Laravel belongsToMany.belongsTo 嵌套关系查询 where child column = parent id答案

【问题标题】：Laravel belongsToMany.belongsTo nested relationship query where child column = parent idLaravel belongsToMany.belongsTo 嵌套关系查询 where child column = parent id
【发布时间】：2020-01-20 18:56:29
【问题描述】：

我有两个模型（和具有 Laravel 命名约定的数据库表），我正在尝试使用 Equipment 和 Equipment.collection_meters 预先加载 Collections，其中 collection_meter 等于 Collection.id。

如何访问子关系$query->with中的collections.id？

或

如何访问子关系$query->with中的equipment.pivot.collection_id？

这是我的模型...

class Collection extends Model {
    public function equipment() {
        return $this->belongsToMany(Equipment::class, 'collection_equipment', 'collection_id', 'equipment_id')->withTimestamps();
    }
}

class CollectionMeter extends Model {
    public function equipment() {
        return $this->belongsTo(Equipment::class); 
    }
}

class Equipment extends Model {
    public function collection_meters() {
        return $this->hasMany(CollectionMeter::class)->latest(); // ->currentStatus('active')
    }
}

equipment_id 列在collection_meters 表中

这是我尝试过的代码，但我似乎无法在子关系查询中获得Collection.id。如果我忽略了孩子$query->where，我会得到ALL的equipment.equipment_meters。

$collections = Collection::with([
    'equipment',
    'equipment.collection_meters' => function($query) {
        $query->where('collection_meters.collection_id', '=', 'collections.id');
    }
])
->get();

我已经尝试用这些代替'collections.id'，结果相同 'equipment.pivot.collection_id' 'equipment.collection_id'

我确实在[equipment] => Array 中看到了这个，我可以通过某种方式访问$query->where 中的[collection_id] => 2 吗？

[pivot] => Array
    (
        [collection_id] => 2
        [equipment_id] => 1
        [created_at] => 2019-09-17 00:17:00
        [updated_at] => 2019-09-17 00:17:00
    )

没有$query->with 的结果（[collection_meters] 有 ALL）

$query->with 的结果（[collection_meters] 为空）

Array
(
    [0] => Array
        (
            [id] => 2
            [name] => Name of Collection
            [operator_id] => 1
            [location_id] => 4
            [account_id] => 1
            [date_time] => 2019-09-16 04:41:26
            [reconciliation_id] => 
            [created_by_id] => 1
            [updated_by_id] => 1
            [created_at] => 2019-09-16 23:44:43
            [updated_at] => 2019-09-18 17:32:53
            [equipment] => Array
                (
                    [0] => Array
                        (
                            [id] => 1
                            [name] => Name of Equipment
                            [ims_identifier] => AFA-64
                            [operator_identifier] => 073076-01
                            [equipment_model_id] => 1
                            [operator_id] => 1
                            [location_id] => 4
                            [created_by_id] => 1
                            [updated_by_id] => 1
                            [created_at] => 2019-07-17 13:17:28
                            [updated_at] => 2019-08-14 00:04:07
                            [pivot] => Array
                                (
                                    [collection_id] => 2
                                    [equipment_id] => 1
                                    [created_at] => 2019-09-17 00:17:00
                                    [updated_at] => 2019-09-17 00:17:00
                                )

                            [collection_meters] => Array
                                (
                                )

                        ) ...

预期结果（[collection_meters] 具有 [id] => 2 等于 [collection_id] => 2）

【问题讨论】：

标签： laravel eloquent relationship has-and-belongs-to-many belongs-to

【解决方案1】：

你使用什么样的关系？ “多对多”还是“一对多”？如果您有三个表，其中一个是“pivot”表，则必须在两个模型中将关系定义为 belongsToMany：

class Collection extends Model {

    public function equipments() {
        return $this->belongsToMany(Equipment::class, 'collection_equipment', 
        'collection_id', 'equipment_id')->withTimestamps();
    }
}

数据透视表的名称是什么？收集设备？你的结构怎么样？

collections => collection_equipment

class Equipment extends Model {

    public function collections() {
       return $this->belongsToMany(Collection::class, 'collection_equipment', 
       'equipment_id', 'collection_id')->withTimestamps();
    }
}

collection_meters 列在哪里？在装备表里？

那么，如果要获取嵌套表信息，只需：

$collections = Collection::with('equipments')->get();

但有时您想使用枢轴模型获取信息：

class CollectionEquipment extends Model {

    protected $table = 'collection_equipment';

    public function collection() {
       return $this->belongsTo(Collection::class, 'collection_id');
    }

    public function equipment() {
       return $this->belongsTo(Equipment::class, 'equipment_id');
    }

}

那么，只需：

$collections = CollectionEquipment::with(['equipment', 'collection'])
               ->get();

由于您已经在所有模型类中定义了 collection_id 和 equipment_id，因此您不需要像使用“join”那样在查询中映射它们

【讨论】：

我已经编辑了我的问题...抱歉，我忘记了Equipment 关系...public function collection_meters() { return $this->hasMany(CollectionMeter::class)->latest(); }
那么，您是否在设备和 CollectionMeter 之间存在“一对多”关系，而在集合和设备之间存在“一对多”关系？如果是这样，我将编辑我的答案
是的，@alexandre-barbosa，这正是我所拥有的……one to manyequipment 和 CollectionMeter 之间的关系以及 collection 和 equipment 之间的另一个 one to many 关系
您可以从我发布的Results (toArray()'s) 中看到，我可以获得所有collection_meters 或没有collection_meters，但不是唯一与@ 匹配的987654337@（根）
我需要这个……在从上面急切加载的场景中……WHERE collection_meters.equipment_id in (1, 5, 9, 10, 11, 12, 16) AND collection_meters.collection_id = collections.id