yii2 failed to connect to database

First of all, let’s take a look at the problem code:

1. The controller code is as follows:

    public function actionIndex()
    {
        $query = Country::find();
 
        $pagination = new Pagination([
            'defaultPageSize' => 5,
            'totalCount' => $query->count()
        ]);
 
        $countries = $query->orderBy('name')
            ->offset($pagination->offset)
            ->limit($pagination->limit)
            ->all();
 
        return $this->render('index', [
            'countries' => $countries,
            'pagination' => $pagination,
        ]);
    }

(Recommended tutorial: yii framework )

2. The code of the database configuration file db.php is as follows:

<?php
 
return [
    &#39;class&#39; => &#39;yii\db\Connection&#39;,
    &#39;dsn&#39; => &#39;mysql:host=localhost;dbname=yii2basic&#39;,
    &#39;username&#39; => &#39;root&#39;,
    &#39;password&#39; => &#39;&#39;,
    &#39;charset&#39; => &#39;utf8&#39;,
 
    // Schema cache options (for production environment)
    //&#39;enableSchemaCache&#39; => true,
    //&#39;schemaCacheDuration&#39; => 60,
    //&#39;schemaCache&#39; => &#39;cache&#39;,
];

Solution:

Change the host of the dsn in the PDO connection from "localhost" Just "127.0.0.1", open the file DB.PHP, and modify it as follows:

<?php
 
return [
    &#39;class&#39; => &#39;yii\db\Connection&#39;,
    &#39;dsn&#39; => &#39;mysql:host=127.0.0.1;dbname=yii2basic&#39;,
    &#39;username&#39; => &#39;root&#39;,
    &#39;password&#39; => &#39;&#39;,
    &#39;charset&#39; => &#39;utf8&#39;,
 
    // Schema cache options (for production environment)
    //&#39;enableSchemaCache&#39; => true,
    //&#39;schemaCacheDuration&#39; => 60,
    //&#39;schemaCache&#39; => &#39;cache&#39;,
];

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