[Zope3-Users] Direct ZODB access in a Zope3 instance
johanc at easypublisher.com
Thu Dec 1 17:37:06 EST 2005
Brad Allen wrote:
> At 11:48 AM +0100 12/1/05, Johan Carlsson wrote:
>> The ZAPI interface gives you several ways to traverse object
>> from a context:
>> For instance getParent, (getParents,) getRoot, traverse, (traverseName)
> On my first reading of your posting, I missed "getRoot".
> That sounds promising. If I can get the root of the ZODB
> then I can use traversal to get to any other object in
> the ZODB.
> However, getRoot takes an argument. The example in
> Philikon's book uses a Location(). I don't think this gets
> me the root of the ZODB, does it?
Without checking I think getRoot only does an "inverse travers"
similare to what acquisition would have done in Zope 2.
It takes a object (that should support the ILocation, which
defines the __parent__ attribute, without it you wouldn't be
able to climb back up :-)
E.g. what you most likely would pass is the context (which most
likely will be the object your accessing (through a request of some kind).
As I have mentioned before, in the normal case your probalby
are writing a BrowserView class or an adapter (that will
have a context object) and it will be very likely this
content object is some kind of Content Type object, e.g.
something that probably exists in the ZODB.
(A lot of probabilities :-)
There is another way to get to object though,
through the registry and in most cases you would look
up a Utility. Now utilities will not necessary be a
a ZODB object, but if they are local utility they are :-)
One of the hardest things to learn about Zope 3 is that
there always is a BrowserView class even if you never
code it in Python. Because it's hidden in the ZCML,
such as the EditView.
Personally I'm trying to avoid high-level ZCML statements,
or at least alway implement a BrowserView, it make think
much clearer in my mine, more explicit :-)
Johan Carlsson Tel: + 46 8 31 24 94
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Torsgatan 72 Email: johanc at easypublisher.com
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