Add oneofci validator (oneof case insensitive) (#1321)

## Fixes Or Enhances - Adds oneofci, a case insensitive version of oneof - resolves #840 **Make sure that you've checked the boxes below before you submit PR:** - [ X] Tests exist or have been written that cover this particular change. @go-playground/validator-maintainers

Author: miscalibrated

baked_in.go

@@ -205,6 +205,7 @@ var (
 "fqdn": isFQDN,
 "unique": isUnique,
 "oneof": isOneOf,
+"oneofci": isOneOfCI,
 "html": isHTML,
 "html_encoded": isHTMLEncoded,
 "url_encoded": isURLEncoded,
@@ -299,6 +300,23 @@ func isOneOf(fl FieldLevel) bool {
 return false
 }
 
+// isOneOfCI is the validation function for validating if the current field's value is one of the provided string values (case insensitive).
+func isOneOfCI(fl FieldLevel) bool {
+vals := parseOneOfParam2(fl.Param())
+field := fl.Field()
+
+if field.Kind() != reflect.String {
+panic(fmt.Sprintf("Bad field type %T", field.Interface()))
+}
+v := field.String()
+for _, val := range vals {
+if strings.EqualFold(val, v) {
+return true
+}
+}
+return false
+}
+
 // isUnique is the validation function for validating if each array|slice|map value is unique
 func isUnique(fl FieldLevel) bool {
 field := fl.Field()

doc.go

@@ -495,6 +495,13 @@ the target string between single quotes. Kind of like an 'enum'.
  oneof='red green' 'blue yellow'
  oneof=5 7 9
 
+# One Of Case Insensitive
+
+Works the same as oneof but is case insensitive and therefore only accepts strings.
+
+Usage: oneofci=red green
+ oneofci='red green' 'blue yellow'
+
 # Greater Than
 
 For numbers, this will ensure that the value is greater than the

validator_test.go

@@ -5680,6 +5680,82 @@ func TestOneOfValidation(t *testing.T) {
 }, "Bad field type float64")
 }
 
+func TestOneOfCIValidation(t *testing.T) {
+validate := New()
+
+passSpecs := []struct {
+f interface{}
+t string
+}{
+{f: "red", t: "oneofci=RED GREEN"},
+{f: "RED", t: "oneofci=red green"},
+{f: "red", t: "oneofci=red green"},
+{f: "RED", t: "oneofci=RED GREEN"},
+{f: "green", t: "oneofci=red green"},
+{f: "red green", t: "oneofci='red green' blue"},
+{f: "blue", t: "oneofci='red green' blue"},
+{f: "GREEN", t: "oneofci=Red Green"},
+{f: "ReD", t: "oneofci=RED GREEN"},
+{f: "gReEn", t: "oneofci=rEd GrEeN"},
+{f: "RED GREEN", t: "oneofci='red green' blue"},
+{f: "red Green", t: "oneofci='RED GREEN' Blue"},
+{f: "Red green", t: "oneofci='Red Green' BLUE"},
+{f: "rEd GrEeN", t: "oneofci='ReD gReEn' BlUe"},
+{f: "BLUE", t: "oneofci='Red Green' BLUE"},
+{f: "BlUe", t: "oneofci='RED GREEN' Blue"},
+{f: "bLuE", t: "oneofci='red green' BLUE"},
+}
+
+for _, spec := range passSpecs {
+t.Logf("%#v", spec)
+errs := validate.Var(spec.f, spec.t)
+Equal(t, errs, nil)
+}
+
+failSpecs := []struct {
+f interface{}
+t string
+}{
+{f: "", t: "oneofci=red green"},
+{f: "yellow", t: "oneofci=red green"},
+{f: "green", t: "oneofci='red green' blue"},
+}
+
+for _, spec := range failSpecs {
+t.Logf("%#v", spec)
+errs := validate.Var(spec.f, spec.t)
+AssertError(t, errs, "", "", "", "", "oneofci")
+}
+
+panicSpecs := []struct {
+f interface{}
+t string
+}{
+{f: 3.14, t: "oneofci=red green"},
+{f: 5, t: "oneofci=red green"},
+{f: uint(6), t: "oneofci=7"},
+{f: int8(5), t: "oneofci=red green"},
+{f: int16(5), t: "oneofci=red green"},
+{f: int32(5), t: "oneofci=red green"},
+{f: int64(5), t: "oneofci=red green"},
+{f: uint(5), t: "oneofci=red green"},
+{f: uint8(5), t: "oneofci=red green"},
+{f: uint16(5), t: "oneofci=red green"},
+{f: uint32(5), t: "oneofci=red green"},
+{f: uint64(5), t: "oneofci=red green"},
+}
+
+panicCount := 0
+for _, spec := range panicSpecs {
+t.Logf("%#v", spec)
+PanicMatches(t, func() {
+_ = validate.Var(spec.f, spec.t)
+}, fmt.Sprintf("Bad field type %T", spec.f))
+panicCount++
+}
+Equal(t, panicCount, len(panicSpecs))
+}
+
 func TestBase32Validation(t *testing.T) {
 validate := New()