Added custom error type when a publisher has no name

models/error.go

@@ -117,3 +117,15 @@ func (err ErrCouldNotGetUserID) Error() string {
 	return fmt.Sprintf("could not get user ID")
 }
 
+// ErrNoPublisherName represents a "ErrNoPublisherName" kind of error.
+type ErrNoPublisherName struct {}
+
+// IsErrNoPublisherName checks if an error is a ErrNoPublisherName.
+func IsErrNoPublisherName(err error) bool {
+	_, ok := err.(ErrNoPublisherName)
+	return ok
+}
+
+func (err ErrNoPublisherName) Error() string {
+	return fmt.Sprintf("you need at least a name to insert a new publisher")
+}

models/publisher_test.go

@@ -44,6 +44,7 @@ func TestAddOrUpdatePublisher(t *testing.T) {
 	// Pass an empty publisher to see if it fails
 	_, err = AddOrUpdatePublisher(Publisher{})
 	assert.Error(t, err)
+	assert.True(t, IsErrNoPublisherName(err))
 
 	// Update the publisher
 	testpublisher.ID = publisher1.ID

models/publishers_add_update.go

@@ -1,12 +1,10 @@
 package models
 
-import "fmt"
-
 // AddOrUpdatePublisher adds or updates a publisher from a publisher struct
 func AddOrUpdatePublisher(publisher Publisher) (newPublisher Publisher, err error) {
 	if publisher.ID == 0 {
 		if publisher.Name == "" { // Only insert it if the name is not empty
-			return Publisher{}, fmt.Errorf("You need at least a name to insert a new publisher")
+			return Publisher{}, ErrNoPublisherName{}
 		}
 
 		_, err = x.Insert(&publisher)

routes/api/v1/books_add_update.go

@@ -67,7 +67,11 @@ func BookAddOrUpdate(c echo.Context) error {
 		}
 
 		if models.IsErrBookTitleCannotBeEmpty(err) {
-			return c.JSON(http.StatusBadRequest, models.Message{"You need to provide at least a Title for the book."})
+			return c.JSON(http.StatusBadRequest, models.Message{"You need to provide at least a title for the book."})
+		}
+
+		if models.IsErrNoPublisherName(err) {
+			return c.JSON(http.StatusBadRequest, models.Message{"You need to provide at least a name to insert a new publisher."})
 		}
 
 		return c.JSON(http.StatusInternalServerError, models.Message{"Error"})

routes/api/v1/publishers_add_update.go

@@ -58,6 +58,10 @@ func PublisherAddOrUpdate(c echo.Context) error {
 	newPublisher, err := models.AddOrUpdatePublisher(*datPublisher)
 
 	if err != nil {
+		if models.IsErrNoPublisherName(err) {
+			return c.JSON(http.StatusBadRequest, models.Message{"You need to provide at least a name to insert a new publisher."})
+		}
+
 		return c.JSON(http.StatusInternalServerError, models.Message{"Error"})
 	}