How to sort and filter JSON data in Golang?

Sort and filter JSON data in Golang: Sort: Use the sort.Slice function to sort JSON data based on specified fields. Filtering: Use for loops and conditional statements to filter JSON data based on specified conditions. Practical case: Read user information from a JSON file, sort by age in descending order and filter out users older than 25.

How to sort and filter JSON data in Golang

JSON (JavaScript Object Notation) is a lightweight , a text-based data exchange format that is widely used in web and mobile applications. When processing JSON data in Golang, we often need to sort and filter the data to get the information we want.

Sort

Use the sort package to sort JSON data:

package main

import (
    "encoding/json"
    "fmt"
    "sort"
)

type Person struct {
    Name  string
    Age   int
    Score float64
}

func main() {
    data := []Person{
        {"John", 25, 85.5},
        {"Mary", 28, 90.0},
        {"Bob", 23, 87.2},
    }

    // 根据 Age 字段升序排序
    sort.Slice(data, func(i, j int) bool {
        return data[i].Age < data[j].Age
    })
    fmt.Println(data) // 输出：[{Bob 23 87.2} {John 25 85.5} {Mary 28 90}]

    // 根据 Score 字段降序排序
    sort.Slice(data, func(i, j int) bool {
        return data[i].Score > data[j].Score
    })
    fmt.Println(data) // 输出：[{Mary 28 90} {Bob 23 87.2} {John 25 85.5}]
}

Filter

Use for loops and conditional statements to filter JSON data:

package main

import (
    "encoding/json"
    "fmt"
)

type Person struct {
    Name  string
    Age   int
    Score float64
}

func main() {
    data := []Person{
        {"John", 25, 85.5},
        {"Mary", 28, 90.0},
        {"Bob", 23, 87.2},
    }

    // 过滤出年龄大于 25 的人员
    filteredData := []Person{}
    for _, person := range data {
        if person.Age > 25 {
            filteredData = append(filteredData, person)
        }
    }
    fmt.Println(filteredData) // 输出：[{Mary 28 90}]
}

Practical case

Let us consider such a scenario: You have a JSON file containing user information and you want to sort the users by age in descending order and get only users whose age is greater than 25.

JSON file:

[
  {
    "name": "John",
    "age": 25,
    "score": 85.5
  },
  {
    "name": "Mary",
    "age": 28,
    "score": 90.0
  },
  {
    "name": "Bob",
    "age": 23,
    "score": 87.2
  }
]

Golang code:

package main

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "os"
    "sort"
)

type Person struct {
    Name  string
    Age   int
    Score float64
}

func main() {
    // 从文件读取 JSON 数据
    jsonFile, err := os.Open("users.json")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer jsonFile.Close()

    byteValue, err := ioutil.ReadAll(jsonFile)
    if err != nil {
        fmt.Println(err)
        return
    }

    // 解码 JSON 数据
    var data []Person
    err = json.Unmarshal(byteValue, &data)
    if err != nil {
        fmt.Println(err)
        return
    }

    // 对数据进行排序和过滤
    sort.Slice(data, func(i, j int) bool {
        return data[i].Age > data[j].Age
    })

    filteredData := []Person{}
    for _, person := range data {
        if person.Age > 25 {
            filteredData = append(filteredData, person)
        }
    }

    // 打印结果
    fmt.Println(filteredData) // 输出：[{Mary 28 90}]
}

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