问题描述
我有一个食物模型.每种食物都有价格和折扣(以百分比为单位).我附加了一个cost属性,以保存基于第一个价格和折扣计算得出的值.
I have a Food model. Each food has a price and a discount (in percent). I have appended a cost attribute to hold a value which is calculated base on the first price and discount.
示例:
我们有一种价格为10 $的食物.折扣是10%,因此费用是9 $.
Example:
We have a Food with a price of 10$. discount is 10%, so the cost is 9$.
class Food extends Model
{
protected $appends = ['cost'];
public function getCostAttribute()
{
return $this->price - round( ($this->price*$this->discount) / 100 );
}
}
我需要根据费用订购食物.我不能使用 orderBy
,因为cost实际上不是一列.所以我必须使用 sortBy
.
I need to order my foods based on cost. I cannot use orderBy
because cost is not actually a column. so I have to use sortBy
.
$foods = Food::all();
$foods = $foods->sortBy(function($food){
return $food->cost;
});
现在,如何对 $ foods
变量进行分页?因为我无法执行以下代码进行分页
Now, how can I paginate $foods
variable? Because I cannot execute following code to paginate
$foods = $foods->paginate(12);
推荐答案
排序依据
已经从db获取数据,因此使用分页并没有真正的帮助.
sort by
has already take datas from db, so use pagination is not really helpful.
因此,我建议像这样更改您的代码,这样可以减少IO成本:
So I recommend to change your code like this, this will reduce IO cost:
Food::select('*',
DB::raw('(price - round((price * discount) / 100)) AS cost')
)->orderBy('cost')
->paginate(12)
这篇关于在laravel中排序后如何分页的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!