如何在 Laravel 中使用 eloquent 基于多对多关系从表中检索记录？

Question

我有三个模型：国籍、国籍_机会、机会。

表格：

-------------------------------------------------------------------
   nationalities   |  nationality_opportunities   |   opportunities
--------------------------------------------------------------------
        id                    nationality_id             id
        name                  opportunity_id             name   

在机会模型中：

 public function nationalities(): \Illuminate\Database\Eloquent\Relations\BelongsToMany
    {
        return $this->belongsToMany(Nationality::class,'nationality_opportunities','opportunity_id','nationality_id');
    }

在国籍模型中：

 public function opportunities()
    {
        return $this->belongsToMany(Opportunity::class,'nationality_opportunities','opportunity_id','nationality_id');

    }

-我想做什么？

我想根据他们选择的国籍检索机会记录，这些记录通过请求作为 id 数组发送，所以我想在数据透视表中检查这些 id 以获取它们的相关机会记录并将它们显示在一个 Vue js 组件。

机会模型中的范围过滤器：

    public function scopeWithFilters($query)
    {
        return $query->when(count(request()->input('categories', [])), function ($query) {

            $query->whereIn('opp_cat_id', request()->input('categories'));

        })->when(count(request()->input('nationalities',[])),function ($query){

            $query->whereIn('nationalities.nationality_id', request()->input('nationalities'));

        });
    }

参数：nationalities = [1,2,3,5]。

api 控制器中的属性函数：

 public function opportunities()
    {
        $opportunities = Opportunity::withFilters()->get();

        return PublicOpportunityResource::collection($opportunities);
    }

Answer 1

您的查询是正确的，但您需要更改当天的返回方式请关注

$nationalities = [1,2,3,5]; //for temperory ids you can change it
$data= Nationality::with('opportunities')->whereIn('id', $nationalities)->get();

//return it as below
return response()->json($nationalities);

Answer 2

您可以使用下面的代码简单地获取机会

$nationalities = Nationality::with('opportunities')->whereIn('id', request()->input('nationalities'))->get(); 

然后您可以通过迭代$nationalities 来访问机会，或者对于第一行您可以使用$nationalities->first()->opportunities，但不确定您为什么在回调函数中使用when。

根据编辑，您可以针对您想要的结果进行此查询

$nationalities = request()->input('nationalities');

$opportunities = Opportunity::with(['nationalities' => fn($q) => $q->whereIn('nationality_id', $nationalities)])->get();