PGGT is a protoc plugin used to add/replace struct tags on generated protobuf messages.
Get it using go get github.com/lookup-cat/protoc-gen-gotag
It supports the following features,
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.
Automatically add custom tags to message field using provided transformer.
It will compile the tag as tag:"snaked_key_name"
by default if no transformer is being provide.
To provide transformer, use: tagName-as-transformer
instruction when running gotag
protoc -I /usr/local/include \
-I . \
--gotag_out=auto="form+db-as-camel":. example/example.proto
The above command will add two addtional tags (form and db) for each field. The form tag will be lower_snake_case and db tag will be lowerCamelCase
Supported transformers:
Keys | Action | Ex |
---|---|---|
"lower_snake", "lower_snake_case", "snake", "snake_case" | Make lower snake case key | someKey -> some_key |
"upper_snake", "upper_snake_case" | Make upper snake case key | someKey -> Some_key |
"lower_camel", "lower_camel_case", "camel", "camel_case" | Make lower camel case key | someKey -> someKey |
"upper_camel", "upper_camel_case" | Make upper camel case key | someKey -> SomeKey |
"dot_notation", "dot", "lower_dot_notation", "lower_dot" | Make lower cased dot notation key | someKey -> some.key |
"upper_dot", "upper_dot_notation" | Make upper cased dot notation key | someKey -> Some.Key |
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
When outputting to a directory other than the current directory, you will need to pass the output path twice using
the "outdir" parameter. If you experience any no such file or directory
, errors, try adding the "outdir" flag.
protoc -I /usr/local/include \
-I ./pkg \
--gotag_out=outdir="./pkg":./pkg example/example.proto
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