validation.md

#Validation

squbs Validation provides a Spray directive for data validation by using Accord Validation Library. Since Spray directives are currently Scala only, there is no equivalent in Java code until future versions of squbs.

##Dependencies

Add the following dependency to your build.sbt or scala build file:

"org.squbs" %% "squbs-pattern" % squbsVersion

##Usage

Given that an implicit Person validator is in the scope, validate directive can be used as other Spray Directives:

import ValidationDirectives._
validate(person) { 
    ...
}

##Example

Here is a sample Person class and corresponding validator (please see Accord Validation Library for more validator usage examples).

case class Person(firstName: String, lastName: String, middleName: Option[String] = None, age: Int)

object SampleValidators {

  import com.wix.accord.dsl._
  implicit val personValidator = com.wix.accord.dsl.validator[ Person ] { p =>
                p.firstName as "First Name" is notEmpty
                p.lastName as "Last Name" is notEmpty
                p.middleName.each is notEmpty // If exists, should not be empty.
                p.age should be >= 0
              }
}

Now you can use the validate directive as follows:

def route =
    path("person") {
      post {
        entity(as[Person]) { person =>
          import ValidationDirectives._
          validate(person) {
            respondWithMediaType(`application/json`) {
              complete {
                person
              }
            }
          }
        }
      }
    }

If a validation rejection happens, a 400 Bad Request is returned with the response body containing the comma separated list of field(s) causing validation rejection. Using the above example, if the request body contains the following:

{
    "firstName" : "John",
    "lastName" : "",
    "age" : -1
}

then, the response body would contain:

Last Name, age