entity

entity

Signature

def entity[T](um: FromRequestUnmarshaller[T]): Directive1[T] 

Description

Unmarshalls the request entity to the given type and passes it to its inner Route. An unmarshaller returns an Either with Right(value) if successful or Left(exception) for a failure. The entity method will either pass the value to the inner route or map the exception to a akka.http.scaladsl.server.Rejection.

The entity directive works in conjuction with as and akka.http.scaladsl.unmarshalling to convert some serialized "wire format" value into a higher-level object structure. The unmarshalling documentation explains this process in detail. This directive simplifies extraction and error handling to the specified type from the request.

An unmarshaller will return a Left(exception) in the case of an error. This is converted to a akka.http.scaladsl.server.Rejection within the entity directive. The following table lists how exceptions are mapped to rejections:

Left(exception) Rejection
ContentExpected RequestEntityExpectedRejection
UnsupportedContentType UnsupportedRequestContentTypeRejection, which lists the supported types
MaformedContent MalformedRequestContentRejection, with an error message and cause

Examples

The following example uses spray-json to unmarshall a json request into a simple Person class. It utilizes SprayJsonSupport via the PersonJsonSupport object as the in-scope unmarshaller.

case class Person(name: String, favoriteNumber: Int)
object PersonJsonSupport extends DefaultJsonProtocol with SprayJsonSupport {
  implicit val PortofolioFormats = jsonFormat2(Person)
}
import PersonJsonSupport._

val route = post {
  entity(as[Person]) { person =>
    complete(s"Person: ${person.name} - favorite number: ${person.favoriteNumber}")
  }
}

// tests:
Post("/", HttpEntity(`application/json`, """{ "name": "Jane", "favoriteNumber" : 42 }""")) ~>
  route ~> check {
    responseAs[String] shouldEqual "Person: Jane - favorite number: 42"
  }

It is also possible to use the entity directive to obtain raw JsValue ( spray-json ) objects, by simply using as[JsValue], or any other JSON type for which you have marshallers in-scope.

import PersonJsonSupport._

val route = post {
  entity(as[JsValue]) { json =>
    complete(s"Person: ${json.asJsObject.fields("name")} - favorite number: ${json.asJsObject.fields("favoriteNumber")}")
  }
}

// tests:
Post("/", HttpEntity(`application/json`, """{ "name": "Jane", "favoriteNumber" : 42 }""")) ~>
  route ~> check {
    responseAs[String] shouldEqual """Person: "Jane" - favorite number: 42"""
  }

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