Generate Swagger description using proto comments.

[neoduan]

when using the comment req's param, but the generated swagger file has not description field?

here is proto file:

syntax = "proto3";
package demoprj;
import "google/api/annotations.proto";
import "protoc-gen-swagger/options/annotations.proto";

option (grpc.gateway.protoc_gen_swagger.options.openapiv2_swagger) = {
    host: "127.0.0.1:8301"
};

message Req {
    string param = 1; //req's param
}


message Rsp {}

// Demoprj
service Demoprj {

    // method's comment
    rpc Method (Req) returns (Rsp) {
        option (google.api.http) = {
            get: "/v1/method"
        };
    }
}

here is the generate swagger json file:

 "/v1/method": {
      "get": {
        "operationId": "Demoprj_Method",
        "parameters": [
          {
            "in": "query",
            "name": "param",
            "required": false,
            "type": "string"
          }
        ],
        "responses": {
          "200": {
            "description": "A successful response.",
            "schema": {
              "$ref": "#/definitions/demoprjRsp"
            }
          },
          "default": {
            "description": "An unexpected error response",
            "schema": {
              "$ref": "#/definitions/runtimeError"
            }
          }
        },
        "summary": "method's comment",
        "tags": [
          "Demoprj"
        ]
      }
    },

[johanbrandhorst]

As you can see in our proto example, you can add a description to the line above the field and it will be added to the description:

https://github.com/grpc-ecosystem/grpc-gateway/blob/master/examples/internal/proto/examplepb/a_bit_of_everything.proto#L205-L206
https://github.com/grpc-ecosystem/grpc-gateway/blob/master/examples/internal/proto/examplepb/a_bit_of_everything.swagger.json#L190-L191