framework/widgets/ActiveForm.php
public function beginField($model, $attribute, $options = [])
    {
        $field = $this->field($model, $attribute, $options);
        $this->_fields[] = $field;
        return $field->begin();
    }
public function beginField($model, $attribute, $options = [])
    {
        $field = $this->field($model, $attribute, $options);
        $this->_fields[] = $field;
        return $field->begin();
    }
Begins a form field.
This method will create a new form field and returns its opening tag.
You should call [[endField()]] afterwards.
@param Model $model the data model.
@param string $attribute the attribute name or expression. See [[Html::getAttributeName()]] for the format
about attribute expression.
@param array $options the additional configurations for the field object.
@return string the opening tag.
@see endField()
@see field()