[Zope3-Users] Re: User preferences for languages- possible?

[Giovannetti, Mark]

Hi Philipp,

You are a great resource, thanks for helping. See below.

> From: zope3-users-bounces at zope.org 
> [mailto:zope3-users-bounces at zope.org] On Behalf Of Philipp 
> von Weitershausen
> Giovannetti, Mark wrote:
> > Hi,
> > 
> > This stuff is crazy.  I just want to implement a user
> > preference for a language (because I have to).  I've
> > read all the user pref. documentation (skinpref, apidoc
> > prefs and zope.app.preference) until I'm blue in the
> > face.  Nothing seems to work and there is no help via
> > google and so forth.
> > 
> > I know that UserPreferences() wants an ILocation object.
> > I can't seem to get one inside the BrowserFormLanguages
> > class.  I am only given the request object.
> > 
> > What do I need to do?  Getting a root site is insane
> > the way I found to do it via a mailing list message.  Not
> > to mention it had issues racking up db connections, then
> > failing on close.
> > 
> > Help! Please! Thank you!
> > 
> > Preferences seem to work since I can edit them using
> > the http://.../++preferences++/ form.
> 
> The zope.app.preference stuff stores the info in principal 
> annotations, in a weird way. I personally find that 
> stuff a bit convoluted.

If you find it convoluted, then how are us mere mortals
supposed to deal with it?  ;-)

> 
> The key, as you've correctly identified, is write your own 
> IUserPreferredLanguages adapter (or a variant thereof). I would store 
> the user's preferences in a cookie or a session. This makes 
> things much easier. Simply adapt the request to 
> ISession(request).

I'll end up having to do something like this, I suppose.
It really sucks, though, because I *want* to use the
preferences machinery.  Why was it built if it can't be
used in certain places - and why aren't the places it can't
be used documented?  Arrg.  

> 
> Note that this might not always work, e.g. when the request is 
> instantiated and the request's locale is first created (because local 
> utilities to store the session data in aren't available at 
> that point). 

How am I supposed to deal with what you say above?  I don't
even understand most of it!  ;-)

> It seems you're hitting that exact problem with the 
> preference stuff as well. The trick here is to stub this 
> out when the adapter is first called, 

'stub this out ... ' - I don't understand, sorry.

> and then later during traversal, when you know the local 
> components are there, you revisit it all again by calling 
> request.setUpLocale() or whatever it is. 

I don't know what you mean.  How is a noob supposed to 
deal with this?

> The ++lang++ implementation might give some pointers.

The ++lang++ implementation (and ensuing errors when I tested using
it) told me that I needed to change BrowserFormLanguages to 
use IModifiableUserPreferredLanguages.  Since I had to do that
in order to allow language preferences I decided to get the
UserPreferences machinery running for the app.  Now I have 
this problem.

The *must* be a common use case.  Why isn't this already solved
and documented as a 'best practice' example?

Mark