iris/_examples/routing/macros/main.go

package main

import (
	"fmt"
	"reflect"
	"strconv"

	"github.com/kataras/iris"
	"github.com/kataras/iris/context"
	// "github.com/kataras/iris/core/memstore"
	"github.com/kataras/iris/hero"
)

func main() {
	app := iris.New()
	app.Logger().SetLevel("debug")

	// Let's see how we can register a custom macro such as ":uint32"  or ":small" for its alias (optionally) for Uint32 types.
	// app.Macros().Register("uint32", "small", false, false, func(paramValue string) bool {
	// 	_, err := strconv.ParseUint(paramValue, 10, 32)
	// 	return err == nil
	// }).
	// 	RegisterFunc("min", func(min uint32) func(string) bool {
	// 		return func(paramValue string) bool {
	// 			n, err := strconv.ParseUint(paramValue, 10, 32)
	// 			if err != nil {
	// 				return false
	// 			}

	// 			return uint32(n) >= min
	// 		}
	// 	})

	/* TODO:
	   somehow define one-time how the parameter should be parsed to a particular type (go std or custom)
	   tip: we can change the original value from string to X using the entry's.ValueRaw
	   ^ Done 27 sep 2018.
	*/

	app.Macros().Register("uint32", "small", false, false, func(paramValue string) (interface{}, bool) {
		v, err := strconv.ParseUint(paramValue, 10, 32)
		return uint32(v), err == nil
	}).
		RegisterFunc("min", func(min uint32) func(uint32) bool {
			return func(paramValue uint32) bool {
				return paramValue >= min
			}
		})

	// optionally, only when mvc or hero features are used for this custom macro/parameter type.
	context.ParamResolvers[reflect.Uint32] = func(paramIndex int) interface{} {
		/* both works but second is faster, we omit the duplication of the type conversion over and over  as of 27 Sep of 2018 (this patch)*/
		// return func(ctx context.Context) uint32 {
		// 	param := ctx.Params().GetEntryAt(paramIndex)
		// 	paramValueAsUint32, _ := strconv.ParseUint(param.String(), 10, 32)
		// 	return uint32(paramValueAsUint32)
		// }
		return func(ctx context.Context) uint32 {
			return ctx.Params().GetEntryAt(paramIndex).ValueRaw.(uint32)
		} /* TODO: find a way to automative it based on the macro's first return value type, if thats the case then we must not return nil even if not found,
		we must return a value i.e 0 for int for its interface{} */
	}
	//

	app.Get("/test_uint32/{myparam:uint32 min(10)}", hero.Handler(func(paramValue uint32) string {
		return fmt.Sprintf("Value of the parameter is: %d\n", paramValue)
	}))

	app.Get("test_uint64/{myparam:uint64 min(5)}", func(ctx context.Context) {
		// works: ctx.Writef("Value of the parameter is: %s\n", ctx.Params().Get("myparam"))
		// but better and faster because the macro converts the string to uint64 automatically:
		ctx.Writef("Value of the parameter is: %d\n", ctx.Params().GetUint64Default("myparam", 0))
	})

	app.Run(iris.Addr(":8080"))
}