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Real-time update example from tutorial does not work #152

eykd opened this Issue Sep 13, 2012 · 4 comments


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eykd commented Sep 13, 2012

In section IV.3 of the tutorial PDF, the pull greeting/pull/ controller is defined as such:

pull('GET', [LastTimestamp]) ->
    {ok, Timestamp, Greetings} = boss_mq:pull("new-greetings", 
    {json, [{timestamp, Timestamp}, {greetings, Greetings}]}.

However, when a web client is waiting on this to resolve and a new greeting gets sent over the channel, the controller errors out with this:


I'm extremely new to reading Erlang and Erlang tracebacks, but after playing around with this a bit and attempting to read the code, it seems like the JSON serializer is choking on a list of models.

Since the controller return value json is documented as supporting lists of models, I think this may be a bug. Either that, or something fundamental has changed between 0.7 (the version of the tutorial) and 0.8 (the version for download).

eykd commented Sep 13, 2012

I should mention that after all the usual request/response cycle stuff, this was the part of the tutorial that made me do my best Keanu Reeves impression: "Whoah." I was really bummed when it didn't work. :(


pellegrino commented Sep 15, 2012

I'm also having the same problem here. I tried replacing the output to use a simple string instead of a Boss Record and it did work. I guess json encoder didn't like the list of models.


pellegrino commented Sep 15, 2012

Update here: i don't know exactly what i did, but this error went away. I probably just restarted my server and cleared the mock database. So i would probably call it as something wrong on my side of things.


zkessin commented Jan 26, 2014

I am closing this

@zkessin zkessin closed this Jan 26, 2014

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