所以，我从Laravel收到以下错误：
SQLSTATE[42000]: Syntax error or access violation: 1066 Not unique table/alias: 'participants' (SQL: select `participants`.*, `participants`.`message_id` as `pivot_message_id`, `participants`.`user_id` as `pivot_user_id`, `participants`.`created_at` as `pivot_created_at`, `participants`.`updated_at` as `pivot_updated_at` from `participants` inner join `participants` on `participants`.`id` = `participants`.`user_id` where `participants`.`deleted_at` is null and `participants`.`message_id` in (2))
我的留言/参与者关系如下：
public function participants()
{
return $this->belongsToMany('Namespace\Modules\Email\Models\Participant', 'participants', 'message_id', 'user_id')->withTimestamps();
}
我想这样称呼它：
public function getAllMessages()
{
return Message::with('user')->with('participants')->get();
}
为什么我收到此错误？到底是怎么回事？
编辑：包含完整模型
消息 class Message扩展了Eloquent { 使用PublishedTrait; 使用SoftDeletingTrait;
/**
* The database table used by the model.
*
* @var string
*/
protected $table = 'messages';
/**
* The attributes that can be set with Mass Assignment.
*
* @var array
*/
protected $fillable = ['subject', 'user_id', 'body', 'status'];
/**
* The attributes that should be mutated to dates.
*
* @var array
*/
protected $dates = ['created_at', 'updated_at', 'deleted_at'];
/**
* Validation rules.
*
* @var array
*/
protected $rules = [
'subject' => 'required|max:255',
'body' => 'required',
];
/**
* User relationship
*
* @return \Illuminate\Database\Eloquent\Relations\BelongsTo
*/
public function user()
{
return $this->belongsTo(Config::get('email.user_model'));
}
public function assets()
{
return $this->belongsToMany('Namespace\Modules\Assets\Models\Asset', 'message_assets');
}
/**
* Participants relationship
*
* @return \Illuminate\Database\Eloquent\Relations\HasMany
*/
public function participants()
{
return $this->belongsToMany('Namespace\Modules\Email\Models\Participant', 'participants', 'message_id', 'user_id')->withTimestamps();
}
/**
* Recipients of this message
*
* @return \Illuminate\Database\Eloquent\Relations\HasMany
*/
public function recipients()
{
return $this->participants()->where('user_id', '!=', $this->user_id);
}
/**
* Returns the latest message from a thread
*
* @return Namespace\Modules\Email\Models\Message
*/
public function getLatestMessageAttribute()
{
return $this->messages()->latest()->first();
}
/**
* Returns threads that the user is associated with
* @param $query
* @param $userId
* @return mixed
*/
public function scopeForUser($query, $userId)
{
return $query->join('participants', 'messages.id', '=', 'participants.message_id')
->where('participants.user_id', $userId)
->where('participants.deleted_at', null)
->select('messages.*');
}
/**
* Returns threads that the user is associated with
* @param $query
* @param $userId
* @return mixed
*/
public function scopeForUserWithDeleted($query, $userId)
{
return $query->join('participants', 'messages.id', '=', 'participants.message_id')
->where('participants.user_id', $userId)
->select('messages.*');
}
/**
* Returns messages that the user has sent
* @param $query
* @param $userId
* @return mixed
*/
public function scopeByUser($query, $userId)
{
return $query->where('user_id', $userId);
}
/**
* Returns threads with new messages that the user is associated with
* @param $query
* @param $userId
* @return mixed
*/
public function scopeForUserWithNewMessages($query, $userId)
{
return $query->join('participants', 'messages.id', '=', 'participants.message_id')
->where('participants.user_id', $userId)
->whereNull('participants.deleted_at')
->where(function ($query) {
$query->where('messages.updated_at', '>', $this->getConnection()->raw($this->getConnection()->getTablePrefix() . 'participants.last_read'))
->orWhereNull('participants.last_read');
})
->select('messages.*');
}
}
参与者
class Participant extends Eloquent
{
use SoftDeletingTrait;
/**
* The database table used by the model.
*
* @var string
*/
protected $table = 'participants';
/**
* The attributes that can be set with Mass Assignment.
*
* @var array
*/
protected $fillable = ['message_id', 'user_id', 'last_read'];
/**
* The attributes that should be mutated to dates.
*
* @var array
*/
protected $dates = ['created_at', 'updated_at', 'deleted_at', 'last_read'];
/**
* Thread relationship
*
* @return \Illuminate\Database\Eloquent\Relations\BelongsTo
*/
public function message()
{
return $this->hasMany('Namespace\Modules\Email\Models\Message');
}
/**
* User relationship
*
* @return \Illuminate\Database\Eloquent\Relations\BelongsTo
*/
public function user()
{
return $this->belongsTo(Config::get('email.user_model'));
}
}
答案 0 :(得分：8)
Answered via the Larachat official Slack:
The relationship is missing a pivot table for this to work. The second argument in the participants method is the pivot table to use:
public function participants()
{
return $this->belongsToMany('Namespace\Modules\Email\Models\Participant', 'PIVOT', 'message_id', 'user_id')->withTimestamps();
}
Therefore, you can't use participants as the pivot because it is one of the tables in the relationship, you need a message_participant pivot table.
答案 1 :(得分：2)
您的错误是
...from `participants` inner join `participants` ...
您需要为每个引用提供别名，如
...from `participants` p1 inner join `participants` p2 ...
然后在正确的位置使用p1和p2，例如
...on p1.`id` = p2.`user_id` ...
（我猜测哪个是p1，哪个是p2;你必须做出这个决定）
答案 2 :(得分：0)
只需确保同一联接在单个查询中应用了多次。
答案 3 :(得分：0)
为以后遇到此错误的任何人解答此问题。
从您的表记录来看，participants table似乎是pivot table和users之间的messages。您正在引用数据透视表，从而导致数据库行为异常。
正确的方法是在您的users模型中：
public function messages(){
return $this->belongsToMany(Message::class, 'participants', 'user_id', 'message_id')->withPivot('last_read');
}
在您的messages模型中：
public function users(){
return $this->belongsToMany(User::class, 'participants', 'message_id', 'user_id')->withPivot('last_read');
}
这样，当您从用户呼叫消息时，请使用以下方法：
$messages = $user->messages()->get();
当您检查用户的消息时，
$user = $message->users()->get()
最后一次阅读
$last_read = $message->pivot->last_read;