output-data-providers.md

Data providers

Note: This section is under development.

Data provider abstracts data set via [[yii\data\DataProviderInterface]] and handles pagination and sorting. It can be used by grids, lists and other data widgets.

In Yii there are three built-in data providers: [[yii\data\ActiveDataProvider]], [[yii\data\ArrayDataProvider]] and [[yii\data\SqlDataProvider]].

Active data provider

ActiveDataProvider provides data by performing DB queries using [[yii\db\Query]] and [[yii\db\ActiveQuery]].

The following is an example of using it to provide ActiveRecord instances:

$provider = new ActiveDataProvider([
    'query' => Post::find(),
    'pagination' => [
        'pageSize' => 20,
    ],
]);

// get the posts in the current page
$posts = $provider->getModels();

And the following example shows how to use ActiveDataProvider without ActiveRecord:

$query = new Query();
$provider = new ActiveDataProvider([
    'query' => $query->from('post'),
    'sort' => [
        // Set the default sort by name ASC and created_at DESC.
        'defaultOrder' => [
            'name' => SORT_ASC, 
            'created_at' => SORT_DESC
        ]
    ],
    'pagination' => [
        'pageSize' => 20,
    ],
]);

// get the posts in the current page
$posts = $provider->getModels();

Array data provider

ArrayDataProvider implements a data provider based on a data array.

The [[yii\data\ArrayDataProvider::$allModels]] property contains all data models that may be sorted and/or paginated. ArrayDataProvider will provide the data after sorting and/or pagination. You may configure the [[yii\data\ArrayDataProvider::$sort]] and [[yii\data\ArrayDataProvider::$pagination]] properties to customize the sorting and pagination behaviors.

Elements in the [[yii\data\ArrayDataProvider::$allModels]] array may be either objects (e.g. model objects) or associative arrays (e.g. query results of DAO). Make sure to set the [[yii\data\ArrayDataProvider::$key]] property to the name of the field that uniquely identifies a data record or false if you do not have such a field.

Compared to ActiveDataProvider, ArrayDataProvider could be less efficient because it needs to have [[yii\data\ArrayDataProvider::$allModels]] ready.

ArrayDataProvider may be used in the following way:

$query = new Query();
$provider = new ArrayDataProvider([
    'allModels' => $query->from('post')->all(),
    'sort' => [
        'attributes' => ['id', 'username', 'email'],
    ],
    'pagination' => [
        'pageSize' => 10,
    ],
]);
// get the posts in the current page
$posts = $provider->getModels();

Note: if you want to use the sorting feature, you must configure the [[sort]] property so that the provider knows which columns can be sorted.

SQL data provider

SqlDataProvider implements a data provider based on a plain SQL statement. It provides data in terms of arrays, each representing a row of query result.

Like other data providers, SqlDataProvider also supports sorting and pagination. It does so by modifying the given [[yii\data\SqlDataProvider::$sql]] statement with "ORDER BY" and "LIMIT" clauses. You may configure the [[yii\data\SqlDataProvider::$sort]] and [[yii\data\SqlDataProvider::$pagination]] properties to customize sorting and pagination behaviors.

SqlDataProvider may be used in the following way:

$count = Yii::$app->db->createCommand('
    SELECT COUNT(*) FROM user WHERE status=:status
', [':status' => 1])->queryScalar();

$dataProvider = new SqlDataProvider([
    'sql' => 'SELECT * FROM user WHERE status=:status',
    'params' => [':status' => 1],
    'totalCount' => $count,
    'sort' => [
        'attributes' => [
            'age',
            'name' => [
                'asc' => ['first_name' => SORT_ASC, 'last_name' => SORT_ASC],
                'desc' => ['first_name' => SORT_DESC, 'last_name' => SORT_DESC],
                'default' => SORT_DESC,
                'label' => 'Name',
            ],
        ],
    ],
    'pagination' => [
        'pageSize' => 20,
    ],
]);

// get the user records in the current page
$models = $dataProvider->getModels();

Note: if you want to use the pagination feature, you must configure the [[yii\data\SqlDataProvider::$totalCount]] property to be the total number of rows (without pagination). And if you want to use the sorting feature, you must configure the [[yii\data\SqlDataProvider::$sort]] property so that the provider knows which columns can be sorted.

Implementing your own custom data provider

TBD