New method Find Column w.r.t. #1619

system/Database/Exceptions/DataException.php

@@ -50,4 +50,9 @@ public static function forTableNotFound(string $table)
 	{
 		return new static(lang('Database.tableNotFound', [$table]));
 	}
+
+	public static function forFindColumnHaveMultipleColumns()
+	{
+		return new static(lang('Database.forFindColumnHaveMultipleColumns'));
+	}
 }

system/Language/en/Database.php

@@ -15,15 +15,16 @@
  */
 
 return [
-   'invalidEvent'          => '{0} is not a valid Model Event callback.',
-   'invalidArgument'       => 'You must provide a valid {0}.',
-   'invalidAllowedFields'  => 'Allowed fields must be specified for model: {0}',
-   'emptyDataset'          => 'There is no data to {0}.',
-   'failGetFieldData'      => 'Failed to get field data from database.',
-   'failGetIndexData'      => 'Failed to get index data from database.',
-   'failGetForeignKeyData' => 'Failed to get foreign key data from database.',
-   'parseStringFail'       => 'Parsing key string failed.',
-   'featureUnavailable'    => 'This feature is not available for the database you are using.',
-   'tableNotFound'         => 'Table `{0}` was not found in the current database.',
-   'noPrimaryKey'          => '`{0}` model class does not specify a Primary Key.',
+	'invalidEvent'                     => '{0} is not a valid Model Event callback.',
+	'invalidArgument'                  => 'You must provide a valid {0}.',
+	'invalidAllowedFields'             => 'Allowed fields must be specified for model: {0}',
+	'emptyDataset'                     => 'There is no data to {0}.',
+	'failGetFieldData'                 => 'Failed to get field data from database.',
+	'failGetIndexData'                 => 'Failed to get index data from database.',
+	'failGetForeignKeyData'            => 'Failed to get foreign key data from database.',
+	'parseStringFail'                  => 'Parsing key string failed.',
+	'featureUnavailable'               => 'This feature is not available for the database you are using.',
+	'tableNotFound'                    => 'Table `{0}` was not found in the current database.',
+	'noPrimaryKey'                     => '`{0}` model class does not specify a Primary Key.',
+	'forFindColumnHaveMultipleColumns' => 'Only single column allowed in Column name.',
 ];

system/Model.php

@@ -349,6 +349,42 @@ public function find($id = null)
 
 	//--------------------------------------------------------------------
 
+	/**
+	 * Fetches the column of database from $this->table
+	 *
+	 * @param string        $column_name Column name
+	 *
+	 * @return array|null   The resulting row of data, or null if no data found.
+	 *
+	 * @throws \CodeIgniter\Database\Exceptions\DataException
+	 */
+	public function findColumn(string $columnName)
+	{
+		if (strpos($columnName, ',') !== false)
+		{
+			throw DataException::forFindColumnHaveMultipleColumns();
+		}
+
+		$resultSet = $this->select($columnName)
+		                  ->asArray()
+		                  ->find();
+
+		if (count($resultSet))
+		{
+			$data = [];
+			foreach ($resultSet as $item)
+			{
+				$data[] = $item[$columnName];
+			}
+
+			return $data;
+		}
+
+		return null;
+	}
+
+	//--------------------------------------------------------------------
+
 	/**
 	 * Works with the current Query Builder instance to return
 	 * all results, while optionally limiting them.

tests/system/Database/Live/ModelTest.php

@@ -1,6 +1,7 @@
 <?php namespace CodeIgniter\Database\Live;
 
 use CodeIgniter\Config\Config;
+use CodeIgniter\Database\Exceptions\DataException;
 use CodeIgniter\I18n\Time;
 use CodeIgniter\Model;
 use CodeIgniter\Test\CIDatabaseTestCase;
@@ -69,6 +70,32 @@ public function testFindReturnsMultipleRows()
 
 	//--------------------------------------------------------------------
 
+	public function testGetColumnWithStringColumnName()
+	{
+		$model = new JobModel($this->db);
+
+		$job = $model->findColumn('name');
+
+		$this->assertEquals('Developer', $job[0]);
+		$this->assertEquals('Politician', $job[1]);
+		$this->assertEquals('Accountant', $job[2]);
+		$this->assertEquals('Musician', $job[3]);
+	}
+
+	//--------------------------------------------------------------------
+
+	public function testGetColumnsWithMultipleColumnNames()
+	{
+		$model = new JobModel($this->db);
+
+		$this->expectException(DataException::class);
+		$this->expectExceptionMessage('Only single column allowed in Column name.');
+
+		$job = $model->findColumn('name,description');
+	}
+
+	//--------------------------------------------------------------------
+
 	public function testFindActsAsGetWithNoParams()
 	{
 		$model = new JobModel($this->db);
@@ -1106,7 +1133,7 @@ public function testValidationIncludingErrors()
 	}
 
 	/**
-	 * @expectedException        CodeIgniter\Exceptions\ModelException
+	 * @expectedException        \CodeIgniter\Exceptions\ModelException
 	 * @expectedExceptionMessage `Tests\Support\Models\UserModel` model class does not specify a Primary Key.
 	 */
 	public function testThrowsWithNoPrimaryKey()

user_guide_src/source/models/model.rst

@@ -228,6 +228,14 @@ of just one::
 If no parameters are passed in, will return all rows in that model's table, effectively acting
 like findAll(), though less explicit.
 
+**findColumn()**
+
+ Returns null or an indexed array of column values::
+
+ 	$user = $userModel->findColumn($column_name);
+
+ $column_name should be a name of single column else you will get the DataException.
+
 **findAll()**
 
 Returns all results::