Fix error unmarshaling when key value is string (#125)

goshopify.go

@@ -511,9 +511,10 @@ func CheckResponseError(r *http.Response) error {
 		// A map, parse each error for each key in the map.
 		// json always serializes into map[string]interface{} for objects
 		for k, v := range shopifyError.Errors.(map[string]interface{}) {
+			switch reflect.TypeOf(v).Kind() {
 			// Check to make sure the interface is a slice
 			// json always serializes JSON arrays into []interface{}
-			if reflect.TypeOf(v).Kind() == reflect.Slice {
+			case reflect.Slice:
 				for _, elem := range v.([]interface{}) {
 					// If the primary message of the response error is not set, use
 					// any message.
@@ -523,6 +524,13 @@ func CheckResponseError(r *http.Response) error {
 					topicAndElem := fmt.Sprintf("%v: %v", k, elem)
 					responseError.Errors = append(responseError.Errors, topicAndElem)
 				}
+			case reflect.String:
+				elem := v.(string)
+				if responseError.Message == "" {
+					responseError.Message = fmt.Sprintf("%v: %v", k, elem)
+				}
+				topicAndElem := fmt.Sprintf("%v: %v", k, elem)
+				responseError.Errors = append(responseError.Errors, topicAndElem)
 			}
 		}
 	}

goshopify_test.go

@@ -738,6 +738,10 @@ func TestCheckResponseError(t *testing.T) {
 			httpmock.NewStringResponse(400, `{"errors": { "order": ["order is wrong"] }}`),
 			ResponseError{Status: 400, Message: "order: order is wrong", Errors: []string{"order: order is wrong"}},
 		},
+		{
+			httpmock.NewStringResponse(400, `{"errors": { "collection_id": "collection_id is wrong" }}`),
+			ResponseError{Status: 400, Message: "collection_id: collection_id is wrong", Errors: []string{"collection_id: collection_id is wrong"}},
+		},
 		{
 			httpmock.NewStringResponse(400, `{error:bad request}`),
 			errors.New("invalid character 'e' looking for beginning of object key string"),