move decoding into the list (reflection interfaces)

interfaces/11-reflection-decoder/_decoder.go

@@ -1,60 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"encoding/json"
-	"reflect"
-)
-
-type decoder map[string]interface{}
-
-type schema struct {
-	Category string
-	Item     json.RawMessage
-}
-
-func (d decoder) decode(data []byte) (list, error) {
-	var schemas []schema
-
-	if err := json.Unmarshal(data, &schemas); err != nil {
-		return nil, err
-	}
-
-	return d.products(schemas)
-}
-
-func (d decoder) products(ss []schema) (list, error) {
-	var store list
-
-	for _, s := range ss {
-		prod, err := d.product(s.Category, s.Item)
-
-		if err != nil {
-			return nil, err
-		}
-
-		store = append(store, prod)
-	}
-
-	return store, nil
-}
-
-func (d decoder) product(kind string, data []byte) (item, error) {
-	p := d.newProduct(kind)
-
-	err := json.Unmarshal(data, p)
-
-	return p, err
-}
-
-func (d decoder) newProduct(kind string) item {
-	t := reflect.TypeOf(d[kind])
-	v := reflect.New(t)
-	return v.Interface().(item)
-}

interfaces/11-reflection-decoder/_decoder_reader.go

@@ -13,24 +13,21 @@ import (
 	"os"
 )
 
-func (d decoder) fromFile(path string) (list, error) {
-	f, err := os.Open(path)
-	if err != nil {
-		return nil, err
-	}
-
-	return d.readFile(f)
+func fromFile(f *os.File) (list, error) {
+	return fromReader(f)
 }
 
-func (d decoder) readFile(f *os.File) (list, error) {
-	return d.read(f)
-}
-
-func (d decoder) read(r io.Reader) (list, error) {
+func fromReader(r io.Reader) (list, error) {	
 	data, err := ioutil.ReadAll(r)
 	if err != nil {
 		return nil, err
 	}
 
-	return d.decode(data)
+	var store list
+
+	if err := json.Unmarshal(data, &store); err != nil {
+		return nil, err
+	}
+
+	return store, nil
 }

interfaces/11-reflection-decoder/_main_reader.go

@@ -21,7 +21,7 @@ func main() {
 		"toy":    toy{},
 	}
 
-	store, err := dec.read(os.Stdin)
+	store, err := fromReader(os.Stdin)
 	if err != nil {
 		log.Fatalln(err)
 	}

interfaces/11-reflection-decoder/decoder.go

@@ -1,77 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import "encoding/json"
-
-type decoderSchema struct {
-	Category string
-
-	// json.RawMessage is a special type of the json package.
-	// It prevents the json package functions encode/decode
-	// the specific parts of the json data.
-	Item json.RawMessage
-}
-
-func decode(data []byte) (list, error) {
-	var schemas []decoderSchema
-
-	if err := json.Unmarshal(data, &schemas); err != nil {
-		return nil, err
-	}
-
-	return toStore(schemas)
-}
-
-func toStore(schemas []decoderSchema) (store list, err error) {
-	for _, s := range schemas {
-		p := newProduct(s.Category)
-
-		if json.Unmarshal(s.Item, &p); err != nil {
-			return nil, err
-		}
-
-		store = append(store, p)
-	}
-	return store, nil
-}
-
-func newProduct(category string) item {
-	// for each product you need to open this code
-	// and add a new case.
-	//
-	// dependency injection should be the responsibility
-	// of the user of this function.
-	switch category {
-	case "book":
-		// var b book
-		// return &b
-		return new(book)
-	case "game":
-		return new(game)
-	case "puzzle":
-		return new(puzzle)
-	case "toy":
-		return new(toy)
-	}
-	return nil
-}
-
-// func (d decoder) newProduct(category string) item {
-// 	t := reflect.TypeOf(d[category])
-// 	v := reflect.New(t)
-// 	return v.Interface().(item)
-// }
-
-// func toProduct(kind string, data []byte) (item, error) {
-// 	p := newProduct(kind)
-
-// 	err := json.Unmarshal(data, p)
-
-// 	return p, err
-// }

interfaces/11-reflection-decoder/list.go

@@ -19,9 +19,9 @@ type item interface {
 	fmt.Stringer
 }
 
-// schema adds an additional category field
+// itemEncode adds an additional category field
 // to the product types.
-type schema struct {
+type itemEncode struct {
 	// Category is the product category field.
 	Category string
 
@@ -30,22 +30,92 @@ type schema struct {
 	Item item
 }
 
+// itemDecode is used to decode the product types from json.
+type itemDecode struct {
+	// Category is the product category field.
+	Category string
+
+	// json.RawMessage is a special type of the json package.
+	// It prevents the json package functions encode/decode
+	// the specific parts of the json data.
+	Item json.RawMessage
+}
+
 type list []item
 
 func (l list) MarshalJSON() ([]byte, error) {
-	var schemas []schema
+	var eitems []itemEncode
 
 	for _, it := range l {
 		// TypeOf -> finds the dynamic type of "it"
 		// Elem   -> returns the element type of the pointer
 		// Name   -> returns the type name as string
 		cat := reflect.TypeOf(it).Elem().Name()
-		schemas = append(schemas, schema{cat, it})
+		eitems = append(eitems, itemEncode{cat, it})
 	}
 
-	return json.Marshal(schemas)
+	return json.Marshal(eitems)
 }
 
+func (l *list) UnmarshalJSON(data []byte) error {
+	var ditems []itemDecode
+
+	if err := json.Unmarshal(data, &ditems); err != nil {
+		return err
+	}
+
+	items, err := decode(ditems)
+	if err != nil {
+		return err
+	}
+
+	*l = items
+	return nil
+}
+
+// decode and return items as a list.
+func decode(data []itemDecode) (items list, err error) {
+	for _, d := range data {
+		item := newItem(d.Category)
+
+		if json.Unmarshal(d.Item, &item); err != nil {
+			return nil, err
+		}
+
+		items = append(items, item)
+	}
+	return items, nil
+}
+
+// newItem creates and returns an item depending on category.
+func newItem(category string) item {
+	// for each product you need to open this code
+	// and add a new case.
+	//
+	// dependency injection should be the responsibility
+	// of the user of this function.
+	switch category {
+	case "book":
+		// var b book
+		// return &b
+		return new(book)
+	case "game":
+		return new(game)
+	case "puzzle":
+		return new(puzzle)
+	case "toy":
+		return new(toy)
+	}
+	return nil
+}
+
+// type decoder map[string]interface{}
+// func (d decoder) newItem(kind string) item {
+// 	t := reflect.TypeOf(d[kind])
+// 	v := reflect.New(t)
+// 	return v.Interface().(item)
+// }
+
 func (l list) String() string {
 	if len(l) == 0 {
 		return "Sorry. We're waiting for delivery 🚚."

interfaces/11-reflection-decoder/main.go

@@ -8,6 +8,7 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -30,14 +31,14 @@ func main() {
 	// }
 
 	// fmt.Println(string(out))
-
+	//---
 	data, err := ioutil.ReadFile("database.json")
 	if err != nil {
 		log.Fatalln(err)
 	}
 
-	store, err := decode(data)
-	if err != nil {
+	var store list
+	if err = json.Unmarshal(data, &store); err != nil {
 		log.Fatalln(err)
 	}