JSON Validation Framework

Finatra provides a simple Validation Framework to integrate with Finatra’s custom case class deserializer to efficiently apply per field and method validations as request parsing is performed.

MixIn Annotations

With Jackson MixIn Annotations support it is possible to specify field-level validation annotations for case classes that are not under your control to be annotated.

For an example on how to use MixIn Annotations with Finatra validations, see the documentation here.


Note this integration will only work for field-level validation annotations since method validations must currently be specified inside of the actual class to be validated.

Validation Errors

By default validation errors are returned alphabetically sorted by validation error message (for determinism when testing). See the CaseClassMappingException.


  "errors" : [
    "location.lat: [9999.0] is not between -85 and 85",
    "location.long: field is required",
    "message: size [0] is not between 1 and 140",
    "nsfw: 'abc' is not a valid boolean"

Bypassing Validation

You may desire to execute validation for specific case classes in certain scenarios, but bypass validation in others. For example, you may want to validate a POST request on the write path and store the JSON results somewhere, but bypass validating that same JSON for a GET request on the read path.

You can create a ScalaObjectMapper that will bypass validation like this:


If you desire to bypass validation in all scenarios throughout your service, you can disable validation when defining a new ScalaObjectMapperModule and replace the default jacksonModule in your server definition.

object NoValidationJacksonModule extends ScalaObjectMapperModule {
  override val validation = false

class ValidationServer extends HttpServer {
  override val name = "validation-server"
  override def jacksonModule: Module = NoValidationJacksonModule
  override protected def configureHttp(router: HttpRouter): Unit = ...