How to get complete request body of a POST request?

[NikK]

Hi,
I'm struggling to get hold of the complete request body as a single
string in my groovlet. The request body is supposed to contain a JSON-
string like:

{"aField":"A value","AnotherField":123247}

I have tried to user the method described in this blog post:
http://ice09.wordpress.com/2010/02/01/resting-with-json-in-gaelyk/


def requestComplete = new StringBuilder();
while ((line = request.getReader().readLine()) != null) {
requestComplete.append(line);
}


Sending a post request to the groovlet with the code above will
however produce the following error:
Error: GroovyServlet Error: script: '/WEB-INF/groovy/
sparaPlats.groovy': Script processing
failed.STREAMEDorg.mortbay.jetty.Request.getReader(Request.java:935)

Is there another way to get hold of the request body as a single
string? I'm using the latest version of gaelyk template project
(0.6.1)

Thanks in advance,
Niklas

[Benjamin Muschko]

Hi Niklas,

Instead of trying to read the request body you could simply set your
JSON in a request parameter. Reading the value would be as simply as
this in your Groovlet:

def jsonString = params.<jsonParamName>

There's a JSON plugin available for Gaelyk that makes it easy for you
to parse the value and map it to an object for example. Check out the
examples: http://bit.ly/cf0Cir.

Hope this helps,

Ben

[Niklas Konstenius]

Thanks for your answer Ben,

Unfortunately I can't change the request schema to assigning the json to a request parameter as you suggest as this will break existing clients.

I have managed to get my code to work though. I turned out that I accidently posted a request to the page with incorrect content-type header: "application/x-www-form-urlencoded". This should of course be "application/json". 

Changing content type in the request magically solved the problem. I'm not sure why though.

Btw, I'll check out the plugin you linked to. Thanks.

/niklas 

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[Guillaume Laforge]

Hi Niklas,

Have you tried also something simpler like:

def jsonPayload = request.reader.text

Guillaume

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[Guillaume Laforge]

Just tried locally with a groovlet containing:

out << request.reader.text

And I also got the error message:

GroovyServlet Error: script: '/receivejson.groovy': Script
processing failed.STREAMEDorg.mortbay.jetty.Request.getReader(Request.java:935)

Hmmm....

Guillaume

[Guillaume Laforge]

Same error in production as well.

[Guillaume Laforge]

Have you found anything new on the topic?
Nothing obvious jumps to mind so far for me.

Guillaume

[Guillaume Laforge]

Okay, actually, I just found something...

I was not properly "posting" my json payload to my groovlet.

Whether it's behind a URL route or not, doesn't matter, in both cases
I managed to make things work, without getting that ugly exception.

Soooo without further ado.

In my groovlet, I have that content:

def content = request.reader.text
System.out.println "Content: $content"

That way, I can see in the console the content I receive.
You can also use request.inputStream.text, and it works, but because
of possible encoding issues, it's better to use the reader instead, as
it should try its best to use the proper encoding.

Then, from the command-line, with curl, I do:

curl -v -H "Content-Type: application/json" -X POST -d
'{"screencast":{"subject":"tools"}}'
http://localhost:8080/receivejson.groovy

And I properly receive the content, and it's printed on the console,
so all's working fine.

I think it all depends on how you send your payload to the groovlet.
I'm not a curl expert, but I found some help on StackOverflow, with
one of the various options folks had submitted:
http://stackoverflow.com/questions/813487/how-to-post-json-to-php-with-curl

Guillaume

[Guillaume Laforge]

And I've also tested this in production, and it's working properly there too.

Hope this helps.

Guillaume

[Niklas Konstenius]

Thanks for your help Guillaume,

as I wrote in an earlier mail I also found out that I have to post the content with the correct content-type header, namely "application/json" instead of the default "application/x-www-form-urlencoded".

I guess something else is consuming the data from the input stream when content-type exuals "application/x-www-form-urlencoded"?

Thanks for the tip of how to get the content:

def content = request.reader.text

That will make my code much more groovy.. :.-)

/niklas

[Guillaume Laforge]

On Thu, Jan 27, 2011 at 13:42, Niklas Konstenius
<niklas.k...@gmail.com> wrote:
> Thanks for your help Guillaume,
> as I wrote in an earlier mail I also found out that I have to post the
> content with the correct content-type header, namely "application/json"
> instead of the default "application/x-www-form-urlencoded".
> I guess something else is consuming the data from the input stream when
> content-type exuals "application/x-www-form-urlencoded"?

I suspect (but not sure 100%) that it's the blobstore filter that does
this, as uploaded files for the blobstore are submitted through forms.
So it certainly calls the getInputStream() to see if there's an
uploaded file, and the magic key expected by the filter (when we
create an upload url).
And then, when you call the reader on the request, too bad, the input
stream had already been acquired, so you can't open the reader
afterwards, and you get that very unhelpful error from Jetty.

> Thanks for the tip of how to get the content:
> def content = request.reader.text
> That will make my code much more groovy.. :.-)

Yeah, I like to teach some cool shortcuts, that makes the code much
more readable and more maintainable in the long run!

Guillaume