我被卡在这里2-3小时了
我有一个多对多关系:
class Category extends Model
{
public function news()
{
return $this->belongsToMany('App'News');
}
}
class News extends Model
{
public function categories()
{
return $this->belongsToMany('App'Category');
}
}
我正在努力获取相关类别的最新消息:
$front_categories = Category::with(array(
'news'=>function($query){
$query->where('publish','1')->orderBy('created_at', 'desc')->take(5);}))
->where('in_front', 1)->get();
上面的查询不适合我，它给了总共五个结果，而不是每个类别的5个结果。
根据我对Laravel的了解，你可以试试这样做。
class Category {
public function recentNews()
{
return $this->news()->orderBy('created_by', 'DESC')
->take(5);
}
}
// Get your categories
$front_categories = Category::where('in_front', 1)->get();
// load the recent news for each category, this will be lazy loaded
// inside any loop that it's used in.
foreach ($front_categories as $category) {
$category->recentNews;
}
这与Lê Trần Tiến Trung的答案具有相同的效果，并导致多个查询。这还取决于您是否重用该功能。如果这是一次性的，最好把它放在别的地方。其他方法也可以更加动态，例如创建一个返回类别集合的方法，您可以向它询问特定的数字:
class CategoriesRepository {
public static function getFrontCategories(array $opts = []) {
$categories = Category::where('in_front', 1)->get();
if (!empty($opts) && isset($opts['withNewsCount']))
{
foreach ($categories as $category)
{
$category->recentNews = static::getRecentNewsForCategory(
$category->id,
$opts['withNewsCount']
);
}
}
return $categories;
}
}
$front_categories = CategoriesRepository::getFrontCategories([
'withNewsCount' => 5
]);
我认为，因为你急于加载一个有多条记录的集合。
要解决这个问题，你需要循环$front_categories = Category::where('in_front', 1)->get();
foreach ($front_categories as $fCategory) {
$fCategory->load(['news' => function($query) {
$query->where('publish','1')->orderBy('created_at', 'desc')->take(5);
}]);
}
此解决方案将对数据库执行许多查询。如果您只想处理1个查询，请签出GROUP BY中的Using LIMIT以获得每个组的N个结果。