Valid types

Valid types are an advanced feature enabled with the plugin option valid_types.

When enabled, @bufbuild/protoc-gen-es generates an extra type for each message. The extra type adjusts optionality based on Protobuf features and validation rules so the TypeScript type can reflect runtime guarantees more closely.

[!NOTE]

Valid types are experimental. Today they primarily affect message field optionality.

valid_types=legacy_required

With legacy_required, proto2 required message fields and Edition LEGACY_REQUIRED message fields become non-optional in the generated Valid type.

syntax = "proto2";

message Example {
  required User user = 2;
}

message User {
  optional string first_name = 1;
}

export type ExampleValid = Message<"Example"> & {
  user: UserValid;
};

valid_types=protovalidate_required

With protovalidate_required, message fields marked with Protovalidate’s required rule become non-optional in the generated Valid type.

syntax = "proto3";

import "buf/validate/validate.proto";

message Example {
  User user = 2 [(buf.validate.field).required = true];
}

This is useful when you want the type system to reflect runtime validation rules more closely.

Combining modes

You can combine both behaviors:

valid_types=legacy_required+protovalidate_required

Utility types

Protobuf-ES also provides:

• MessageValidType: Extract the Valid type from a message descriptor.

When writing plugins, GeneratedFile.importValid() imports a generated Valid type.

For a concrete integration example, see the Protovalidate-ES example.