Path parsing for ReST API in Spray

Question

I have following code in Spray to parse the REST service called by user:

val route = {
  pathPrefix("v0") {
    pathPrefix("pets") {
      pathEndOrSingleSlash {
        pathEnd {
          get {
            complete("/v0/pets")
          }
        } ~
        get {
          complete("/v0/pets/")
        }
      } ~
      parameters('id ?) {
        id =>
          get {
            complete("/v0/pets?id=" + id)
          }
      }
    }
  }
}

The problem is that it is not behaving as expected. I am expecting following behaviour from the code:

http://127.0.0.1/v0/pets => /v0/pets
http://127.0.0.1/v0/pets/ => /v0/pets/
http://127.0.0.1/v0/pets?id=1234 = > /v0/pets?id=Some(1234)

But, I am getting following results for the queries:

http://127.0.0.1/v0/pets => /v0/pets
http://127.0.0.1/v0/pets/ => /v0/pets
http://127.0.0.1/v0/pets?id=1234 => /v0/pets

Answer 1

pathPrefix("v0") {
  pathPrefix("pets") {
    pathEndOrSingleSlash {
      get {
      }
    }
  }
}

matches http://127.0.0.1/v0/pets?id=1234.

This is why

GET /v0/pets?id=1234
 ^   ^   ^  ^
 |___|___|__|____ get  
     |   |  |
     |   |  |
     |   |  |__ pathEndOrSlash
     |   |  
     |   |__ pathPrefix("pets")
     |
     |__ pathPrefix("v0")

You need to intercept the parameter before. Try

val route = {
  pathPrefix("v0") {
    pathPrefix("pets") {
      parameters('id ?) {
        id =>
          get {
            complete("/v0/pets?id=" + id)
          }
      } ~
      pathEndOrSingleSlash {
        pathEnd {
          get {
            complete("/v0/pets")
          }
        } ~
        get {
          complete("/v0/pets/")
        }
      }
    }
  }
}

Answer 2

One of the issue here is that since id is declared as optional your parameter route handles both the presence and the absence of it (and that is handling v0/pets).

One way of doing it (and I also assume you only want to handle get requests).

You basically just declare id not optional on your parameter route:

val route = get {
  pathPrefix("v0") {
    pathPrefix("pets") {
      pathEnd {
        parameter('id) { id =>
          complete("/v0/pets?id=" + id)
        } ~ complete("/v0/pets")
      } ~
      pathSingleSlash {
        complete("/v0/pets/")
      }
    }
  }
}

Another way basically just exploits the fact that id is an optional parameter, so you just pattern match on the Option:

val route = {
  pathPrefix("v0") {
    pathPrefix("pets") {
      pathEnd {
        get {
          parameters('id ?) { id =>
            id match {
              case Some(id) => complete("/v0/pets?id=" + id)
              case None => complete("/v0/pets")
            }
          }
        }
      } ~
      pathSingleSlash {
        get {
          complete("/v0/pets/")
        }
      }
    }
  }
}