How Can I Efficiently Convert a Go Map to a Struct Without Using JSON?

Converting Map to Struct Without JSON

In Go, you can encounter scenarios where you need to convert a map to a struct. While JSON can serve as an intermediary method, it may not be the most efficient approach. Here's how you can achieve this conversion:

One straightforward alternative is employing the powerful mapstructure library from GitHub. By importing it, you can leverage its Decode() functionality as follows:

import "github.com/mitchellh/mapstructure"

mapstructure.Decode(myData, &result)

For a hands-on implementation, consider the following approach:

package main

import (
    "fmt"
    "reflect"
)

type MyStruct struct {
    Name string
    Age  int64
}

func SetField(obj interface{}, name string, value interface{}) error {
    structValue := reflect.ValueOf(obj).Elem()
    structFieldValue := structValue.FieldByName(name)

    if !structFieldValue.IsValid() {
        return fmt.Errorf("No such field: %s in obj", name)
    }

    if !structFieldValue.CanSet() {
        return fmt.Errorf("Cannot set %s field value", name)
    }

    structFieldType := structFieldValue.Type()
    val := reflect.ValueOf(value)
    if structFieldType != val.Type() {
        return errors.New("Provided value type didn't match obj field type")
    }

    structFieldValue.Set(val)
    return nil
}

func (s *MyStruct) FillStruct(m map[string]interface{}) error {
    for k, v := range m {
        err := SetField(s, k, v)
        if err != nil {
            return err
        }
    }
    return nil
}

func main() {
    myData := make(map[string]interface{})
    myData["Name"] = "Tony"
    myData["Age"] = int64(23)

    result := &MyStruct{}
    err := result.FillStruct(myData)
    if err != nil {
        fmt.Println(err)
    }
    fmt.Println(result)
}

By using reflection and the custom SetField() function, this code iterates over the map's entries and sets the corresponding struct fields, providing a versatile solution for converting maps to structs in Go.

The above is the detailed content of How Can I Efficiently Convert a Go Map to a Struct Without Using JSON?. For more information, please follow other related articles on the PHP Chinese website!