JSON support

Proteus is able to generate Circe JSON Encoder instances from ProtobufCodec instances, which can be useful for logging requests and responses in gRPC services.

For that, you need to add the following dependency to your build.sbt file:

"com.github.ghostdogpr" %% "proteus-json" % "0.1.0"

Then, importing proteus.json.* will automatically provide an implicit Encoder for all the types that have a ProtobufCodec instance, as long as you also have implicit Registry and Options in scope.

import io.circe.syntax.*

import proteus.*
import proteus.json.*

given ProtobufDeriver = ProtobufDeriver
given Registry        = Registry.empty
given Options         = Options.default

case class HelloRequest(name: String) derives ProtobufCodec
val json = HelloRequest("world").asJson.noSpaces
println(json)
// {"name":"world"}

TIP

Field names are automatically converted to camelCase in the JSON output (e.g., release_date becomes releaseDate). Null values are filtered out.

Registry

Registry allows you to register custom Circe encoders for specific types instead of deriving them automatically. Use Registry.empty to get an empty registry.

import io.circe.*

case class MyId(value: String) derives ProtobufCodec

given Registry = Registry.empty.add[MyId](Encoder[String].contramap(_.value))

With this, MyId will be encoded as a plain JSON string instead of an object.

Options

Options allows configuring the encoding behavior. Use Options.default to get the default options.

The following options are available:

• formatMapEntriesAsKeyValuePairs: By default, map entries are encoded as an array of objects where the key is used as the field name ([{"myKey": "myValue"}]). When set to true, map entries are encoded as an array of objects with explicit key and value fields ([{"key": "myKey", "value": "myValue"}]).

given Options = Options(formatMapEntriesAsKeyValuePairs = true)