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[英]Laravel - eager loading a method (not a relationship) of an Eloquent model
[英]Laravel: Where selection for Eloquent Eager Loading relationship
我有两个数据库表:
帖子
$table->increments('id');
$table->integer('country_id')->unsigned();
$table->foreign('country_id')->references('id')->on('countries');
国别
$table->increments('id');
$table->string('name', 70);
我使用laravel作为后端。 现在,我想为前端实现过滤数据。 因此,用户可以选择一个国家名称,而laravel仅应使用具有指定名称国家的帖子来回答请求。
如何将此条件添加到现有的分页查询中? 我尝试了这个:
$query = app(Post::class)->with('country')->newQuery();
// ...
if ($request->exists('country')) {
$query->where('country.name', $request->country);
}
// ...
...导致以下错误:
Column not found: 1054 Unknown column 'country.name' in 'where clause' (SQL: select count(*) as aggregate from `posts` where `country`.`name` = Albania)
其中,方法根据Laravel代码库接受参数,
/**
* Add a relationship count / exists condition to the query with where clauses.
*
* @param string $relation
* @param \Closure|null $callback
* @param string $operator
* @param int $count
* @return \Illuminate\Database\Eloquent\Builder|static
*/
public function whereHas($relation, Closure $callback = null, $operator = '>=', $count = 1)
{
return $this->has($relation, $operator, $count, 'and', $callback);
}
所以稍微修改一下代码,
$query = ""
if ($request->has('country'){
$query = Post::with("country")->whereHas("country",function($q) use($request){
$q->where("name","=",$request->country);
})->get()
}else{
$query = Post::with("country")->get();
}
顺便说一下,上面的代码可以简化如下:
$query = ""
if ($request->has('country'){
$query = Post::with(["country" => function($q) use($request){
$q->where("name","=",$request->country);
}])->first()
}else{
$query = Post::with("country")->get();
}
$query = ""
if ($request->has('country'){
$query = Post::with("country")->whereHas("country", function($q) use($request){
$q->where("name","=",$request->country);
})->get()
}else{
$query = Post::with("country")->get();
}
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