diff --git a/application/models/Admins_model.php b/application/models/Admins_model.php
index ee7883d9..69733296 100644
--- a/application/models/Admins_model.php
+++ b/application/models/Admins_model.php
@@ -41,9 +41,9 @@ class Admins_model extends EA_Model {
         'city' => 'city',
         'state' => 'state',
         'zip' => 'zip_code',
-        'notes' => 'notes',
         'timezone' => 'timezone',
         'language' => 'language',
+        'notes' => 'notes',
         'roleId' => 'id_roles',
     ];
 
@@ -499,6 +499,7 @@ class Admins_model extends EA_Model {
             ->select()
             ->from('users')
             ->where('id_roles', $role_id)
+            ->group_start()
             ->like('first_name', $keyword)
             ->or_like('last_name', $keyword)
             ->or_like('email', $keyword)
@@ -509,6 +510,7 @@ class Admins_model extends EA_Model {
             ->or_like('state', $keyword)
             ->or_like('zip_code', $keyword)
             ->or_like('notes', $keyword)
+            ->group_end()
             ->limit($limit)
             ->offset($offset)
             ->order_by($order_by)
diff --git a/application/models/Appointments_model.php b/application/models/Appointments_model.php
index 114ac8f6..a64743e0 100644
--- a/application/models/Appointments_model.php
+++ b/application/models/Appointments_model.php
@@ -28,6 +28,22 @@ class Appointments_model extends EA_Model {
         'id_services' => 'integer',
     ];
 
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'book' => 'book_datetime',
+        'start' => 'start_datetime',
+        'end' => 'end_datetime',
+        'location' => 'location',
+        'notes' => 'notes',
+        'hash' => 'hash',
+        'providerId' => 'id_users_provider',
+        'googleCalendarId' => 'id_google_calendar',
+    ];
+
+
     /**
      * Save (insert or update) an appointment.
      *
@@ -179,8 +195,6 @@ class Appointments_model extends EA_Model {
      */
     protected function update(array $appointment): int
     {
-        $this->db->where('id', $appointment['id']);
-
         if ( ! $this->db->update('appointments', $appointment, ['id' => $appointment['id']]))
         {
             throw new RuntimeException('Could not update appointment record.');
@@ -292,7 +306,7 @@ class Appointments_model extends EA_Model {
             $this->db->order_by($order_by);
         }
 
-        $appointments = $this->db->get('appointments', $limit, $offset)->result_array();
+        $appointments = $this->db->get_where('appointments', ['is_unavailable' => FALSE], $limit, $offset)->result_array();
 
         foreach ($appointments as &$appointment)
         {
@@ -302,56 +316,6 @@ class Appointments_model extends EA_Model {
         return $appointments;
     }
 
-    /**
-     * Save (insert or update) an unavailable.
-     *
-     * @param array $unavailable Associative array with the unavailable data.
-     *
-     * @return int Returns the unavailable ID.
-     *
-     * @throws InvalidArgumentException
-     */
-    public function save_unavailable(array $unavailable): int
-    {
-        // Make sure the start date time is before the end date time.
-        $start = strtotime($unavailable['start_datetime']);
-
-        $end = strtotime($unavailable['end_datetime']);
-
-        if ($start > $end)
-        {
-            throw new InvalidArgumentException('Unavailable period start date time must be before the end date time.');
-        }
-
-        // Make sure the provider ID really exists in the database.
-        $role = $this->db->get_where('roles', ['slug' => DB_SLUG_PROVIDER])->row_array();
-
-        $count = $this->db->get_where('users', [
-            'id' => $unavailable['id_users_provider'],
-            'id_roles' => $role['id'],
-        ])->num_rows();
-
-        if ( ! $count)
-        {
-            throw new InvalidArgumentException('Provider id was not found in database.');
-        }
-
-        if (empty($unavailable['id']))
-        {
-            $unavailable['book_datetime'] = date('Y-m-d H:i:s');
-
-            $unavailable['is_unavailable'] = TRUE;
-
-            $this->db->insert('appointments', $unavailable);
-
-            return $this->db->insert_id();
-        }
-        else
-        {
-            return $this->db->update('appointments', $unavailable, ['id' => $unavailable['id']]);
-        }
-    }
-
     /**
      * Remove all the Google Calendar event IDs from appointment records.
      *
@@ -472,6 +436,8 @@ class Appointments_model extends EA_Model {
             ->join('services', 'services.id = appointments.id_services', 'left')
             ->join('users AS providers', 'providers.id = appointments.id_users_provider', 'inner')
             ->join('users AS customers', 'customers.id = appointment.id_users_customer', 'left')
+            ->where('is_unavailable', FALSE)
+            ->group_start()
             ->like('appointments.start_datetime', $keyword)
             ->or_like('appointments.end_datetime', $keyword)
             ->or_like('appointments.location', $keyword)
@@ -487,6 +453,7 @@ class Appointments_model extends EA_Model {
             ->or_like('customers.last_name', $keyword)
             ->or_like('customers.email', $keyword)
             ->or_like('customers.phone_number', $keyword)
+            ->group_end()
             ->limit($limit)
             ->offset($offset)
             ->order_by($order_by)
diff --git a/application/models/Customers_model.php b/application/models/Customers_model.php
index b31508e3..f330bb80 100644
--- a/application/models/Customers_model.php
+++ b/application/models/Customers_model.php
@@ -27,6 +27,24 @@ class Customers_model extends EA_Model {
         'id_roles' => 'integer',
     ];
 
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'firstName' => 'first_name',
+        'lastName' => 'last_name',
+        'email' => 'email',
+        'phone' => 'phone_number',
+        'address' => 'address',
+        'city' => 'city',
+        'state' => 'state',
+        'zip' => 'zip_code',
+        'timezone' => 'timezone',
+        'language' => 'language',
+        'notes' => 'notes',
+    ];
+
     /**
      * Save (insert or update) a customer.
      *
@@ -380,6 +398,7 @@ class Customers_model extends EA_Model {
             ->select()
             ->from('users')
             ->where('id_roles', $role_id)
+            ->group_start()
             ->like('first_name', $keyword)
             ->or_like('last_name', $keyword)
             ->or_like('email', $keyword)
@@ -390,6 +409,7 @@ class Customers_model extends EA_Model {
             ->or_like('state', $keyword)
             ->or_like('zip_code', $keyword)
             ->or_like('notes', $keyword)
+            ->group_end()
             ->limit($limit)
             ->offset($offset)
             ->order_by($order_by)
diff --git a/application/models/Providers_model.php b/application/models/Providers_model.php
index e72b9315..a507afe1 100755
--- a/application/models/Providers_model.php
+++ b/application/models/Providers_model.php
@@ -27,6 +27,25 @@ class Providers_model extends EA_Model {
         'id_roles' => 'integer',
     ];
 
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'firstName' => 'first_name',
+        'lastName' => 'last_name',
+        'email' => 'email',
+        'mobile' => 'mobile_number',
+        'phone' => 'phone_number',
+        'address' => 'address',
+        'city' => 'city',
+        'state' => 'state',
+        'zip' => 'zip_code',
+        'timezone' => 'timezone',
+        'language' => 'language',
+        'notes' => 'notes',
+        'roleId' => 'id_roles',
+    ];
 
     /**
      * Save (insert or update) a provider.
@@ -89,11 +108,7 @@ class Providers_model extends EA_Model {
         }
 
         // Validate provider services.
-        if (empty($provider['services']) || ! is_array($provider['services']))
-        {
-            throw new InvalidArgumentException('The provided provider services are invalid: ' . print_r($provider, TRUE));
-        }
-        else
+        if ( ! empty($provider['services']))
         {
             // Make sure the provided service entries are numeric values.
             foreach ($provider['services'] as $service_id)
@@ -464,9 +479,9 @@ class Providers_model extends EA_Model {
      *
      * @param int $provider_id Provider ID.
      * @param string $name Setting name.
-     * @param string|null $value Setting value.
+     * @param mixed $value Setting value.
      */
-    public function set_setting(int $provider_id, string $name, string $value = NULL)
+    public function set_setting(int $provider_id, string $name, $value = NULL)
     {
         if ( ! $this->db->update('user_settings', [$name => $value], ['id_users' => $provider_id]))
         {
@@ -665,6 +680,7 @@ class Providers_model extends EA_Model {
             ->select()
             ->from('users')
             ->where('id_roles', $role_id)
+            ->group_start()
             ->like('first_name', $keyword)
             ->or_like('last_name', $keyword)
             ->or_like('email', $keyword)
@@ -675,6 +691,7 @@ class Providers_model extends EA_Model {
             ->or_like('state', $keyword)
             ->or_like('zip_code', $keyword)
             ->or_like('notes', $keyword)
+            ->group_end()
             ->limit($limit)
             ->offset($offset)
             ->order_by($order_by)
diff --git a/application/models/Secretaries_model.php b/application/models/Secretaries_model.php
index a07aa68e..ebd89bab 100644
--- a/application/models/Secretaries_model.php
+++ b/application/models/Secretaries_model.php
@@ -27,6 +27,26 @@ class Secretaries_model extends EA_Model {
         'id_roles' => 'integer',
     ];
 
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'firstName' => 'first_name',
+        'lastName' => 'last_name',
+        'email' => 'email',
+        'mobile' => 'mobile_number',
+        'phone' => 'phone_number',
+        'address' => 'address',
+        'city' => 'city',
+        'state' => 'state',
+        'zip' => 'zip_code',
+        'timezone' => 'timezone',
+        'language' => 'language',
+        'notes' => 'notes',
+        'roleId' => 'id_roles',
+    ];
+
     /**
      * Save (insert or update) a secretary.
      *
@@ -88,11 +108,7 @@ class Secretaries_model extends EA_Model {
         }
 
         // Validate secretary providers.
-        if (empty($secretary['providers']) || ! is_array($secretary['providers']))
-        {
-            throw new InvalidArgumentException('The provided secretary providers are invalid: ' . print_r($secretary, TRUE));
-        }
-        else
+        if ( ! empty($secretary['providers']))
         {
             // Make sure the provided provider entries are numeric values.
             foreach ($secretary['providers'] as $secretary_id)
@@ -529,6 +545,7 @@ class Secretaries_model extends EA_Model {
             ->select()
             ->from('users')
             ->where('id_roles', $role_id)
+            ->group_start()
             ->like('first_name', $keyword)
             ->or_like('last_name', $keyword)
             ->or_like('email', $keyword)
@@ -539,6 +556,7 @@ class Secretaries_model extends EA_Model {
             ->or_like('state', $keyword)
             ->or_like('zip_code', $keyword)
             ->or_like('notes', $keyword)
+            ->group_end()
             ->limit($limit)
             ->offset($offset)
             ->order_by($order_by)
diff --git a/application/models/Service_categories_model.php b/application/models/Service_categories_model.php
index 2d4139ad..274eb183 100644
--- a/application/models/Service_categories_model.php
+++ b/application/models/Service_categories_model.php
@@ -26,6 +26,15 @@ class Service_categories_model extends EA_Model {
         'id' => 'integer',
     ];
 
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'name' => 'name',
+        'description' => 'description',
+    ];
+
     /**
      * Save (insert or update) a service category.
      *
diff --git a/application/models/Services_model.php b/application/models/Services_model.php
index 59a4faea..a83a2a43 100644
--- a/application/models/Services_model.php
+++ b/application/models/Services_model.php
@@ -29,6 +29,22 @@ class Services_model extends EA_Model {
         'id_service_categories' => 'boolean',
     ];
 
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'name' => 'name',
+        'duration' => 'duration',
+        'price' => 'price',
+        'currency' => 'currency',
+        'description' => 'description',
+        'location' => 'location',
+        'availabilitiesType' => 'availabilities_type',
+        'attendantsNumber' => 'attendants_number',
+        'categoryId' => 'id_service_categories',
+    ];
+
     /**
      * Save (insert or update) a service.
      *
diff --git a/application/models/Settings_model.php b/application/models/Settings_model.php
index e24a47d1..ffe2dd14 100644
--- a/application/models/Settings_model.php
+++ b/application/models/Settings_model.php
@@ -26,6 +26,14 @@ class Settings_model extends EA_Model {
         'id' => 'integer',
     ];
 
+    /**
+     * @var array 
+     */
+    protected $api_resource = [
+        'name' => 'name',  
+        'value' => 'value',  
+    ];
+
     /**
      * Save (insert or update) a setting.
      *
diff --git a/application/models/Users_model.php b/application/models/Users_model.php
index 23ed1791..4e7b7125 100644
--- a/application/models/Users_model.php
+++ b/application/models/Users_model.php
@@ -26,6 +26,26 @@ class Users_model extends EA_Model {
         'id' => 'integer',
         'id_roles' => 'integer',
     ];
+
+    /**
+     * @var array
+     */
+    protected $api_resource = [
+        'id' => 'id',
+        'firstName' => 'first_name',
+        'lastName' => 'last_name',
+        'email' => 'email',
+        'mobile' => 'mobile_number',
+        'phone' => 'phone_number',
+        'address' => 'address',
+        'city' => 'city',
+        'state' => 'state',
+        'zip' => 'zip_code',
+        'timezone' => 'timezone',
+        'language' => 'language',
+        'notes' => 'notes',
+        'roleId' => 'id_roles',
+    ];
     
     /**
      * Save (insert or update) a user.