content-type content-disposition

[SteveB]

Hello, 

I'm currently returning csv data from a liberator web-service with a {:representation {:media-type "application/csv"}} which causes the browser to download as a file.

When my URL is localhost:3000/my-service?param=xyz  the file downloaded is "my-service"

I'd like to give the hint to the browser to use data.csv as the file name.

Where can I put this in the response header?  Is there liberator docs on this topic?

Something like ...

{:content-type "application/csv; charset=utf-8" :content-disposition "attachment; filename=data.csv"}

Thank you!

Steve

[SteveB]

After seeing "add extra custom response headers" post from 12/18/2014. I figured it out.

(assoc-in [:headers "Content-Disposition"] "attachment; filename=data.csv")

The docs are here https://clojure-liberator.github.io/liberator/doc/representations.html

[SteveB]

After I added :as-response to add in the headers to name the downloaded file, I'm getting an java.lang.Exception Unrecognized body: {:invalid-results {:extra-params #{"formdat"}, :missing-params #{"format"}}

when I have invalid parameters in my URL.

I'm thinking now :malformed? and :handle-malformed are not the correct place to do the checks I'm doing, but let's see..

I have a :malformed? function which returns a Vector indicating the Liberator if the URL is malformed or not. i.e. [true {:my-invalid-results  {:error1 "some-error}  :representation {media-type "application/json"} ]

true tells Liberator that the URL is malformed and to therefore call the :handle-malformed function.

In handle-malformed I was simply pulling out some-data from the map and returning it. (ctx-map :my-invalid-results) This worked until I added :as-response

Worked meaning the map was formatted and shown in the browser as a table, to indicate to the caller was is wrong when calling the restful service.

After adding the :as-response function, I see the return value of handle-malformed is (the map) is passed as the first param (i.e. body) to this function yielding the Exception noted above. It seems it's expecting a String as the body.

Here's a boiled down negative case example:

(defresource testit
  :available-media-types ["text/plain"]
  :malformed? (fn [ctx]
                [true                                       ; true = the request is malformed
                 {:invalid-results {:extra-params #{"formdat"}, :missing-params #{"format"}} :representation {:media-type "text/html"}}])
  :handle-malformed (fn [ctx]
                      (println "In handle-malformed = " (ctx :invalid-results))

                      (ctx :invalid-results))

  :handle-ok (fn [ctx]
               "some,csv,data")
  :as-response (fn [resp-body ctx]
                 (println "In as-response = " resp-body)
                 (let [media-type "csv"]                    ; declare media-type for demo purposes only
                   (if (= media-type "csv")
                     (-> {:body resp-body}
                       (assoc-in [:headers "Content-Disposition"] "attachment; filename=data.csv"))
                     {:body resp-body}))))

With :as-response I get...

In handle-malformed =  {:extra-params #{formdat}, :missing-params #{format}}

In as-response =  {:extra-params #{formdat}, :missing-params #{format}}

2015-02-23 17:38:12 WARN  AbstractHttpConnection:521 - /testit

java.lang.Exception: Unrecognized body: {:extra-params #{"formdat"}, :missing-params #{"format"}}

        at ring.util.servlet$set_body.invoke(servlet.clj:103)

        at ring.util.servlet$update_servlet_response.invoke(servlet.clj:113)

        at ring.adapter.jetty$proxy_handler$fn__97.invoke(jetty.clj:22)

        at ring.adapter.jetty.proxy$org.eclipse.jetty.server.handler.AbstractHandler$ff19274a.handle(Unknown Source)

        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)

        at org.eclipse.jetty.server.Server.handle(Server.java:369)

        at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:486)

        at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:933)

        at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:995)

        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644)

        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)

        at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)

        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668)

        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)

        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)

        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)

        at java.lang.Thread.run(Thread.java:745)

If I comment the :as-response out, I see the map nicely formatted as html.. in the browser.

extra-params	#{"formdat"}
missing-params	#{"format"}

How can I add in the filename in as-response when needed and to have error checking and pass back what is wrong with the url (currently in map form, but married to it)?

Thanks,

Steve

[Philipp Meier]

Hi Steve,

Am Dienstag, 24. Februar 2015 00:00:30 UTC+1 schrieb SteveB:

After I added :as-response to add in the headers to name the downloaded file, I'm getting an java.lang.Exception Unrecognized body: {:invalid-results {:extra-params #{"formdat"}, :missing-params #{"format"}}

when I have invalid parameters in my URL.

[...] 

The function "as-response" must return a proper ring response map. 

-billy. 

[SteveB]

Thanks Billy that worked for the example. 

:as-response (fn [resp-body ctx]
                 (println "In as-response = " resp-body)
                 (let [media-type "csv"]                    ; declare media-type for demo purposes only
                   (if (= media-type "csv")
                     (-> {:body resp-body}
                       (assoc-in [:headers "Content-Disposition"] "attachment; filename=data.csv")

                       (assoc-in [:status] 200))

                     {:body resp-body :status 200}))))

It seems the as-response function is going down a level in the abstraction from Liberator down to Ring and is called after handle-ok and handle-malformed which both return there own status 200 and 400 respectively. By adding :as-response I won't want to have to manage state of the status code. Is there a way to get this code from Liberator since as-response just was called by an upstream method that set this somewhere?  Or is it expected to assoc :status 200 from handle-ok and 400 from handle-malformed when using :as-response?

WfG,

Steve

[SteveB]

I think this example answers my question..

(ns foo.core
  (:require [liberator.core :refer [defresource]]
            [liberator.representation :refer [as-response]]))

(defresource example
  :available-media-types ["text/plain"]

  :as-response (fn [d ctx]
                 (-> (as-response d ctx)                    ; wrap the map returned from malformed? as a response
                   (assoc-in [:headers "X-FOO"] "Bar")))    ; add on some extra headers.

  :handle-ok (fn [_] "test")                                ; never gets called since malformed is always true.

               
  :malformed? (fn [ctx]
                [true                                       ; hard code a negative case - malformed true

                 {:invalid-results {:extra-params #{"formdat"}, :missing-params #{"format"}} :representation {:media-type "text/html"}}])

  :handle-malformed (fn [ctx]
                      (ctx :invalid-results)) )             ; return the unwrapped invalid results