allow custom validation rule validate empty or nil values

util/gvalid/gvalid_check_map.go

@@ -87,20 +87,27 @@ func CheckMap(params interface{}, rules interface{}, messages ...CustomMsg) *Err
 		if v, ok := data[key]; ok {
 			value = v
 		}
+		// It checks each rule and its value in loop.
 		if e := doCheck(key, value, rule, customMsgs[key], data); e != nil {
 			_, item := e.FirstItem()
 			// ===========================================================
-			// If value is nil or empty string and has no required* rules,
-			// clear the error message.
+			// Only in map and struct validations, if value is nil or empty
+			// string and has no required* rules, it clears the error message.
 			// ===========================================================
 			if gconv.String(value) == "" {
 				required := false
 				// rule => error
 				for k := range item {
+					// Default required rules.
 					if _, ok := mustCheckRulesEvenValueEmpty[k]; ok {
 						required = true
 						break
 					}
+					// Custom rules are also required in default.
+					if _, ok := customRuleFuncMap[k]; ok {
+						required = true
+						break
+					}
 				}
 				if !required {
 					continue

util/gvalid/gvalid_check_struct.go

@@ -149,20 +149,27 @@ func CheckStruct(object interface{}, rules interface{}, messages ...CustomMsg) *
 		if v, ok := params[key]; ok {
 			value = v
 		}
+		// It checks each rule and its value in loop.
 		if e := doCheck(key, value, rule, customMessage[key], params); e != nil {
 			_, item := e.FirstItem()
 			// ===========================================================
-			// If value is nil or empty string and has no required* rules,
-			// clear the error message.
+			// Only in map and struct validations, if value is nil or empty
+			// string and has no required* rules, it clears the error message.
 			// ===========================================================
 			if value == nil || gconv.String(value) == "" {
 				required := false
 				// rule => error
 				for k := range item {
+					// Default required rules.
 					if _, ok := mustCheckRulesEvenValueEmpty[k]; ok {
 						required = true
 						break
 					}
+					// Custom rules are also required in default.
+					if _, ok := customRuleFuncMap[k]; ok {
+						required = true
+						break
+					}
 				}
 				if !required {
 					continue

util/gvalid/gvalid_custom_rule.go

@@ -16,6 +16,7 @@ type RuleFunc func(rule string, value interface{}, message string, params map[st
 
 var (
 	// customRuleFuncMap stores the custom rule functions.
+	// map[Rule]RuleFunc
 	customRuleFuncMap = make(map[string]RuleFunc)
 )
 

util/gvalid/gvalid_unit_custom_rule_test.go

@@ -106,3 +106,48 @@ func Test_CustomRule2(t *testing.T) {
 		t.Assert(err, nil)
 	})
 }
+
+func Test_CustomRule_AllowEmpty(t *testing.T) {
+	rule := "allow-empty-str"
+	err := gvalid.RegisterRule(rule, func(rule string, value interface{}, message string, params map[string]interface{}) error {
+		s := gconv.String(value)
+		if len(s) == 0 || s == "gf" {
+			return nil
+		}
+		return errors.New(message)
+	})
+	gtest.Assert(err, nil)
+	// Check.
+	gtest.C(t, func(t *gtest.T) {
+		errStr := "error"
+		t.Assert(gvalid.Check("", rule, errStr).String(), "")
+		t.Assert(gvalid.Check("gf", rule, errStr).String(), "")
+		t.Assert(gvalid.Check("gf2", rule, errStr).String(), errStr)
+	})
+	// Error with struct validation.
+	gtest.C(t, func(t *gtest.T) {
+		type T struct {
+			Value string `v:"uid@allow-empty-str#自定义错误"`
+			Data  string `p:"data"`
+		}
+		st := &T{
+			Value: "",
+			Data:  "123456",
+		}
+		err := gvalid.CheckStruct(st, nil)
+		t.Assert(err.String(), "")
+	})
+	// No error with struct validation.
+	gtest.C(t, func(t *gtest.T) {
+		type T struct {
+			Value string `v:"uid@allow-empty-str#自定义错误"`
+			Data  string `p:"data"`
+		}
+		st := &T{
+			Value: "john",
+			Data:  "123456",
+		}
+		err := gvalid.CheckStruct(st, nil)
+		t.Assert(err.String(), "自定义错误")
+	})
+}