[go] Add constructor and IsValid method to enum types (#8224)

* Add constructor and IsValid method to enum types

* Add samples

modules/openapi-generator/src/main/resources/go/model_enum.mustache

@@ -12,6 +12,14 @@ const (
 	{{/allowableValues}}
 )
 
+var allowed{{{classname}}}EnumValues = []{{{classname}}}{
+	{{#allowableValues}}
+	{{#enumVars}}
+	{{{value}}},
+	{{/enumVars}}
+	{{/allowableValues}}
+}
+
 func (v *{{{classname}}}) UnmarshalJSON(src []byte) error {
 	var value {{^format}}{{dataType}}{{/format}}{{#format}}{{{format}}}{{/format}}
 	err := json.Unmarshal(src, &value)
@@ -19,7 +27,7 @@ func (v *{{{classname}}}) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := {{{classname}}}(value)
-	for _, existing := range []{{classname}}{ {{#allowableValues}}{{#enumVars}}{{{value}}}, {{/enumVars}} {{/allowableValues}} } {
+	for _, existing := range allowed{{{classname}}}EnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -29,6 +37,27 @@ func (v *{{{classname}}}) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid {{classname}}", value)
 }
 
+// New{{{classname}}}FromValue returns a pointer to a valid {{{classname}}}
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func New{{{classname}}}FromValue(v {{^format}}{{dataType}}{{/format}}{{#format}}{{{format}}}{{/format}}) (*{{{classname}}}, error) {
+	ev := {{{classname}}}(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for {{{classname}}}: valid values are %v", v, allowed{{{classname}}}EnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v {{{classname}}}) IsValid() bool {
+	for _, existing := range allowed{{{classname}}}EnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to {{{name}}} value
 func (v {{{classname}}}) Ptr() *{{{classname}}} {
 	return &v

samples/client/petstore/go/go-petstore/model_enum_class.go

@@ -25,6 +25,12 @@ const (
 	XYZ EnumClass = "(xyz)"
 )
 
+var allowedEnumClassEnumValues = []EnumClass{
+	"_abc",
+	"-efg",
+	"(xyz)",
+}
+
 func (v *EnumClass) UnmarshalJSON(src []byte) error {
 	var value string
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *EnumClass) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := EnumClass(value)
-	for _, existing := range []EnumClass{ "_abc", "-efg", "(xyz)",   } {
+	for _, existing := range allowedEnumClassEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *EnumClass) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid EnumClass", value)
 }
 
+// NewEnumClassFromValue returns a pointer to a valid EnumClass
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewEnumClassFromValue(v string) (*EnumClass, error) {
+	ev := EnumClass(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for EnumClass: valid values are %v", v, allowedEnumClassEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v EnumClass) IsValid() bool {
+	for _, existing := range allowedEnumClassEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to EnumClass value
 func (v EnumClass) Ptr() *EnumClass {
 	return &v

samples/client/petstore/go/go-petstore/model_outer_enum.go

@@ -25,6 +25,12 @@ const (
 	DELIVERED OuterEnum = "delivered"
 )
 
+var allowedOuterEnumEnumValues = []OuterEnum{
+	"placed",
+	"approved",
+	"delivered",
+}
+
 func (v *OuterEnum) UnmarshalJSON(src []byte) error {
 	var value string
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *OuterEnum) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := OuterEnum(value)
-	for _, existing := range []OuterEnum{ "placed", "approved", "delivered",   } {
+	for _, existing := range allowedOuterEnumEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *OuterEnum) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid OuterEnum", value)
 }
 
+// NewOuterEnumFromValue returns a pointer to a valid OuterEnum
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewOuterEnumFromValue(v string) (*OuterEnum, error) {
+	ev := OuterEnum(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for OuterEnum: valid values are %v", v, allowedOuterEnumEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v OuterEnum) IsValid() bool {
+	for _, existing := range allowedOuterEnumEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to OuterEnum value
 func (v OuterEnum) Ptr() *OuterEnum {
 	return &v

samples/openapi3/client/petstore/go/go-petstore/model_enum_class.go

@@ -25,6 +25,12 @@ const (
 	ENUMCLASS_XYZ EnumClass = "(xyz)"
 )
 
+var allowedEnumClassEnumValues = []EnumClass{
+	"_abc",
+	"-efg",
+	"(xyz)",
+}
+
 func (v *EnumClass) UnmarshalJSON(src []byte) error {
 	var value string
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *EnumClass) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := EnumClass(value)
-	for _, existing := range []EnumClass{ "_abc", "-efg", "(xyz)",   } {
+	for _, existing := range allowedEnumClassEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *EnumClass) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid EnumClass", value)
 }
 
+// NewEnumClassFromValue returns a pointer to a valid EnumClass
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewEnumClassFromValue(v string) (*EnumClass, error) {
+	ev := EnumClass(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for EnumClass: valid values are %v", v, allowedEnumClassEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v EnumClass) IsValid() bool {
+	for _, existing := range allowedEnumClassEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to EnumClass value
 func (v EnumClass) Ptr() *EnumClass {
 	return &v

samples/openapi3/client/petstore/go/go-petstore/model_outer_enum.go

@@ -25,6 +25,12 @@ const (
 	OUTERENUM_DELIVERED OuterEnum = "delivered"
 )
 
+var allowedOuterEnumEnumValues = []OuterEnum{
+	"placed",
+	"approved",
+	"delivered",
+}
+
 func (v *OuterEnum) UnmarshalJSON(src []byte) error {
 	var value string
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *OuterEnum) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := OuterEnum(value)
-	for _, existing := range []OuterEnum{ "placed", "approved", "delivered",   } {
+	for _, existing := range allowedOuterEnumEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *OuterEnum) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid OuterEnum", value)
 }
 
+// NewOuterEnumFromValue returns a pointer to a valid OuterEnum
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewOuterEnumFromValue(v string) (*OuterEnum, error) {
+	ev := OuterEnum(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for OuterEnum: valid values are %v", v, allowedOuterEnumEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v OuterEnum) IsValid() bool {
+	for _, existing := range allowedOuterEnumEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to OuterEnum value
 func (v OuterEnum) Ptr() *OuterEnum {
 	return &v

samples/openapi3/client/petstore/go/go-petstore/model_outer_enum_default_value.go

@@ -25,6 +25,12 @@ const (
 	OUTERENUMDEFAULTVALUE_DELIVERED OuterEnumDefaultValue = "delivered"
 )
 
+var allowedOuterEnumDefaultValueEnumValues = []OuterEnumDefaultValue{
+	"placed",
+	"approved",
+	"delivered",
+}
+
 func (v *OuterEnumDefaultValue) UnmarshalJSON(src []byte) error {
 	var value string
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *OuterEnumDefaultValue) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := OuterEnumDefaultValue(value)
-	for _, existing := range []OuterEnumDefaultValue{ "placed", "approved", "delivered",   } {
+	for _, existing := range allowedOuterEnumDefaultValueEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *OuterEnumDefaultValue) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid OuterEnumDefaultValue", value)
 }
 
+// NewOuterEnumDefaultValueFromValue returns a pointer to a valid OuterEnumDefaultValue
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewOuterEnumDefaultValueFromValue(v string) (*OuterEnumDefaultValue, error) {
+	ev := OuterEnumDefaultValue(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for OuterEnumDefaultValue: valid values are %v", v, allowedOuterEnumDefaultValueEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v OuterEnumDefaultValue) IsValid() bool {
+	for _, existing := range allowedOuterEnumDefaultValueEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to OuterEnumDefaultValue value
 func (v OuterEnumDefaultValue) Ptr() *OuterEnumDefaultValue {
 	return &v

samples/openapi3/client/petstore/go/go-petstore/model_outer_enum_integer.go

@@ -25,6 +25,12 @@ const (
 	OUTERENUMINTEGER__2 OuterEnumInteger = 2
 )
 
+var allowedOuterEnumIntegerEnumValues = []OuterEnumInteger{
+	0,
+	1,
+	2,
+}
+
 func (v *OuterEnumInteger) UnmarshalJSON(src []byte) error {
 	var value int32
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *OuterEnumInteger) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := OuterEnumInteger(value)
-	for _, existing := range []OuterEnumInteger{ 0, 1, 2,   } {
+	for _, existing := range allowedOuterEnumIntegerEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *OuterEnumInteger) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid OuterEnumInteger", value)
 }
 
+// NewOuterEnumIntegerFromValue returns a pointer to a valid OuterEnumInteger
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewOuterEnumIntegerFromValue(v int32) (*OuterEnumInteger, error) {
+	ev := OuterEnumInteger(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for OuterEnumInteger: valid values are %v", v, allowedOuterEnumIntegerEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v OuterEnumInteger) IsValid() bool {
+	for _, existing := range allowedOuterEnumIntegerEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to OuterEnumInteger value
 func (v OuterEnumInteger) Ptr() *OuterEnumInteger {
 	return &v

samples/openapi3/client/petstore/go/go-petstore/model_outer_enum_integer_default_value.go

@@ -25,6 +25,12 @@ const (
 	OUTERENUMINTEGERDEFAULTVALUE__2 OuterEnumIntegerDefaultValue = 2
 )
 
+var allowedOuterEnumIntegerDefaultValueEnumValues = []OuterEnumIntegerDefaultValue{
+	0,
+	1,
+	2,
+}
+
 func (v *OuterEnumIntegerDefaultValue) UnmarshalJSON(src []byte) error {
 	var value int32
 	err := json.Unmarshal(src, &value)
@@ -32,7 +38,7 @@ func (v *OuterEnumIntegerDefaultValue) UnmarshalJSON(src []byte) error {
 		return err
 	}
 	enumTypeValue := OuterEnumIntegerDefaultValue(value)
-	for _, existing := range []OuterEnumIntegerDefaultValue{ 0, 1, 2,   } {
+	for _, existing := range allowedOuterEnumIntegerDefaultValueEnumValues {
 		if existing == enumTypeValue {
 			*v = enumTypeValue
 			return nil
@@ -42,6 +48,27 @@ func (v *OuterEnumIntegerDefaultValue) UnmarshalJSON(src []byte) error {
 	return fmt.Errorf("%+v is not a valid OuterEnumIntegerDefaultValue", value)
 }
 
+// NewOuterEnumIntegerDefaultValueFromValue returns a pointer to a valid OuterEnumIntegerDefaultValue
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewOuterEnumIntegerDefaultValueFromValue(v int32) (*OuterEnumIntegerDefaultValue, error) {
+	ev := OuterEnumIntegerDefaultValue(v)
+	if ev.IsValid() {
+		return &ev, nil
+	} else {
+		return nil, fmt.Errorf("invalid value '%v' for OuterEnumIntegerDefaultValue: valid values are %v", v, allowedOuterEnumIntegerDefaultValueEnumValues)
+	}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v OuterEnumIntegerDefaultValue) IsValid() bool {
+	for _, existing := range allowedOuterEnumIntegerDefaultValueEnumValues {
+		if existing == v {
+			return true
+		}
+	}
+	return false
+}
+
 // Ptr returns reference to OuterEnumIntegerDefaultValue value
 func (v OuterEnumIntegerDefaultValue) Ptr() *OuterEnumIntegerDefaultValue {
 	return &v