[okfn-help] CKAN/Microfacts questions

Thu Feb 14 21:21:02 GMT 2008

John Bywater wrote:
> Hi Rufus,
> 
> I've basically finished CKAN things. Three questions:

Sorry for the delay in reply but it took me longer to get things working 
than I imagined (on the new machine etc). Part of this was my own fault 
in that I installed Genshi 0.4 and then had to work out why it wasn't 
working. The good side of this is that a) I've removed the dependency on 
markdown (markdown is in webhelpers) b) ckan now works with genshi 0.4 
c) I have found one genuine bug.

Hope I haven't broken anything and all the gory details in the log messages:

http://knowledgeforge.net/ckan/trac/changeset/245
http://knowledgeforge.net/ckan/trac/changeset/244

As detailed in this 2nd message there is one genuine bug: package create 
action returns 201 but also returns content which is apparently illegal 
for http spec (using my version of paste fixture i get an assertion error).

> Firstly, have you seen/tried the package tag autocompletion function? 
> It's very like the full-screen version of delicious's edit page (ie you 
> get a horizontal list that starts hard-left). Only thing is that editing 
> mid-list doesn't autocomplete, but I haven't tried to address that.

Looks really nice. Great stuff :)

> Secondly, I fixed up the package controller error handling and HTTP 
> response status codes. The REST thing also just clicked, so I wrote 
> about it here, here, and here:
> http://desire.appropriatesoftware.net/requirements/60/
> http://knowledgeforge.net/ckan/trac/ticket/27#comment:3
> http://knowledgeforge.net/ckan/trac/ticket/27#comment:4
> 
> Following that general conception and CKAN-specific analysis, I wrote 
> this piece of documentation:
> http://knowledgeforge.net/ckan/trac/wiki/RestfulAPI

Again this all looks really good.

> Basically, I wanted to ask you whether you understand Routes/Pylons/CKAN 
> enough to match the 'api/rest' path and set a request param (or context 
> attribute?) called 'format' to 'json'. I didn't look into this cos I 
> thought you might just know. If we can just map the URLs I wrote in that 
> document to the same controllers but with the request param set that 
> would be very nice.

There are two obvious ways to do this:

a) Mess around with routes so that it does this. This would mean messing 
around with the setup of config/routing.py

b) create a new controller controllers/api.py with a method called rest 
whose job is to strip off the rest of the url and then redispatch based 
on that adding format=json to the request

However personally I think we should not bother with this and just have 
an extra query parameter named 'format' (which perhaps we can just 
extract out in the BaseController). This then determines what is 
returned out  (html/json at this point defaulting to html). If this 
seems a bit repetitive in that each controller has to extract the 
parameter and then act on it we could move to the decorator model where 
every action returns a dict which is either converted to json or to 
template ...

> BTW I think it makes a lot of sense to distinguish the locations of your 
> web browser interface and your machine client interfaces. This is how 
> many of the more famous web services (esp. flickr.com) have been done.

I see that but is it worth the added complexity at this point in time? 
I'm undecided.

> Thirdly, what's the state of microfacts? Should I be able to do pretty 
> much the same as I can with CKAN? I notice there is no microfacts-admin, 
> so am I correct to infer there no special test data?

No, not at present. Everything is setup in the (one current) test 
itself. There is some json data in demo/ but that is not yet used by the 
code.

> Also, might I ask you to check that you have no uncommitted changes 
> (that I need) on your machines?

No. Everything committed.

> Other than that, what did you think about AJAX-style aspects to 
> microfacts thread view? Shall we start without any for now? (Is there 
> already a thread view?? I didn't get it running yet....)

There is no WUI at all at present (i.e. no controllers, no templates etc 
etc). Just a bare-bones model. First step is probably to copy and paste 
ckan css (and js if necessary) and start on thread/factlet views.

~rufus