reflection-playground.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"reflect"
	"strings"
)

type EmbeddedData struct {
	Name    string `json:"name"`
	Id      int    `json:"id"`
	Content string `json:"content"`
}

type RootData struct {
	Name string       `json:"name"`
	Data EmbeddedData `json:"data"`
}

func main() {
	// Part 1: Simple struct and serialization
	fmt.Println("PART1")
	d1 := EmbeddedData{
		Name:    "data1",
		Id:      1,
		Content: "embeddedData1",
	}

	fmt.Printf("Struct: %v\n", d1)
	w1 := bytes.Buffer{}
	_ = json.NewEncoder(&w1).Encode(d1)
	fmt.Printf("JSON: %s\n", w1.String())

	// Part 2: Adding embedded data to root data
	fmt.Println("PART2")
	d2 := RootData{
		Name: "rootdata1",
		Data: d1,
	}

	fmt.Printf("Struct: %v\n", d2)
	w2 := bytes.Buffer{}
	_ = json.NewEncoder(&w2).Encode(d2)
	fmt.Printf("JSON: %s\n", w2.String())

	// Part 3: Creating a simple struct using reflection
	fmt.Println("PART3")

	t3 := reflect.StructOf([]reflect.StructField{
		{
			Name: "Name",
			Type: reflect.TypeOf(""),
		},
		{
			Name: "Data",
			Type: reflect.TypeOf(d1),
		},
	})
	d3 := reflect.New(t3).Elem()
	d3.Field(0).SetString("data3")
	d3.Field(1).Set(reflect.ValueOf(d1))

	v3 := d3.Addr().Interface()
	fmt.Printf("Struct: %v\n", d3)
	w3 := bytes.Buffer{}
	_ = json.NewEncoder(&w3).Encode(v3)
	fmt.Printf("JSON: %s\n", w3.String())

	// Part 4: Creating a simple struct through a function using reflection
	fmt.Println("PART4")
	d4 := GetData4("Data4", d1)

	fmt.Printf("Struct: %v\n", d4)
	w4 := bytes.Buffer{}
	_ = json.NewEncoder(&w4).Encode(d4)
	fmt.Printf("JSON: %s\n", w4.String())

	// Part 5: Creating a simple struct through a function using reflection
	fmt.Println("PART5")
	data5 := []interface{}{
		d1,
		d1,
		d1,
	}
	d5 := GetData5("Data5", data5)

	fmt.Printf("Struct: %v\n", d5)
	w5 := bytes.Buffer{}
	_ = json.NewEncoder(&w5).Encode(d5)
	fmt.Printf("JSON: %s\n", w5.String())

}

func GetData4(name string, data interface{}) interface{} {
	tag := strings.ToLower(`json:"` + name + `"`)
	t := reflect.StructOf([]reflect.StructField{
		{
			Name: "Name",
			Type: reflect.TypeOf(data),
			Tag:  reflect.StructTag(tag),
		},
	})

	d := reflect.New(t).Elem()
	d.Field(0).Set(reflect.ValueOf(data))

	return d.Addr().Interface()
}

func GetData5(name string, data []interface{}) interface{} {
	tag := strings.ToLower(`json:"` + name + `"`)
	t := reflect.StructOf([]reflect.StructField{
		{
			Name: "Name",
			Type: reflect.TypeOf(data),
			Tag:  reflect.StructTag(tag),
		},
	})

	d := reflect.New(t).Elem()
	d.Field(0).Set(reflect.ValueOf(data))

	return d.Addr().Interface()
}

Output:

Struct: {data1 1 embeddedData1}
JSON: {"name":"data1","id":1,"content":"embeddedData1"}

PART2
Struct: {rootdata1 {data1 1 embeddedData1}}
JSON: {"name":"rootdata1","data":{"name":"data1","id":1,"content":"embeddedData1"}}

PART3
Struct: {data3 {data1 1 embeddedData1}}
JSON: {"Name":"data3","Data":{"name":"data1","id":1,"content":"embeddedData1"}}

PART4
Struct: &{{data1 1 embeddedData1}}
JSON: {"data4":{"name":"data1","id":1,"content":"embeddedData1"}}

PART5
Struct: &{[{data1 1 embeddedData1} {data1 1 embeddedData1} {data1 1 embeddedData1}]}
JSON: {"data5":[{"name":"data1","id":1,"content":"embeddedData1"},{"name":"data1","id":1,"content":"embeddedData1"},{"name":"data1","id":1,"content":"embeddedData1"}]}