Golang 实现结构体数组按多字段排序

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发布于: 2020 年 07 月 19 日
近期因项目重构（php->golang），涉及到一些将对象列表中的对象按不同的字段（属性）排序；
在php中，可以使用usort + 自定义的排序函数轻松实现；
[usort官方文档](https://www.php.net/manual/zh/function.usort.php)
下面我们先看一个在php中的例子:  
下面是一个待排序待数组
<?php
    $result = array(
        array(
            "val" => "f",
            "mtime" =>  1595144638,
            "orderval"=>4
        ),
        array(
            "val" => "d",
            "mtime" =>  1595144646,
            "orderval"=>2
        ),
        array(
            "val" => "a",
            "mtime" =>  1595144648,
            "orderval"=>8
        ),
        array(
            "val" => "t",
            "mtime" =>  1595144648,
            "orderval"=>5
        ),
        array(
            "val" => "e",
            "mtime" =>  1595144650,
            "orderval"=>3
        )
    );
我们目前待目标是将该数组中待对象
按mtime 从大到小排序；如果mtime字段
的值相等，则按orderval从大到小排，最终想要的结果为：
e,a,t,d,f
[
﻿
    {"val"=>"e","mtime"=>1595144650,"orderval"=>3},
﻿
    {"val"=>"a","mtime"=>1595144648,"orderval"=>8},
﻿
    {"val"=>"t","mtime"=>1595144648,"orderval"=>5},
﻿
    {"val"=>"d","mtime"=>1595144646,"orderval"=>2},
﻿
    {"val"=>"f","mtime"=>1595144638,"orderval"=>4}
﻿
]
我们首先定义一个自定义函数，然后巧妙使用usort函数去调用的自定义函数，最终实现目标，直接上代码：
php
   $result = array(
        array(
            "val" => "f",
            "mtime" =>  1595144638,
            "orderval"=>4
        ),
        array(
            "val" => "d",
            "mtime" =>  1595144646,
            "orderval"=>2
        ),
        array(
            "val" => "a",
            "mtime" =>  1595144648,
            "orderval"=>8
        ),
        array(
            "val" => "t",
            "mtime" =>  1595144648,
            "orderval"=>5
        ),
        array(
            "val" => "e",
            "mtime" =>  1595144650,
            "orderval"=>3
        )
    );
    //按mtime 从大到小；如果mtime 相等，则按orderval 从大到小;
    usort($result, function ($v1, $v2) {
        if ($v1['mtime'] < $v2['mtime'] || ($v1['mtime'] == $v2['mtime'] && $v1['orderval'] < $v2['orderval'])) {
            return 1;
        } else {
            return -1;
        }
    });
    var_dump($result);
运行结果：
array(5) {
﻿
  [0]=>
﻿
  array(3) {
﻿
    ["val"]=>
﻿
    string(1) "e"
﻿
    ["mtime"]=>
﻿
    int(1595144650)
﻿
    ["orderval"]=>
﻿
    int(3)
﻿
  }
﻿
  [1]=>
﻿
  array(3) {
﻿
    ["val"]=>
﻿
    string(1) "a"
﻿
    ["mtime"]=>
﻿
    int(1595144648)
﻿
    ["orderval"]=>
﻿
    int(8)
﻿
  }
﻿
  [2]=>
﻿
  array(3) {
﻿
    ["val"]=>
﻿
    string(1) "t"
﻿
    ["mtime"]=>
﻿
    int(1595144648)
﻿
    ["orderval"]=>
﻿
    int(5)
﻿
  }
﻿
  [3]=>
﻿
  array(3) {
﻿
    ["val"]=>
﻿
    string(1) "d"
﻿
    ["mtime"]=>
﻿
    int(1595144646)
﻿
    ["orderval"]=>
﻿
    int(2)
﻿
  }
﻿
  [4]=>
﻿
  array(3) {
﻿
    ["val"]=>
﻿
    string(1) "f"
﻿
    ["mtime"]=>
﻿
    int(1595144638)
﻿
    ["orderval"]=>
﻿
    int(4)
﻿
  }
﻿
}
﻿
那么同样的功能，如果要用golang来实现，应如何办呢？ 
下面我们首先讲讲golang 官方对排序 对支持，然后给出具体对例子;
﻿
……
……
﻿
package main
import (
    "fmt"
    "sort"
)
type Obj struct {
    Var      string `json:"var"`
    Mtime    int    `json:"mtime"`
    Orderval int    `json:"orderval"`
}
type List []Obj
func (p List) Len() int {
    return len(p)
}
func (p List) Less(i, j int) bool {
    if p[i].Mtime > p[j].Mtime {
        return true
    }
    if p[i].Mtime < p[j].Mtime {
        return false
    }
    return p[i].Orderval > p[j].Orderval
}
func (p List) Swap(i, j int) {
    p[i], p[j] = p[j], p[i]
}
func (p *List) Sort() {
    sort.Sort(p)
}
func main() {
    s := List{{"f", 1595144638, 4}, {"d", 1595144646, 2}, {"a", 1595144648, 8}, {"t", 1595144648, 5}, {"e", 1595144650, 3}}
    fmt.Println(s)
    s.Sort()
    fmt.Println(s)
}
﻿
发布于: 2020 年 07 月 19 日阅读数: 101
原文链接:【http://xie.infoq.cn/article/1a029cd083c699618cf98f54f】。文章转载请联系作者。
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