Sending POST with groovy and data is already URL-encoded

Question

I'm trying to send a POST using Groovy HTTPBuilder but the data I want to send is already URL-encoded so I want HTTPBuilder to POST it as is. I tried the following:

def validationString = "cmd=_notify-validate&" + postData
def http = new HTTPBuilder(grailsApplication.config.grails.paypal.server)
http.request(Method.POST) {
    uri.path = "/"
    body = validationString
    requestContentType = ContentType.TEXT

    response.success = { response ->
            println response.statusLine
    }
}

But it gives me a NullPointerException:

java.lang.NullPointerException
at groovyx.net.http.HTTPBuilder$RequestConfigDelegate.setBody(HTTPBuilder.java:1200)

Answer 1

Since you're using pre-encoded form values you cannot use the default map-based content type encoder. You must specify the content type so the EncoderRegistry knows how to handle the body.

You may create the HttpBuilder with a content type that specifies the body is a URL-encoded string:

def http = new HTTPBuilder(url, ContentType.URLENC)

Or make the request passing the content type explicitly:

http.request(Method.POST, ContentType.URLENC) {
  // etc.

---

For reference, here's how I figured it out--I didn't know before I read the question.

• Looked at the request method's API docs to see what the closure was expected to contain. I've used HTTPBuilder only in passing, so I wanted to see what, specifically, the body "should" be, or "may" be, and if the two were different.
• The four-arg version of the request method links to the RequestConfigDelegate class and said the options were discussed in its docs.
• The RequestConfigDelegate.setBody method, which is what the body setter is, states the body "[...] may be of any type supported by the associated request encoder. That is, the value of body will be interpreted by the encoder associated with the current request content-type."
• The request encoder link is to the EncoderRegistry class. It has an encode_form method taking a string and states it "assumes the String is an already-encoded POST string". Sounds good.
• The request content-type link was to an HttpBuilder inner class method, RequestConfigDelegate.getRequestContentType, which in turn had a link to the ContentType enum.
• That enum has a URLENC value that led me to believe it'd be the best first guess.
• I tried the HTTPBuilder ctor taking a content type, and that worked.
• Circled back to the request methods and noticed there's a version also taking a content type.

I'd guess the total time was ~5-10 minutes, much shorter than it took to type up what I did. Hopefully it'll convince you, though, that finding this kind of stuff out is possible via the docs, in relatively short order.

IMO this is a critical skill for developers to groom, and make you look like a hero. And it can be fun.