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Protobuf JSON Converter

This CLI tool is a thin wrapper over the Protobuf C++ API for converting back and forth between JSON and Protobuf.

It is intended to be used as part of scripts that talk to services that speak proto-over-http, but it can also be used in isolation for decoding protobuf messages, if you prefer JSON over the protobuf text format.

Installation

This tool can be installed by downloading the latest release and unzipping it into your PATH, or building from source. It runs on MacOS and Linux.

git clone https://github.com/hq6/ProtobufJson.git
cd ProtobufJson
make

Example usage

Here's an invocation to convert JSON to protobuf.

./JsonToProto -I exampleProtoSearchPath Example '{"x": 5, "text": "Hello World"}' > Output.bin

Here's an invocation to convert protobuf to JSON.

./ProtoToJson -I exampleProtoSearchPath Example < Output.bin

A full "round trip" looks like:

./JsonToProto \
  --proto_path=exampleProtoSearchPath \
  Example \
  '{"x": 5, "text": "Hello World"}' | \
  ./ProtoToJson \
  --proto_path=exampleProtoSearchPath \
  Example

producing output:

{
 "x": 5,
 "text": "Hello World"
}

Proto imports are resolved relative to proto_path

In the following example, Example2.proto imports anotherSubdirectory/Example3.proto, and both protos are resolved resolved relative to the import path exampleProtoSearchPath, rather than relative to the path of Example2.proto.

./JsonToProto \
  --proto_path=exampleProtoSearchPath \
  -P anotherSubdirectory/Example2.proto \
  Example2 \
  '{"message":{"y": 5, "name": "Hello ProtobufJson"}}' > Output.bin


## Optimized usage

As an optimization for larger collections of protos, one can reduce search time
by explicitly specifying the proto file that defines the relevant proto.

```bash
./JsonToProto -I exampleProtoSearchPath -P example.proto Example '{"x": 5, "text": "Hello World"}' > Output.bin
./ProtoToJson -I exampleProtoSearchPath -P example.proto Example < Output.bin

Note that the reference to the .proto file must be provided relative to the proto search paths specified with --proto_path. Attempts to reference a .proto file by a full path (such as ${HOME}/path/to/example.proto) will fail.

If you specify -I without -P, the tool will print a hint to stderr with the correct relative path.

Dependencies