Laravel 属于关系不起作用

Question

我有三个模型，我创建了帖子和评论以及用户。我正在尝试在两者之间建立关系。评论和发布它们都有一个与用户表上的 id 匹配的字段“user_id”。以下是我要设置的关系：

comment.php：

<?php

namespace App;


class Comment extends Model
{
    //
    public function post(){

        return $this->belongsTo(Post::class);
    }



    public function user(){ 

        return $this->belongsTo(User::class);
    }
}

Post.php：

<?php

namespace App;

class Post extends Model
{

    public function comments(){

        return $this->hasMany(Comment::class);
    }

    public function addComment($body, $name, $email){




        $this->comments()->create(compact('body','name','email'));
    }

       public function user(){ // $comment->user->name

        return $this->belongsTo(User::class);
    }
}

用户.php

    <?php

namespace App;
use App\Post;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];

    public function post(){

        return $this->hasMany(Post::class);
    }



}

现在您可以看到评论属于用户，帖子属于用户。

但是，当我尝试通过 tinker 创建新帖子时（没有在数据库上创建用户或登录用户），我可以毫无问题地创建帖子；

这告诉我，帖子必须有用户和评论也必须有用户的关系不起作用！知道如何解决这个问题吗？

迁移：

create_posts_migration：

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreatePostsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('posts', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('user_id');
            $table->string('title');
            $table->text('body');
            $table->string('image');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('posts');
    }
}

create_comment_migration：

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCommentsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('comments', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('post_id');
            $table->integer('user_id');
            $table->string('email');
            $table->string('name');
            $table->string('body');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('comments');
    }
}

Answer 1

在您的迁移中添加外键约束以在创建帖子时检查有效用户，并在创建 cmets 时检查有效用户和帖子。这应该可以解决您的问题。

Schema::create('posts', function (Blueprint $table) {
    $table->increments('id');
    $table->unsignedInteger('user_id');
    $table->string('title');
    $table->text('body');
    $table->string('image');
    $table->timestamps();

    $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
});

Schema::create('comments', function (Blueprint $table) {
    $table->increments('id');
    $table->unsignedInteger('post_id');
    $table->unsignedInteger('user_id');
    $table->string('email');
    $table->string('name');
    $table->string('body');
    $table->timestamps();

    $table->foreign('post_id')->references('id')->on('posts')->onDelete('cascade');
    $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
});

根据您的需要更改onDelete 选项。 cascade 将在删除父级时删除子级关系。