protoc-gen-gotag (PGGT)

PGGT is a protoc plugin used to add/replace struct tags on generated protobuf messages. It is forked from: ``srikrsna/protoc-gen-gotag````to add some nice tag features. Get it using go get github.com/taankyou/protoc-gen-gotag It supports the following features,

Add/Replace Tags

New tags like xml, sql, bson etc... can be added to struct messages of protobuf. Example

syntax = "proto3";

package example;

import "tagger/tagger.proto";

message Example {
    string with_new_tags = 1 [(tagger.tags) = "graphql:\"withNewTags,optional\"" ];
    string with_new_multiple = 2 [(tagger.tags) = "graphql:\"withNewTags,optional\" xml:\"multi,omitempty\"" ];
    
    string replace_default = 3 [(tagger.tags) = "json:\"replacePrevious\""] ; 

    oneof one_of {
        option (tagger.oneof_tags) = "graphql:\"withNewTags,optional\"";
        string a = 5 [(tagger.tags) = "json:\"A\""];
        int32 b_jk = 6 [(tagger.tags) = "json:\"b_Jk\""];
    }
}

message SecondMessage {
    string with_new_tags = 1 [(tagger.tags) = "graphql:\"withNewTags,optional\"" ];
    string with_new_multiple = 2 [(tagger.tags) = "graphql:\"withNewTags,optional\" xml:\"multi,omitempty\"" ];
    
    string replace_default = 3 [(tagger.tags) = "json:\"replacePrevious\""] ; 
}

Then struct tags can be added by running this command after the regular protobuf generation command.

    protoc -I /usr/local/include \
    	-I . \
    	--gotag_out=:. example/example.proto

In the above example tags like graphql and xml will be added whereas existing tags such as json are replaced with the supplied values.

Auto add tags on field

Automatically add custom tags to message field using the same format as JSON tag. It will compile the tag as tag:"snaked_key_name".

    protoc -I /usr/local/include \
    	-I . \
    	--gotag_out=auto="form+db":. example/example.proto

Add tags to XXX* fields

It is very useful to ignore XXX* fields in protobuf generated messages. The go protocol buffer compiler adds json:"-" tag to all XXX* fields. Additional tags can be added to these fields using the 'xxx' option of PGGT. It can be done like this. All '+' characters will be replaced with ':'.

    protoc -I /usr/local/include \
    	-I . \
    	--gotag_out=xxx="graphql+\"-\" bson+\"-\"":. example/example.proto

Note

This should always run after protocol buffer compiler has run. The command such as the one below will fail/produce unexpected results.

   protoc -I /usr/local/include \
       	-I . \
       	--go_out=:. \
       	--gotag_out=xxx="graphql+\"-\" bson+\"-\"":. example/example.proto