Added a proto enum option to only encode values as strings (not numbe…

…rs) (#106)

* Added a proto enum option to only encode values as strings (not numbers)

* Bringing the converterFlag logic into the convertEnumType method

* Using the proto option for the testdata proto

Co-authored-by: Chrusty <>

README.md

@@ -96,6 +96,7 @@ If you don't want to use the configuration parameters (admittedly quite a nasty
 These apply to specifically marked enums, giving you more finely-grained control than with the CLI flags.
 
 - [enums_as_constants](internal/converter/testdata/proto/ImportedEnum.proto): Encode ENUMs (and their annotations) as CONST
+- [enums_as_strings_only](internal/converter/testdata/proto/OptionEnumsAsStringsOnly.proto): ENUM values are only strings (not the numeric counterparts)
 
 ### Field Options
 

internal/converter/converter.go

@@ -129,6 +129,9 @@ func (c *Converter) parseGeneratorParameters(parameters string) {
 // Converts a proto "ENUM" into a JSON-Schema:
 func (c *Converter) convertEnumType(enum *descriptor.EnumDescriptorProto, converterFlags ConverterFlags) (jsonschema.Type, error) {
 
+	// Inherit the CLI converterFlags:
+	converterFlags.EnumsAsStringsOnly = c.Flags.EnumsAsStringsOnly
+
 	// Set some per-enum flags from config and options:
 	if opts := enum.GetOptions(); opts != nil && proto.HasExtension(opts, protos.E_EnumOptions) {
 		if opt := proto.GetExtension(opts, protos.E_EnumOptions); opt != nil {
@@ -138,6 +141,11 @@ func (c *Converter) convertEnumType(enum *descriptor.EnumDescriptorProto, conver
 				if enumOptions.GetEnumsAsConstants() {
 					converterFlags.EnumsAsConstants = true
 				}
+
+				// ENUM values as strings only:
+				if enumOptions.GetEnumsAsStringsOnly() {
+					converterFlags.EnumsAsStringsOnly = true
+				}
 			}
 		}
 	}
@@ -225,7 +233,7 @@ func (c *Converter) convertFile(file *descriptor.FileDescriptorProto, fileExtens
 			c.logger.WithField("proto_filename", protoFileName).WithField("enum_name", enum.GetName()).WithField("jsonschema_filename", jsonSchemaFileName).Info("Generating JSON-schema for stand-alone ENUM")
 
 			// Convert the ENUM:
-			enumJSONSchema, err := c.convertEnumType(enum, ConverterFlags{EnumsAsStringsOnly: c.Flags.EnumsAsStringsOnly})
+			enumJSONSchema, err := c.convertEnumType(enum, ConverterFlags{})
 			if err != nil {
 				c.logger.WithError(err).WithField("proto_filename", protoFileName).Error("Failed to convert")
 				return nil, err

internal/converter/testdata/proto/OptionEnumsAsStringsOnly.proto

@@ -1,7 +1,9 @@
 syntax = "proto3";
 package samples;
+import "options.proto";
 
 enum Currency {
+    option (protoc.gen.jsonschema.enum_options).enums_as_strings_only = true;
     NOT_SPECIFIED = 0;
     USD = 1;
     GBP = 2;

jsonschemas/EnumOptions.json

@@ -7,6 +7,10 @@
                 "enums_as_constants": {
                     "type": "boolean",
                     "description": "Enums tagged with this will have be encoded to use constants instead of simple types (supports value annotations):"
+                },
+                "enums_as_strings_only": {
+                    "type": "boolean",
+                    "description": "Enums tagged with this will only provide string values as options (not their numerical equivalents):"
                 }
             },
             "additionalProperties": true,

options.proto

@@ -55,6 +55,9 @@ message EnumOptions {
 
   // Enums tagged with this will have be encoded to use constants instead of simple types (supports value annotations):
   bool enums_as_constants = 1;
+
+  // Enums tagged with this will only provide string values as options (not their numerical equivalents):
+  bool enums_as_strings_only = 2;
 }