->CI->Appointments_Model->get_value($wrong_field_name, $appointment_data['id']);
-        } catch (DatabaseException $dbExc) {
+        } catch (InvalidArgumentException $db_exc) {
-            $hasThrownException = TRUE;
+            $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($hasThrownException, TRUE, 'Test get_value() with record id that does not exist.');
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that does not exist.');
         
         // Delete inserted record.
         $this->CI->db->delete('ea_appointments', array('id' => $appointment_data['id']));

src/application/libraries/Unit_tests/drivers/Unit_tests_customers_model.php

@@ -2,11 +2,19 @@
 
 class Unit_tests_customers_model extends CI_Driver {
     private $CI;
+    private $customer_role_id;
     
+    /**
+     * Class Constructor
+     */
     public function __construct() {
+        // CodeIgniter initialization.
         $this->CI =& get_instance();
         $this->CI->load->library('Unit_test');
         $this->CI->load->model('Customers_Model');
+        
+        // Use this when creating test records.
+        $this->customer_role_id = $this->CI->db->get_where('ea_roles', array('slug' => DB_SLUG_CUSTOMER))->row()->id;
     }
     
     /**
@@ -27,12 +35,508 @@ class Unit_tests_customers_model extends CI_Driver {
     /////////////////////////////////////////////////////////////////////////
     // UNIT TESTS
     /////////////////////////////////////////////////////////////////////////   
-    private function test_true() {
+    
-        $this->CI->unit->run(TRUE, TRUE, 'True!');
+    // TEST ADD() CUSTOMER METHOD
+    private function test_add_insert() {
+        // Insert new customer record.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $customer_data['id'] = $this->CI->Customers_Model->add($customer_data);
+        $this->CI->unit->run($customer_data['id'], 'is_int', 'Test add() customer (insert operation) has returned the new row id.');
+        
+        // Check if the record was successfully added to the database.
+        $db_data = $this->CI->db->get_where('ea_users', array('id' => $customer_data['id']))->row_array();
+        $are_the_same = TRUE;
+        if ($customer_data['last_name'] != $db_data['last_name'] 
+                || $customer_data['first_name'] != $db_data['first_name'] 
+                || $customer_data['email'] != $db_data['email'] 
+                || $customer_data['phone_number'] != $db_data['phone_number'] 
+                || $customer_data['address'] != $db_data['address'] 
+                || $customer_data['city'] != $db_data['city'] 
+                || $customer_data['zip_code'] != $db_data['zip_code'] 
+                || $customer_data['id_roles'] != $db_data['id_roles']) {
+            $are_the_same = FALSE;
+        }
+        $this->CI->unit->run($are_the_same, TRUE, 'Test add() customer (insert operation) has successfully been added to the datbase.');
+        
+        // Delete inserted record.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
     }
     
+    private function test_add_update() {
+        // Insert new customer record (will be updated later).
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Update customer record.
+        $new_phone_number = 'THE PHONE NUMBER IS UPDATED';
+        $customer_data['phone_number'] = $new_phone_number;
+        $update_result = $this->CI->Customers_Model->add($customer_data);
+        $this->CI->unit->run($update_result, 'is_int', 'Test add() customer (update operation) has returned the row id.');
+        
+        // Check if record was successfully updated.
+        $db_phone_number = $this->CI->db->get_where('ea_users', array('id' => $customer_data['id']))->row()->phone_number;
+        $this->CI->unit->run($customer_data['phone_number'], $db_phone_number, 'Test add() customer (update operation) has successfully updated the phone number field.');
+        
+        // Delete inserted record.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+    }
     
+    private function test_add_invalid_email() {
+        // Prepare customer's data (email address is invalid).
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'THIS IS INVALID',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->add($customer_data);
+        } catch(ValidationException $valExc) {
+            $has_thrown_exception = TRUE;
+        }
+        
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test add() customer with invalid email address');
+    }
     
+    private function test_add_missing_no_last_name() {
+        // Prepare customer's data (last name field is missing).
+        $customer_data = array(
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->add($customer_data);
+        } catch(ValidationException $valExc) {
+            $has_thrown_exception = TRUE;
+        }
+        
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test add() customer with no last name value provided.');
+    }
+    
+    // TEST CUSTOMER EXISTS() METHOD
+    private function test_exists() {
+        // Insert new customer record (will be updated later).
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Test that exists returns true.
+        $exists_result = $this->CI->Customers_Model->exists($customer_data);
+        $this->CI->unit->run($exists_result, TRUE, 'Tests exists() with customer that exists.');
+        
+        // Delete inserted record.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+    }
+    
+    private function test_exists_record_does_not_exist() {
+        // Prepare customer's data with email that does not exist.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'THIS DOES NOT EXIST',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        // Test that exists return false on email that doesn't exist.
+        $exists_result = $this->CI->Customers_Model->exists($customer_data);
+        $this->CI->unit->run($exists_result, FALSE, 'Test exists() method with customer data that does not exist in the database.');
+    }
+    
+    private function test_exists_no_email_provided() {
+        // Prepare customer's data with no email value.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        // Test that exists return false on email that doesn't exist.
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->exists($customer_data);
+        } catch (InvalidArgumentException $ia_exc) {
+            $has_thrown_exception = TRUE;
+        }
+
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test exists() method with email argument missing.');
+    }
+    
+    // TEST DELETE() CUSTOMER METHOD
+    private function test_delete() {
+        // Insert new customer record.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Delete new customer record.
+        $delete_result = $this->CI->Customers_Model->delete($customer_data['id']);
+        $this->CI->unit->run($delete_result, TRUE, 'Test delete() method returned TRUE.');
+        
+        // Check that the record is actually deleted (if not delete).
+        $num_rows = $this->CI->db->get_where('ea_users', array('id' => $customer_data['id']))->num_rows();
+        $this->CI->unit->run($num_rows, 0, 'Test delete() method has actually deleted the record from the db.');
+        
+        if ($num_rows > 0) {
+            $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+        }
+    }
+    
+    private function test_delete_record_that_does_not_exist() {
+        $random_record_id = 879653245;
+        
+        $delete_result = $this->CI->Customers_Model->delete($random_record_id);
+        $this->CI->unit->run($delete_result, FALSE, 'Test delete() method with customer id that does not exist.');
+    }
+    
+    private function test_delete_record_with_invalid_argument() {
+        $invalid_argument = 'THIS IS INVALID'; 
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->delete($invalid_argument);
+        } catch (InvalidArgumentException $ia_exc) {
+            $has_thrown_exception = TRUE;
+        }
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test delete() method with invalid argument (not integer).');
+    }
+    
+    // TEST VALIDATE CUSTOMER DATA METHOD
+    private function test_validate_data() {
+        // Prepare customer's data.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        // Validate customers data.
+        $validation_result = $this->CI->Customers_Model->validate_data($customer_data);
+        $this->CI->unit->run($validation_result, TRUE, 'Test validate_data() method.');
+    }
+    
+    private function test_validate_data_no_last_name_provided() {
+        // Prepare customer's data (no last_name value provided).
+        $customer_data = array(
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        // Validate customers data.
+        $validation_result = $this->CI->Customers_Model->validate_data($customer_data);
+        $this->CI->unit->run($validation_result, FALSE, 'Test validate_data() method without a last_name value.');
+    }
+    
+    private function test_validate_data_invalid_email_address() {
+        // Prepare customer's data (invalid email address).
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'THIS IS INVALID',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        
+        // Validate customers data.
+        $validation_result = $this->CI->Customers_Model->validate_data($customer_data);
+        $this->CI->unit->run($validation_result, FALSE, 'Test validate_data() method with invalid email address.');
+    }
+    
+    // TEST FIND RECORD ID METHOD
+    private function test_find_record_id() {
+        // Insert new customer to database.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $inserted_id = intval($this->CI->db->insert_id());
+        
+        // Try to find the db id of the new customer record.
+        $method_id = $this->CI->Customers_Model->find_record_id($customer_data);
+        $this->CI->unit->run($inserted_id, $method_id, 'Test find_record_id() method.');
+        
+        // Delete inserted customer record.
+        $this->CI->db->delete('ea_users', array('id' => $inserted_id));
+    }
+    
+    private function test_find_record_id_without_email_address() {
+        // Prepare customer's data without an email address.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->find_record_id($customer_data);
+        } catch (InvalidArgumentException $ia_exc) {
+            $has_thrown_exception = TRUE;
+        }
+
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test find_record_id() without providing an email address.');
+    }
+    
+    private function test_find_record_id_record_does_not_exist() {
+        // Prepare customer's data with an email address that does not exist in db.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'THIS EMAIL DOES NOT EXIST IN DB',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->find_record_id($customer_data);
+        } catch (DatabaseException $db_exc) {
+            $has_thrown_exception = TRUE;
+        }
+
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test find_record_id() with email address that does not exist in db.');
+    }
+    
+    // TEST GET BATCH METHOD    ---------------------------------------------------
+    private function test_get_batch() {
+        // Get all the customer rows without using the model.
+        $db_data = $this->CI->db->get_where('ea_users', array('id_roles' => $this->customer_role_id))->result_array();
+        // Get all the customer rows by using the model.
+        $model_data = $this->CI->Customers_Model->get_batch();
+        // Check that the two arrays are the same.
+        $this->CI->unit->run($db_data, $model_data, 'Test get_batch() method.');
+    }
+    
+    private function test_get_batch_with_where_clause() {
+        // Insert new customer record.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Get data without using the model.
+        $no_model_data = $this->CI->db->get_where('ea_users', array('id' => $customer_data['id']))->result_array();
+        
+        // Get data by using the model. 
+        $model_data = $this->CI->Customers_Model->get_batch(array('id' => $customer_data['id']));
+        
+        // Check that the data arrays are the same.
+        $this->CI->unit->run($no_model_data, $model_data, 'Test get_batch() with where clause.');
+        
+        // Delete inserted record from database.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+    }
+
+    private function unabled_test_get_batch_with_invalid_where_clause() {
+        // CodeIgniter auto raises an exception if the where section is invalid.
+    }
+
+    // TEST GET ROW METHOD
+    private function test_get_row() {
+        // Insert a new customer record. 
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Get the new customer record from db.
+        $no_model_data = $this->CI->db->get_where('ea_users', array('id' => $customer_data['id']))->row_array();
+        $model_data = $this->CI->Customers_Model->get_row($customer_data['id']);
+        
+        // Check that the row is the correct one.
+        $this->CI->unit->run($no_model_data, $model_data, 'Test get_row() method');
+        
+        // Delete inserted customer record.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+    }
+    
+    private function test_get_row_that_does_not_exist() {
+        $random_record_id = 486868412;
+        $row_data = $this->CI->Customers_Model->get_row($random_record_id);
+        $this->CI->unit->run($row_data, NULL, 'Test get_row() with record id that does ' 
+                . 'not exist in the database.');
+    }
+    
+    private function test_get_row_with_invalid_argument() {
+        $invalid_id = 'THIS IS NOT AN INTEGER';
+        
+        $has_thrown_exception = FALSE;
+        try {
+            $this->CI->Customers_Model->get_row($invalid_id);        
+        } catch (InvalidArgumentException $ia_exc) {
+            $has_thrown_exception = TRUE;
+        }
+        
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_row() with wrong argument.');
+    }
+    
+    // TEST GET VALUE METHOD
+    private function test_get_value() {
+        // Insert new customer record.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Get a specific value from the database.
+        $model_value = $this->CI->Customers_Model->get_value('email', $customer_data['id']);
+        
+        // Check if the value was correctly fetched from the database.
+        $this->CI->unit->run($model_value, $customer_data['email'], 'Test get_value() method.');
+        
+        // Delete inserted appointment record.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+    }
+    
+    private function test_get_value_record_does_not_exist() {
+        $random_record_id = 843521368768;
+        
+        $has_thrown_exception = FALSE;
+        
+        try {
+            $this->CI->Customers_Model->get_value('email', $random_record_id);
+        } catch (InvalidArgumentException $db_exc) {
+            $has_thrown_exception = TRUE;
+        }
+        
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that does not exist.');
+    }
+    
+    private function test_get_value_field_does_not_exist() {
+        // Insert new customer record.
+        $customer_data = array(
+                            'last_name' => 'Doe',
+                            'first_name' => 'John',
+                            'email' => 'alextselegidis@gmail.com',
+                            'phone_number' => '0123456789',
+                            'address' => 'Abbey Road 18',
+                            'city' => 'London',
+                            'zip_code' => '12345',
+                            'id_roles' => $this->customer_role_id
+                        );
+        $this->CI->db->insert('ea_users', $customer_data);
+        $customer_data['id'] = intval($this->CI->db->insert_id());
+        
+        // Try to get record value with wrong field name.
+        $wrong_field_name = 'THIS IS WRONG';
+        $has_thrown_exception = FALSE;
+        
+        try {
+            $this->CI->Customers_Model->get_value($wrong_field_name, $customer_data['id']);
+        } catch (InvalidArgumentException $db_exc) {
+            $has_thrown_exception = TRUE;
+        }
+        
+        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that does not exist.');
+        
+        // Delete inserted customer record.
+        $this->CI->db->delete('ea_users', array('id' => $customer_data['id']));
+    }
 }
 
 /* End of file Unit_tests_customers_model.php */

src/application/models/appointments_model.php

@@ -41,23 +41,36 @@ class Appointments_Model extends CI_Model {
     /**
      * Check if a particular appointment record already exists.
      * 
-     * This method checks wether the given appointment already exists in 
+     * This method checks wether the given appointment already exists  
-     * the database. This method does not search with the id, but with a
+     * in the database. It doesn't search with the id, but by using the 
-     * combination of the appointments field values.
+     * following fields: "start_datetime", "end_datetime", "id_users_provider",
+     * "id_users_customer", "id_services".
      * 
-     * @uses find_record_id() 
+     * @expectedException InvalidArgumentException When the $appointment_data
+     * array does not contain the necessary field.
      * 
      * @param array $appointment_data Associative array with the appointment's
      * data. Each key has the same name with the database fields.
      * @return bool Returns wether the record exists or not.
      */
     public function exists($appointment_data) {   
-        try {
+        if (!isset($appointment_data['start_datetime'])
-            $this->find_record_id($appointment_data);
+                || !isset($appointment_data['end_datetime'])
-            return TRUE;
+                || !isset($appointment_data['id_users_provider'])
-        } catch(DatabaseException $dbExc) {
+                || !isset($appointment_data['id_users_customer'])
-            return FALSE;
+                || !isset($appointment_data['id_services'])) {
+            throw new InvalidArgumentException('Not all appointment field values are provided : ' . print_r($appointment_data, TRUE));
         }
+        
+        $num_rows = $this->db->get_where('ea_appointments', array(
+                            'start_datetime' => $appointment_data['start_datetime'],
+                            'end_datetime' => $appointment_data['end_datetime'],
+                            'id_users_provider' => $appointment_data['id_users_provider'],
+                            'id_users_customer' => $appointment_data['id_users_customer'],
+                            'id_services' => $appointment_data['id_services'],
+                        ))->num_rows();
+        
+        return ($num_rows > 0) ? TRUE : FALSE;
     }
     
     /**
@@ -192,12 +205,15 @@ class Appointments_Model extends CI_Model {
     /**
      * Delete an existing appointment record from the database.
      * 
+     * @expectedException InvalidArgumentException Raises when the $appointment_id
+     * is not an integer.
+     * 
      * @param int $appointment_id The record id to be deleted.
      * @return bool Returns the delete operation result.
      */
     public function delete($appointment_id) {
         if (!is_int($appointment_id)) { 
-            return FALSE; // Invalid parameter given.
+            throw new InvalidArgumentException('Invalid argument type $appointment_id : ' . $appointment_id);
         }
         
         $num_rows = $this->db->get_where('ea_appointments', array('id' => $appointment_id))->num_rows();
@@ -220,7 +236,7 @@ class Appointments_Model extends CI_Model {
      */
     public function get_row($appointment_id) {
         if (!is_int($appointment_id)) {
-            throw new DatabaseException('Invalid argument given. Expected integer for the $appointment_id.');
+            throw new InvalidArgumentException('Invalid argument given. Expected integer for the $appointment_id : ' . $appointment_id);
         }
         return $this->db->get_where('ea_appointments', array('id' => $appointment_id))->row_array();
     }
@@ -235,21 +251,21 @@ class Appointments_Model extends CI_Model {
      */
     public function get_value($field_name, $appointment_id) {
         if (!is_int($appointment_id)) {
-            throw new DatabaseException('Invalid argument given, expected integer for the $appointment_id.');
+            throw new InvalidArgumentException('Invalid argument given, expected integer for the $appointment_id : ' . $appointment_id);
         }
         
         if (!is_string($field_name)) {
-            throw new DatabaseException('Invalid argument given, expected string for the $field_name.');
+            throw new InvalidArgumentException('Invalid argument given, expected string for the $field_name : ' . $field_name);
         }
         
         if ($this->db->get_where('ea_appointments', array('id' => $appointment_id))->num_rows() == 0) {
-            throw new DatabaseException('The record with the provided id does not exist in the datbase.');
+            throw new InvalidArgumentException('The record with the provided id does not exist in the database : ' . $appointment_id);
         }
         
         $row_data = $this->db->get_where('ea_appointments', array('id' => $appointment_id))->row_array();
         
         if (!isset($row_data[$field_name])) {
-            throw new DatabaseException('The given field name does not exist in the database.');
+            throw new InvalidArgumentException('The given field name does not exist in the database : ' . $field_name);
         }
         
         return $row_data[$field_name];

src/application/models/customers_model.php

@@ -15,47 +15,57 @@ class Customers_Model extends CI_Model {
      * doesn't exists it is going to be inserted, otherwise the 
      * record is going to be updated.
      * 
+     * @expectedException ValidationException When customer's data are invalid.
+     * @expectedException DatabaseException When update or insert method fails.
+     * 
      * @param array $customer_data Associative array with the customer's 
      * data. Each key has the same name with the database fields.
      * @return int Returns the customer id.
      */
     public function add($customer_data) {
-        try {
+        // Validate the appointment data before doing anything.
-            $customer_id = $this->exists($customer_data['email']);
+        if (!$this->validate_data($customer_data)) {
-            
+            throw new ValidationException('Customer data are not valid.');
-            if (!$customer_id) {
-                $customer_id = $this->insert($customer_data);
-            } else {
-                $customer_data['id'] = $customer_id;
-                $this->update($customer_data);
-            }
-            
-            return $customer_id;
-            
-        } catch(Exception $exc) {
-            // Send some info for the exception back to the browser.
-            echo $exc->getTraceAsString();
         }
+
+        if (!$this->exists($customer_data)) {
+            $customer_data['id'] = $this->insert($customer_data);
+        } else {
+            $customer_data['id'] = $this->update($customer_data);
+        }
+
+        return $customer_data['id'];
     }
     
     /**
      * Check if a particular customer record already exists.
      * 
      * This method checks wether the given customer already exists in 
-     * the database. This method does not search with the id, but witha
+     * the database. It doesn't search with the id, but with the following
-     * the email value of the customer. 
+     * fields: "email"
      * 
-     * @param string $customer_email The email field value is used to 
+     * @expectedException InvalidArgumentException When the $customer_data
-     * distinguish customer records.
+     * array does not contain all the necessary fields.
-     * @return int|bool Returns the record id or FALSE if it doesn't exist.
+     * 
+     * @param array $customer_data Associative array with the customer's 
+     * data. Each key has the same name with the database fields.
+     * @return bool Returns wether the record exists or not.
      */
-    public function exists($customer_email) {
+    public function exists($customer_data) {
-        $this->db->where(array(
+        if (!isset($customer_data['email'])) {
-            'email'     => $customer_email,
+            throw new InvalidArgumentException('Customer\'s email is not provided.');
-            'id_roles'  => $this->get_customers_role_id()
+        }
-        ));
+        
-        $result = $this->db->get('ea_users');
+        // This method shouldn't depend on another method of this class.
-        return ($result->num_rows() > 0) ? $result->row()->id : FALSE;
+        $num_rows = $this->db
+                            ->select('*')
+                            ->from('ea_users')
+                            ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
+                            ->where('ea_users.email', $customer_data['email'])
+                            ->where('ea_roles.slug', DB_SLUG_CUSTOMER)
+                            ->get()->num_rows();
+        
+        return ($num_rows > 0) ? TRUE : FALSE;
     }
     
     /**
@@ -68,22 +78,19 @@ class Customers_Model extends CI_Model {
     private function insert($customer_data) {
         // Before inserting the customer we need to get the customer's role id
         // from the database and assign it to the new record as a foreign key.
-        $this->db
+        $customer_role_id = $this->db
-            ->select('id')
+                                    ->select('id')
-            ->from('ea_roles')
+                                    ->from('ea_roles')
-            ->where('slug', DB_SLUG_CUSTOMER);
+                                    ->where('slug', DB_SLUG_CUSTOMER)
+                                    ->get()->row()->id;
         
-        $customer_role_id = $this->db->get()->row()->id;
+        $customer_data['id_roles'] = $customer_role_id;
-        
-        if ($customer_role_id !== NULL) {
-            $customer_data['id_roles'] = $customer_role_id;
-        }
         
         if (!$this->db->insert('ea_users', $customer_data)) {
-            throw new Exception('Could not insert customer to the database.');
+            throw new DatabaseException('Could not insert customer to the database.');
         }
         
-        return $this->db->insert_id();
+        return intval($this->db->insert_id());
     }
     
     /**
@@ -97,20 +104,104 @@ class Customers_Model extends CI_Model {
      * @return int Returns the updated record id.
      */
     private function update($customer_data) {
+        if (!isset($customer_data['id'])) {
+            $customer_data['id'] = $this->find_record_id($customer_data);
+        }
+        
         $this->db->where('id', $customer_data['id']);
         if (!$this->db->update('ea_users', $customer_data)) {
-            throw new Exception('Could not update customer to the database.');
+            throw new DatabaseException('Could not update customer to the database.');
+        }
+        
+        return intval($customer_data['id']);
+    }
+    
+    /**
+     * Find the database id of a customer record. 
+     * 
+     * The customer data should include the following fields in order to 
+     * get the unique id from the database: "email"
+     * 
+     * <strong>IMPORTANT!</strong> The record must already exists in the 
+     * database, otherwise an exception is raised.
+     * 
+     * @expectedException DatabaseException When the record is not found.
+     * 
+     * @param array $customer_data Array with the customer data. The 
+     * keys of the array should have the same names as the db fields.
+     * @return int Returns the id.
+     */
+    public function find_record_id($customer_data) {
+        if (!isset($customer_data['email'])) {
+            throw new InvalidArgumentException('Customer\'s email was not provided : ' 
+                    . print_r($customer_data, TRUE));
+        }
+        
+        // Get customer's role id
+        $result = $this->db
+                            ->select('ea_users.id')
+                            ->from('ea_users')
+                            ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
+                            ->where('ea_users.email', $customer_data['email'])
+                            ->where('ea_roles.slug', DB_SLUG_CUSTOMER)
+                            ->get();
+        
+        if ($result->num_rows() == 0) {
+            throw new DatabaseException('Could not find appointment record id.');
+        }
+        
+        return $result->row()->id;
+    }
+    
+    /**
+     * Validate customer data before the insert or 
+     * update operation is executed.
+     * 
+     * @param array $customer_data Contains the customer data.
+     * @return bool Returns the validation result.
+     */
+    public function validate_data($customer_data) {
+        $this->load->helper('data_validation');
+        
+        try {
+            // Validate required fields
+            if (!isset($customer_data['last_name'])
+                    || !isset($customer_data['email'])
+                    || !isset($customer_data['phone_number'])) { 
+                throw new Exception('Not all required fields are provided : ' 
+                        . print_r($customer_data, TRUE));
+            }
+            
+            // Validate email address
+            if (!filter_var($customer_data['email'], FILTER_VALIDATE_EMAIL)) {
+                throw new Exception('Invalid email address provided : ' . $customer_data['email']);
+            }
+            
+            return TRUE;
+        } catch (Exception $exc) {
+            return FALSE;
         }
-        return $this->db->get_where('ea_users', array('email' => $customer_data['email']))->row()->id;
     }
     
     /**
      * Delete an existing customer record from the database.
      * 
+     * @expectedException InvalidArgumentException Raises when 
+     * the $customer_id is not an integer.
+     * 
      * @param int $customer_id The record id to be deleted.
      * @return bool Returns the delete operation result.
      */
     public function delete($customer_id) {
+        if (!is_int($customer_id)) {
+            throw new InvalidArgumentException('Invalid argument type $customer_id : ' . $customer_id);
+        }
+        
+        $num_rows = $this->db->get_where('ea_users', array('id' => $customer_id))->num_rows();
+        if ($num_rows == 0) {
+            return FALSE;
+        }
+        
         $this->db->where('id', $customer_id);
         return $this->db->delete('ea_users');
     }
@@ -124,6 +215,9 @@ class Customers_Model extends CI_Model {
      * field names.
      */
     public function get_row($customer_id) {
+        if (!is_int($customer_id)) {
+            throw new InvalidArgumentException('Invalid argument provided as $customer_id : ' . $customer_id);
+        }
         return $this->db->get_where('ea_users', array('id' => $customer_id))->row_array();
     }
     
@@ -136,6 +230,23 @@ class Customers_Model extends CI_Model {
      * @return string Returns the records value from the database.
      */
     public function get_value($field_name, $customer_id) {
+        if (!is_int($customer_id)) {
+            throw new InvalidArgumentException('Invalid argument provided as $customer_id : ' . $customer_id);
+        }
+        
+        if (!is_string($field_name)) {
+            throw new InvalidArgumentException('$field_name argument is not a string : ' . $field_name);
+        }
+        
+        if ($this->db->get_where('ea_users', array('id' => $customer_id))->num_rows() == 0) {
+            throw new InvalidArgumentException('The record with the $customer_id argument does not exist in the database : ' . $customer_id);
+        }
+        
+        $row_data = $this->db->get_where('ea_users', array('id' => $customer_id))->row_array();
+        if (!isset($row_data[$field_name])) {
+            throw new InvalidArgumentException('The given $field_name argument does not exist in the database : ' . $field_name);
+        }
+        
         return $this->db->get_where('ea_users', array('id' => $customer_id))->row_array()[$field_name];
     }
     
@@ -148,10 +259,10 @@ class Customers_Model extends CI_Model {
      * the query to be executed. DO NOT INCLUDE 'WHERE' KEYWORD.
      * @return array Returns the rows from the database.
      */
-    public function get_batch($where_clause = NULL) {
+    public function get_batch($where_clause = '') {
         $customers_role_id = $this->get_customers_role_id();
         
-        if ($where_clause != NULL) {
+        if ($where_clause != '') {
             $this->db->where($where_clause);
         }
         

src/application/models/providers_model.php

@@ -17,6 +17,9 @@ class Providers_Model extends CI_Model {
      * field names.
      */
     public function get_row($provider_id) {
+        if (!is_int($provider_id)) {
+            throw new InvalidArgumentException('$provider_id argument is not an integer : ' . $provider_id);
+        }
         return $this->db->get_where('ea_users', array('id' => $provider_id))->row_array();
     }
     
@@ -29,6 +32,23 @@ class Providers_Model extends CI_Model {
      * @return string Returns the records value from the database.
      */
     public function get_value($field_name, $provider_id) {
+        if (!is_int($provider_id)) {
+            throw new InvalidArgumentException('Invalid argument provided as $customer_id : ' . $provider_id);
+        }
+        
+        if (!is_string($field_name)) {
+            throw new InvalidArgumentException('$field_name argument is not a string : ' . $field_name);
+        }
+        
+        if ($this->db->get_where('ea_users', array('id' => $provider_id))->num_rows() == 0) {
+            throw new InvalidArgumentException('The record with the $provider_id argument does not exist in the database : ' . $provider_id);
+        }
+        
+        $row_data = $this->db->get_where('ea_users', array('id' => $provider_id))->row_array();
+        if (!isset($row_data[$field_name])) {
+            throw new InvalidArgumentException('The given $field_name argument does not exist in the database : ' . $field_name);
+        }
+        
         return $this->db->get_where('ea_users', array('id' => $provider_id))->row_array()[$field_name];
     }
     

src/application/models/services_model.php

@@ -16,6 +16,9 @@ class Services_Model extends CI_Model {
      * field names.
      */
     public function get_row($service_id) {
+        if (!is_int($service_id)) {
+            throw new InvalidArgumentException('$service_id argument is not an integer : ' . $service_id);
+        }
         return $this->db->get_where('ea_services', array('id' => $service_id))->row_array();
     }
     
@@ -28,6 +31,23 @@ class Services_Model extends CI_Model {
      * @return string Returns the records value from the database.
      */
     public function get_value($field_name, $service_id) {
+        if (!is_int($service_id)) {
+            throw new InvalidArgumentException('Invalid argument provided as $service_id : ' . $service_id);
+        }
+        
+        if (!is_string($field_name)) {
+            throw new InvalidArgumentException('$field_name argument is not a string : ' . $field_name);
+        }
+        
+        if ($this->db->get_where('ea_services', array('id' => $service_id))->num_rows() == 0) {
+            throw new InvalidArgumentException('The record with the $service_id argument does not exist in the database : ' . $service_id);
+        }
+        
+        $row_data = $this->db->get_where('ea_services', array('id' => $service_id))->row_array();
+        if (!isset($row_data[$field_name])) {
+            throw new InvalidArgumentException('The given $field_name argument does not exist in the database : ' . $field_name);
+        }
+        
         return $this->db->get_where('ea_services', array('id' => $service_id))->row_array()[$field_name];
     }
     

src/application/models/settings_model.php

@@ -13,11 +13,22 @@ class Settings_Model extends CI_Model {
      * This method returns a system setting from the 
      * database.
      * 
+     * @expectedException InvalidArgumentException Raises whenever the 
+     * $name argument is not a string, or does not exist in the database.
+     * 
      * @param string $name The database setting name.
      * @return string Returns the database value for 
      * the selected setting.
      */
     function get_setting($name) {
+        if (!is_string($name)) { // Check argument type.
+            throw new InvalidArgumentException('$name argument is not a string : ' . $name);
+        }
+        
+        if ($this->db->get_where('ea_settings', array('name' => $name))->num_rows() == 0) { // Check if setting exists in db.
+            throw new InvalidArgumentException('$name setting does not exist in database : ' . $name);
+        }
+        
         $query = $this->db->get_where('ea_settings', array('name' => $name));
         $setting = ($query->num_rows() > 0) ? $query->row() : '';
         return $setting->value;
@@ -28,31 +39,63 @@ class Settings_Model extends CI_Model {
      * on the database. If the setting doesn't exist, it
      * is going to be created, otherwise updated.
      * 
+     * @expectedException DatabaseException Raises whenever an error 
+     * occures during the insert or the update operation.
+     * @expectedException InvalidArgumentException Raises whenever 
+     * the $name argument is not a string.
+     * 
      * @param string $name The setting name.
      * @param type $value The setting value.
-     * @return bool Returns the operation success - failure 
+     * @return int Returns the setting database id.
-     * result.
      */
     function set_setting($name, $value) {
+        if (!is_string($name)) {
+            throw new InvalidArgumentException('$name argument is not a string : ' . $name);
+        }            
+        
         $query = $this->db->get_where('ea_settings', array('name' => $name));
         if ($query->num_rows() > 0) {
             // Update setting
-            $update_data = array('value' => $value);
+            if (!$this->db->update('ea_settings', array('value' => $value), array('name' => $name))) {
-            $this->db->where('name', $name);
+                throw new DatabaseException('Could not update database setting.');
-            $result = $this->db->update('ea_settings', $update_data);
+            }
+            $setting_id = intval($this->db->get_where('ea_settings', array('name' => $name))->row()->id);
         } else {
             // Insert setting
             $insert_data = array(
                 'name'  => $name,
                 'value' => $value
             );
-            $result = $this->db->insert('ea_settings', $insert_data);
+            if (!$this->db->insert('ea_settings', $insert_data)) {
+                throw new DatabaseException('Could not insert database setting');
+            }
+            $setting_id = intval($this->db->insert_id());
         }
         
-        return $result;
+        return $setting_id;
+    }
+    
+    /**
+     * Remove a setting from the database.
+     * 
+     * @expectedException InvalidArgumentException Raises whenever 
+     * the $name parameter is not a string.
+     * 
+     * @param string $name The setting name to be removed.
+     * @return bool Returns the delete operation result.
+     */
+    function remove_setting($name) {
+        if (!is_string($name)) {
+            throw new InvalidArgumentException('$name is not a string : ' . $name);
+        }
+        
+        if ($this->db->get_where('ea_settings', array('name' => $name))->num_rows() == 0) {
+            return FALSE; // There is no such setting.
+        }
+        
+        return $this->db->delete('ea_settings', array('name' => $name));
     }
 }
 
-
 /* End of file settings_model.php */
 /* Location: ./application/models/settings_model.php */