How to compare two structures through reflection mechanism in Go language and modify the value of the third structure?

Go language reflection mechanism: compare two structures and modify the third one

This article explores how to compare two structures using reflection mechanism in Go language and modify the third structure when the difference is found. This is a high-level topic that requires a deep understanding of Go's reflection mechanism.

Suppose we have the following structure definition:

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

type Hobby struct {
    Car Car
    Game Game
}

type Car struct {
    Brand string
    Color string
    Price string
}

type Game struct {
    Number int64
    Style string
}

Our goal is to compare user1 and user2 and update the corresponding fields of user3 if the difference is found.

First, initialize three User structure instances:

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

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

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

    compareAndModify(user1, user2, &user3)
    fmt.Printf("% v\n", user3)
}

Next, use the reflection mechanism to achieve comparison and modification:

 import (
    "fmt"
    "reflect"
)

func compareAndModify(a, b interface{}, c interface{}) {
    aValue := reflect.ValueOf(a)
    bValue := reflect.ValueOf(b)
    cValue := reflect.ValueOf(c).Elem()

    for i := 0; i <p> This code traverses the fields of <code>user1</code> and <code>user2</code> . If a difference is found, the corresponding field value of <code>user2</code> is assigned to <code>user3</code> . It should be noted that the <code>c</code> parameter needs to be a pointer type in order to modify its value.</p><p> Although this method uses reflection, the performance impact is relatively small for situations where there are fewer structure field types. For more complex structures or higher performance requirements, it is recommended to consider using a dedicated library such as <code>github.com/r3labs/diff</code> , which provides more advanced differences comparison and processing capabilities.</p>

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