上一篇文章我们介绍了 Symfony 4 带来的一些变化，我们尝试用一个 demo 示例说明一下。
首先是安装项目：
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composer create-project symfony/skeleton:3.3.x-dev demo cd demo |
此命令只下载了一个骨架文件 composer.json，并自动运行 composer install 命令。
Symfony Flex 是第一个下载的包。flex 安装完毕之后立马通过钩子程序勾住 composer 的安装过程。所以当 composer 开始安装其他组件包的时候，flex 通过与『食谱』服务器交互，并执行『食谱』里指定的操作。如果大家执行了上面的命令，一定会看到『食谱』执行的结果：
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Installing symfony/skeleton (3.3.x-dev 19daacfd7ca93335963b7dd0e5ea4e18c228135c) - Installing symfony/skeleton (3.3.x-dev 19daacf): Cloning 19daacfd7c from cache Created project in demo Loading composer repositories with package information Updating dependencies (including require-dev) Package operations: 28 installs, 0 updates, 0 removals - Installing symfony/flex (dev-master 979058c): Downloading (100%) Detected auto-configuration settings for "symfony/flex" Setting configuration and copying files - Installing symfony/stopwatch (dev-master 602a152): Loading from cache - Installing symfony/polyfill-util (dev-master 746bce0): Loading from cache - Installing symfony/polyfill-php56 (dev-master 1dd42b9): Loading from cache - Installing paragonie/random_compat (v2.0.10): Loading from cache - Installing symfony/polyfill-php70 (dev-master 13ce343): Loading from cache - Installing symfony/security-core (dev-master 66aa40a): Loading from cache - Installing symfony/security-csrf (dev-master 307136b): Loading from cache - Installing symfony/routing (dev-master fadf939): Loading from cache Detected auto-configuration settings for "symfony/routing" - Installing symfony/polyfill-mbstring (dev-master e79d363): Loading from cache - Installing psr/log (dev-master 4ebe3a8): Loading from cache - Installing symfony/debug (dev-master 2a23722): Loading from cache - Installing symfony/http-foundation (dev-master af2d53e): Loading from cache - Installing symfony/event-dispatcher (dev-master a9f8b02): Downloading (100%) - Installing symfony/http-kernel (dev-master 669e819): Loading from cache - Installing symfony/finder (dev-master ce30991): Loading from cache - Installing symfony/filesystem (dev-master 57ecfd1): Loading from cache - Installing psr/container (dev-master b7ce3b1): Loading from cache - Installing symfony/dependency-injection (dev-master aa8e45d): Downloading (100%) - Installing symfony/config (dev-master a20ae35): Loading from cache - Installing symfony/class-loader (dev-master b0aff75): Loading from cache - Installing psr/simple-cache (dev-master 753fa59): Loading from cache - Installing psr/cache (dev-master 78c5a01): Loading from cache - Installing symfony/cache (dev-master a06e189): Loading from cache - Installing doctrine/cache (dev-master 0da649f): Loading from cache - Installing symfony/framework-bundle (dev-master 312a59d): Downloading (100%) Detected auto-configuration settings for "symfony/framework-bundle" Enabling the package as a Symfony bundle Setting configuration and copying files Adding environment variable defaults Adding Makefile entries Adding entries to .gitignore - Installing symfony/yaml (dev-master dcbd318): Loading from cache - Installing symfony/dotenv (dev-master 0f9d2e0): Loading from cache Writing lock file Generating autoload files Executing script make cache-warmup [OK] Skipping "assets:install --symlink --relative web" (needs symfony/console to run). What's next? * Run your application: 1. Change to the project directory 2. Execute the make serve command; 3. Browse to the http://localhost:8000/ URL. * Read the documentation at https://symfony.com/doc |
你可以发现，composer install 命令输出的内容比没有使用 flex 的内容要丰富很多，比如告诉终端用户，已经自动注册 framework-bundle；将默认配置复制到项目中；将默认环境变量添加到环境中；添加 Makefile 的任务，更新了 .gitignore 里的内容……
另外还告诉用户，因为没有安装 symfony/console，所以无法执行 assets:install 命令，以及安装后提示……
既然已经提示需要安装 symfony/console，那么我们就来安装他，不过，有了 flex，我们可以不用再老老实实用 composer require symfony/console，因为 flex 给 symfony/console 设置了更简短的别名：
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composer req cli |
flex 给很多常用组件都设置了别名，比如 symfony/web-server-bundle：
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composer req webserver |
删除某个依赖的时候，也是可以使用别名的：
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composer rem cli |
你也可以删除 framework-bundle 试试，看看 flex 是如何在删除某个依赖组件后，自动删除相关的配置信息的
最后我们安装一个有意思的完整项目——EasyAdminBundle：
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composer req admin |
然后我们再在 src/Entity/ 目录下，创建 Product.php
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namespace App\Entity; use Doctrine\ORM\Mapping as ORM; /** * @ORM\Entity * @ORM\Table(name="product") */ class Product { /** * @ORM\Column(type="integer") * @ORM\Id * @ORM\GeneratedValue(strategy="AUTO") */ public $id; /** * @ORM\Column(type="string", length=100) */ public $name; /** * @ORM\Column(type="decimal", scale=2) */ public $price; /** * @ORM\Column(type="text") */ public $description; } |
在 .env 文件可以调整一下数据库连接信息
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###> doctrine/doctrine-bundle ### DB_URL=mysql://root@127.0.0.1:3306/symfony?charset=utf8mb4 ###< doctrine/doctrine-bundle ### |
执行熟悉的创建数据库和表的命令
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bin/console doctrine:database:create bin/console doctrine:schema:update --force |
最后到 etc/packages/easy_admin.yaml 添加要做后台管理的 Entity
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easy_admin: entities: - App\Entity\Product |
此时你可以通过熟悉的启动 web 服务命令来开启一个服务。如果你并不想安装 webserver，也可通过 make 来启动服务
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make serve # or bin/console server:start |
此时访问 http://localhost:8000，就可以访问 admin 的页面了
此外你还可以尝试安装 mailer、profiler 等一大堆准备好的『食谱』，而这些都并不再默认包含在框架代码中，你可以按需安装了。
基于 Symfony 4 的开发示例 by Chrisyue's Blog is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.