Laravel hasManyThrough
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Laravel hasManyThrough
提问by Greg
I'm struggling to get my head around a hasManyThrough concept with laravel. I have three tables:
我正在努力理解 laravel 的 hasManyThrough 概念。我有三个表：
Bookings
-id (int)
-some other fields
Meta
-id (int)
-booking_id (int)
-metatype_id (int)
-some other fields
MetaType
-id (int)
-name (string)
-some other fields
What I am trying to get is an Eloquent model that allows me to have a single booking record with multiple Meta records of type MetaType. I thought that hasManyThrough might have solved this, but now I am thinking that perhaps this is not the best way.
我想要得到的是一个 Eloquent 模型，它允许我拥有一个带有多个 MetaType 类型的 Meta 记录的单一预订记录。我认为 hasManyThrough 可能已经解决了这个问题，但现在我认为这可能不是最好的方法。
In my booking model I have
在我的预订模型中，我有
public function bookingmeta() {
return $this->hasMany('bookingmeta','booking_id');
}
public function bookingmetatype() {
return $this->hasManyThrough('bookingmetatype','bookingmeta','booking_id','bookingmetatype_id');
}
But this fails to generate the correct SQL and fails. I get
但这无法生成正确的 SQL 并失败。我得到
select `new_bookingmetatype`.*, `new_bookingmeta`.`booking_id`
from `new_bookingmetatype`
inner join `new_bookingmeta`
on `new_bookingmeta`.`bookingmetatype_id` = `new_bookingmetatype`.`id`
where `new_bookingmeta`.`booking_id` in (57103)
Whereas what I am really trying to achieve is
而我真正想要实现的是
select `new_bookingmetatype`.*, `new_bookingmeta`.`booking_id`
from `new_bookingmetatype`
inner join `new_bookingmeta`
on `new_bookingmeta`.`id` = `new_bookingmetatype`.`bookingmetatype_id`
where `new_bookingmeta`.`booking_id` in (57103)
If anyone can point me in the right direction I'd really appreciate it. Thanks.
如果有人能指出我正确的方向，我将不胜感激。谢谢。
回答by Jarek Tkaczyk
hasManyThroughis not the way at all. It works only for relations like this:
hasManyThrough根本不是办法。它只适用于这样的关系：
A hasMany/hasOne B, B hasMany/hasOne C, then A hasManyThrough C (through B)
What you have here is a many to many (belongsToMany), with metabeing the pivot table.
您在这里拥有的是多对多 ( belongsToMany)，meta作为数据透视表。
So you can do this (assuming metais table name, Booking and MetaType are models):
所以你可以这样做（假设meta是表名，Booking 和 MetaType 是模型）：
// Booking model
public function meta()
{
return $this->belongsToMany('MetaType', 'meta', 'booking_id', 'metatype_id')
->withPivot([ ARRAY OF FIELDS YOU NEED FROM meta TABLE ]);
}
Then you can access all associated MetaType:
然后你可以访问所有关联的 MetaType：
$booking->meta; // collection of MetaType models
query it like this (eager loading):
像这样查询（急切加载）：
$booking = Booking::with(['meta' => function ($q) {
// query related table
$q->where('someFieldOnMetaTypeTable', 'someValue')
// and / or pivot table
->wherePivot('someFieldOnMetaTable', 'anotherValue');
}])->first();
or set constraints on the related table to filter the Booking:
或在相关表上设置约束以过滤预订：
$booking = Booking::whereHas('meta', function ($q) {
// query related table
$q->where('someFieldOnMetaTypeTable', 'someValue')
// and / or pivot table
->where('meta.someFieldOnMetaTable', 'anotherValue');
})->first();
Note: wherePivotworks only when you eager load the relationship, so you can't use it in whereHasclosure.
注意：wherePivot仅当您急切加载关系时才有效，因此您不能在whereHas闭包中使用它。
