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[英]How to do order by the eloquent query without using join relationship in laravel?
[英]How to have query by 3 join in Laravel Eloquent model without foreach
无论如何,要从此代码中删除foreach
吗?
$user = \Auth::user();
foreach ($user->categories as $category) {
$channels[] = $category->channel();
}
return $channels;
我想使用分页功能,但是foreach
不可能的!
Eloquent不执行JOIN查询,如果您确实需要JOIN,则需要下拉至查询构建器并编写自己的查询。
但是,如果您只是想避免N + 1问题,则应使用预先加载。 每个关系类型将创建1个额外的WHERE foreign_id IN(...)
查询。 因此总共会有:
由于您已经在内存中存储了用户实例,因此可以避免通过延迟加载而重新获取用户记录。
Laravel分页器文档有些简短,尤其是像您必须手动创建/分页一样。...这里是它们如何工作的简要概述,以及如何使其工作...
没什么大不了的,分页器会在每一页上调用您的控制器函数。 该请求中将包含分页信息。 实际选择并切片页面是您的工作。 分页器只是呈现它...这是工作的重要部分...
您的$ channels []数组将必须被切片并正确返回...像这样...
public function channels(){
// we have to build the paginator ourselves, your result is an array...
$user = \Auth::user();
foreach ($user->categories as $category) {
$channels[] = $category->channel();
}
// this basically gets the request's page variable...This is how pagination works under the hood... we defaults to 1
$page = Paginator::resolveCurrentPage('page') ?: 1;
// Assume 15 items per page... so start index to slice our array
$startIndex = ($page - 1) * 15;
// Length aware paginator needs a total count of items... to paginate properly
$total = count($channels);
// Eliminate the non relevant items... We have to slice the array ourselves...
$results = array_slice($channels, $startIndex, 15);
$paginatedChannels = new LengthAwarePaginator($results, $total, 15, $page, [
'path' => Paginator::resolveCurrentPath(),
'pageName' => 'page',
]);
return view('yourViews', compact('paginatedChannels'));
}
关键是您必须自己准备数据切片...
您可以发布数据结构,以便我们为查询本身提供更好的选择...但是,如果$ category-> channel()函数有效,则此方法应该有效...
那这样呢
$categories = \Auth::user()->categories()->pluck('id')->toArray();
return \App\Channel::wherein('category_id', $categories)->paginate();
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