Play framework 2.1 HTTP HEAD method response - scala

Question

How can I return a only response header(HTTP HEAD method) on scala play framework 2.1?

Answer 1

Unfortunatelly there is Java solution but maybe you will 'convert' it to Scala, general concept is:
Catch HEAD request send it to dedicated method
The method autoHead(String originalPath) sends a GET request using WebServices forwarding params and returning only status of the response.
It adds additional header X_FORWARD_FROM_HEAD so if ie your action is logging something to the DB after each hit you can avoid that for HEAD requests.
code:
/**
* Tries to get headers of resource with WebServices and return headers only.
*
* #param originalPath Path of the resource
* #return Headers for HEAD request
* #throws IllegalAccessException
*/
public static Result autoHead(String originalPath) throws IllegalAccessException {
WS.WSRequestHolder forwardedRequest = WS.url("http://" + request().host() + request().path());
// this header will allow you to make additional choice i.e. avoid tracking the request or something else
// see condition in index() action
forwardedRequest.setHeader("X_FORWARD_FROM_HEAD", "true");
// Forward original headers
for (String header : request().headers().keySet()) {
forwardedRequest.setHeader(header, request().getHeader(header));
}
// Forward original queryString
for (String key : request().queryString().keySet()) {
for (String val : request().queryString().get(key)) {
forwardedRequest.setQueryParameter(key, val);
}
}
// Call the same path but with GET
WS.Response wsResponse = forwardedRequest.get().get();
// Set returned headers to the response
for (Field f : Http.HeaderNames.class.getFields()) {
String headerName = f.get(null).toString();
if (wsResponse.getHeader(headerName) != null) {
response().setHeader(headerName, wsResponse.getHeader(headerName));
}
}
return status(wsResponse.getStatus());
}
/**
* Checks if request if forwarded from HEAD request
*
* #return true if 'X_FORWARD_FROM_HEAD' header exists and is set to true
*/
public static boolean forwardedFromHead() {
return (request().getHeader("X_FORWARD_FROM_HEAD") != null && "true".equals(request().getHeader("X_FORWARD_FROM_HEAD")));
}
routes:
HEAD / controllers.Application.autoHead(originalPath:String ?= "/")
HEAD /*originalPath controllers.Application.autoHead(originalPath:String)

Answer 2

You can add a HEAD route, next to the GET route, like this:
GET /assertion controllers.Assertion.get
HEAD /assertion controllers.Assertion.head
In the implementing method, you can call the GET method and pass a flag to suppress the body, I guess.

Answer 3

What about returning EmptyContent as a content
Action {
....
Ok(EmptyContent())
}