Pbjson

Pbjson is a set of crates to automatically generate serde Serialize and Deserialize implementations for auto-generated prost types.

See pbjson-build for usage instructions

lib.rs:

pbjson-build consumes the descriptor output of prost-build and generates serde::Serialize and serde::Deserialize implementations that are compliant with the protobuf JSON mapping

Usage

It is recommended you first follow the example in prost-build to familiarise yourself with prost

Add prost-build, prost, pbjson, pbjson-build and pbjson-types to your Cargo.toml

[dependencies]
prost = <prost-version>
pbjson = <pbjson-version>
pbjson-types = <pbjson-version>

[build-dependencies]
prost-build = <prost-version>
pbjson-build = <pbjson-version>

Next create a build.rs containing the following

// This assumes protobuf files are under a directory called `protos`
// and in a protobuf package `mypackage`

let root = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("protos");
let proto_files = vec![root.join("myproto.proto")];

// Tell cargo to recompile if any of these proto files are changed
for proto_file in &proto_files {
    println!("cargo:rerun-if-changed={}", proto_file.display());
}

let descriptor_path = PathBuf::from(env::var("OUT_DIR").unwrap())
    .join("proto_descriptor.bin");

prost_build::Config::new()
    // Save descriptors to file
    .file_descriptor_set_path(&descriptor_path)
    // Override prost-types with pbjson-types
    .compile_well_known_types()
    .extern_path(".google.protobuf", "::pbjson_types_any")
    // Generate prost structs
    .compile_protos(&proto_files, &[root])?;

let descriptor_set = std::fs::read(descriptor_path)?;
pbjson_build::Builder::new()
    .register_descriptors(&descriptor_set)?
    .build(&[".mypackage"])?;

Finally within lib.rs

/// Generated by [`prost-build`]
include!(concat!(env!("OUT_DIR"), "/mypackage.rs"));
/// Generated by [`pbjson-build`]
include!(concat!(env!("OUT_DIR"), "/mypackage.serde.rs"));

The module will now contain the generated prost structs for your protobuf definition along with compliant implementations of serde::Serialize and serde::Deserialize