Using Golang reflection to implement structure field traversal and modification

Go reflection can be used to traverse and modify structure fields. Field traversal: Use reflect.TypeOf and reflect.Field to traverse structure fields. Field modification: Access and modify the values of structure fields through Elem and Set. Practical case: Use reflection to convert the structure into a map, and then convert the map into JSON.

Use Go reflection to implement structure field traversal and modification

Go reflection is a powerful technology that allows us to check and Modify types and values in the program. It is ideal for working with unknown or dynamic data, as well as reflecting on existing structures for introspection operations.

Field traversal

To traverse the fields of a structure, you can use thereflect.TypeOffunction to retrieve the type information of the structure, and then useNumFieldmethod gets the number of fields. Each field can be accessed through theFieldmethod, which returns areflect.StructFieldobject.

type Person struct { Name string Age int } func main() { person := Person{"Alice", 25} t := reflect.TypeOf(person) for i := 0; i < t.NumField(); i++ { field := t.Field(i) fmt.Println(field.Name, field.Type) } }

Field modification

You can access the value of the structure field through theElemmethod, which will returnreflect.ValueObject. To modify a field, you can use theSetmethod, which accepts areflect.Valueparameter:

// 使用 Elem 访问字段值 nameField := reflect.ValueOf(person).Elem().FieldByName("Name") // 使用 Set 修改字段值 nameField.SetString("Bob") fmt.Println(person.Name) // 输出：Bob

Practical case

Let's say we have a struct that stores a user's personal information, but we want to return it in JSON format. We can use reflection to convert the structure intomap[string]interface{}:

type User struct { Name string Age int Password string } func main() { user := User{"Alice", 25, "secret"} // 将结构体转换为 map userMap := make(map[string]interface{}) t := reflect.TypeOf(user) for i := 0; i < t.NumField(); i++ { field := t.Field(i) value := reflect.ValueOf(user).Elem().FieldByName(field.Name) userMap[field.Name] = value.Interface() } // 将 map 转换为 JSON json, err := json.Marshal(userMap) if err != nil { // 处理错误 } fmt.Println(string(json)) // 输出：{"Name":"Alice","Age":25} }

Conclusion

Go reflection provides a powerful way to traverse and modify structure fields. By usingreflect.TypeOf,reflect.StructField,reflect.Valueandreflect.Setwe can handle unknown or dynamic data, And perform reflection operations on existing structures to achieve code scalability and flexibility.

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