User 'errors.Is' instead of parsing the error message

api/member.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"encoding/json"
+	"errors"
 	"log"
 	"net/http"
 	"strconv"
@@ -90,7 +91,7 @@ func (a *api) getMemberNum(num int, w http.ResponseWriter, req *http.Request) {
 	var member Member
 	err := a.db.Where("num = ?", num).First(&member).Error
 	if err != nil {
-		if err.Error() == "record not found" {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
 			w.WriteHeader(http.StatusNotFound)
 			return
 		}
@@ -132,7 +133,7 @@ func (a *api) UpdateMember(w http.ResponseWriter, req *http.Request) {
 	var dbMember Member
 	err = a.db.Where("num = ?", vars["num"]).First(&dbMember).Error
 	if err != nil {
-		if err.Error() == "record not found" {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
 			w.WriteHeader(http.StatusNotFound)
 			return
 		}

api/order.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"encoding/json"
+	"errors"
 	"log"
 	"net/http"
 	"time"
@@ -130,7 +131,7 @@ func (a *api) GetOrder(num int, w http.ResponseWriter, req *http.Request) {
 	err := a.db.Preload(clause.Associations).
 		First(&order, vars["id"]).Error
 	if err != nil {
-		if err.Error() == "record not found" {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
 			w.WriteHeader(http.StatusNotFound)
 			return
 		}

api/product.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"encoding/json"
+	"errors"
 	"log"
 	"net/http"
 
@@ -65,7 +66,7 @@ func (a *api) GetProduct(w http.ResponseWriter, req *http.Request) {
 	var product Product
 	err := a.db.Where("code = ?", vars["code"]).First(&product).Error
 	if err != nil {
-		if err.Error() == "record not found" {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
 			w.WriteHeader(http.StatusNotFound)
 			return
 		}
@@ -107,7 +108,7 @@ func (a *api) UpdateProduct(w http.ResponseWriter, req *http.Request) {
 	var dbProduct Product
 	err = a.db.Where("code = ?", vars["code"]).First(&dbProduct).Error
 	if err != nil {
-		if err.Error() == "record not found" {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
 			w.WriteHeader(http.StatusNotFound)
 			return
 		}

api/transaction.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log"
 	"net/http"
@@ -54,7 +55,7 @@ func (a *api) GetTransaction(num int, role string, w http.ResponseWriter, req *h
 		Preload(clause.Associations).
 		First(&transaction, vars["id"]).Error
 	if err != nil {
-		if err.Error() == "record not found" {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
 			w.WriteHeader(http.StatusNotFound)
 			return
 		}