Laravel Eager Loading 删除子项的空值

Posted 2023-02-16

【中文标题】Laravel Eager Loading 删除子项的空值

【英文标题】：Laravel Eager Loading removing empty values on children

【发布时间】：2021-12-03 14:28:16

【问题描述】：

我有这种急切的加载关系：

$companies = Company::with('employees.records')->get();

如果员工没有记录，我不想将其包含在结果中。这是我的最终查询：

$companies = Company::whereIn('name', ['A', 'B'])->with([
    'employees' => function ($employee) use ($startDate, $endDate) 
        return $employee->with([
            'records' => function ($record) use ($startDate, $endDate) 
                return $record->whereBetween('date', [$startDate, $endDate]);
            
        ]);
    
])->get();

如果有记录或没有员工，我想要的输出：

  "data": [
    
      "id": 1,
      "name": A,
      "records": [] 
    ,
    
      "id": 2,
      "name": B,
      "records": [
        
          "id": 1,
          "name": "Check in at the office.",
          "date": "2018/09/08"
        
      ] 
    
  ]

现在这就是我得到的：

  "data": [
    
      "id": 1,
      "name": A,
      "employees": [
        
          "id": 1,
          "company_id": 1,
          "records": []
        
      ] 
    ,
    
      "id": 2,
      "name": B,
      "employees": [
        
          "id": 1,
          "company_id": 2,
          "records": [
            
              "id": 1,
              "employee_id": 1,
              "name": "Check in at the office.",
              "date": "2018/09/08"
            
          ]
        
      ] 
    
  ]

如果员工没有交易，我如何修改查询以删除记录？需要一些很棒的帮助。

【参考方案1】：

您很可能可以使用 Has Many Through 关系。

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Company extends Model

    /**
     * Get all of the records for the company.
     */
    public function records()
    
        return $this->hasManyThrough(Record::class, Employee::class);
    

https://laravel.com/docs/8.x/eloquent-relationships#has-many-through

那么您的查询将如下所示

$companies = Company::with(['records' => function ($query) use ($startDate, $endDate) 
    $query->whereBetween('date', [$startDate, $endDate]);
])->whereIn('name', ['A', 'B'])->get();

【讨论】：

谢谢！这绝对有很大帮助！