Extend google.protobuf.EnumOptions for Schema

docs/docs/mapping/customizing_openapi_output.md

@@ -24,7 +24,7 @@ You can disable this behavior and exclude all protobuf comments from OpenAPI out
 
 ## Using proto options
 
-You can define options on your Protocol Buffer services, operations, messages, and field definitions to customize your Open API output. For instance, to customize the [OpenAPI Schema Object](https://swagger.io/specification/v2/#schemaObject) for messages and fields:
+You can define options on your Protocol Buffer services, operations, messages, enums and field definitions to customize your Open API output. For instance, to customize the [OpenAPI Schema Object](https://swagger.io/specification/v2/#schemaObject) for messages and fields:
 
 ```protobuf
 import "protoc-gen-openapiv2/options/annotations.proto";
@@ -52,6 +52,32 @@ message ABitOfEverything {
     string uuid = 1 [(grpc.gateway.protoc_gen_openapiv2.options.openapiv2_field) = {description: "The UUID field."}];
 }
 ```
+Enums can be customized like messages:
+
+```protobuf
+// NumericEnum is one or zero.
+enum NumericEnum {
+  option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_enum) = {
+    description: "NumericEnum is one or zero."
+    title: "NumericEnum"
+    extensions: {
+      key: "x-a-bit-of-everything-foo"
+      value {
+        string_value: "bar"
+      }
+    }
+    external_docs: {
+      url: "https://github.com/grpc-ecosystem/grpc-gateway"
+      description: "Find out more about ABitOfEverything"
+    }
+    example: "\"ZERO\""
+  };
+  // ZERO means 0
+  ZERO = 0;
+  // ONE means 1
+  ONE = 1;
+}
+```
 
 Operations can also be customized:
 

examples/internal/clients/abe/api/swagger.yaml

@@ -6001,12 +6001,17 @@ definitions:
         $ref: "#/definitions/examplepbErrorObject"
   examplepbNumericEnum:
     type: "string"
-    description: "NumericEnum is one or zero.\n\n - ZERO: ZERO means 0\n - ONE: ONE\
-      \ means 1"
+    externalDocs:
+      description: "Find out more about ABitOfEverything"
+      url: "https://github.com/grpc-ecosystem/grpc-gateway"
+    title: "NumericEnum"
+    description: "NumericEnum is one or zero."
+    example: "ZERO"
     enum:
     - "ZERO"
     - "ONE"
     default: "ZERO"
+    x-a-bit-of-everything-foo: "bar"
   examplepbRequiredMessageTypeRequest:
     type: "object"
     required:

examples/internal/clients/abe/model_examplepb_numeric_enum.go

@@ -9,7 +9,7 @@
  */
 
 package abe
-// ExamplepbNumericEnum : NumericEnum is one or zero.   - ZERO: ZERO means 0  - ONE: ONE means 1
+// ExamplepbNumericEnum : NumericEnum is one or zero.
 type ExamplepbNumericEnum string
 
 // List of examplepbNumericEnum

examples/internal/proto/examplepb/a_bit_of_everything.proto

@@ -419,6 +419,19 @@ message MessageWithBody {
 
 // NumericEnum is one or zero.
 enum NumericEnum {
+  option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_enum) = {
+    description: "NumericEnum is one or zero."
+    title: "NumericEnum"
+    extensions: {
+      key: "x-a-bit-of-everything-foo"
+      value: {string_value: "bar"}
+    }
+    external_docs: {
+      url: "https://github.com/grpc-ecosystem/grpc-gateway"
+      description: "Find out more about ABitOfEverything"
+    }
+    example: "\"ZERO\""
+  };
   // ZERO means 0
   ZERO = 0;
   // ONE means 1

examples/internal/proto/examplepb/a_bit_of_everything.swagger.json

@@ -7813,12 +7813,19 @@
     },
     "examplepbNumericEnum": {
       "type": "string",
+      "example": "ZERO",
       "enum": [
         "ZERO",
         "ONE"
       ],
       "default": "ZERO",
-      "description": "NumericEnum is one or zero.\n\n - ZERO: ZERO means 0\n - ONE: ONE means 1"
+      "description": "NumericEnum is one or zero.",
+      "title": "NumericEnum",
+      "externalDocs": {
+        "description": "Find out more about ABitOfEverything",
+        "url": "https://github.com/grpc-ecosystem/grpc-gateway"
+      },
+      "x-a-bit-of-everything-foo": "bar"
     },
     "examplepbRequiredMessageTypeRequest": {
       "type": "object",

examples/internal/proto/examplepb/generated_input.swagger.json

@@ -355,12 +355,19 @@
     },
     "examplepbNumericEnum": {
       "type": "string",
+      "example": "ZERO",
       "enum": [
         "ZERO",
         "ONE"
       ],
       "default": "ZERO",
-      "description": "NumericEnum is one or zero.\n\n - ZERO: ZERO means 0\n - ONE: ONE means 1"
+      "description": "NumericEnum is one or zero.",
+      "title": "NumericEnum",
+      "externalDocs": {
+        "description": "Find out more about ABitOfEverything",
+        "url": "https://github.com/grpc-ecosystem/grpc-gateway"
+      },
+      "x-a-bit-of-everything-foo": "bar"
     },
     "pathenumPathEnum": {
       "type": "string",

examples/internal/proto/examplepb/stream.swagger.json

@@ -532,12 +532,19 @@
     },
     "examplepbNumericEnum": {
       "type": "string",
+      "example": "ZERO",
       "enum": [
         "ZERO",
         "ONE"
       ],
       "default": "ZERO",
-      "description": "NumericEnum is one or zero.\n\n - ZERO: ZERO means 0\n - ONE: ONE means 1"
+      "description": "NumericEnum is one or zero.",
+      "title": "NumericEnum",
+      "externalDocs": {
+        "description": "Find out more about ABitOfEverything",
+        "url": "https://github.com/grpc-ecosystem/grpc-gateway"
+      },
+      "x-a-bit-of-everything-foo": "bar"
     },
     "pathenumPathEnum": {
       "type": "string",

protoc-gen-openapiv2/internal/genopenapi/template.go

@@ -100,7 +100,8 @@ var wktSchemas = map[string]schemaCore{
 		Items: (*openapiItemsObject)(&openapiSchemaObject{
 			schemaCore: schemaCore{
 				Type: "object",
-			}}),
+			},
+		}),
 	},
 	".google.protobuf.NullValue": {
 		Type: "string",
@@ -737,6 +738,7 @@ func shouldExcludeField(name string, excluded []descriptor.Parameter) bool {
 	}
 	return false
 }
+
 func filterOutExcludedFields(fields []string, excluded []descriptor.Parameter) []string {
 	var filtered []string
 	for _, f := range fields {
@@ -904,7 +906,7 @@ func primitiveSchema(t descriptorpb.FieldDescriptorProto_Type) (ftype, format st
 }
 
 // renderEnumerationsAsDefinition inserts enums into the definitions object.
-func renderEnumerationsAsDefinition(enums enumMap, d openapiDefinitionsObject, reg *descriptor.Registry) {
+func renderEnumerationsAsDefinition(enums enumMap, d openapiDefinitionsObject, reg *descriptor.Registry, customRefs refMap) {
 	for _, enum := range enums {
 		swgName, ok := fullyQualifiedNameToOpenAPIName(enum.FQEN(), reg)
 		if !ok {
@@ -926,12 +928,37 @@ func renderEnumerationsAsDefinition(enums enumMap, d openapiDefinitionsObject, r
 				Default: defaultValue,
 			},
 		}
+
 		if reg.GetEnumsAsInts() {
 			enumSchemaObject.Type = "integer"
 			enumSchemaObject.Format = "int32"
 			enumSchemaObject.Default = getEnumDefaultNumber(reg, enum)
 			enumSchemaObject.Enum = listEnumNumbers(reg, enum)
 		}
+		opts, err := getEnumOpenAPIOption(reg, enum)
+		if err != nil {
+			panic(err)
+		}
+		if opts != nil {
+			protoSchema := openapiSchemaFromProtoEnumSchema(opts, reg, customRefs, enum)
+			// Warning: Make sure not to overwrite any fields already set on the schema type.
+			// This is only a subset of the fields from JsonSchema since most of them only apply to arrays or objects not enums
+			enumSchemaObject.ExternalDocs = protoSchema.ExternalDocs
+			enumSchemaObject.ReadOnly = protoSchema.ReadOnly
+			enumSchemaObject.extensions = protoSchema.extensions
+			if protoSchema.Type != "" || protoSchema.Ref != "" {
+				enumSchemaObject.schemaCore = protoSchema.schemaCore
+			}
+			if protoSchema.Title != "" {
+				enumSchemaObject.Title = protoSchema.Title
+			}
+			if protoSchema.Description != "" {
+				enumSchemaObject.Description = protoSchema.Description
+			}
+			if protoSchema.Example != nil {
+				enumSchemaObject.Example = protoSchema.Example
+			}
+		}
 		if err := updateOpenAPIDataFromComments(reg, &enumSchemaObject, enum, enumComments, false); err != nil {
 			panic(err)
 		}
@@ -971,8 +998,10 @@ func lookupMsgAndOpenAPIName(location, name string, reg *descriptor.Registry) (*
 
 // registriesSeen is used to memoise calls to resolveFullyQualifiedNameToOpenAPINames so
 // we don't repeat it unnecessarily, since it can take some time.
-var registriesSeen = map[*descriptor.Registry]map[string]string{}
-var registriesSeenMutex sync.Mutex
+var (
+	registriesSeen      = map[*descriptor.Registry]map[string]string{}
+	registriesSeenMutex sync.Mutex
+)
 
 // Take the names of every proto message and generate a unique reference for each, according to the given strategy.
 func resolveFullyQualifiedNameToOpenAPINames(messages []string, namingStrategy string) map[string]string {
@@ -1265,7 +1294,7 @@ func renderServices(services []*descriptor.Service, paths *openapiPathsObject, r
 				// extract any constraints specified in the path placeholders into ECMA regular expressions
 				pathParamRegexpMap := partsToRegexpMap(parts)
 				// Keep track of path parameter overrides
-				var pathParamNames = make(map[string]string)
+				pathParamNames := make(map[string]string)
 				for _, parameter := range pathParams {
 
 					var paramType, paramFormat, desc, collectionFormat string
@@ -1578,7 +1607,8 @@ func renderServices(services []*descriptor.Service, paths *openapiPathsObject, r
 								Key: "error",
 								Value: openapiSchemaObject{
 									schemaCore: schemaCore{
-										Ref: fmt.Sprintf("#/definitions/%s", statusDef)},
+										Ref: fmt.Sprintf("#/definitions/%s", statusDef),
+									},
 								},
 							})
 						}
@@ -1917,7 +1947,7 @@ func applyTemplate(p param) (*openapiSwaggerObject, error) {
 	if err := renderMessagesAsDefinition(messages, s.Definitions, p.reg, customRefs, nil); err != nil {
 		return nil, err
 	}
-	renderEnumerationsAsDefinition(enums, s.Definitions, p.reg)
+	renderEnumerationsAsDefinition(enums, s.Definitions, p.reg, requestResponseRefs)
 
 	// File itself might have some comments and metadata.
 	packageProtoPath := protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "Package")
@@ -2651,11 +2681,13 @@ func goTemplateComments(comment string, data interface{}, reg *descriptor.Regist
 	return temp.String()
 }
 
-var messageProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "MessageType")
-var nestedProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.DescriptorProto)(nil)), "NestedType")
-var packageProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "Package")
-var serviceProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "Service")
-var methodProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.ServiceDescriptorProto)(nil)), "Method")
+var (
+	messageProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "MessageType")
+	nestedProtoPath  = protoPathIndex(reflect.TypeOf((*descriptorpb.DescriptorProto)(nil)), "NestedType")
+	packageProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "Package")
+	serviceProtoPath = protoPathIndex(reflect.TypeOf((*descriptorpb.FileDescriptorProto)(nil)), "Service")
+	methodProtoPath  = protoPathIndex(reflect.TypeOf((*descriptorpb.ServiceDescriptorProto)(nil)), "Method")
+)
 
 func isProtoPathMatches(paths []int32, outerPaths []int32, typeName string, typeIndex int32, fieldPaths []int32) bool {
 	if typeName == "Package" && typeIndex == packageProtoPath {
@@ -2787,6 +2819,23 @@ func extractSchemaOptionFromMessageDescriptor(msg *descriptorpb.DescriptorProto)
 	return opts, nil
 }
 
+// extractEnumSchemaOptionFromEnumDescriptor extracts the message of type
+// openapi_options.EnumSchema from a given proto enum's descriptor.
+func extractEnumSchemaOptionFromEnumDescriptor(enum *descriptorpb.EnumDescriptorProto) (*openapi_options.EnumSchema, error) {
+	if enum.Options == nil {
+		return nil, nil
+	}
+	if !proto.HasExtension(enum.Options, openapi_options.E_Openapiv2Enum) {
+		return nil, nil
+	}
+	ext := proto.GetExtension(enum.Options, openapi_options.E_Openapiv2Enum)
+	opts, ok := ext.(*openapi_options.EnumSchema)
+	if !ok {
+		return nil, fmt.Errorf("extension is %T; want a EnumSchema", ext)
+	}
+	return opts, nil
+}
+
 // extractTagOptionFromServiceDescriptor extracts the tag of type
 // openapi_options.Tag from a given proto service's descriptor.
 func extractTagOptionFromServiceDescriptor(svc *descriptorpb.ServiceDescriptorProto) (*openapi_options.Tag, error) {
@@ -2941,6 +2990,14 @@ func getMessageOpenAPIOption(reg *descriptor.Registry, msg *descriptor.Message)
 	return opts, nil
 }
 
+func getEnumOpenAPIOption(reg *descriptor.Registry, enum *descriptor.Enum) (*openapi_options.EnumSchema, error) {
+	opts, err := extractEnumSchemaOptionFromEnumDescriptor(enum.EnumDescriptorProto)
+	if err != nil {
+		return nil, err
+	}
+	return opts, nil
+}
+
 func getServiceOpenAPIOption(reg *descriptor.Registry, svc *descriptor.Service) (*openapi_options.Tag, error) {
 	if opts, ok := reg.GetOpenAPIServiceOption(svc.FQSN()); ok {
 		return opts, nil
@@ -3112,6 +3169,24 @@ func updateSwaggerObjectFromFieldBehavior(s *openapiSchemaObject, j []annotation
 	}
 }
 
+func openapiSchemaFromProtoEnumSchema(s *openapi_options.EnumSchema, reg *descriptor.Registry, refs refMap, data interface{}) openapiSchemaObject {
+	ret := openapiSchemaObject{
+		ExternalDocs: protoExternalDocumentationToOpenAPIExternalDocumentation(s.GetExternalDocs(), reg, data),
+	}
+	jsonSchema := &openapi_options.JSONSchema{
+		Ref:         s.Ref,
+		Title:       s.Title,
+		Extensions:  s.Extensions,
+		Description: s.Description,
+		Default:     s.Default,
+		ReadOnly:    s.ReadOnly,
+		Example:     s.Example,
+	}
+	ret.schemaCore = protoJSONSchemaToOpenAPISchemaCore(jsonSchema, reg, refs)
+	updateswaggerObjectFromJSONSchema(&ret, jsonSchema, reg, data)
+	return ret
+}
+
 func openapiSchemaFromProtoSchema(s *openapi_options.Schema, reg *descriptor.Registry, refs refMap, data interface{}) openapiSchemaObject {
 	ret := openapiSchemaObject{
 		ExternalDocs: protoExternalDocumentationToOpenAPIExternalDocumentation(s.GetExternalDocs(), reg, data),
@@ -3229,7 +3304,7 @@ func addCustomRefs(d openapiDefinitionsObject, reg *descriptor.Registry, refs re
 	if err := renderMessagesAsDefinition(msgMap, d, reg, refs, nil); err != nil {
 		return err
 	}
-	renderEnumerationsAsDefinition(enumMap, d, reg)
+	renderEnumerationsAsDefinition(enumMap, d, reg, refs)
 
 	// Run again in case any new refs were added
 	return addCustomRefs(d, reg, refs)