yii2-bootstrap/docs/model.md

Model

Attributes

Attributes store the actual data represented by a model and can be accessed like object member variables. For example, a Post model may contain a title attribute and a content attribute which may be accessed as follows:

$post->title = 'Hello, world';
$post->content = 'Something interesting is happening';
echo $post->title;
echo $post->content;

A model should list all its available attributes in the attributes() method.

Attributes may be implemented in various ways. The \yii\base\Model class implements attributes as public member variables of the class, while the \yii\db\ActiveRecord class implements them as DB table columns. For example,

// LoginForm has two attributes: username and password
class LoginForm extends \yii\base\Model
{
	public $username;
	public $password;
}

// Post is associated with the tbl_post DB table.
// Its attributes correspond to the columns in tbl_post
class Post extends \yii\db\ActiveRecord
{
	public function table()
	{
		return 'tbl_post';
	}
}

Attribute Labels

Scenarios

A model may be used in different scenarios. For example, a User model may be used to collect user login inputs, and it may also be used for user registration purpose. For this reason, each model has a property named scenario which stores the name of the scenario that the model is currently being used in. As we will explain in the next few sections, the concept of scenario is mainly used in validation and massive attribute assignment.

Associated with each scenario is a list of attributes that are active in that particular scenario. For example, in the login scenario, only the username and password attributes are active; while in the register scenario, additional attributes such as email are active.

Possible scenarios should be listed in the scenarios() method which returns an array whose keys are the scenario names and whose values are the corresponding active attribute lists. Below is an example:

class User extends \yii\db\ActiveRecord
{
	public function table()
	{
		return 'tbl_user';
	}

	public function scenarios()
	{
		return array(
			'login' => array('username', 'password'),
			'register' => array('username', 'email', 'password'),
		);
	}
}

Sometimes, we want to mark that an attribute is not safe for massive assignment (but we still want it to be validated). We may do so by prefixing an exclamation character to the attribute name when declaring it in scenarios(). For example,

array('username', 'password', '!secret')

Validation

When a model is used to collect user input data via its attributes, it usually needs to validate the affected attributes to make sure they satisfy certain requirements, such as an attribute cannot be empty, an attribute must contain letters only, etc. If errors are found in validation, they may be presented to the user to help him fix the errors. The following example shows how the validation is performed:

$model = new LoginForm;
$model->username = $_POST['username'];
$model->password = $_POST['password'];
if ($model->validate()) {
	// ...login the user...
} else {
	$errors = $model->getErrors();
	// ...display the errors to the end user...
}

The possible validation rules for a model should be listed in its rules() method. Each validation rule applies to one or several attributes and is effective in one or several scenarios. A rule can be specified using a validator object - an instance of a \yii\validators\Validator child class, or an array with the following format:

array(
	'attribute1, attribute2, ...',
	'validator class or alias',
	// specifies in which scenario(s) this rule is active.
	// if not given, it means it is active in all scenarios
	'on' => 'scenario1, scenario2, ...',
	// the following name-value pairs will be used
	// to initialize the validator properties...
	'name1' => 'value1',
	'name2' => 'value2',
	....
)

When validate() is called, the actual validation rules executed are determined using both of the following criteria:

• the rules must be associated with at least one active attribute;
• the rules must be active for the current scenario.

Active Attributes

An attribute is active if it is subject to some validations in the current scenario.

Safe Attributes

An attribute is safe if it can be massively assigned in the current scenario.

Massive Access of Attributes

Massive Attribute Retrieval

Attributes can be massively retrieved via the attributes property. The following code will return all attributes in the $post model as an array of name-value pairs.

$attributes = $post->attributes;
var_dump($attributes);

Massive Attribute Assignment

Safe Attributes

Safe attributes are those that can be massively assigned. For example,

Validation rules and mass assignment

In Yii2 unlike Yii 1.x validation rules are separated from mass assignment. Validation rules are described in rules() method of the model while what's safe for mass assignment is described in scenarios method:

function rules() {
 return array(
  // rule applied when corresponding field is "safe"
  array('username', 'length', 'min' => 2),
  array('first_name', 'length', 'min' => 2),
  array('password', 'required'),

  // rule applied when scenario is "signup" no matter if field is "safe" or not
  array('hashcode', 'check', 'on' => 'signup'),
 );
}

function scenarios() {
 return array(
  // on signup allow mass assignment of username
  'signup' => array('username', 'password'),
  'update' => array('username', 'first_name'),
 );
}

Note that everything is unsafe by default and you can't make field "safe" without specifying scenario.