laravel-5 - Eloquent 关系返回空数组

Question

我是 laravel 的新手，我正在尝试实现一些非常基本的东西，但仍然卡住了。

我有两个模型，即 Post.php 和 Like.php

我正在尝试使用 Eloquent 关系获取链接到帖子的所有喜欢，但它返回一个空数组。这是我的代码-

Post.php

public function likes(){
  return $this->hasMany('App\Like');
}

Route.php

Route::get('/', function(){
  $posts = Post::all()->sortByDesc("post_id");
  return view('index')->with(['posts' => $posts]);
});

View.blade.php

@foreach($posts as $post)
  {{ $post->likes }}
@endforeach

我在这里做错了什么？

更新-喜欢表迁移

public function up()
{
    Schema::create('likes', function (Blueprint $table) {
        $table->increments('like_id');
        $table->integer('post_id')->unsigned();
        $table->integer('user_id')->unsigned();
        $table->foreign('post_id')->references('post_id')->on('posts')->onDelete('cascade');
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
        $table->timestamps();
    });
}

迁移后

public function up()
{
    Schema::create('posts', function (Blueprint $table) {
        $table->increments('post_id');
        $table->integer('user_id')->unsigned();
        $table->string('post_message');
        $table->timestamps();
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
    });
}

后模型

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{

  public function user(){
    return $this->belongsTo('App\User');
  }

  public function likes(){
    return $this->hasMany('App\Like');
  }
}

Answer 1

Laravel 期望主键是 id，但您使用的是自定义 post_id。

在你的模型中指定它并调整关系:

class Post extends Model {
    protected $primaryKey = 'post_id';

    public function likes() {
        return $this->hasMany('App\Like', 'post_id');
    }
}