Custom options

Custom options annotate schema elements with extra metadata. They are extensions to the google.protobuf.*Options messages defined in google/protobuf/descriptor.proto.

Define an option

Create an option to mark sensitive fields:

syntax = "proto3";
package example.options;

import "google/protobuf/descriptor.proto";

extend google.protobuf.FieldOptions {
  bool sensitive = 8765;
}

Use the option

message User {
  string first_name = 1;
  string last_name = 2 [(example.options.sensitive) = true];
}

Read the option

Regenerate code, then read the option with getOption() or hasOption().

import { getOption, hasOption } from "@bufbuild/protobuf";
import { sensitive } from "./gen/example_options_pb";
import { UserSchema } from "./gen/example_pb";

hasOption(UserSchema.field.lastName, sensitive); // true
getOption(UserSchema.field.lastName, sensitive); // true

Custom options can be read from generated schemas, from schemas passed to a plugin, or from descriptors loaded into a registry.