显示一个数组，但返回空

Question

早上好，我有一个laravel 5.8项目，但我遇到了一些问题 我有这个代码

public function doctor_details($doctor_id){

$doctor = DB::table('doctors')->select('specification')->where('doctor_id', $doctor_id)->get>first(); 

$specs_data = explode(',', $doctor_specs);
$specs_array = [];

foreach ($specs_data as $doctor_spec) {

    $doctor_spec_result =  DB::table('specializations')->where { return explode('speciality_id'',', $doctor_spec)->get();

    foreach ($doctor_spec_result as $doctor_spec_res) {

        $specs_array[] = $doctor_spec_res->speciality_name;

    }  
 }

return view ('doctor_details', compact('doctor', 'specs_array'));

}

现在我是否做dd（$ doctor_spec_result）;结果是

如您所见，我得到一个空数组，但是如果我做dd（$ specs_data）;结果是

如您所见，肯定有数据，但我无法使其工作

这是我的刀刃

<div class="row">
     <div class="col-lg-12">
         <h3>{{ $doctor->doctor_name }}</h3>
     </div>
     <div class="col-lg-12">
         @foreach( $specs_array as $spec_output )
             <p>{!! $spec_output !!}</p>
         @endforeach
     </div>
 </div>

Answer 1

我认为您正在尝试获取仅包含所查询的特定行的specification字段值的列表，以便随后可以获取specialty_name。您可以在构建器上使用pluck方法来为您执行此操作。如果doctor_id进行的搜索可以返回多个结果：

$doctor_specs = DB::table('doctors')
    ->where('doctor_id', $doctor_id)
    ->pluck('specification')
    ->transform(function ($item) { return explode(',', $item); })
    ->flatten();

$specs_array = DB::table('specializations')
    // use whereIn to find all the rows by 'specialty_id'
    ->whereIn('speciality_id', $doctor_specs)
    ->pluck('specialty_name')
    ->toArray();

return view ('doctor_details', compact('doctor', 'specs_array'));

Laravel 6.x Docs - Database - Query Builder - Retrieving Results pluck

Laravel 6.x Docs - Collections - Methods - transform

Laravel 6.x Docs - Collections - Methods - flatten

更新：

尽管doctor_id是一个密钥，但是只有一个，因此我们可以删除收集方法并简化处理：

$doctor_specs = explode(
    ',',
    DB::table('doctors')->where('doctor_id', $doctor_id)
        ->value('specification')
);

理想：

或者如果$doctor是从doctors表的所有列中检索到的，包括specification：

$doctor_specs = explode(',', $doctor->specification);

Answer 2

您可以使用join简化代码

$doctor_spec_result = DB::table('doctors')
->select('specializations.speciality_name')
->join('specializations','specializations.speciality_id','doctors.specification')
->where('doctors.doctor_id', $doctor_id)
->get();

return view ('doctor_details', compact('doctor', 'doctor_spec_result '));

Answer 3

更改此行。

 $doctor_spec_result = DB::table('specializations')->where('speciality_id', $doctor_spec)->get();

您正在检查Wearg属性。当您在0索引中获得规格时。

speciality_id to specification