Laravel外键有什么问题？

Question

我正尝试使用Laravel的迁移来创建外键。

Schema::create('articles', function (Blueprint $table) { 
     $table->increments('id'); 
     $table->integer('user_id')->unsinged(); 
     $table->string('title'); 
     $table->longText('body'); 
     $table->timestamp('published_at'); 
     $table->timestamps(); 

    }); 


    Schema::table('articles', function($table) { 
     $table->foreign('user_id') 
      ->references('id') 
      ->on('users') 
      ->onDelete('cascade'); 

    }); 

我收到以下错误，当我做php artisan migrate

[Illuminate\Database\QueryException]
SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter ta ble laravel_articles add constraint articles_user_id_foreign foreign key (user_id ) references laravel_users (id) on delete cascade) `

Answer 1

你有方法的名称拼写错误。它应该是unsigned()不unsinged()：

Schema::create('articles', function (Blueprint $table) { 
    $table->increments('id'); 
    $table->integer('user_id')->unsigned(); 
    $table->string('title'); 
    $table->longText('body'); 
    $table->timestamp('published_at'); 
    $table->timestamps(); 
}); 

的架构Builder使用Fluent到链中的方法，即使链式方法unsinged不存在不抛出异常。尽管有错字，articles表仍然会被创建，但user_id列将是一个有符号的整数，并且由于users表中的id列是无符号整数，所以它将阻止创建约束。