How to compare two structures using reflection and third-party libraries in Go language and modify the value of the third structure?

Efficient comparison and modification of nested structures in Go language

In Go, comparing two complex structures and modifying the third structure often requires handling nested structures, which makes using reflection directly complicated and error-prone. This article will introduce a more concise and efficient method to simplify this process using the third-party library github.com/r3labs/diff .

Problem Description: Two nested structures need to be compared and the difference is applied to the third structure.

Sample structure:

 type User struct {
    Name string
    Age int64
    Hobbys Hobby
    Sex string
}

type Hobby struct {
    Cars Car
    Games Game
}

type Car struct {
    Brand string
    Color string
    Price string
}

type Game struct {
    Number int64
    Style string
}

Solution using r3labs/diff library:

This library provides a clean API for comparing structures and applying differences. The following code demonstrates how to use the library:

 package main

import (
    "fmt"
    "github.com/r3labs/diff"
)

func main() {
    user1 := User{
        Name: "Zhang San",
        Age: 15,
        Hobbys: Hobby{
            Cars: Car{
                Brand: "Benz",
                Color: "White",
                Price: "1 million",
            },
            Games: Game{
                Number: 10000,
                Style: "Arcade",
            },
        },
        Sex: "Male",
    }

    user2 := User{
        Name: "Zhang San",
        Age: 15,
        Hobbys: Hobby{
            Cars: Car{
                Brand: "BMW",
                Color: "White",
                Price: "1 million",
            },
            Games: Game{
                Number: 10000,
                Style: "Arcade",
            },
        },
        Sex: "Male",
    }

    user3 := User{
        Name: "Zhang San",
        Age: 15,
        Hobbys: Hobby{
            Cars: Car{
                Brand: "Benz",
                Color: "White",
                Price: "1 million",
            },
            Games: Game{
                Number: 10000,
                Style: "Arcade",
            },
        },
        Sex: "Male",
    }

    changes, err := diff.Diff(user1, user2)
    if err != nil {
        fmt.Println("Error:", err)
        Return
    }

    for _, change := range changes {
        diff.Apply(change, &user3)
    }

    fmt.Printf("% v\n", user3)
}

This code first defines three User structure instances: user1 , user2 , user3 . It then compares user1 and user2 using diff.Diff(user1, user2) , returning a list of differences. Finally, it applies these differences to user3 using diff.Apply(change, &user3) . The output user3 will reflect the difference between user1 and user2 . This is simpler and easier to maintain and understand than using reflection manually. Remember to install github.com/r3labs/diff library: go get github.com/r3labs/diff

By using r3labs/diff library, we can avoid complex reflection operations, thereby handling the comparison and modification of nested structures in Go more clearly and efficiently.

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