README.md

Example Usage

Warn! Text encoding for urls has not been implemented.

package main

import "fmt"

type Parrams struct {
  Query string `url:"q"`
  Count int `url:"count"`
  Scope []string `url:"scope" separator:"comma"`
}

func main() {

  params := Params {
    Query: "project",
    Count: 1,
    Scope: []string{ "projects", "files" },
  }
  
  qs := QueryString(params)
  
  fmt.Println(qs) // => ?q=project&count=1&scope=projects,files
}

struct-to-querystring.go

package api

import (
	"fmt"
	"reflect"
	"strconv"
	"strings"
)

func QueryString[T any](p T) string {
	t := reflect.TypeOf(p)
	v := reflect.ValueOf(p)
	result := ""

	for i := 0; i < t.NumField(); i++ {
		value := v.Field(i)
		field := t.Field(i)
		tag := field.Tag

		if len(tag) == 0 {
			continue
		}

		if len(result) == 0 {
			result = "?"
		}

		var joinChar rune
		var val string

		if result != "?" {
			joinChar = '&'
		}

		switch field.Type.Kind() {
		case reflect.Slice:
			var separator string

			// TODO: convert separator to encoded string such as `%20` for space
			switch tag.Get("separator") {
			case "space":
				separator = " "
			default:
				separator = ","
			}

			val = strings.Join(value.Interface().([]string), separator)
		case reflect.Int:
			val = strconv.FormatInt(value.Int(), 10)
		default:
			// TODO: convert string to encoded uri
			val = value.String()
		}

		if len(val) > 0 {
			result += fmt.Sprintf("%s%s=%s", string(joinChar), tag.Get("url"), val)
		}
	}

	return result
}