moshi-gson-interop

A tool for bidirectional interop between Moshi and Gson.

This is targeted at codebases that are in the process of migrating from Gson to Moshi and not a
general-purpose tool that should be used for other reasons.

Usage

In order to properly link two Moshi and Gson instances, you must pass two complete
instances (i.e. not intended to newBuilder() later) to Moshi.interopWith() and use
the returned instances.

val seedMoshi: Moshi = ...
val seedGson: Gson = ...
// Use the returned instances!
val (moshi, gson) = seedMoshi.interopWith(seedGson)

By default, the interop mechanism will attempt to best-guess which serializer to use based on a combination
of things (see DefaultMoshiClassChecker‘s kdoc). You can alternatively provide your own logic for this.

Advanced

You can use the Moshi.interopBuilder() extension to create an InteropBuilder for advanced usage and adding
your own ClassChecker logic.

Installation

dependencies {
  implementation("com.slack.moshi:gson-interop:<version>")
}

Snapshots of the development version are available in Sonatype’s snapshots repository.

Caveats

• JsonQualifiers on a type in a Gson class will not be passed on to Moshi, as Gson (and the various
  tools around it) don’t capture them.
• Performance
  • A Moshi adapter delegating to Gson should have no performance issues as it is able
    to stream data directly.
  • Streaming from Gson to Moshi will, however, be degraded as Gson has no equivalent
    streaming APIs to Moshi’s nextSource() or valueSink() APIs. This means that it
    must either decode the entire source into an intermediary object (i.e. a Map, List,
    etc) first when reading or encode the entire value into a JSON String first when writing.

License

Copyright 2020 Slack Technologies, LLC
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
   http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.