laravel 多对多 belonsToMany

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1. 建库，建model

   php artisan make:migration create_tags_table --create=tags
   php artisan make:model Tag

    

2. 加字段

   <?php
   
   use Illuminate\Database\Schema\Blueprint;
   use Illuminate\Database\Migrations\Migration;
   
   class CreateTagsTable extends Migration
   {
   
       public function up()
       {
           Schema::create(‘tags‘, function (Blueprint $table) {
               $table->increments(‘id‘);
               $table->string(‘name‘);
               $table->timestamps();
           });
   　　　　　　//字母顺序，单数形式表名下划线结合定义中间表名
           Schema::create(‘article_tag‘, function (Blueprint $table) {
               $table->integer(‘tag_id‘)->unsigned()->index();
               $table->foreign(‘tag_id‘)->references(‘id‘)->on(‘tags‘)->onDelete(‘cascade‘);
               $table->integer(‘article_id‘)->unsigned()->index();
               $table->foreign(‘article_id‘)->references(‘id‘)->on(‘articles‘)->onDelete(‘cascade‘);
               $table->timestamps();
           });
       }
   
       public function down()
       {
           Schema::drop(‘tags‘);
           Schema::drop(‘article_tag‘);
       }
   }

    

3. 添加关系

   //在Article模型中
       public function tag()
       {
           return $this->belongsToMany(‘App\Tag‘);
       }
   //在Tag中
       public function article()
       {
           return $this->belongsToMany(‘App\Article‘);
       }

    

4. 调用

   $article->tag()->attach($id)
   $tag->article()->attach($id)

    

laravel 多对多 belonsToMany

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原文地址：http://www.cnblogs.com/fenle/p/4808898.html