# EloquentORM關聯關系之多對多多態關聯 多對多多態最常見的應用場景就是標簽，比如一篇文章對應多個標簽，一個視頻也對應多個標簽，同時一個標簽可能對應多篇文章或多個視頻，這就是所謂的“多對多多態關聯”。 此時僅僅在標簽表 `tags` 上定義一個 `item_id` 和 `item_type` 已經不夠了，因為這個標簽可能對應多個文章或視頻，那么如何建立關聯關系呢，我們可以通過一張中間表 `taggables` 來實現：該表中定義了文章/視頻與標簽的對應關系。 ## 軟件版本 * Laravel Version 5.4.19 * PHP Version 7.0.8 ## 關鍵字和表 * `morphToMany()` * `morphedByMany()` * `attach()` * `detach()` * `sync()` * `toggle()` * `posts` 、`videos` 、`tags`、`taggables` 和 `users` 表 ## 生成模型和遷移文件 ``` php artisan make:model Post -m php artisan make:model Video -m php artisan make:model Tag -m php artisan make:model Taggable -m ``` ### 編輯遷移文件 文件 `<project>/database/migrate/*_create_users_table.php` 內容如下 ``` Schema::create('users' , function(Blueprint $table){ $table->increments('id'); $table->string('name'); $table->string('email' , 30)->unique(); $table->string('password'); $table->rememberToken(); $table->timestamps(); }); ``` 文件 `<project>/database/migrate/*_create_posts_table.php` 內容如下 ``` Schema::create('posts' , function(Blueprint $table){ $table->increments('id'); $table->unsignedInteger('user_id'); $table->string('title' , 60); $table->unsignedInteger('views')->comment('瀏覽數'); $table->text('body'); $table->timestamp('published_at')->nullable(); $table->timestamps(); $table->foreign('user_id') ->references('id') ->on('users') ->onUpdate('cascade') ->onDelete('cascade'); }); ``` 文件 `<project>/database/migrate/*_create_videos_table.php` 內容如下 ``` Schema::create('videos' , function(Blueprint $table){ $table->increments('id'); $table->unsignedInteger('user_id')->comment('用戶id'); $table->unsignedTinyInteger('status')->comment('數據狀態'); $table->string('title' , 30)->comment('標題'); $table->string('description' , 120)->comment('描述'); $table->text('body')->comment('內容'); $table->timestamps(); $table->foreign('user_id') ->references('id') ->on('users') ->onUpdate('cascade') ->onDelete('cascade'); }); ``` 文件 `<project>/database/migrate/*_create_tags_table.php` 內容如下 ``` Schema::create('tags', function (Blueprint $table) { $table->increments('id'); $table->string('name',20)->default('')->comment('標簽名'); $table->timestamps(); }); ``` 文件 `<project>/database/migrate/*_create_taggables_table.php` 內容如下 ``` Schema::create('taggables' , function(Blueprint $table){ $table->increments('id'); $table->unsignedInteger('taggable_id')->comment('數據id'); $table->string('taggable_type' , 40)->comment('關聯模型'); $table->unsignedInteger('tag_id')->comment('標簽id'); $table->timestamps(); }); ``` ### 運行 php artisan 命令保存修改到數據庫 ~~~ php artisan migrate ~~~ > 執行上面的命令后數據庫將生成七張表， > migrations > password_resets > posts > taggables > tags > users > videos ## 定義關聯關系和修改模型的 fillable 屬性 在 `Post` 模型中定義關聯關系： ``` public function tags() { return $this->morphToMany('App\Tag','taggable'); } ``` 在 `Video` 模型中定義關聯關系： ``` public function tags() { return $this->morphToMany('App\Tag','taggable'); } ``` 在 `Tag` 模型中定義關聯關系： ``` public $timestamps = false; // 多對多多態關聯 public function posts() { return $this->morphedByMany('App\Post','taggable')->withTimestamps(); } // 多對多多態關聯 public function videos() { return $this->morphedByMany('App\Video','taggable')->withTimestamps(); } ``` ## 使用 tinker 填充數據 修改?`/databases/factories/ModelFactory.php`，新增關聯數據。 ``` /** @var \Illuminate\Database\Eloquent\Factory $factory */ $factory->define(App\User::class, function (Faker\Generator $faker) { static $password; return [ 'name' => $faker->name, 'email' => $faker->unique()->safeEmail, 'password' => $password ?: $password = bcrypt('secret'), 'remember_token' => str_random(10), ]; }); $factory->define(App\Post::class, function (Faker\Generator $faker) { $user_ids = \App\User::pluck('id')->toArray(); return [ 'user_id' => $faker->randomElement($user_ids), 'title' => $faker->title, 'body' => $faker->text(), 'views' => $faker->numberBetween(0, 1000), ]; }); $factory->define(App\Video::class, function (Faker\Generator $faker) { $user_ids = \App\User::pluck('id')->toArray(); return [ 'user_id' => $faker->randomElement($user_ids), 'title' => $faker->title, 'body' => $faker->text(), 'description' => $faker->title, 'status' => 1 ]; }); $factory->define(App\Tag::class, function (Faker\Generator $faker) { return [ 'name' => $faker->lastName, ]; }); ``` 使用 tinker 命令 ~~~ php artisan tinker ## 進入到 tinker 界面執行如下命令 namespace App factory(User::class,4)->create(); // 生成4個用戶 factory(Post::class,20)->create() // 生成20條 posts 表的測試數據 factory(Video::class,20)->create() // 生成20條 videos 表的測試數據 ~~~ ## 關聯操作 ### 新增數據 #### 添加一個文章標簽 ``` $tag = new \App\Tag(['name' => 'A Post Tag For 1.']); $post = \App\Post::find(1); $post->tags()->save($tag); // 新增的 `tag` 模型中 `taggable_id` 和 `taggable_type` 字段會被自動設定 ``` #### 添加多個文章標簽 ``` $tags = [ new \App\Tag(['name' => 'A Post Tag For 2.']), new \App\Tag(['name' => 'A Post Tag For 2.']) ]; $post = \App\Post::find(2); $post->tags()->saveMany($tags); // 新增的 `tag` 模型中 `taggable_id` 和 `taggable_type` 字段會被自動設定 ``` #### 添加一個視頻標簽 ``` $tag = new \App\Tag(['name' => 'A Post Tag For 2.']); $video = \App\Video::find(2); $video->tags()->save($tag); // 新增的 `tag` 模型中 `taggable_id` 和 `taggable_type` 字段會被自動設定 ``` #### 添加多個視頻標簽 ``` $tags = [ new \App\Tag(['name' => 'A Video Tag For 1.']), new \App\Tag(['name' => 'A Video Tag For 1.']), ]; $video = \App\Video::find(1); $video->tags()->saveMany($tags); ``` ### 刪除數據 #### 刪除一篇文章下的所有標簽 ``` $post = \App\Post::find(1); $post->tags()->delete(); // 刪除tags Table 中的關聯數據 $post->tags()->detach(); // 同步刪除 toggables Table中的關聯數據 ``` ### 查詢數據 #### 查詢一篇文章的標簽 ``` $post = \App\Post::find(2); $tags = $post->tags; ``` #### 查詢一個視頻的標簽 ``` $video = \App\Video::find(1); $tags = $video->tags; ``` #### 查詢標簽對應節點 ``` $tag = \App\Tag::find(1); $posts = $tag->posts; ``` ### 編輯數據 ## 其他 ### 建立關聯 #### `tags`?跟?`videos`,?`posts`?做關聯 ``` $tag->videos()->attach($video->id); $tag->posts()->attach($post->id); ``` #### `videos`,?`posts`?跟?`tag`?做關聯 ``` $videos->tags()->attach($tag->id); $post->tags()->attach($tag->id); ``` > 將視頻或者文字添加某個標簽 #### 刪除關聯 ``` $tag->videos()->detach($vedio->id); $tag->posts()->detach($post->id); ```