Laravel/Eloquent : hasManyThrough WHERE

2021-12-26 00:00:00 php laravel eloquent relational-database

在 Eloquent 的文档中，据说我可以将所需关系的键传递给 hasManyThrough.

In the documentation of Eloquent it is said that I can pass the keys of a desired relationship to hasManyThrough.

假设我有名为 Country、User、Post 的模型.通过用户模型，国家模型可能有许多帖子.也就是说，我可以直接调用:

Lets say I have Models named Country, User, Post. A Country model might have many Posts through a Users model. That said I simply could call:

$this->hasManyThrough('Post', 'User', 'country_id', 'user_id');

到目前为止一切正常！但是我如何才能只为 id 为 3 的用户获取这些帖子?

有人可以帮忙吗?

推荐答案

就这样:

models: Country 有很多 User 有很多 Post

models: Country has many User has many Post

这允许我们在您的问题中使用 hasManyThrough :

This allows us to use hasManyThrough like in your question:

// Country model
public function posts()
{
  return $this->hasManyThrough('Post', 'User', 'country_id', 'user_id');
}

您想获取此关系的给定用户的帖子，因此:

You want to get posts of a given user for this relation, so:

$country = Country::first();
$country->load(['posts' => function ($q) {
  $q->where('user_id', '=', 3);
}]);
// or
$country->load(['posts' => function ($q) {
  $q->has('user', function ($q) {
    $q->where('users.id', '=', 3);
  });
})

$country->posts; // collection of posts related to user with id 3

<小时>

但是如果你改用它，它会更容易、更易读和更有说服力:(因为当您在寻找 id 为 3 的用户的帖子时，它与国家无关)

BUT it will be easier, more readable and more eloquent if you use this instead: (since it has nothing to do with country when you are looking for the posts of user with id 3)

// User model
public function posts()
{
  return $this->hasMany('Post');
}

// then
$user = User::find(3);
// lazy load
$user->load('posts');
// or use dynamic property
$user->posts; // it will load the posts automatically
// or eager load
$user = User::with('posts')->find(3);

$user->posts; // collection of posts for given user

总结一下:hasManyThrough是一种直接获取嵌套关系的方法，即.给定国家/地区的所有帖子，而不是搜索特定的 through 模型.

To sum up: hasManyThrough is a way to get nested relation directly, ie. all the posts for given country, but rather not to search for specific through model.

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