Update doc

Author: Eugene Tupikov

README.md

@@ -109,7 +109,7 @@ function($data) { return 'something'; }
 Widget supports several use cases:
 
 - [Single column example](docs/single_column.md)
-- [Several columns example](docs/several_columns.md)
+- [Multiple columns example](docs/multiple_columns.md)
 
 You cad find source code of examples [here](./examples/)
 ##License

docs/images/multiple-column.gif

@@ -0,0 +1,116 @@
+#Multiple columns example
+
+![Multiple columns example](./images/multiple-column.gif?raw=true)
+
+For example you want to have an interface for manage user schedule. For simpliсшен we will store the schedule in json string.
+
+In this case you can use `yii2-multiple-input` widget for supporting multiple inputs how to describe below.
+
+Our test model can looks like as the following snippet
+
+```php
+class ExampleModel extends Model
+{
+    public $schedule;
+
+    public function init()
+    {
+        parent::init();
+
+        $this->schedule = [
+            [
+                'day'       => 0,
+                'user_id'   => 1,
+                'priority'  => 1
+            ],
+            [
+                'day'       => 0,
+                'user_id'   => 2,
+                'priority'  => 2
+            ],
+        ];
+    }
+```
+
+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, 'schedule')->widget(MultipleInput::className(), [
+    'limit' => 4,
+    'columns' => [
+        [
+            'name'  => 'user_id',
+            'type'  => 'dropDownList',
+            'title' => 'User',
+            'defaultValue' => 1,
+            'items' => [
+                1 => 'User 1',
+                2 => 'User 2'
+            ]
+        ],
+        [
+            'name'  => 'day',
+            'type'  => 'dropDownList',
+            'title' => 'Day',
+            'value' => function($data) {
+                return $data['day'];
+            },
+            'defaultValue' => 1,
+            'items' => [
+                '0' => 'Saturday',
+                '1' => 'Monday'
+            ],
+            'options' => [
+
+            ]
+        ],
+        [
+            'name'  => 'priority',
+            'title' => 'Priority',
+            'options' => [
+                'class' => 'input-priority'
+            ]
+        ]
+    ]
+ ]);
+?>
+<?= Html::submitButton('Update', ['class' => 'btn btn-success']);?>
+<?php ActiveForm::end();?>
+```
+
+
+For validation the schedule you can use the following code
+
+```php
+
+    public function validateSchedule($attribute)
+    {
+        $requiredValidator = new RequiredValidator();
+
+        foreach($this->$attribute as $index => $row) {
+            $error = null;
+            $requiredValidator->validate($row['priority'], $error);
+            if (!empty($error)) {
+                $key = $attribute . '[' . $index . '][priority]';
+                $this->addError($key, $error);
+            }
+        }
+    }
+```