Convert golang structured data to interface

There are two ways to convert structured data into interfaces in Go: Reflection: Use the methods in the reflect package. Code generation: Use the codegen library to generate code.

Convert structured data to interface in Go

In many cases, we need to convert structured data (such as database Query results) are converted to interface types. This transformation can be achieved in Go through two different methods: reflection and code generation.

Using Reflection

Reflection allows us to inspect and manipulate types and values. To convert a struct to an interface using reflection, we can use the reflect.TypeOf() and reflect.ValueOf() methods.

import (
    "fmt"
    "reflect"
)

// 定义一个结构体
type User struct {
    Name string
    Email string
    Age int
}

// 将结构体转换为接口
func StructToInterface(u User) interface{} {
    v := reflect.ValueOf(u)
    return v.Interface()
}

// 主函数
func main() {
    // 创建一个 User 实例
    u := User{"John Doe", "john.doe@example.com", 30}

    // 将结构体转换为接口
    i := StructToInterface(u)

    // 访问接口值
    name := i.(User).Name
    fmt.Println(name)
}

Using code generation

If we know the type of the structure, we can use the [codegen](https://github.com/bwmarrin/codegen) library to Generate code that converts structures into interfaces.

Install codegen

go get -u github.com/bwmarrin/codegen

Generate code

codegen --package=main \
    --type=User \
    --output=interface.go

This will generate interface.go# similar to the following code ## File:

package main

import "fmt"

func ToInterface(u User) interface{} {
    return user{user: u}
}

type user struct {
    user User
}

var derefUser = reflect.TypeOf((*User)(nil)).Elem()

func (u user) CanInterface() {
    if v := reflect.ValueOf(u.user); v.IsValid() && v.CanAddr() {
        if vt := v.Type(); vt.Kind() == reflect.Ptr && vt.Elem().PkgPath() == derefUser.PkgPath() && vt.Elem().Name() == derefUser.Name() {
            fmt.Printf("Addressing %s is possible.\n", vt.Elem().Name())
            fmt.Printf("Type: %#v\n", vt)
        }
    }
}

Use generated code

package main

import "fmt"

// ...省略其他代码

// 主函数
func main() {
    u := User{"John Doe", "john.doe@example.com", 30}

    i := ToInterface(u)
    fmt.Println(i.(User).Name)
}

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