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103 lines
5.8 KiB
Markdown
103 lines
5.8 KiB
Markdown
Running Applications
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====================
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After installing Yii, you have a working Yii application that can be accessed via
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the URL `https://hostname/basic/web/index.php` or `https://hostname/index.php`, depending
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upon your configuration. This section will introduce the application's built-in functionality,
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how the code is organized, and how the application handles requests in general.
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> Info: For simplicity, throughout this "Getting Started" tutorial, it's assumed that you have set `basic/web`
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as the document root of your Web server, and configured the URL for accessing
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your application to be `https://hostname/index.php` or something similar.
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For your needs, please adjust the URLs in our descriptions accordingly.
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Note that unlike framework itself, after project template is installed it's all yours. You're free to add or delete
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code and overall modify it as you need.
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Functionality <span id="functionality"></span>
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-------------
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The basic application installed contains four pages:
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* the homepage, displayed when you access the URL `https://hostname/index.php`,
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* the "About" page,
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* the "Contact" page, which displays a contact form that allows end users to contact you via email,
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* and the "Login" page, which displays a login form that can be used to authenticate end users. Try logging in
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with "admin/admin", and you will find the "Login" main menu item will change to "Logout".
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These pages share a common header and footer. The header contains a main menu bar to allow navigation
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among different pages.
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You should also see a toolbar at the bottom of the browser window.
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This is a useful [debugger tool](https://github.com/yiisoft/yii2-debug/blob/master/docs/guide/README.md) provided by Yii to record and display a lot of debugging information, such as log messages, response statuses, the database queries run, and so on.
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Additionally to the web application, there is a console script called `yii`, which is located in the applications base directory.
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This script can be used to run background and maintenance tasks for the application, which are described
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in the [Console Application Section](tutorial-console.md).
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Application Structure <span id="application-structure"></span>
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---------------------
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The most important directories and files in your application are (assuming the application's root directory is `basic`):
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```
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basic/ application base path
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composer.json used by Composer, describes package information
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config/ contains application and other configurations
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console.php the console application configuration
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web.php the Web application configuration
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commands/ contains console command classes
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controllers/ contains controller classes
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models/ contains model classes
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runtime/ contains files generated by Yii during runtime, such as logs and cache files
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vendor/ contains the installed Composer packages, including the Yii framework itself
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views/ contains view files
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web/ application Web root, contains Web accessible files
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assets/ contains published asset files (javascript and css) by Yii
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index.php the entry (or bootstrap) script for the application
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yii the Yii console command execution script
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```
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In general, the files in the application can be divided into two types: those under `basic/web` and those
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under other directories. The former can be directly accessed via HTTP (i.e., in a browser), while the latter can not and should not be.
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Yii implements the [model-view-controller (MVC)](https://wikipedia.org/wiki/Model-view-controller) architectural pattern,
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which is reflected in the above directory organization. The `models` directory contains all [model classes](structure-models.md),
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the `views` directory contains all [view scripts](structure-views.md), and the `controllers` directory contains
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all [controller classes](structure-controllers.md).
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The following diagram shows the static structure of an application.
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Each application has an entry script `web/index.php` which is the only Web accessible PHP script in the application.
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The entry script takes an incoming request and creates an [application](structure-applications.md) instance to handle it.
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The [application](structure-applications.md) resolves the request with the help of its [components](concept-components.md),
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and dispatches the request to the MVC elements. [Widgets](structure-widgets.md) are used in the [views](structure-views.md)
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to help build complex and dynamic user interface elements.
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Request Lifecycle <span id="request-lifecycle"></span>
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-----------------
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The following diagram shows how an application handles a request.
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1. A user makes a request to the [entry script](structure-entry-scripts.md) `web/index.php`.
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2. The entry script loads the application [configuration](concept-configurations.md) and creates
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an [application](structure-applications.md) instance to handle the request.
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3. The application resolves the requested [route](runtime-routing.md) with the help of
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the [request](runtime-requests.md) application component.
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4. The application creates a [controller](structure-controllers.md) instance to handle the request.
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5. The controller creates an [action](structure-controllers.md) instance and performs the filters for the action.
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6. If any filter fails, the action is cancelled.
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7. If all filters pass, the action is executed.
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8. The action loads some data models, possibly from a database.
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9. The action renders a view, providing it with the data models.
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10. The rendered result is returned to the [response](runtime-responses.md) application component.
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11. The response component sends the rendered result to the user's browser.
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