[Grok-dev] Re: New Grok user with some questions

[Martijn Faassen]

Kevin Teague wrote:
>>
>> - I found some references about local utilities but no real 
>> documentation about it. Is there some documentation or sample code on 
>> how to use local utilities in Grok?
>>
> 
> There is a small mention in the Official Grok Reference, but the 
> reference isn't finsihed and published on the web site yet:
> 
> http://svn.zope.org/grok/trunk/doc/reference/components.rst?rev=82908&view=markup 
> 
> 
> In the absence of documentation, the ftests and tests directories in the 
> grok source package make for reasonable examples of how to do things. 
> But asking questions on the list is also good, since it has a chance of 
> prodding someone into documentating something :)

Yes, for now I think the ftests in Grok are most instructive.

In brief, there is a 'grok.local_utility' directive which you can use on 
a grok.Application (or sites in general). When this site is created, it 
will automatically create and install the local utility for you.

>> - One of my main problems with ZODB is how to implement m:n relations. 
>> I think most people comming from relational databases have this 
>> problem and a short how-to would be quite helpfull. Perhaps this would 
>> be a nice lighting talk on the Europython 2008? ;-)
> 
> lovely.relation (http://svn.zope.org/lovely.relation/) is AFAIK the best 
> place to start for modeling many to many relationships (um, M:N to is 
> many-to-many)? It's a Zope 3 package built on the lower level 
> zc.relationship package. I've only gone far enough with this package to 
> create a very simple relationship in Grok 0.12, but maybe once I've used 
> it a bit more I'll write up a how-to - there is a fair bit of docs 
> within the package itself as well.

I just mentioned my stealth package z3c.relationfield. I just realized 
it is actually in Zope's SVN already. It only does 1 to 1 relations 
right now, but it does index them and so on, making quite powerful 
queries on the relations possible. It also hasn't been publically 
released yet. 1 to many relations are still coming.

http://svn.zope.org/z3c.relationfield/trunk/src/z3c/relationfield/README.txt

The nice thing about this package is that it is relatively simple to use 
in an existing schema, while it still offers powerful indexing. That 
said, I can't promote it too much yet, as it needs a bit more polishing.

Regards,

Martijn