easypbgen

An easy code generating tool for transport and model files out from a .proto file.

Русская версия

Example of usage

1. Create a folder, e.g. pbgen
2. Put there a .proto file, e.g. service.proto
3. Create a file (e.g. pbgen.go) with the following content:

package main

import (
  "github.com/balduser/easypbgen"
  "fmt"
  "os"
)

func main() {
  pbgen, err := easypbgen.ParseFile(os.Args[1], nil)
  if err != nil {
    fmt.Println(err)
    os.Exit(1)
  }
  easypbgen.PrintAll(pbgen)          // необязательно
  easypbgen.GenerateTransport(pbgen)
  easypbgen.GenerateModel(pbgen)
}

4. Move to this folder in CLI.
5. Create a module pbgen:
   go mod init pbgen
6. Install easypbgen from github:
   go mod tidy
7. Launch code generation with a command
   go run pbgen.go -service.proto

Files will appear in the same folder.

---

Tips

• You should have at least one Service in your file
• Service should be defined before it's messages

---

Configuration and templates

It's impossible to create an ultimate tool for any task, so the code generated by easypbgen may not be optimal. Some parts of generated code may not satisfy project's requirements. So to have the proper code generation and the opportunity to launch code generation few times without editing same parts every time it is possible to determine correct parts of code manually and place it in variables of main script or in the config file. To place them in the launching script boby you have to make map[string]string, and the pointer to in must be given as a second argument to the ParseFile() function. Following keys are valid:

Parameters of generated files:

• <service_name>TransportFile - uri of the transport code file to be generated

• <service_name>ModelFile - uri of the model code file to be generated

Hardcoding some parts of code

• model<service_name>Message<message_name> - code of a distinct message

• transport<service_name><method_name> - code of a distinct method in transport layer (adapter)

• transport<service_name>Decode<message_name> - code of a distinct decoder

• transport<service_name>Encode<message_name> - code of a distinct encoder

• model<service_name>Ending - text or a code for inserting in the end of model file

Overriding existing templates

• transportHeading - generated transport file heading
• templateG - transport layer adapter template
• templateDec - transport layer decoder template
• templateEnc - transport layer encoder template
• encFieldTypeTemplate - encoder's "type" field template
• modelHeading - generated model file heading
• modelTemplate - generated model file stucture template

Examples

---

• some message code

"modelBlogpostAPIServiceMessageCreatePostRequest":
`type CreatePostRequest struct {
  userID         uint32
  postText       string
  hellobug       float64
}

`

• some transport layer method (adapter) code

func (g grpcTransport) CreatePost(ctx context.Context, request *pb.CreatePostRequest) (*pb.CreatePostResponse, error) {
  _, response, err := g.createPost.ServeGRPC(ctx, request)
  if err != nil {
    g.log.Error().Err(err).Msg("WE LOVE BUGS!")
    return nil, err
  }
  resp := response.(*pb.CreatePostResponse)
  return resp, nil
}

• some decoder code

func decodeCreatePost(ctx context.Context, grpcRequest interface{}) (interface{}, error) {
  req := grpcRequest.(*pb.CreatePostRequest)
  result := &model.CreatePostRequest{
    UserID:         req.UserID,
    PostText:       req.PostText,
    hellobug:       float64,
  }
  return result, nil
}

• some encoder code

func encodeCreatePost(ctx context.Context, grpcResponse interface{}) (interface{}, error) {
  resp := grpcResponse.(*model.CreatePostResponse)
  response := &pb.CreatePostResponse{
    CreatePostSuccess: resp.CreatePostSuccess,
    ErrorText:         resp.ErrorText,
    hellobug:          0,
  }
  return response, nil
}

---

Default templates may be seen in templates.go

Example of a script with the configuration parameters in the body

---

package main

import (
  "github.com/balduser/easypbgen"
  "fmt"
  "os"
)

func main() {
  config := map[string]string {
    "transportHeading": `package transport
// Hello there!
`,
    "modelBlogpostAPIServiceEnding":
`type CreatePostRequest struct {
    myPrettyFieldName    bug64
}
`,
  }

  pbgen, err := easypbgen.ParseFile(os.Args[1], &config)
  if err != nil {
    fmt.Println(err)
    os.Exit(1)
  }
  easypbgen.GenerateTransport(pbgen)
  easypbgen.GenerateModel(pbgen)
}

---

Moving code templates to the configuration file

For encreasing the readability of a launching script some parts of a code may be moved to the configuration file, which is a .go file placed in the script's folder. It must have package main and it should contain map[string]string instead of a launching script. The pointer to this map must anyway be given to the ParseFile() as a second argument In case if configuration file is used, the project must be built with go build before the code generation.

---

Model code generation

Sometimes your model should implement more structures than the transport code. In this case you may place special comments for the data model in a .proto file. This can be done with symbols /*# and #*/ in separate (necessary) lines e.g.:

...
// Protocol buffers code

/*#
message LikePostRequest {
  uint32 postID = 1;
}

message LikeCommentRequest {
  uint32 commentID = 1;
}

message SuccessResponse {
  bool Success = 1; // true for success, false for failure
  string errorText = 2;
}
#*/

---

Not yet implemented

• Tests!
• "reserved" in messages
• "default" in messages
• enum in messages (check, maybe refactor)
• stream in rpcs ( https://golang-blog.blogspot.com/2021/03/grpc-golang-basic-tutorial.html & https://github.com/grpc/grpc-go/blob/master/examples/route_guide/routeguide/route_guide.proto )