Adding more descriptive error messages

constraints.go

@@ -12,19 +12,19 @@ Numerical Type Constraints
 */
 
 func min(field field, param string) error {
-	return checkMin(field.value, field.typ, param, false)
+	return checkMin(field, param, false)
 }
 
 func max(field field, param string) error {
-	return checkMax(field.value, field.typ, param, false)
+	return checkMax(field, param, false)
 }
 
 func exclusiveMin(field field, param string) error {
-	return checkMin(field.value, field.typ, param, true)
+	return checkMin(field, param, true)
 }
 
 func exclusiveMax(field field, param string) error {
-	return checkMax(field.value, field.typ, param, true)
+	return checkMax(field, param, true)
 }
 
 func multipleOf(field field, param string) error {
@@ -39,10 +39,10 @@ func multipleOf(field field, param string) error {
 		}
 		valid := in%cInt == 0
 		if !valid {
-			return ErrMultipleOf
+			return fmt.Errorf(ErrMultipleOf, field.name)
 		}
 	default:
-		return ErrInvalidValidationForField
+		return fmt.Errorf(ErrInvalidValidationForField, field.name)
 	}
 	return nil
 }
@@ -56,16 +56,16 @@ func notnull(field field, param string) error {
 	case reflect.String:
 		c, err := convertBool(param)
 		if err != nil {
-			return err
+			return fmt.Errorf(ErrBadConstraint, "notnull", param, field.name)
 		}
 		if c == true {
 			in, _ := field.value.Interface().(string)
 			if in == "" {
-				return ErrNoNull
+				return fmt.Errorf(ErrNotNull, field.name)
 			}
 		}
 	default:
-		return ErrInvalidValidationForField
+		return fmt.Errorf(ErrInvalidValidationForField, field.name)
 	}
 	return nil
 }
@@ -77,10 +77,10 @@ func minLength(field field, param string) error {
 		lv := len(fmt.Sprint(field.value))
 		valid := lv > lc
 		if !valid {
-			return ErrMinLength
+			return fmt.Errorf(ErrMinLength, field.name)
 		}
 	default:
-		return ErrInvalidValidationForField
+		return fmt.Errorf(ErrInvalidValidationForField, field.name)
 	}
 	return nil
 }
@@ -92,10 +92,10 @@ func maxLength(field field, param string) error {
 		lv := len(fmt.Sprint(field.value))
 		valid := lv < lc
 		if !valid {
-			return ErrMaxLength
+			return fmt.Errorf(ErrMaxLength, field.name)
 		}
 	default:
-		return ErrInvalidValidationForField
+		return fmt.Errorf(ErrInvalidValidationForField, field.name)
 	}
 	return nil
 }
@@ -106,13 +106,13 @@ func pattern(field field, param string) error {
 		in, _ := field.value.Interface().(string)
 		re, err := regexp.Compile(param)
 		if err != nil {
-			return ErrBadConstraint
+			return fmt.Errorf(ErrBadConstraint, "pattern", param, field.name)
 		}
 		if !re.MatchString(in) {
-			return ErrPattern
+			return fmt.Errorf(ErrPattern, field.name)
 		}
 	default:
-		return ErrInvalidValidationForField
+		return fmt.Errorf(ErrInvalidValidationForField, field.name)
 	}
 	return nil
 }
@@ -129,7 +129,7 @@ func enum(field field, param string) error {
 	}
 
 	if flag == false {
-		return ErrEnums
+		return fmt.Errorf(ErrEnums, field.name)
 	}
 	return nil
 }

default.go

@@ -2,38 +2,32 @@ package validator
 
 import "errors"
 
-type ErrMsg struct {
-	Err error
-}
-
-func (e ErrMsg) Error() string {
-	return e.Err.Error()
-}
-
 var (
-	ErrNoNull = ErrMsg{errors.New("notnull validation failed")}
+	ErrNotNull = "notnull validation failed for field %s"
+
+	ErrMin = "min value validation failed for field %s"
 
-	ErrInvalidValidationForField = ErrMsg{errors.New("invalid validation applied to the field")}
+	ErrMax = "max value validation failed for field %s"
 
-	ErrMin = ErrMsg{errors.New("min value validation failed")}
+	ErrExclusiveMin = "exclusive min validation failed for field %s"
 
-	ErrMax = ErrMsg{errors.New("max value validation failed")}
+	ErrExclusiveMax = "exclusive max validation failed for field %s"
 
-	ErrExclusiveMin = ErrMsg{errors.New("exclusive min validation failed")}
+	ErrMultipleOf = "multipleOf validation failed for field %s"
 
-	ErrExclusiveMax = ErrMsg{errors.New("exclusive max validation failed")}
+	ErrMinLength = "min-length validation failed for field %s"
 
-	ErrMultipleOf = ErrMsg{errors.New("multipleOf validation failed")}
+	ErrMaxLength = "max-length validation failed for field %s"
 
-	ErrMinLength = ErrMsg{errors.New("min-length validation failed")}
+	ErrPattern = "pattern validation failed for field %s"
 
-	ErrMaxLength = ErrMsg{errors.New("max-length validation failed")}
+	ErrEnums = "enum validation failed for field %s"
 
-	ErrPattern = ErrMsg{errors.New("pattern validation failed")}
+	ErrBadConstraint = "invalid constraint %s with value '%s' for field %s"
 
-	ErrBadConstraint = ErrMsg{errors.New("invalid constraint value")}
+	ErrInvalidValidationForField = "invalid validation applied to the field %s"
 
-	ErrNotSupported = ErrMsg{errors.New("unsupported constraint on type")}
+	ErrNotSupported = errors.New("unsupported constraint on type")
 
-	ErrEnums = ErrMsg{errors.New("enum validation failed")}
+	ErrConversionFailed = errors.New("conversion failed")
 )