Set HTTP GET Parameters in Finagle

Question

In Finagle, how do I create a request an HTTP GET request with parameters in a safe, clean way?

val request = RequestBuilder()
  .url("http://www.example.com/test")
  .addParameter("key", "value")   // this doesn't exist
  .buildGet()
request    // should be a GET request for http://www.example.com/test?key=value

Answer 1

You can use the confusingly-named Request.queryString:

val request = RequestBuilder()
  .url(Request.queryString("http://www.example.com/test", Map("key" -> "value"))
  .buildGet()

Answer 2

The arguments passed to RequestBuilder.url() are expected to be fully-formed, so Finagle doesn't provide any way to tack on more query parameters.

One way to solve this would be to construct a URL object outside of the context of the RequestBuilder chain. You could define your query parameters in a Map, turn it into a query string, and then concatenate it to the base URL:

val paramStr = Map("key" -> "value", ...) map { case (k, v) =>
  k + '=' + v
} mkString("?", "&", "")

val request = RequestBuilder.safeBuildGet(
  RequestBuilder.create()
    .url("http://www.example.com/test" + paramsStr)
)

Note that you'll need to encode any query parameters that you specify in the Map.