Laravel 多对多急切加载总是返回空结果

Question

我正在尝试获取所有类别的条目，并对其属性进行一些条件。一种关系，标签，应该是预先加载的。

模型看起来像这样

class Tag extends Eloquent {
    protected $table = 'tags';
    protected $guarded = array();
    public function entries()
    {
        return $this->belongsToMany('Entry');
    }
}

class Entry extends Eloquent {
    protected $table = 'entries';
    protected $guarded = array();
    public function tags()
    {
        return $this->belongsToMany('Tag');
    }

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

    public function votes()
    {
        return $this->hasMany('Votes');
    }
}

存在具有双外键 entry_id,tag_id 的表 entry_tag。

我正在尝试使用此代码。 (1)

$testEntries = Entry::with(array('tags' => function($query)
{
    $query->where('tag_id', '=', '1');
}))->get();

但是，它什么也不返回。 即使使用下面的代码也会完全产生 zilch。 (2)

$testEntries = Entry::with('tags')->get();

检查数据库日志，我可以看到查询正常。他们产生 (3)

select `tags`.*, `entry_tag`.`entry_id` as `pivot_entry_id`, `entry_tag`.`tag_id` as `pivot_tag_id` from `tags` inner join `entry_tag` on `tags`.`id` = `entry_tag`.`tag_id` where `entry_tag`.`entry_id` in (?, ?, ?, ?, ?, ?, ?, ?)","bindings":["1","2","3","4","5","6","7","8"]

和 (4)

select `tags`.*, `entry_tag`.`entry_id` as `pivot_entry_id`, `entry_tag`.`tag_id` as `pivot_tag_id` from `tags` inner join `entry_tag` on `tags`.`id` = `entry_tag`.`tag_id` where `entry_tag`.`entry_id` in (?, ?, ?, ?, ?, ?, ?, ?) and `tag_id` = ?","bindings":["1","2","3","4","5","6","7","8","1"]

在手动执行查询时两者都有效（并找到结果）。

我错过了什么？我已经抓了几个小时了！

编辑：

我尝试过显示结果，但没有任何运气，如下所示

Log::debug('testing fetching entries:: ' . json_encode($testEntries));

和

foreach(Entry::with('tags')->get() as $entry)
        {
            Log::debug('test1!! ' . json_encode($entry));           
        }

编辑 2： 我试过用它们的条目来获取标签，就像这样

Tag::with('entries')->get();

但它（连同其他组合）每次都返回零结果。我在想也许我在设置表格的方式上错过了一些基本的东西。以下是尝试 (2) 的完整 sql 输出，以防万一。

{"query":"select * from `entries`","bindings":[],"time":0.33},{"query":"select `tags`.*, `entry_tag`.`entry_id` as `pivot_entry_id`, `entry_tag`.`tag_id` as `pivot_tag_id` from `tags` inner join `entry_tag` on `tags`.`id` = `entry_tag`.`tag_id` where `entry_tag`.`entry_id` in (?, ?, ?, ?, ?, ?, ?, ?)","bindings":["1","2","3","4","5","6","7","8"],"time":0.74}

Answer 1

如果您使用软删除 trait，请检查 deleted_at 是否具有默认值 NULL。