在Eloquent中按关系字段执行排序

Question

我想用Eloquent创建产品过滤器.

我是这样开始的

$query = Product::whereHas('variants')
        ->with('variants')
        ->with('reviews')

$query = $this->addOrderConstraints($request, $query);

$products = $query->paginate(20);

哪里

private function addOrderConstraints($request, $query)
{
    $order = $request->input('sort');

    if ($order === 'new') {
        $query->orderBy('products.created_at', 'DESC');
    }

    if ($order === 'price') {
        $query->orderBy('variants.price', 'ASC');
    }

    return $query;
}

但是,这不起作用,因为Eloquent正在执行此查询(来自Laravel DebugBar的信息)

select count(*) as aggregate from `products` where exists 
(select * from `variants` where `products`.`id` = `variants`.`product_id`)

select * from `products` where exists 
(select * from `variants` where `products`.`id` = `variants`.`product_id`)

select * from `variants` where `variants`.`product_id` in ('29', '30', '31', '32', '33', '34', '35', '36', '37', '38', '39', '40', '41', '42', '43', '44', '45', '46', '47', '48')

等等

因此,当我尝试按价格使用排序时,它只是明显的错误

Unknown column 'variants.price' in 'order clause' (SQL: select * from 
`products` where exists (select * from `variants` where `products`.`id` =

variants.product_id订购variants.priceasc limit 20 offset 0)

那么是否可以与Eloquent进行关系排序？

Answer 1

这将对子查询进行排序.不是"第一个查询(产品查询)".

基本上,你的子查询将是: select * from variants where product_id in (....) order by price,这不是你想要的,对吧？

<?php 
// ...

$order = $request->sort;

$products = Product::whereHas('variants')->with(['reviews',  'variants' => function($query) use ($order) {
  if ($order == 'price') {
    $query->orderBy('price');
  }
}])->paginate(20);

如果要对产品+ /或变体进行排序,则需要使用join.

$query = Product::select([
          'products.*',
          'variants.price',
          'variants.product_id'
        ])->join('variants', 'products.id', '=', 'variants.product_id');

if ($order === 'new') {
    $query->orderBy('products.created_at', 'DESC');
}

if ($order === 'price') {
    $query->orderBy('variants.price');
}

return $query->paginate(20);

Answer 2

如果您想对产品和变体进行排序，则不需要联接，因为您不会加载相关模型（如$product->variants），而仅加载变体表的所有字段。

要按相关子模型对模型进行排序，我们可以使用Eloquent - Subquery Ordering。

要通过相关模型而不是相关模型本身来对整个模型进行排序，我们可以这样做：

return Product::with('variants')->orderBy(
    Variants::select('price')
        // This can vary depending on the relationship
        ->whereColumn('variant_id', 'variants.id')
        ->orderBy('price')
        ->limit(1)
)->get();