Using Yii2 Bootstrap Alerts with JavaScript

The simple solution is to create a model form, controller and view to display your alert and then use AJAX to display the message.

First, we will add a DIV container with an id of jquery-alert-message-container to our main layout (line 6) views/layouts/main.php. This is so that all pages that use this main layout can use this area to display our alert message.

    <div class="container">
        <?= Breadcrumbs::widget([
            'links' => isset($this->params['breadcrumbs']) ? $this->params['breadcrumbs'] : [],
        ]) ?>
        <div id="jquery-alert-message-container"></div>
        <?= Alert::widget() ?>
        <?= $content ?>
    </div>

In the site controller we will add a new action called alert. If you are using yii\filters\AccessControl, set permission so everyone has access to this action.

    /**
     * Renders Yii Alert notification
     * @return string
     * @throws ServerErrorHttpException
     */
    public function actionAlert()
    {
        if (Yii::$app->request->isAjax)
        {
            $model = new JqueryAlertForm();
            if ($model->load(Yii::$app->request->post()))
                return $this->renderAjax('_alert', ['model' => $model]);
        }

        throw new ServerErrorHttpException('Illegal http call');
    }

This is the model form we are using for the alert. For the purpose of this demo is called frontend\models\JqueryAlertForm.php

<?php
namespace frontend\models;

use Yii;
use yii\base\Model;

/**
 * JQuery Alert form
 *
 * @property string $alert_class
 */
class JqueryAlertForm extends Model
{
    const TYPE_DANGER = 'danger';
    const TYPE_INFO = 'info';
    const TYPE_SUCCESS = 'success';
    const TYPE_WARNING = 'warning';

    public $message;
    public $type;

    /**
     * @inheritdoc
     */
    public function attributeLabels()
    {
        return [
            'message' => 'Message',
            'type' => 'Type',
        ];
    }

    public function getAlert_class()
    {
        if ($this->type == self::TYPE_DANGER)
            return 'alert-danger';

        if ($this->type == self::TYPE_WARNING)
            return 'alert-warning';

        if ($this->type == self::TYPE_SUCCESS)
            return 'alert-success';

        return 'alert-info';
    }

    public static function getTypeList()
    {
        return [
            self::TYPE_DANGER => 'Danger',
            self::TYPE_INFO => 'Info',
            self::TYPE_SUCCESS => 'Success',
            self::TYPE_WARNING => 'Warning',
        ];
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            [
                [
                    'message',
                    'type',
                ],
                'required'
            ],
            [
                [
                    'message',
                    'type',
                ],
                'string'
            ],
            [
                'type',
                'in',
                'range' => array_keys(self::getTypeList())
            ]
        ];
    }
}

Finally, we render the alert using this view frontend/views/site/_alert:

<?php
use yii\bootstrap\Alert;

/* @var $model frontend\models\JqueryAlertForm */

echo Alert::widget([
    'options' => [
        'class' => $model->alert_class,
    ],
    'body' => $model->message,
]);

Now lets create a view to use our new alert. To do this we just need one line of JavaScript. Line 45, calls our site/alert action and passes the message and message type as a POST and then loads the result into the jquery-alert-message-container DIV.

<?php
use frontend\models\JqueryAlertForm;
use rmrevin\yii\fontawesome\FAS;
use yii\helpers\Html;
use yii\bootstrap\ActiveForm;

/* @var $this yii\web\View */
/* @var $form yii\bootstrap\ActiveForm */
/* @var $model frontend\models\JqueryAlertForm */

$this->title = 'JQuery Alert';
$this->params['breadcrumbs'][] = ['label' => $this->title, 'url' => ['jquery-alert']];
?>
<div class="jquery-alert-form">
    <h1><?= Html::encode($this->title) ?></h1>

    <p>Enter your message and select the message type:</p>
    <div class="panel panel-primary">
        <?php
        $form = ActiveForm::begin(['id' => $model->formName()]);
        ?>
        <div class="panel-body">
            <?php
            echo $form->field($model, 'message')->textInput();
            echo $form->field($model, 'type')->dropDownList(JqueryAlertForm::getTypeList());
            ?>
        </div>

        <div class="panel-footer clearfix">
            <div class="form-group">
                <?= Html::submitButton('Display Alert '.FAS::icon(FAS::_BELL),
                    ['class' => 'btn btn-primary', 'name' => 'jquery-alert-button']) ?>
            </div>
        </div>

        <?php ActiveForm::end(); ?>
    </div>
</div>

<?php
$js = <<<JS
// Handles submit action
$(document).on("beforeSubmit", 'form#JqueryAlertForm', function()
{
    $('#jquery-alert-message-container').load('/site/alert', {'JqueryAlertForm[message]': $('#jqueryalertform-message').val(), 'JqueryAlertForm[type]': $('#jqueryalertform-type').val()});
    return false;
});
JS;

$this->registerJs($js);

This is the site controller used to render the above view:

    /**
     * Example of JQuery Alerts
     * @return string
     */
    public function actionJqueryAlert()
    {
        $model = new JqueryAlertForm();
        return $this->render('jquery-alert', ['model' => $model]);
    }