GridView columns title depends of $provider->query->modelClass only, not use both / only $this->grid->filterModel in common case of usage

[bscheshirwork]

Order of applied ifelse is not ideal for default-like case

yii2/framework/grid/DataColumn.php

Lines 138 to 173 in a86c67d

	/**
	* @inheritdoc
	* @since 2.0.8
	*/
	protected function getHeaderCellLabel()
	{
	$provider = $this->grid->dataProvider;
	if ($this->label === null) {
	if ($provider instanceof ActiveDataProvider && $provider->query instanceof ActiveQueryInterface) {
	/* @var $modelClass Model */
	$modelClass = $provider->query->modelClass;
	$model = $modelClass::instance();
	$label = $model->getAttributeLabel($this->attribute);
	} elseif ($provider instanceof ArrayDataProvider && $provider->modelClass !== null) {
	/* @var $modelClass Model */
	$modelClass = $provider->modelClass;
	$model = $modelClass::instance();
	$label = $model->getAttributeLabel($this->attribute);
	} elseif ($this->grid->filterModel !== null && $this->grid->filterModel instanceof Model) {
	$label = $this->grid->filterModel->getAttributeLabel($this->attribute);
	} else {
	$models = $provider->getModels();
	if (($model = reset($models)) instanceof Model) {
	/* @var $model Model */
	$label = $model->getAttributeLabel($this->attribute);
	} else {
	$label = Inflector::camel2words($this->attribute);
	}
	}
	} else {
	$label = $this->label;
	}
	return $label;
	}

What steps will reproduce the problem?

1. Gii-generated CRUD: Search model + GridView::widget
2. Expand Search model with addition field - for example name of relation model.
   order rule + search rule + join in query
3. Expand Search model attributeLabels

    /**
     * @inheritDoc
     */
    public function attributeLabels()
    {
        return ArrayHelper::merge(parent::attributeLabels(), [
            'relationName' => Yii::t('relation', 'Name'),
        ]);
    }

4. Use array-definition for column with attribute

        'columns' => [
            [
                'format' => 'raw',
                'attribute' => 'relationName',
                'content' => \backend\views\ViewHelper::relatedName(),//function with view
            ],
        ],

What is the expected result?

Table header fill from searchModel attributeLabels()

What do you get instead?

Table header fill from dataProviders model attributeLabels()
case of line 147

if ($provider instanceof ActiveDataProvider && $provider->query instanceof ActiveQueryInterface)...

and I must put unexpected additional label

        'columns' => [
            [
                'format' => 'raw',
                'attribute' => 'relationName',
                'label' => $searchModel->getAttributeLabel('relationName'),
                'content' => \backend\views\ViewHelper::relatedName(),//function with view
            ],
        ],

Additional info

Q	A
Yii version	2.0.13@dev

[klimov-paul]

Duplicates #4504

[bscheshirwork]

@klimov-paul please, see changes in PR.

I read origin thread... So... Same situation year by year.

may be this is mark for review the opinion?

[bscheshirwork]

Data in grid not get from only one model, can be from many case, generated in cascade view, etc
Search model is representation of header. Same for header. (In default case)