protoc-gen-cue

protoc-gen-cue

This protoc plugin generates CUE files.

Conversions

Complies with protojson.

Basic Types

Message

import "github.com/Bestowinc/protoc-gen-cue/pkg/options/cue.proto";

message Foo {
  string name = 1 [(cue.field).expr = '!="xxx"'];
  int32 age = 2 [(cue.field).expr = '<100'];
  int32 age_next_year = 3 [(cue.field).expr = 'age+1'];
}

To:

#Foo: {
  name: string
  name: !="xxx"
  age: int32
  age: <100
  ageNextYear: int32
  ageNextYear: age+1
}

Default Values

You can specify default values using the default field option:

message User {
  bool active = 1 [(cue.field).default = "*true"];
  int32 age = 2 [(cue.field).default = "*18"];
  string role = 3 [(cue.field).default = "*\"user\""];
}

To:

#User: {
  active: *true | bool
  age: *18 | int32
  role: *"user" | string
}

Custom CUE Package

You can specify a custom CUE import path for your proto files:

option (cue.cue_package) = "example.com/schemas/v1";

This allows you to control the CUE import path independently from the Go package path.

Enum

enum Bar {
  ZERO = 0;
  ONE = 1;
}

To:

#Bar: *#Bar_ZERO | #Bar_ONE

#Bar_ZERO: "ZERO"
#Bar_ONE:  "ONE"

Oneof

message Car {
  oneof id {
    string product_name = 1;
    int32 serial_number = 2;
  }
}

To:

#Car: {
  _oneof_id: productName & serialNumber
  productName?: string
  serialNumber?: int32
}

Timestamp

Currently defined by an unconstrained string. This is due to the fact that CUE's built-in time.Time constraint is incompatible with the JSON format defined in the timestamppb. We plan to fix this issue in a future version to follow the original format. See for more details: time.Time on pkg.go.dev and timestamppb.Timestamp

Duration

Currently defined by an unconstrained string. This is due to the fact that CUE's built-in time.Duration constraint is incompatible with the JSON format defined in the durationpb. We plan to fix this issue in a future version to follow the original format. See for more details: time.Duration in pkg.go.dev and descriptorpb.Duration

Optional (proto3)

message Dog {
  optional string nick_name = 1;
}

To:

#Dog: {
  nickName?: string
}