[#1651] added more detailed file upload errors

forms/validators/file.go

@@ -22,7 +22,10 @@ func UploadedFileSize(maxBytes int) validation.RuleFunc {
 		}
 
 		if int(v.Size) > maxBytes {
-			return validation.NewError("validation_file_size_limit", fmt.Sprintf("Maximum allowed file size is %v bytes.", maxBytes))
+			return validation.NewError(
+				"validation_file_size_limit",
+				fmt.Sprintf("Failed to upload %q - the maximum allowed file size is %v bytes.", v.OriginalName, maxBytes),
+			)
 		}
 
 		return nil
@@ -42,19 +45,24 @@ func UploadedFileMimeType(validTypes []string) validation.RuleFunc {
 			return nil // nothing to validate
 		}
 
+		baseErr := validation.NewError(
+			"validation_invalid_mime_type",
+			fmt.Sprintf("Failed to upload %q due to unsupported file type.", v.OriginalName),
+		)
+
 		if len(validTypes) == 0 {
-			return validation.NewError("validation_invalid_mime_type", "Unsupported file type.")
+			return baseErr
 		}
 
 		f, err := v.Reader.Open()
 		if err != nil {
-			return validation.NewError("validation_invalid_mime_type", "Unsupported file type.")
+			return baseErr
 		}
 		defer f.Close()
 
 		filetype, err := mimetype.DetectReader(f)
 		if err != nil {
-			return validation.NewError("validation_invalid_mime_type", "Unsupported file type.")
+			return baseErr
 		}
 
 		for _, t := range validTypes {
@@ -63,9 +71,13 @@ func UploadedFileMimeType(validTypes []string) validation.RuleFunc {
 			}
 		}
 
-		return validation.NewError("validation_invalid_mime_type", fmt.Sprintf(
-			"The following mime types are only allowed: %s.",
-			strings.Join(validTypes, ","),
-		))
+		return validation.NewError(
+			"validation_invalid_mime_type",
+			fmt.Sprintf(
+				"%q mime type must be one of: %s.",
+				v.Name,
+				strings.Join(validTypes, ", "),
+			),
+		)
 	}
 }