Does the println show you what you expect?
On Fri, Oct 19, 2012 at 5:35 PM, larry google groups <
lawrencecloj...@gmail.com> wrote:
>
> > 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, red...@gmail.com 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 <seanco...@gmail.com>
>> wrote:
>> > On Fri, Oct 19, 2012 at 12:10 AM, larry google groups
>> > <lawrenc...@gmail.com> 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)
>> >
>> > --
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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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--
I may be wrong or incomplete.
Please express any corrections / additions,
they are encouraged and appreciated.
At least one entity is bound to be transformed if you do ;)
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