[sqlalchemy] Re: Announcing Elixir!

2007-02-15 Thread Karl Guertin

On 2/15/07, Jonathan Ellis [EMAIL PROTECTED] wrote:
 For instance, I remember reading somewhere that AM wasn't very good at
 playing well with the rest of SA when AM wasn't enough, so I never
 bothered looking at AM very hard.  I don't see anything on the elixir
 site about this issue, but maybe I am looking in the wrong place.

That would be my FUD. I only had it happen in a particular 0.2 release
(forget which). Everybody else who has used the two together seems to
have never had a problem and I know I haven't had any problems mixing
the TurboGears identity (AM) with non-AM classes in SA 0.3. I doubt
it'd be listed in the Elixir docs because it hasn't been a widespread
problem. I'm just noisy.

P.S. I hear if you mix Elixir and SQLSoup you get magic DSL jellybeans.

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[sqlalchemy] Re: Assign mapper many-to-many with extra columns

2007-02-03 Thread Karl Guertin

On 2/3/07, iain duncan [EMAIL PROTECTED] wrote:
 InvalidRequestError: Given column 'page_article.ordering', attached to
 table 'page_article', failed to locate a corresponding column from table
 'article_36c9'

I'd think that you're missing the .c. in the middle:

page_article.c.ordering

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[sqlalchemy] Re: Persistence Layer best practices with SQLAlchemy

2007-01-27 Thread Karl Guertin

On 1/27/07, Allen Bierbaum [EMAIL PROTECTED] wrote:
 I agree that a complete separation is probably either a) impossible or
 b) going to lead to code that is so complex and difficult to maintain
 that it removes any advantage gained.

I modify the schema and code in step during development, once the
project is finished and enters into maintanence, the object model
stays pretty much fixed. From your initial message, I'm sure whether
you wanted to use raw SQL or SA's interface. The latter isolates
changes much better than the former, so the rest assumes that's what
you're using.

Table name changes are pretty simple, change the first argument to
Table and all the ForeignKeys that reference it. Field name changes
are less obvious. I make use of the key= argument of the Column class
because that means my queries don't need to be rewritten. Flexibility
beyond that is dependent on how many queries you have scattered around
your code.

For code that's just using the final mapped objects, you can map
pretty much anything you can query onto a particular attribute. I've
done a few mapping changes where a field is normalized or
de-normalized and the object stays the same. The code using the
objects doesn't have to change, but the queries that touch that field
generally do. Certain changes are simpler than others, your mileage
may vary.

 I am starting to think that it still has all the power and flexibility
 of the other methods of using SA but simple encapsulates the Table and
 Mapper creation in a single unit.  Can anyone tell me if this is a
 correct assessment?

ActiveMapper implements the active record pattern while the standard
SA ORM interface implements the data mapper pattern (see Fowler's
Patterns of Enterprise Architecture for explanations). For basic
usage, ActiveMapper is more convenient and is basically a thin wrapper
over the standard. The problem is that it's relations are less
powerful -- there's no primaryjoin or secondaryjoin, this is an
implementation limit and can be fixed -- and quite a few of the
features listed in the Advanced Datamapping section of the docs are
unavailable to you. You cannot, for example, map multiple tables onto
a single object, this is a design limit.

You can mix and match ActiveMapper and normal SA mapped objects and
definitions, but I prefer to just use active_mapper exclusively. The
biggest disadvantage is that the code is spread into three locations.
I work around this using code folds in Vim, but it's still a bit
clunky.

There is another active record mapper called TurboEntity (no ties to
TurboGears despite the name), which a number of people on the TG
mailing list like. The authors of ActiveMapper and TurboEntity are
collaborating on a joint project to replace both with a mapper that
implements a DSL which, to me, looks like a mix between Rails'
ActiveRecord and Smalltalk.

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[sqlalchemy] Re: class-object-like attribute lookup

2007-01-25 Thread Karl Guertin

On 1/25/07, Christopher Arndt [EMAIL PROTECTED] wrote:
 It doesn't need to be recursive, just a two-level parent-child relation. And I
 don't want to add any columns, so I was thinking that table inheritance is not
 the right approach, but I'm not sure about that.

I was thinking that you could check parent_id for null or not null and
map that way, but it doesn't look like  the polymorphic mapper can
handle that. Ah well.

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[sqlalchemy] Re: SQLAlchemy at pycon 07

2006-11-29 Thread Karl Guertin

On 11/29/06, Jonathan Ellis [EMAIL PROTECTED] wrote:
 My proposal for a talk on SqlSoup was accepted.  It looks like someone
 else's talk on SA itself was accepted too.  Woot! :)

I'm not seeing a list of accepted talks on us.pycon.org; any links?

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[sqlalchemy] Re: GUI + SQLAlchemy?

2006-11-15 Thread Karl Guertin

On 11/14/06, Basil Shubin [EMAIL PROTECTED] wrote:
 Is there standalone GUI application that using SQLAlchemy? Of course it
 should be open source apps.

There is neither an open source nor a commercial GUI interface for SQLAlchemy.

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[sqlalchemy] Re: [Sqlalchemy-users] Typed Relations - Any Easier way to do Association Object?

2006-11-01 Thread Karl Guertin

On 11/1/06, Michael Bayer [EMAIL PROTECTED] wrote:
 (moving to google groups)

Eh, sorry cached email address.

 the idea of using an instrumented list subclass is that you *would*
 use the association object, and just have the list subclass handle
 the references to the association object for you, i.e.:

Simple enough

 class MyList(list):
  def append(self, item):
  super(MyList, self).append(new ItemAssociation(item))
  def __getitem__(self, index):
  return super(MyList, self).__getitem__(index).item

 ..etc

I'm not understanding what's happening in the append. I know item is
one side of my relation, but how to I get access to the other? Is the
InstrumentedList magic supposed to handle this somehow?

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