Go 使用 LINQ 对内部数组进行排序

首先，构建一个产品的有序查询，该查询先按shop ID排序，然后按降序按价格排序.

这允许相应地对每个组的内部数组进行排序.

package main

import (
    "fmt"

    "github.com/ahmetb/go-linq/v3"
)

// Inner struct
type product struct {
    name   string
    price  int64
    shopId int64
}
func (x product) String() string { return fmt.Sprintf("<%s, [%d]> ", x.name, x.price) }

// Outer struct
type oneGroup struct {
    shopId   int64
    products []*product
}

// Final Outer array
var groupOut []oneGroup

func main() {
    products := make([]*product, 0, 20)
    products = append(products, &product{name: "product66", price: 6666, shopId: 100})
    products = append(products, &product{name: "product11", price: 1111, shopId: 100})
    products = append(products, &product{name: "product44", price: 4444, shopId: 100})

    products = append(products, &product{name: "product22", price: 2222, shopId: 200})
    products = append(products, &product{name: "product77", price: 9999, shopId: 200})
    products = append(products, &product{name: "product00", price: 0000, shopId: 200})

    products = append(products, &product{name: "product33", price: 3333, shopId: 300})
    products = append(products, &product{name: "product88", price: 8888, shopId: 300})
    products = append(products, &product{name: "product55", price: 5555, shopId: 300})

    products = append(products, &product{name: "product99", price: 7777, shopId: 400})

    var query []linq.Group
    // Sort products first by shopId and the price in descending order
    var productsByShopIdAndPrice linq.OrderedQuery = linq.From(products).OrderByT(func(p interface{}) int64  {
        return p.(*product).shopId
    }).ThenByDescending(func(p interface{}) interface{} {
        return p.(*product).price
    })
    // Grouping and sorting outer layers in descending order according to the largest price in the group after grouping
    productsByShopIdAndPrice.GroupByT(
        func(p *product) int64 { return p.shopId },
        func(p *product) *product { return p },
    ).OrderByT(
        func(g linq.Group) int64 {
            //return g.Key.(int64)
            return linq.From(g.Group).Select(
                func(x interface{}) interface{} { return x.(*product).price },
            ).Max().(int64)

        },
    ).ToSlice(&query)
    fmt.Printf("%v \n", query)
}