問題描述

我正在使用 Laravel 5.0 開發 Web API，但我不確定我正在嘗試構建的特定查詢.

I'm developing a web API with Laravel 5.0 but I'm not sure about a specific query I'm trying to build.

我的課程如下:

class Event extends Model {

    protected $table = 'events';
    public $timestamps = false;

    public function participants()
    {
        return $this->hasMany('AppParticipant', 'IDEvent', 'ID');
    }

    public function owner()
    {
        return $this->hasOne('AppUser', 'ID', 'IDOwner');
    }
}

和

class Participant extends Model {

    protected $table = 'participants';
    public $timestamps = false;

    public function user()
    {
        return $this->belongTo('AppUser', 'IDUser', 'ID');
    }

    public function event()
    {
        return $this->belongTo('AppEvent', 'IDEvent', 'ID');
    }
}

現在，我想獲取特定參與者的所有事件.我試過:

Now, I want to get all the events with a specific participant. I tried with:

Event::with('participants')->where('IDUser', 1)->get();

但是 where 條件應用于 Event 而不是它的 Participants.以下給了我一個例外:

but the where condition is applied on the Event and not on its Participants. The following gives me an exception:

Participant::where('IDUser', 1)->event()->get();

我知道我可以寫這個:

$list = Participant::where('IDUser', 1)->get();
for($item in $list) {
   $event = $item->event;
   // ... other code ...
}

但是向服務器發送這么多查詢似乎效率不高.

but it doesn't seem very efficient to send so many queries to the server.

使用 Laravel 5 和 Eloquent 通過模型關系執行 where 的最佳方法是什么?

What is the best way to perform a where through a model relationship using Laravel 5 and Eloquent?

推薦答案

對您的關系執行此操作的正確語法是:

The correct syntax to do this on your relations is:

Event::whereHas('participants', function ($query) {
    return $query->where('IDUser', '=', 1);
})->get();

這將返回參與者的用戶 ID 為 1 的事件.如果參與者的用戶 ID 不為 1，則不會返回該事件.

This will return Events where Participants have a user ID of 1. If the Participant doesn't have a user ID of 1, the Event will NOT be returned.

在 https://laravel.com/docs/5.8/eloquent 閱讀更多-relationships#eager-loading

這篇關于Laravel 在關系對象上的位置的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！