如何在多对多关系中显示查找表的值

Question

我有很多表如下

植物：模型

  public function species()
     {
         return $this->belongsToMany(Species::class,'phyto_species')->withPivot(['destination_id', 
 'preservation_id','weight']);
   
     }

物种：模型

  public function phytos()
     {
         return $this->belongsToMany(Phyto::class,'phyto_species')->withPivot(['destination_id', 
 'preservation_id','weight']);
   
     }

数据透视表

  public function up()
{
    Schema::create('phyto_species', function (Blueprint $table) {
        $table->id();
        $table->integer('phyto_id')->unsigned();
        $table->integer('species_id')->unsigned();
        $table->integer('destination_id')->unsigned();
        $table->integer('preservation_id')->unsigned();
        $table->double('weight', 8,2);
        // $table->double('charge', 8,2);
        $table->softdeletes();
        $table->timestamps();
    });
}

我的另外两个查找表的目的地和保存如下

 public function up()
{
    Schema::create('destinations', function (Blueprint $table) {
        $table->id();
        $table->string('destination_name');
        $table->softdeletes();
        $table->timestamps();
    });
}

 public function up()
{
    Schema::create('preservations', function (Blueprint $table) {
        $table->id();
        $table->string('preservation_name');
        $table->softdeletes();
        $table->timestamps();
    });
}

我的问题是我能够显示重量、物种名称保存 ID 和目的地 ID，但我不想显示保存 ID 和目的地 ID，而是显示保存名称和目的地名称

      @foreach ($phyto->species as $item) 
         <ul>
            <li> 
            {{$item->pivot->weight}} {{$item->species_name}} {{$item->pivot->preservation_id}} {{$item->pivot->destination_id}}
            </li>
        </ul>
        @endforeach

我可以使用下面显示的 sql 查询来获取保存名称和目的地名称，但我正在寻找在关系中使用函数的其他方法

 select phytos.customer_name, phytos.phyto_number, phyto_species.weight, 
 preservations.preservation_name, destinations.destination_name from phytos 
 left join phyto_species on phytos.id = phyto_species.phyto_id left JOIN 
 destinations on destinations.id = phyto_species.destination_id left JOIN 
 preservations on preservations.id = phyto_species.preservation_id limit 5

请帮忙！

Answer 1

第 1 步：

  public function species()
     {
         return $this->belongsToMany(Species::class,'phyto_species')->withPivot(['destination_id', 'preservation_id','weight'])->using(PhytoSpecies::class); //use keyword using and pass pivot table class as a parameter
      }

第 2 步：

 <?php

 namespace App\Models\Consignment;

 use Eloquent as Model;
 use Illuminate\Database\Eloquent\SoftDeletes;
 use \Illuminate\Database\Eloquent\Relations\Pivot; //import pivot class

 /**
  * Class PhytoSpecies
  * @package App\Models\Consignment
  * @version November 24, 2020, 3:32 am UTC
  *
  * @property integer $phyto_id
  * @property integer $species_id
  * @property integer $destination_id
  * @property integer $preservation_id
  * @property number $weight
  */
 class PhytoSpecies extends Pivot //replace Model with Pivot
 {
     use SoftDeletes;

     public $table = 'phyto_species';

     const CREATED_AT = 'created_at';
     const UPDATED_AT = 'updated_at';


     protected $dates = ['deleted_at'];



     public $fillable = [
        'phyto_id',
        'species_id',
        'destination_id',
        'preservation_id',
        'weight'
     ];

     /**
     * The attributes that should be casted to native types.
     *
     * @var array
     */
     protected $casts = [
         'id' => 'integer',
         'phyto_id' => 'integer',
         'species_id' => 'integer',
         'destination_id' => 'integer',
         'preservation_id' => 'integer',
         'weight' => 'float'
     ];

     /**
      * Validation rules
      *
      * @var array
      */
     public static $rules = [
         'phyto_id' => 'required|integer',
         'species_id' => 'required|integer',
         'destination_id' => 'required|integer',
         'preservation_id' => 'required|integer',
         'weight' => 'required|numeric',
         'deleted_at' => 'nullable',
         'created_at' => 'nullable',
         'updated_at' => 'nullable'
     ];

     public function preservation(){
         return $this->belongsTo(Preservation::class); // add this relationship
     }

     public function destination(){
    return $this->belongsTo(Destination::class); // add this relationship
     }


}

第 3 步：

 @foreach ($phyto->species as $item) 
       <ul>
          <li> 
             <strong>
                 {{$item->species_name}} &nbsp&nbsp {{$item->pivot->weight}} {{$item->pivot->preservation->preservation_name}}
             </strong>
          </li>
       </ul>
 @endforeach

参考：Accessing Pivot table "3rd Model relationship" in Laravel Eloquent

How to add additional column relationship in pivot table in Laravel