feature/boolean (#804)

Author: xvello

README.md

@@ -126,6 +126,7 @@ Baked-in Validations
 | alphanumunicode | Alphanumeric Unicode |
 | alphaunicode | Alpha Unicode |
 | ascii | ASCII |
+| boolean | Boolean |
 | contains | Contains |
 | containsany | Contains Any |
 | containsrune | Contains Rune |

baked_in.go

@@ -107,6 +107,7 @@ var (
 		"alphanum":                      isAlphanum,
 		"alphaunicode":                  isAlphaUnicode,
 		"alphanumunicode":               isAlphanumUnicode,
+		"boolean":                       isBoolean,
 		"numeric":                       isNumeric,
 		"number":                        isNumber,
 		"hexadecimal":                   isHexadecimal,
@@ -1438,6 +1439,12 @@ func isAlphaUnicode(fl FieldLevel) bool {
 	return alphaUnicodeRegex.MatchString(fl.Field().String())
 }
 
+// isBoolean is the validation function for validating if the current field's value can be safely converted to a boolean.
+func isBoolean(fl FieldLevel) bool {
+	_, err := strconv.ParseBool(fl.Field().String())
+	return err == nil
+}
+
 // isDefault is the opposite of required aka hasValue
 func isDefault(fl FieldLevel) bool {
 	return !hasValue(fl)

doc.go

@@ -726,6 +726,12 @@ This validates that a string value contains unicode alphanumeric characters only
 
 	Usage: alphanumunicode
 
+Boolean
+
+This validates that a string value can successfully be parsed into a boolean with strconv.ParseBool
+
+	Usage: boolean
+
 Number
 
 This validates that a string value contains number values only.

validator_test.go

@@ -71,6 +71,7 @@ type TestString struct {
 	Gt        string `validate:"gt=10"`
 	Gte       string `validate:"gte=10"`
 	OmitEmpty string `validate:"omitempty,min=1,max=10"`
+	Boolean   string `validate:"boolean"`
 	Sub       *SubTest
 	SubIgnore *SubTest `validate:"-"`
 	Anonymous struct {
@@ -7943,6 +7944,7 @@ func TestStructStringValidation(t *testing.T) {
 		Lte:       "0123456789",
 		Gt:        "01234567890",
 		Gte:       "0123456789",
+		Boolean:   "true",
 		OmitEmpty: "",
 		Sub: &SubTest{
 			Test: "1",
@@ -7974,6 +7976,7 @@ func TestStructStringValidation(t *testing.T) {
 		Gt:        "1",
 		Gte:       "1",
 		OmitEmpty: "12345678901",
+		Boolean:   "nope",
 		Sub: &SubTest{
 			Test: "",
 		},
@@ -7991,7 +7994,7 @@ func TestStructStringValidation(t *testing.T) {
 
 	// Assert Top Level
 	NotEqual(t, errs, nil)
-	Equal(t, len(errs.(ValidationErrors)), 13)
+	Equal(t, len(errs.(ValidationErrors)), 14)
 
 	// Assert Fields
 	AssertError(t, errs, "TestString.Required", "TestString.Required", "Required", "Required", "required")
@@ -8004,6 +8007,7 @@ func TestStructStringValidation(t *testing.T) {
 	AssertError(t, errs, "TestString.Gt", "TestString.Gt", "Gt", "Gt", "gt")
 	AssertError(t, errs, "TestString.Gte", "TestString.Gte", "Gte", "Gte", "gte")
 	AssertError(t, errs, "TestString.OmitEmpty", "TestString.OmitEmpty", "OmitEmpty", "OmitEmpty", "max")
+	AssertError(t, errs, "TestString.Boolean", "TestString.Boolean", "Boolean", "Boolean", "boolean")
 
 	// Nested Struct Field Errs
 	AssertError(t, errs, "TestString.Anonymous.A", "TestString.Anonymous.A", "A", "A", "required")