Creating a Drop-Down List in Yii2

To create a drop-down list populated with data from the database, you can use the ArrayHelper class. Here’s a detailed guide on how to create a drop-down list of companies in a form:

Step 1: Prepare the Form

In your form view file, add the following code to create a drop-down list:

<?= $form->field($model, 'companies_company_id')->dropDownList(
    ArrayHelper::map(Companies::find()->all(), 'company_id', 'company_name'),
    ['prompt' => 'Select company']
) ?>

Explanation:

• Retrieving Data:

  • Companies::find()->all() retrieves all records from the companies table in the database.

• Mapping Data:

  • ArrayHelper::map(Companies::find()->all(), 'company_id', 'company_name') converts the list of companies into an array suitable for a drop-down list.

    • The first parameter is the data (all company records).

    • The second parameter is the key field (company_id), which will be used as the value in the drop-down options.

    • The third parameter is the value field (company_name), which will be displayed in the drop-down options.

• Prompt:

  • The ['prompt' => 'Select company'] option adds a prompt at the top of the drop-down list to guide users to select a company.

Step 2: Import Necessary Classes

To make the ArrayHelper and Companies functions work, you need to import them at the top of your form view file:

use yii\helpers\ArrayHelper;
use backend\models\Companies;

Step 3: Customize the Attribute Label

If you want to change the label displayed on top of the drop-down list from 'Company companies id' to a more user-friendly label like 'Company name', you need to update the attributeLabels function in the Companies model.

In backend\models\Companies.php, update the attributeLabels function:

public function attributeLabels()
{
    return [
        'companies_company_id' => 'Company name',
        // other labels
    ];
}

Full Code Example

Here’s how your form view file might look with the drop-down list:

<?php
use yii\helpers\ArrayHelper;
use backend\models\Companies;

/* @var $form yii\widgets\ActiveForm */
/* @var $model backend\models\YourModel */

?>

<?= $form->field($model, 'companies_company_id')->dropDownList(
    ArrayHelper::map(Companies::find()->all(), 'company_id', 'company_name'),
    ['prompt' => 'Select company']
) ?>

By following these steps, you will create a drop-down list in your Yii2 application that is populated with data from the companies table. This allows users to select a company by name, with company_id being used as the underlying value.