Category data now includes their subcategories. Categories can now be requested by ID in a prettier way.

category.go

@@ -1,17 +1,18 @@
 package main
 
 type Category struct {
-	Id   int32  `json:"id"`
+	ID            int64         `json:"id"`
-	Name string `json:"name"`
+	Name          string        `json:"name"`
+	Subcategories []Subcategory `json:"subcategories"`
 }
 
 type Subcategory struct {
-	Id         int32  `json:"id"`
+	ID         int64  `json:"id"`
 	Name       string `json:"name"`
-	CategoryId int32  `json:"categoryId"`
+	CategoryId int64  `json:"categoryId"`
 }
 
-func getAllCategories() []Category {
+func getAllCategories() (categories []Category, ok bool) {
 	db := getSQLConnection()
 
 	defer db.Close()
@@ -19,22 +20,121 @@ func getAllCategories() []Category {
 	rows, err := db.Query("SELECT * FROM category;")
 
 	if err != nil {
-		panic(err)
+		//TODO: log this error
+		return nil, false
+		//panic(err)
 	}
 
 	defer rows.Close()
 
-	var categories []Category
-
 	for rows.Next() {
 		var category Category
 
-		if err = rows.Scan(&category.Id, &category.Name); err != nil {
+		if err = rows.Scan(&category.ID, &category.Name); err != nil {
 			println(err.Error())
 		}
 
+		subcategories, ok := getSubcategories(category.ID)
+
+		if ok {
+			category.Subcategories = subcategories
+		}
+
 		categories = append(categories, category)
 	}
 
-	return categories
+	return categories, true
+}
+
+func insertNewCategory(name string) (recordID int32, ok bool) {
+	db := getSQLConnection()
+
+	defer db.Close()
+
+	err := db.QueryRow("INSERT INTO category (category_name) VALUES ($1) RETURNING category_id;", name).Scan(&recordID)
+
+	if err != nil {
+		//TODO: log this error
+		println(err.Error())
+		return 0, false
+		//panic(err)
+	}
+
+	return recordID, true
+}
+
+func deleteCategory(id int64) bool {
+	db := getSQLConnection()
+
+	defer db.Close()
+
+	_, err := db.Exec("DELETE FROM category WHERE category_id = $1;", id)
+	//TODO: log this if an error happened
+	if err != nil {
+		println(err.Error())
+		return false
+	}
+
+	return true
+}
+
+func getCategoryByID(id int64) (category Category, ok bool) {
+	db := getSQLConnection()
+
+	defer db.Close()
+
+	if err := db.QueryRow("SELECT * FROM category WHERE category_id = $1;", id).Scan(&category.ID, &category.Name); err != nil {
+		return category, false
+	}
+
+	subcategories, ok := getSubcategories(category.ID)
+
+	if !ok {
+		//TODO: do something about not getting the subcategories, for now ignore.
+		return category, true
+	}
+
+	category.Subcategories = subcategories
+
+	return category, true
+}
+
+// func getSubcategoryByID(id int64) (subcategory Subcategory, ok bool) {
+// 	db := getSQLConnection()
+
+// 	defer db.Close()
+
+// 	if err := db.QueryRow("SELECT * FROM subcategory WHERE subcategory_id = $1;", id).Scan(&subcategory.ID, &subcategory.Name, &subcategory.CategoryId); err != nil {
+// 		return subcategory, false
+// 	}
+
+// 	return subcategory, true
+// }
+
+func getSubcategories(categoryID int64) (subcategories []Subcategory, ok bool) {
+	db := getSQLConnection()
+
+	defer db.Close()
+
+	rows, err := db.Query("SELECT * FROM subcategory WHERE category_id = $1;", categoryID)
+
+	if err != nil {
+		//TODO: log this error
+		return nil, false
+		//panic(err)
+	}
+
+	defer rows.Close()
+
+	for rows.Next() {
+		var subcategory Subcategory
+
+		if err = rows.Scan(&subcategory.ID, &subcategory.Name, &subcategory.CategoryId); err != nil {
+			println(err.Error())
+		}
+
+		subcategories = append(subcategories, subcategory)
+	}
+
+	return subcategories, true
 }

database.go

@@ -7,6 +7,8 @@ import (
 	_ "github.com/lib/pq"
 )
 
+//TODO: maybe we can do the whole databaase connection things on application start and panic right away
+//if we can't connect to the database.
 func getSQLConnection() *sql.DB {
 	//Note: The postgres driver seems to get confused when no password is supplied, so omit it in the connection sting.
 	//https://rajyavardhan.medium.com/when-you-get-relation-does-not-exist-in-postgres-7ffb0c3c674b

go.mod

@@ -2,4 +2,4 @@ module copyrightcrusader.org/inv
 
 go 1.16
 
-require github.com/lib/pq v1.10.2 // indirect
+require github.com/lib/pq v1.10.2

main.go

@@ -1,18 +1,18 @@
 package main
 
 import (
-	"database/sql"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 )
 
 //Go Best practices: https://github.com/golovers/effective-go
 type Item struct {
-	Id                int32       `json:"id"`
+	ID                int32       `json:"id"`
 	Name              int32       `json:"name"`
 	ValueCents        int32       `json:"valueCents"`
 	PurchaseCostCents int32       `json:"purchasedCostCents"`
@@ -27,8 +27,11 @@ type Item struct {
 
 func main() {
 	http.HandleFunc("/categories", categories)
-	http.HandleFunc("/category", category)
+	//Note: seems adding a trailing slash allows routing URLs like /category/ID#
-	err := http.ListenAndServe(":8080", nil)
+	//No need for query parameters.
+	http.HandleFunc("/category/", category)
+
+	err := http.ListenAndServe(":8088", nil)
 
 	if err != nil {
 		panic(err)
@@ -39,7 +42,7 @@ func main() {
 func categories(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case "GET":
-		getCategories(w, r)
+		getCategoriesHandler(w, r)
 	default:
 		w.WriteHeader(http.StatusMethodNotAllowed)
 		w.Write([]byte("Method not allowed"))
@@ -49,19 +52,19 @@ func categories(w http.ResponseWriter, r *http.Request) {
 func category(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case "GET":
-		getCategory(w, r)
+		getCategoryHandler(w, r)
 	case "POST":
-		insertCategory(w, r)
+		insertCategoryHandler(w, r)
 	case "DELETE":
-		deleteCategory(w, r)
+		deleteCategoryHandler(w, r)
 	default:
 		w.WriteHeader(http.StatusMethodNotAllowed)
 		w.Write([]byte("Method not allowed"))
 	}
 }
 
-func getCategory(w http.ResponseWriter, r *http.Request) {
+func getCategoryHandler(w http.ResponseWriter, r *http.Request) {
-	id := r.URL.Query().Get("id")
+	id := strings.TrimPrefix(r.URL.Path, "/category/")
 
 	value, err := strconv.ParseInt(id, 0, 64)
 
@@ -71,19 +74,11 @@ func getCategory(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	db := getSQLConnection()
+	category, ok := getCategoryByID(value)
 
-	defer db.Close()
+	if !ok {
-
+		w.WriteHeader(http.StatusInternalServerError)
-	var category Category
+		w.Write([]byte("Failed to get category."))
-
-	if err := db.QueryRow("SELECT * FROM category WHERE category_id = $1;", value).Scan(&category.Id, &category.Name); err != nil {
-		if err == sql.ErrNoRows {
-			w.Write([]byte("No rows found"))
-			return
-		}
-
-		w.Write([]byte(err.Error()))
 		return
 	}
 
@@ -99,8 +94,8 @@ func getCategory(w http.ResponseWriter, r *http.Request) {
 	w.Write(jsonBytes)
 }
 
-func deleteCategory(w http.ResponseWriter, r *http.Request) {
+func deleteCategoryHandler(w http.ResponseWriter, r *http.Request) {
-	id := r.URL.Query().Get("id")
+	id := strings.TrimPrefix(r.URL.Path, "/category/")
 
 	value, err := strconv.ParseInt(id, 0, 64)
 
@@ -110,24 +105,23 @@ func deleteCategory(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	db := getSQLConnection()
+	if !deleteCategory(value) {
-
-	defer db.Close()
-
-	_, err = db.Exec("DELETE FROM category WHERE category_id = $1;", value)
-
-	if err != nil {
 		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte(err.Error()))
+		w.Write([]byte(fmt.Sprintf("Failed to delete %d", value)))
 		return
 	}
 
 	w.WriteHeader(http.StatusOK)
-	w.Write([]byte(fmt.Sprintf("Deleted category '%d'.", value)))
 }
 
-func getCategories(w http.ResponseWriter, r *http.Request) {
+func getCategoriesHandler(w http.ResponseWriter, r *http.Request) {
-	categories := getAllCategories()
+	categories, ok := getAllCategories()
+
+	if !ok {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("Failed to fetch a list of categories."))
+		return
+	}
 
 	jsonBytes, err := json.Marshal(categories)
 
@@ -141,12 +135,12 @@ func getCategories(w http.ResponseWriter, r *http.Request) {
 	w.Write(jsonBytes)
 }
 
-func insertCategory(w http.ResponseWriter, r *http.Request) {
+func insertCategoryHandler(w http.ResponseWriter, r *http.Request) {
 	ct := r.Header.Get("content-type")
 
 	if ct != "application/json" {
 		w.WriteHeader(http.StatusUnsupportedMediaType)
-		w.Write([]byte(fmt.Sprintf("Unsupported media type '%s'", ct)))
+		w.Write([]byte(fmt.Sprintf("Unsupported media type '%s', expected application/json", ct)))
 		return
 	}
 
@@ -170,17 +164,11 @@ func insertCategory(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	db := getSQLConnection()
+	id, ok := insertNewCategory(category.Name)
 
-	defer db.Close()
+	if !ok {
-
-	id := 0
-
-	err = db.QueryRow("INSERT INTO category (category_name) VALUES ($1) RETURNING category_id;", category.Name).Scan(&id)
-
-	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
-		w.Write([]byte(err.Error()))
+		w.Write([]byte("Failed to create the new category."))
 		return
 	}