There are many differences between Yii version 2.0 and 1.1, because Yii is completely rewritten for 2.0.
As a result, upgrading from version 1.1 is not as trivial as upgrading between minor versions. In this chapter,
we will summarize the major differences between the two versions.
There are many differences between versions 1.1 and 2.0 of the Yii as the framework was completely rewritten for 2.0.
As a result, upgrading from version 1.1 is not as trivial as upgrading between minor versions. In this guide you'll find the major differences between the two versions.
Please note that Yii 2.0 introduces many new features which are not covered in this summary. It is highly recommended
that you read through the whole definitive guide to learn about these features. Chances could be that
some features you previously have to develop by yourself are already part of the core code now.
Please note that Yii 2.0 introduces more new features than are covered in this summary. It is highly recommended
that you read through the whole definitive guide to learn about them all. Chances are that
some features you previously had to develop for yourself are now part of the core code.
Installation
------------
Yii 2.0 fully embraces [Composer](https://getcomposer.org/), a de facto PHP package manager. Installation
of the core framework as well as extensions are all installed through Composer. Please refer to
the [Starting from Basic App](start-basic.md)chapter to learn how to install Yii 2.0. If you want to
create new extensions or turn your existing 1.1 extensions into 2.0, please refer to
the [Creating Extensions](extend-creating-extensions.md)chapter.
Yii 2.0 fully embraces [Composer](https://getcomposer.org/), the de facto PHP package manager. Installation
of the core framework, as well as extensions, are handled through Composer. Please refer to
the [Starting from Basic App](start-basic.md)section to learn how to install Yii 2.0. If you want to
create new extensions, or turn your existing 1.1 extensions into 2.0-compatible extensions, please refer to
the [Creating Extensions](extend-creating-extensions.md)section of the guide.
PHP Requirements
----------------
Yii 2.0 requires PHP 5.4 or above, which is a huge improvement over PHP 5.2 as required by Yii 1.1.
As a result, there are many differences at language level that you should pay attention to.
Yii 2.0 requires PHP 5.4 or above, which is a huge improvement over PHP version 5.2 that is required by Yii 1.1.
As a result, there are many differences on the language level that you should pay attention to.
Below is a summary of the major changes regarding PHP:
More details about configurations can be found in the [Object Configurations](concept-configurations.md)chapter.
More details about configurations can be found in the [Object Configurations](concept-configurations.md)section.
Events
------
There is no longer the need to define an `on`-method in order to define an event in Yii 2.0.
Instead, you can use whatever event names. You can trigger an event by calling
In Yii 1, events were created by defining an `on`-method (e.g., `onBeforeSave`). In Yii 2, you can now use any event name. You trigger an event by calling
the [[yii\base\Component::trigger()|trigger()]] method:
```php
...
...
@@ -120,7 +119,7 @@ $event = new \yii\base\Event;
$component->trigger($eventName,$event);
```
And to attach a handler to an event, you can use the [[yii\base\Component::on()|on()]] method:
To attach a handler to an event, use the [[yii\base\Component::on()|on()]] method:
There are many enhancements to the event features. For more details, please refer to the [Events](concept-events.md)chapter.
There are many enhancements to the event features. For more details, please refer to the [Events](concept-events.md)section.
Path Aliases
------------
Yii 2.0 expands the usage of path aliases to both file/directory paths and URLs. It also requires
an alias name to start with a `@` character so that it can be differentiated from normal file/directory paths and URLs.
Yii 2.0 expands the usage of path aliases to both file/directory paths and URLs. Yii 2.0 also now requires
an alias name to start with the `@` character, to differentiate aliases from normal file/directory paths or URLs.
For example, the alias `@yii` refers to the Yii installation directory. Path aliases are
supported in most places in the Yii core code. For example, [[yii\caching\FileCache::cachePath]] can take
both a path alias and a normal directory path.
Path alias is also closely related with class namespaces. It is recommended that a path
alias be defined for each root namespace so that you can use Yii the class autoloader without
A path alias is also closely related to a class namespace. It is recommended that a path
alias be defined for each root namespace, thereby allowing you to use Yii the class autoloader without
any further configuration. For example, because `@yii` refers to the Yii installation directory,
a class like `yii\web\Request` can be autoloaded by Yii. If you use a third party library
such as Zend Framework, you may define a path alias `@Zend` which refers to its installation
directory and Yii will be able to autoload any class in this library.
a class like `yii\web\Request` can be autoloaded. If you use a third party library,
such as the Zend Framework, you may define a path alias `@Zend` that refers to that framework's installation
directory. Once you've done that, Yii will be able to autoload any class in that Zend Framework library, too.
More on path aliases can be found in the [Path Aliases](concept-aliases.md)chapter.
More on path aliases can be found in the [Path Aliases](concept-aliases.md)section.
Views
-----
The most significant change about views is that`$this` in a view no longer refers to
the current controller or widget. Instead, it refers to a *view* object which is a new concept
introduced in 2.0. The *view* object is of class [[yii\web\View]] which represents the view part
of the MVC pattern. In you want to access the controller or widget in a view, you should use `$this->context`.
The most significant change about views in Yii 2 is that the special variable`$this` in a view no longer refers to
the current controller or widget. Instead, `$this` now refers to a *view* object, a new concept
introduced in 2.0. The *view* object is of type [[yii\web\View]], which represents the view part
of the MVC pattern. In you want to access the controller or widget in a view, you can use `$this->context`.
To render a partial view within another view, you should use `$this->render()` now.
And you have to echo it explicitly because the `render()` method will return the rendering
result rather than directly displaying it. For example,
To render a partial view within another view, you use `$this->render()`, not `$this->renderPartial()`. The call to `render` also now has to be explicitly echoed, as the `render()` method returns the rendering
result, rather than directly displaying it. For example:
```php
echo$this->render('_item',['item'=>$item]);
...
...
@@ -170,18 +168,17 @@ Besides using PHP as the primary template language, Yii 2.0 is also equipped wit
support for two popular template engines: Smarty and Twig. The Prado template engine is no longer supported.
To use these template engines, you need to configure the `view` application component by setting the
[[yii\base\View::$renderers|View::$renderers]] property. Please refer to the [Template Engines](tutorial-template-engines.md)
chapter for more details.
section for more details.
Models
------
Yii 2.0 uses [[yii\base\Model]] as the base model class which is similar to `CModel` in 1.1.
The class `CFormModel`is dropped. Instead, you should extend [[yii\base\Model]] to create a form model class.
Yii 2.0 uses [[yii\base\Model]] as the base model, similar to `CModel` in 1.1.
The class `CFormModel`has been dropped entirely. Instead, in Yii 2 you should extend [[yii\base\Model]] to create a form model class.
Yii 2.0 introduces a new method called [[yii\base\Model::scenarios()|scenarios()]] to declare
supported scenarios and under which scenario an attribute needs to be validated and can be considered as safe or not.
For example,
supported scenarios, and to indicate under which scenario an attribute needs to be validated, can be considered as safe or not, etc. For example:
```php
publicfunctionscenarios()
...
...
@@ -193,28 +190,27 @@ public function scenarios()
}
```
In the above, two scenarios are declared: `backend` and `frontend`. For the `backend` scenario, both of the
`email` and `role` attributes are safe and can be massively assigned; for the `frontend` scenario,
`email` can be massively assigned while `role` cannot. Both `email` and `role` should be validated.
In the above, two scenarios are declared: `backend` and `frontend`. For the `backend` scenario, both the
`email` and `role` attributes are safe, and can be massively assigned. For the `frontend` scenario,
`email` can be massively assigned while `role` cannot. Both `email` and `role` should be validated using rules.
The [[yii\base\Model::rules()|rules()]] method is still used to declare validation rules. Note that because
of the introduction of [[yii\base\Model::scenarios()|scenarios()]], there is no more `unsafe` validator.
The [[yii\base\Model::rules()|rules()]] method is still used to declare the validation rules. Note that due to the introduction of [[yii\base\Model::scenarios()|scenarios()]], there is no longer an `unsafe` validator.
In most cases, you do not need to override [[yii\base\Model::scenarios()|scenarios()]]
if the [[yii\base\Model::rules()|rules()]] method fully specifies the scenarios and there is no need to declare
if the [[yii\base\Model::rules()|rules()]] method fully specifies the scenarios that will exist, and if there is no need to declare
`unsafe` attributes.
To learn more details about models, please refer to the [Models](basic-models.md)chapter.
To learn more details about models, please refer to the [Models](basic-models.md)section.
Controllers
-----------
Yii 2.0 uses [[yii\web\Controller]] as the base controller class which is similar to `CWebController` in 1.1.
And [[yii\base\Action]] is the base class for action classes.
Yii 2.0 uses [[yii\web\Controller]] as the base controller class, similar to `CWebController` in Yii 1.1.
[[yii\base\Action]] is the base class for action classes.
The most obvious change when you write code in a controller action is that you should return the content
that you want to render instead of echoing it. For example,
The most obvious impact of these changes on your code is that a controller action should return the content
that you want to render instead of echoing it:
```php
publicfunctionactionView($id)
...
...
@@ -228,17 +224,17 @@ public function actionView($id)
}
```
Please refer to the [Controllers](structure-controllers.md)chapter for more details about controllers.
Please refer to the [Controllers](structure-controllers.md)section for more details about controllers.
Widgets
-------
Yii 2.0 uses [[yii\base\Widget]] as the base widget class which is similar to `CWidget` in 1.1.
Yii 2.0 uses [[yii\base\Widget]] as the base widget class, similar to `CWidget` in Yii 1.1.
To get better IDE support, Yii 2.0 introduces a new syntax for using widgets. The static methods
[[yii\base\Widget::begin()|begin()]], [[yii\base\Widget::end()|end()]] and [[yii\base\Widget::widget()|widget()]]
are introduced and can be used as follows,
To get better support for the framework in IDEs, Yii 2.0 introduces a new syntax for using widgets. The static methods
[[yii\base\Widget::begin()|begin()]], [[yii\base\Widget::end()|end()]], and [[yii\base\Widget::widget()|widget()]]
have been introduced, to be used like so:
```php
useyii\widgets\Menu;
...
...
@@ -256,29 +252,29 @@ $form = ActiveForm::begin([
ActiveForm::end();
```
Please refer to the [Widgets](structure-widgets.md)chapter for more details.
Please refer to the [Widgets](structure-widgets.md)section for more details.
Themes
------
Themes work completely different in 2.0. They are now based on a path mapping mechanism which maps a source
Themes work completely differently in 2.0. They are now based on a path mapping mechanism that maps a source
view file path to a themed view file path. For example, if the path map for a theme is
`['/web/views' => '/web/themes/basic']`, then the themed version for a view file
`['/web/views' => '/web/themes/basic']`, then the themed version for the view file
`/web/views/site/index.php` will be `/web/themes/basic/site/index.php`. For this reason, themes can now
be applied to any view file, even if a view rendered outside of the context of a controller or a widget.
be applied to any view file, even a view rendered outside of the context of a controller or a widget.
Also, there is no more `CThemeManager`. Instead, `theme` is a configurable property of the `view`
Also, there is no more `CThemeManager` component. Instead, `theme` is a configurable property of the `view`
application component.
Please refer to the [Theming](tutorial-theming.md)chapter for more details.
Please refer to the [Theming](tutorial-theming.md)section for more details.
Console Applications
--------------------
Console applications are now organized as controllers, like Web applications. Console controllers
should extend from [[yii\console\Controller]] which is similar to `CConsoleCommand` in 1.1.
should extend from [[yii\console\Controller]], similar to `CConsoleCommand` in 1.1.
To run a console command, use `yii <route>`, where `<route>` stands for a controller route
(e.g. `sitemap/index`). Additional anonymous arguments are passed as the parameters to the
...
...
@@ -293,13 +289,13 @@ Please refer to the [Console Commands](tutorial-console.md) chapter for more det
I18N
----
Yii 2.0 removes date formatter and number formatter in favor of the PECL intl PHP module.
Yii 2.0 removes the built-in date formatter and number formatter pieces in favor of the [PECL intl PHP module](http://pecl.php.net/package/intl).
Message translation is now performed via the `i18n` application component.
The component manages a set of message sources, which allows you to use different message
This component manages a set of message sources, which allows you to use different message
sources based on message categories.
Please refer to the [Internationalization](tutorial-i18n.md)chapter for more details.
Please refer to the [Internationalization](tutorial-i18n.md)section for more details.
