Update single_column.md

Author: unclead

docs/single_column.md

@@ -1,17 +1,77 @@
 #Single column example
 
+![Single column example](./images/single-column.gif?raw=true)
+
 For example your application contains the model `User` that has the related model `UserEmail` 
 You can add virtual attribute `emails` for collect emails from form and then you can save them to database. 
 
 In this case you can use `yii2-multiple-input` widget for supporting multiple inputs how to describe below.
 
 First of all we have to declare virtual attribute in model
 
-```
+```php
 class ExampleModel extends Model
 {
     /**
      * @var array virtual attribute for keeping emails
      */
     public $emails;
-```
+```
+
+Then we have to use `MultipleInput` widget for rendering form field in the view file
+
+```php
+use yii\bootstrap\ActiveForm;
+use unclead\widgets\MultipleInput;
+use unclead\widgets\examples\models\ExampleModel;
+use yii\helpers\Html;
+
+/* @var $this \yii\base\View */
+/* @var $model ExampleModel */
+?>
+
+<?php $form = ActiveForm::begin([
+    'enableAjaxValidation'      => true,
+    'enableClientValidation'    => false,
+    'validateOnChange'          => false,
+    'validateOnSubmit'          => true,
+    'validateOnBlur'            => false,
+]);?>
+
+<?= $form->field($model, 'emails')->widget(MultipleInput::className(), [
+    'limit' => 4,
+ ]);
+?>
+<?= Html::submitButton('Update', ['class' => 'btn btn-success']);?>
+<?php ActiveForm::end();?>
+```
+
+Options `limit` means that user able to input only 4 emails
+
+For validation emails you can use the following code
+
+```php
+    /**
+     * Email validation.
+     *
+     * @param $attribute
+     */
+    public function validateEmails($attribute)
+    {
+        $items = $this->$attribute;
+
+        if (!is_array($items)) {
+            $items = [];
+        }
+
+        foreach ($items as $index => $item) {
+            $validator = new EmailValidator();
+            $error = null;
+            $validator->validate($item, $error);
+            if (!empty($error)) {
+                $key = $attribute . '[' . $index . ']';
+                $this->addError($key, $error);
+            }
+        }
+    }
+```