Restructure a json in scala play - json

Question

The following code gets the request body and validates and creates a json:
object ValidateDBConfigJson {
implicit val reads: Reads[ValidateDetails] = (
(JsPath \ "name").read[String].filter(JsonValidationError("Invalid name"))(_.length > 0) and
(JsPath \ "email").read[String].filter(JsonValidationError("Invalid email"))(_.length > 0) and
)(ValidateDetails.apply _)
}
def index() = Action { implicit request =>
val bodyAsJson = request.body.asJson.get
bodyAsJson.validate[ValidateDetails] match {
case success: JsSuccess[ValidateDetails] => {
Ok(Json.parse("succeeded!"))
}
case JsError(error) =>
BadRequest(JsError.toJson(error))
}
}
The json looks like this:
{
"obj.name": [
{
"msg": [
"error.expected.jsstring"
],
"args": []
}
],
"obj.email": [
{
"msg": [
"Invalid email"
],
"args": []
}
]
}
I want structured in the following format:
{
"ErrorMessages" :
[
"error.expected.jsstring",
"Invalid email"
]
}

Answer 1

Preamble: when I am parsing JSON using Play I prefer to use case class/objects rather than implicit reads, so this answer will cover that method of doing this. There may be a simpler method of doing this with implicit reads but I am not as familiar with implicit reads.
Firstly, define a case class for everything you will be taking from JSON:
object Input {
case class Err(msg: Seq[String], args: Seq[String])
object Err {
implicit val format: OFormat[Err] = Json.format[Err]
}
case class ValidateDetails(`obj.name`: Seq[Err], `obj.email`: Seq[Err])
object ValidateDetails {
implicit val format: OFormat[ValidateDetails] = Json.format[ValidateDetails]
}
}
Note: Play won't know how to handle user-defined case classes so I've made one for Err as well. The implicit val format: OFormat[ValidateDetails] = Json.format[ValidateDetails] and implicit val format: OFormat[Err] = Json.format[Err] lines are magic and do all of the reads/writes for you.
Next, define a case class for your output JSON and define a function which will turn your input case class into your output one:
object Output {
case class OutputJson(`ErrorMessages`: Seq[String])
object OutputJson {
implicit val format: OFormat[OutputJson] = Json.format[OutputJson]
}
// take msg Seq from name & email and add together into single Seq
def inputToOutput(input: Input.ValidateDetails): OutputJson = {
OutputJson(input.`obj.name`.flatMap(_.msg) ++ input.`obj.email`.flatMap(_.msg))
}
}
Finally, put this into a method which maps to a POST route in your routes file:
def index() = Action { implicit request =>
val bodyAsJson = request.body.asJson.get
bodyAsJson.validate[Input.ValidateDetails] match {
case success: JsSuccess[Input.ValidateDetails] =>
// turn the JSON into the Output case class and parse that as JSON
val output: JsValue = Json.toJson(Output.inputToOutput(success.value))
Ok(output)
case JsError(error) =>
BadRequest(JsError.toJson(error))
}
}
Now, if you run the Play app on port 9000 and POST to http://localhost:9000/ with the below JSON body...
{
"obj.name": [
{
"msg": [
"error.expected.jsstring"
],
"args": []
}
],
"obj.email": [
{
"msg": [
"Invalid email"
],
"args": []
}
]
}
...the output will be:
{
"ErrorMessages": [
"error.expected.jsstring",
"Invalid email"
]
}
I hope this answers your question.