Laravel ManyToMany 关系正在反转表名称

Question

我需要让帖子接受我需要的尽可能多的语言，所以我有两个模型 post和 language在后模型中:

public function languages(){
    return $this->belongsToMany(\App\Models\Language::class);
}

在我的语言模型中:

public function posts()
{
    return $this->belongsToMany(\App\Models\Post::class);
}

迁移后:

  Schema::create('posts', function (Blueprint $table) {
        $table->id();
        $table->string('title');
        $table->text('body');
        $table->boolean('puplished')->default(false);
        $table->bigInteger('user_id')->unsigned();
        $table->foreign('user_id')->references('id')->on('users');
        $table->timestamps();
    });

语言迁移:

Schema::create('languages', function (Blueprint $table) {
        $table->id();
        $table->string('text')->unique();
        $table->string('value');
        $table->timestamps();
    });

我还创建了 post_language_table 迁移来连接帖子和语言:

Schema::create('post_language', function (Blueprint $table) {
        $table->id();
        $table->unsignedInteger('post_id');
        $table->unsignedInteger('language_id');
        $table->timestamps();
    });

在我的 Controller 中:

$langs = collect(json_decode($request->languages,true))->pluck('id');
    $post = [];
    $post['body'] = $request->body;
    $post['title'] = $request->title;
    $post['user_id'] = 1;
    $new_post = \App\Models\Post::create($post);
    $new_post->languages()->attach($langs);

但是当我尝试将新记录插入到 tha 数据库时，此错误显示:

Illuminate\Database\QueryException
SQLSTATE[42S02]: Base table or view not found: 1146 Table 'laravel.language_post' doesn't exist (SQL: 
insert into `language_post` (`language_id`, `post_id`) values (1, 4), (3, 4), (4, 4))

所以问题是由于某种原因表名被交换了!

Answer 1

基于模型的数据透视表的 Laravel 约定是 table1_table2 ，其中 table1是字母表中排在第一位的模型的小写单数版本，和 table2是字母表中最后一个模型的小写单数版本。所以在你的情况下，pivot表应该是 language_post ，因为 L 在 P 之前。
您可以在迁移中修改数据透视表:

Schema::create('language_post', ...)

或者在关系上覆盖它: Post.php :

public function languages() {
  return $this->belongsToMany(Language::class, 'post_language');
}

Language.php

public function posts() {
  return $this->belongsToMany(Post::class, 'post_language');
}

第二个参数传递给 belongsToMany是数据透视表的名称。
从文档:

To determine the table name of the relationship's intermediate table, Eloquent will join the two related model names in alphabetical order.

https://laravel.com/docs/8.x/eloquent-relationships#many-to-many