Crate capnp_json 

A Cap’n Proto JSON codec, implementing the codec defined in json.capnp.

The wire format is compatible with the C++ capnp::JsonCodec that ships with Cap’n Proto: messages encoded by this crate can be decoded by the C++ codec, and vice-versa.

Quick start

use capnp::message;
use capnp_json::{from_json, to_json};

let mut builder = message::Builder::new_default();
let root: my_schema_capnp::my_struct::Builder<'_> = builder.init_root();
// ... populate `root` ...

let json: String = to_json(root.reborrow_as_reader())?;

let mut decoded = message::Builder::new_default();
let decoded_root: my_schema_capnp::my_struct::Builder<'_> =
  decoded.init_root();
from_json(&json, decoded_root)?;

JSON annotations

To use any of the JSON annotations defined in json.capnp (for example $Json.name, $Json.flatten, $Json.discriminator, $Json.base64, $Json.hex), tell capnpc to resolve references to the annotation schema to this crate from your build.rs:

capnpc::CompilerCommand::new()
    .crate_provides("capnp_json", [0x8ef99297a43a5e34])
    .file("my_schema.capnp")
    .run()
    .expect("compiling schema");

Functions

from_json

Decode a JSON string into a Cap’n Proto struct builder.

to_json

Encode a Cap’n Proto value as a JSON string.