Laravel雄辩计数关系 [英] Laravel eloquent counting a relation

问题描述

我是新来的laravel和雄辩，我不知道这是否可能。但我有2个表与一对多的关系。一个是位置，一个是用户。一个位置可以有很多用户。

所以如果我想要获得所有用户的所有位置，我只想这样做：

  Location :: with（users） - > get（）; 
  

但我也想知道每个位置有多少用户，尝试这样做

  Location :: with（users） - > count（users） - > get ）; 
  

但这没有用。

解决方案

如果您使用热心加载，则不会出现提及的n + 1个问题。

  $ locations = Location :: with（'users'） - > get（）; 
 
 $ locations-> users（） - > count（）; 
  

无论您有多少用户或位置，都应该产生三个查询。

• 根据位置模型计数查询


• 从位置选择*


• 从

中的用户选择*来自这一点也可以产生混淆：

  $ locations = Location :: all（）; 
 
 $ locations-> users（） - > count（）; 
  

但是在这种情况下，它会为每个位置查询一次。

查看文档了解更多信息：
http：// laravel .com / docs / eloquent＃eager-loading

I'm new to laravel and eloquent and I'm not sure if this is even possible. but I have 2 tables with a one to many relationship. One is "locations" and one is "users". One location can have many users.

So if I wanted to get all locations with all users I would just do this:

Location::with("users")->get();

But I also want to know how many users each location has, I tried doing this

Location::with("users")->count("users")->get();

But that didn't work.

解决方案

The n+1 issue that was mentioned doesn't occur if you use eager loading.

$locations = Location::with('users')->get();

$locations->users()->count();

This should result in three queries, no matter how many users or locations you have.

• count query against the location model
• select * from locations
• select * from users where in

The confusion arises from the fact that this also works:

$locations = Location::all();

$locations->users()->count();

But in this case, it does query once for each location.

See the docs for more info: http://laravel.com/docs/eloquent#eager-loading

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