php - Laravel 4.2 中无法识别外键

Question

根据Dayle Rees

All foreign key columns follow a similar naming convention. The singular form of the related model appended with _id.

考虑此迁移:

class CreateTables extends Migration {
// ...
    public function up()
    {
    Schema::create('artists', function($table) {
        $table->increments('id');
        $table->string('name',64);
        $table->timestamps();
    });
    Schema::create('albums', function($table) {
        $table->increments('id');
        $table->string('name',64);
        $table->integer('artist_id')->unsigned();
        $table->foreign('artist_id')->references('id')->on('artists');
        $table->timestamps();
    });
}

这是我的 Eloquent 模型:

<?php
// Artist model
class Artist extends Eloquent {
    public function albums() {
        return $this->hasMany('Album');
    }
}

<?php
// Album model
class Album extends Eloquent {
    public function artists() {
        return $this->belongsTo('Artist');
    }
}

我这样使用它们:

Route::get('/', function() {
    $artist = new Artist;
    $artist->name = "Morbid Angel";
    $artist->save();
    $album = new Album;
    $album->name = "Altars of Madness";
    $album->artists()->associate($artist);
    $album->save();
    return View::make('hello');
});

根据日志，这似乎不起作用:

[2015-06-09 06:01:12] production.ERROR: exception 'PDOException' with message 'SQLSTATE[42S22]: Column not found: 1054 Unknown column 'artists_id' in 'field list''

但我没有创建artists_id。这是什么意思？ laravel 不应该找到 artist_id 因为它应该是单数，后面跟着 _id 吗？

Answer 1

这是你的问题。您已将您的关系命名为 artists，但它应该是 artist。这就是为什么它要查找名为 artists_id 的列。

您应该如下定义您的关系，因为在我看来它是一对多。

在您的艺术家模型中

public function albums()
{
    return $this->hasMany('Album');
}

在您的相册模型中

public function artist()
{
    return $this->belongsTo('Artist');
}

然后尝试您的代码。

Route::get('/', function() {
    $artist = new Artist;
    $artist->name = "Morbid Angel";
    $artist->save();

    $album = new Album;
    $album->name = "Altars of Madness";

    $artist->albums()->save($album);

    return View::make('hello');
});