Hi,

I am wondering if and why it's standard behavior that couchdb-python
is adding empty attributes of an object to couchdb. I am just feeling
when an attribute (e.g. name) is None, then it would not end up in the
DB. As i understood CouchDB is returning null for non-existing and
empty attributes anyway.

This way attributes could maybe assigned to a doc dynamically. (Some
docs have it, some not, ...)

Maybe I am thinking into the absolute wrong direction.

Thomas

On 16 November 2011 06:24, Thomas <thomm...@gmx.net> wrote:

couchdb-python's couchdb.client module doesn't alter attributes (apart
from _id and _rev) at all, it sends whatever the application gives it
to the CouchDB server. For some applications, the absence of an
attribute vs a None value may even be significant. The couchdb.mapping
Document seems to set all its schema attributes to None during
__init__ but that doesn't seem totally unreasonable given that
attribute access has to return *something*.

Like couchdb.client, CouchDB also stores whatever it's given. It's
really just the default JavaScript view engine that treats
JavaScript's undefined as a null. If you need to, you can
differentiate between undefined and null in a map function by using
JS's === strict comparison operator.

Yep, and this is the the behaviour you get with couchb.client already.
There may be an argument for making couchdb.mapping produce sparse
documents but not set and None are still different and I'm not
convinced it would be practical to use if document attributes
disappeared to represent the not set case.

Are you using talking about the mapping layer objects?

I am not sure what the sensible behavior for mapping objects would be.
In JavaScript you would have the difference between undefined and
null, but Python doesn't have that. As such, I don't think it'd be a
good idea to skip the attributes that are None, but I agree that it's
a bit ugly.

Unless you're talking about the client layer of couchdb-python, where
you're talking about item keys instead of attributes, and leaving out
the key vs. setting it to None seems to communicate the intent
trivially.

Cheers,

Dirkjan

Sorry, I thing I was a bit confused about couchdb.client and
couchdb.mapping module. It's getting more clear now thanks to both of
your help.

I think I am then talking about the mapping module, that's what I am
using and what produces a lot of "empty" (None) values in couchDB.
After your explanations I understand that it might make sense to know
the difference between a not existing key and an empty one.

You are right, I compared this behavior with the standard js view
engine.

Thanks.