support custom message

.gitignore

@@ -26,5 +26,6 @@ _testmain.go
 *.test
 *.out
 *.txt
+.idea
 cover.html
 README.html

cache.go

@@ -79,6 +79,7 @@ type cField struct {
 	name       string
 	altName    string
 	namesEqual bool
+	tagValues  map[string]string // custom multiple tag information tagname:tagvalue
 	cTags      *cTag
 }
 
@@ -154,11 +155,21 @@ func (v *Validate) extractStructCache(current reflect.Value, sName string) *cStr
 			ctag = new(cTag)
 		}
 
+		// handle custom tag map
+		length := len(v.customTags)
+		tagValues := make(map[string]string, length)
+
+		for i := 0; i < length; i++ {
+			ctname := v.customTags[i]
+			tagValues[ctname] = strings.TrimSpace(fld.Tag.Get(ctname))
+		}
+
 		cs.fields = append(cs.fields, &cField{
 			idx:        i,
 			name:       fld.Name,
 			altName:    customName,
 			cTags:      ctag,
+			tagValues:  tagValues,
 			namesEqual: fld.Name == customName,
 		})
 	}

errors.go

@@ -177,6 +177,7 @@ type fieldError struct {
 	structfieldLen uint8
 	value          interface{}
 	param          string
+	cem            string // custom error message
 	kind           reflect.Kind
 	typ            reflect.Type
 }
@@ -251,6 +252,9 @@ func (fe *fieldError) Type() reflect.Type {
 
 // Error returns the fieldError's error message
 func (fe *fieldError) Error() string {
+	if len(fe.cem) != 0 {
+		return fe.cem
+	}
 	return fmt.Sprintf(fieldErrMsg, fe.ns, fe.Field(), fe.tag)
 }
 

validator.go

@@ -128,6 +128,7 @@ func (v *validate) traverseField(ctx context.Context, parent reflect.Value, curr
 						fieldLen:       uint8(len(cf.altName)),
 						structfieldLen: uint8(len(cf.name)),
 						param:          ct.param,
+						cem:            cf.tagValues[defaultErrTagName],
 						kind:           kind,
 					},
 				)
@@ -152,6 +153,7 @@ func (v *validate) traverseField(ctx context.Context, parent reflect.Value, curr
 						structfieldLen: uint8(len(cf.name)),
 						value:          current.Interface(),
 						param:          ct.param,
+						cem:            cf.tagValues[defaultErrTagName],
 						kind:           kind,
 						typ:            current.Type(),
 					},
@@ -197,6 +199,7 @@ func (v *validate) traverseField(ctx context.Context, parent reflect.Value, curr
 								structfieldLen: uint8(len(cf.name)),
 								value:          current.Interface(),
 								param:          ct.param,
+								cem:            cf.tagValues[defaultErrTagName],
 								kind:           kind,
 								typ:            typ,
 							},
@@ -402,6 +405,7 @@ OUTER:
 								structfieldLen: uint8(len(cf.name)),
 								value:          current.Interface(),
 								param:          ct.param,
+								cem:            cf.tagValues[defaultErrTagName],
 								kind:           kind,
 								typ:            typ,
 							},
@@ -422,6 +426,7 @@ OUTER:
 								structfieldLen: uint8(len(cf.name)),
 								value:          current.Interface(),
 								param:          ct.param,
+								cem:            cf.tagValues[defaultErrTagName],
 								kind:           kind,
 								typ:            typ,
 							},
@@ -463,6 +468,7 @@ OUTER:
 						structfieldLen: uint8(len(cf.name)),
 						value:          current.Interface(),
 						param:          ct.param,
+						cem:            cf.tagValues[defaultErrTagName],
 						kind:           kind,
 						typ:            typ,
 					},

validator_instance.go

@@ -50,9 +50,22 @@ var (
 	timeDurationType = reflect.TypeOf(time.Duration(0))
 	timeType         = reflect.TypeOf(time.Time{})
 
-	defaultCField = &cField{namesEqual: true}
+	defaultCField     = &cField{namesEqual: true}
+	defaultErrTagName = "message"
 )
 
+// StringSlice is custom tag slice data
+type StringSlice []string
+
+func (s StringSlice) Position(name string) int {
+	for i := 0; i < len(s); i++ {
+		if s[i] == name {
+			return i
+		}
+	}
+	return -1
+}
+
 // FilterFunc is the type used to filter fields using
 // StructFiltered(...) function.
 // returning true results in the field being filtered/skiped from
@@ -75,6 +88,7 @@ type internalValidationFuncWrapper struct {
 // Validate contains the validator settings and cache
 type Validate struct {
 	tagName          string
+	customTags       StringSlice
 	pool             *sync.Pool
 	hasCustomFuncs   bool
 	hasTagNameFunc   bool
@@ -99,6 +113,7 @@ func New() *Validate {
 
 	v := &Validate{
 		tagName:     defaultTagName,
+		customTags:  StringSlice{defaultErrTagName},
 		aliases:     make(map[string]string, len(bakedInAliases)),
 		validations: make(map[string]internalValidationFuncWrapper, len(bakedInValidators)),
 		tagCache:    tc,
@@ -143,6 +158,15 @@ func (v *Validate) SetTagName(name string) {
 	v.tagName = name
 }
 
+// SetErrTagName allows for changing of the default tag name of 'message'
+func (v *Validate) SetErrTagName(name string) {
+	index := v.customTags.Position(defaultErrTagName)
+	if index != -1 {
+		v.customTags[index] = name
+	}
+	defaultErrTagName = name
+}
+
 // ValidateMapCtx validates a map using a map of validation rules and allows passing of contextual
 // validation validation information via context.Context.
 func (v Validate) ValidateMapCtx(ctx context.Context, data map[string]interface{}, rules map[string]interface{}) map[string]interface{} {