> I suggesting adding printlns or logging or a debugger
> and checking the
> value of this-users-params, it is almost certainly not
> what you expect
> it to be.
I already showed the output of the println statements I'd done, but I'll go
through this again.
I eventually try to output my info as JSON, like this:
(defn current-users [request]
"The default action of this app. Add new users to the registry, and
delete the ones that are more than 15 seconds old"
(let [this-users-params (:params request)]
(add-to-logged-in-registry this-users-params)
(remove-old-registrants)
(response (apply str (json/write-str @registry)))))
When I ran this at the REPL, everything worked great, but I was feeding it
ideal information (no nil values). When I uploaded it to the server and the
site users started hitting this thing (the Javascript in their browsers
sent all kinds of calls). Then I started getting strange values, including
a lot of empty calls. I can fix the Javascript, and I will, but I decided I
also needed to protect the Clojure code.
I originally had this:
(def registry (atom {}))
(defn add-to-logged-in-registry [this-users-params]
(let [right-now (. (Date.) getTime)
new-user-entry (conj this-users-params { "updated" right-now })]
(println apply str new-user-entry)
(swap! registry assoc (:username new-user-entry) new-user-entry)))
But on the server I would get errors like:
2012-10-19
02:01:26.214:WARN:oejs.AbstractHttpConnection:/?username=karlorihoo&first_name=Karlo&last_name=Rihoo&user_image=java.lang.Exception:
JSON object properties may not be nil
at clojure.data.json$default_write_key_fn.invoke(json.clj:28)
at clojure.data.json$write_object.invoke(json.clj:313)
at clojure.data.json$fn__109$G__104__116.invoke(json.clj:279)
So I wanted to add this if statement:
(defn add-to-logged-in-registry [this-users-params]
"We assume some user is looking at a site such as wpquestions.com and the
Javascript on that site is sending an Ajax request to this app, every 10
seconds, with a map of information about the user, which we need to store
in the registry."
(let [right-now (. (Date.) getTime)
new-user-entry (conj this-users-params { "updated" right-now })]
(println apply str new-user-entry)
(if-not (nil? (:username new-user-entry))
(swap! registry assoc (:username new-user-entry) new-user-entry))))
But then the line with swap! never seemed to get called and the registry
remained empty no matter what I threw at this, including hardcoded "nil"s.
On Friday, October 19, 2012 3:53:26 AM UTC-4, [email protected] wrote:
>
> conj can surely produce maps, and does so happily in the following cases:
>
> (conj {} [:foo :bar])
> (conj {} {:foo :bar})
>
> I suggesting adding printlns or logging or a debugger and checking the
> value of this-users-params, it is almost certainly not what you expect
> it to be.
>
> as a side note creating a date object just to call getTime is kind of
> gross, try (System/currentTimeMillis)
>
> On Fri, Oct 19, 2012 at 12:42 AM, Sean Corfield
> <[email protected]<javascript:>>
> wrote:
> > On Fri, Oct 19, 2012 at 12:10 AM, larry google groups
> > <[email protected] <javascript:>> wrote:
> >>
> >> (defn add-to-logged-in-registry [this-users-params]
> >> (let [right-now (. (Date.) getTime)
> >> new-user-entry (conj this-users-params { "updated" right-now
> })]
> >> (if (:username new-user-entry)
> >> (swap! registry assoc (:username new-user-entry)
> new-user-entry))))
> >>
> >> The if statement seems to never be true.
> >
> >
> > conj produces a sequence, not a map, so the lookup of :username fails.
> Try
> > new-user-entry (assoc this-users-params "updated" right-now)
> > --
> > Sean A Corfield -- (904) 302-SEAN
> > An Architect's View -- http://corfield.org/
> > World Singles, LLC. -- http://worldsingles.com/
> >
> > "Perfection is the enemy of the good."
> > -- Gustave Flaubert, French realist novelist (1821-1880)
> >
> > --
> > You received this message because you are subscribed to the Google
> > Groups "Clojure" group.
> > To post to this group, send email to [email protected]<javascript:>
> > Note that posts from new members are moderated - please be patient with
> your
> > first post.
> > To unsubscribe from this group, send email to
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>
>
>
> --
> And what is good, Phaedrus,
> And what is not good—
> Need we ask anyone to tell us these things?
>
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