framework/widgets/ActiveField.php
public function textInput($options = [])
    {
        $options = array_merge($this->inputOptions, $options);

        if ($this->form->validationStateOn === ActiveForm::VALIDATION_STATE_ON_INPUT) {
            $this->addErrorClassIfNeeded($options);
        }

        $this->addAriaAttributes($options);
        $this->adjustLabelFor($options);
        $this->parts['{input}'] = Html::activeTextInput($this->model, $this->attribute, $options);

        return $this;
    }
public function textInput($options = [])
    {
        $options = array_merge($this->inputOptions, $options);

        if ($this->form->validationStateOn === ActiveForm::VALIDATION_STATE_ON_INPUT) {
            $this->addErrorClassIfNeeded($options);
        }

        $this->addAriaAttributes($options);
        $this->adjustLabelFor($options);
        $this->parts['{input}'] = Html::activeTextInput($this->model, $this->attribute, $options);

        return $this;
    }
Renders a text input.
This method will generate the `name` and `value` tag attributes automatically for the model attribute
unless they are explicitly specified in `$options`.
@param array $options the tag options in terms of name-value pairs. These will be rendered as
the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].

The following special options are recognized:

- `maxlength`: int|bool, when `maxlength` is set `true` and the model attribute is validated
by a string validator, the `maxlength` option will take the value of [[\yii\validators\StringValidator::max]].
This is available since version 2.0.3.

Note that if you set a custom `id` for the input element, you may need to adjust the value of [[selectors]] accordingly.

@return $this the field object itself.