add omit empty check

allow for optional value checking

baked_in.go

@@ -1,12 +1,203 @@
 package validator
 
-import "reflect"
+import (
+	"log"
+	"reflect"
+	"regexp"
+	"strconv"
+)
 
 var bakedInValidators = map[string]ValidationFunc{
 	"required": isRequired,
+	"length":   length,
+	"min":      min,
+	"max":      max,
+	"regex":    regex,
 }
 
 func isRequired(field interface{}, param string) bool {
 
 	return field != nil && field != reflect.Zero(reflect.TypeOf(field)).Interface()
 }
+
+// length tests whether a variable's length is equal to a given
+// value. For strings it tests the number of characters whereas
+// for maps and slices it tests the number of items.
+func length(field interface{}, param string) bool {
+
+	st := reflect.ValueOf(field)
+
+	switch st.Kind() {
+
+	case reflect.String:
+		p := asInt(param)
+
+		return int64(len(st.String())) == p
+
+	case reflect.Slice, reflect.Map, reflect.Array:
+		p := asInt(param)
+
+		return int64(st.Len()) == p
+
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		p := asInt(param)
+
+		return st.Int() == p
+
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		p := asUint(param)
+
+		return st.Uint() == p
+
+	case reflect.Float32, reflect.Float64:
+		p := asFloat(param)
+
+		return st.Float() == p
+
+	default:
+		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
+		return false
+	}
+}
+
+// min tests whether a variable value is larger or equal to a given
+// number. For number types, it's a simple lesser-than test; for
+// strings it tests the number of characters whereas for maps
+// and slices it tests the number of items.
+func min(field interface{}, param string) bool {
+
+	st := reflect.ValueOf(field)
+
+	switch st.Kind() {
+
+	case reflect.String:
+		p := asInt(param)
+
+		return int64(len(st.String())) >= p
+
+	case reflect.Slice, reflect.Map, reflect.Array:
+		p := asInt(param)
+
+		return int64(st.Len()) >= p
+
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		p := asInt(param)
+
+		return st.Int() >= p
+
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		p := asUint(param)
+
+		return st.Uint() >= p
+
+	case reflect.Float32, reflect.Float64:
+		p := asFloat(param)
+
+		return st.Float() >= p
+
+	default:
+		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
+		return false
+	}
+}
+
+// max tests whether a variable value is lesser than a given
+// value. For numbers, it's a simple lesser-than test; for
+// strings it tests the number of characters whereas for maps
+// and slices it tests the number of items.
+func max(field interface{}, param string) bool {
+
+	st := reflect.ValueOf(field)
+
+	switch st.Kind() {
+
+	case reflect.String:
+		p := asInt(param)
+
+		return int64(len(st.String())) <= p
+
+	case reflect.Slice, reflect.Map, reflect.Array:
+		p := asInt(param)
+
+		return int64(st.Len()) <= p
+
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		p := asInt(param)
+
+		return st.Int() <= p
+
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		p := asUint(param)
+
+		return st.Uint() <= p
+
+	case reflect.Float32, reflect.Float64:
+		p := asFloat(param)
+
+		return st.Float() <= p
+
+	default:
+		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
+		return false
+	}
+}
+
+// regex is the builtin validation function that checks
+// whether the string variable matches a regular expression
+func regex(field interface{}, param string) bool {
+
+	s, ok := field.(string)
+	if !ok {
+		log.Fatalf("Bad field type %s\n", field)
+	}
+
+	re, err := regexp.Compile(param)
+	if err != nil {
+		log.Fatalf("Bad regex param %s\n", param)
+	}
+
+	if !re.MatchString(s) {
+		return false
+	}
+
+	return true
+}
+
+// asInt retuns the parameter as a int64
+// or panics if it can't convert
+func asInt(param string) int64 {
+
+	i, err := strconv.ParseInt(param, 0, 64)
+
+	if err != nil {
+		log.Fatalf("Bad Input Param %s\n", param)
+	}
+
+	return i
+}
+
+// asUint returns the parameter as a uint64
+// or panics if it can't convert
+func asUint(param string) uint64 {
+
+	i, err := strconv.ParseUint(param, 0, 64)
+
+	if err != nil {
+		log.Fatalf("Bad Input Param %s\n", param)
+	}
+
+	return i
+}
+
+// asFloat returns the parameter as a float64
+// or panics if it can't convert
+func asFloat(param string) float64 {
+
+	i, err := strconv.ParseFloat(param, 64)
+
+	if err != nil {
+		log.Fatalf("Bad Input Param %s\n", param)
+	}
+
+	return i
+}

validator.go

@@ -8,6 +8,10 @@ import (
 	"unicode"
 )
 
+const (
+	omitempty string = "omitempty"
+)
+
 // FieldValidationError contains a single fields validation error
 type FieldValidationError struct {
 	Field    string
@@ -161,7 +165,7 @@ func (v *Validator) ValidateStruct(s interface{}) map[string]*StructValidationEr
 		}
 	}
 
-	if currentStructError.Errors != nil {
+	if len(currentStructError.Errors) > 0 {
 		errorArray[currentStructError.Struct] = currentStructError
 		// free up memory
 		currentStructError = nil
@@ -206,6 +210,10 @@ func (v *Validator) validateFieldByNameAndTag(f interface{}, name string, tag st
 		return nil
 	}
 
+	if strings.Contains(tag, omitempty) && !isRequired(f, "") {
+		return nil
+	}
+
 	valueField := reflect.ValueOf(f)
 
 	if valueField.Kind() == reflect.Ptr && !valueField.IsNil() {
@@ -229,6 +237,10 @@ func (v *Validator) validateFieldByNameAndTag(f interface{}, name string, tag st
 			log.Fatalf("Invalid validation tag on field %s", name)
 		}
 
+		if key == omitempty {
+			continue
+		}
+
 		valFunc := v.validationFuncs[key]
 		if valFunc == nil {
 			log.Fatalf("Undefined validation function on field %s", name)

validator_test.go

@@ -8,7 +8,7 @@ import (
 )
 
 type UserDetails struct {
-	Address string `validate:"required"`
+	Address string `validate:"omitempty,length=6"`
 }
 
 type User struct {