[sqlalchemy] Obtaining primitive columns from a select

2008-07-15 Thread Lele Gaifax 

Hi all,

I'd like to have a generic function that executes a given SQL query
filtering it with conditions passed as keyword args, but I do not find
a clean way to refer to the primitive columns (on the underlying
table) instead of those already bound to the select.

Given a simple select::

   query = sometable.select()

and a dictionary::

   args = { 'somecolname': 'avalue', 'othercolname': 1 }

I tried to implement a simple function::

   def apply_filters(query, args):
  ... for colname in args:
  ... query = query.where(XXX(colname) == args[colname])
  ... return query

I first tried using query.columns[colname] in place of the XXX()
stub, but that does not do the job, because it brings in a subselect.

Of course it works when I refer to the table columns, but how can I
reach them having just the query on the table? I tried inspecting the
query, that carries a _raw_columns, or _froms, but it does not
seem a clean approach. What am I missing?

Thanks in advance for any hint,
ciao, lele.

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[sqlalchemy] Re: M2M relationship

2008-07-15 Thread Heston James - Cold Beans 

Hi Michael,

 create a file called something like globals.py, and in all other  
 modules that use SQLAlchemy, say import globals. A primer on  
 modules, packages and such is at http://www.python.org/doc/tut/node8.html 

Excellent! This seems to have done the job, I am now successfully saving and
pulling these objects from the database, very cool!

Thank you again.

Heston


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[sqlalchemy] Filter by optional attributes.

2008-07-15 Thread Heston James - Cold Beans 
Good morning guys,

 

I'm looking for a way in which I can query my database for records which
meet multiple, optional arguments. I'm looking to encapsulate access to this
using a service layer, I want to create a method like this:

 

def get_foos(self, foo_id=, foo_firstname=, foo_lastname=):

foos = session.query(Foo).filter_by(foo_id=foo_id,
foo_firstname=foo_firstname, foo_lastname=foo_lastname)



return foos

 

Now, the thing I'm struggling with is how to make all those attributes
optional. Because at the moment I call that method like so:

 

get_foos(foo_id=2)

 

I get no results returned because SQLAlchemy is looking for records that not
only have an id of 2 but also have a first and last name which is an empty
string.

 

What I would ideally like to do is only have it filter by the arguments for
getfoos() which are not empty strings. This would allow me to build a more
reusable query method.

 

Is this possible? And how would one achieve it?

 

Cheers,

 

Heston


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[sqlalchemy] Re: Filter by optional attributes.

2008-07-15 Thread az 

use keywordargs as dictionary, i.e.
...query.filter( **kwargs)
where the kwargs are a dict made by u containing only the required 
fields. e.g. 

kwargs={}
if foo_id: kwargs['fooid']=fooid
...
u can make it more generic (but more dangerous) by passing any kwargs 
coming to your func straight down to filter():

def myfunc( self, whateverotherstuff, **filterkwargs):
 .. query.filter( **filterkwargs)

or some combination inbetween.
dont forget that filter( ...) does AND of the criterias.

svil

On Tuesday 15 July 2008 14:55:01 Heston James - Cold Beans wrote:
 Good morning guys,



 I'm looking for a way in which I can query my database for records
 which meet multiple, optional arguments. I'm looking to encapsulate
 access to this using a service layer, I want to create a method
 like this:



 def get_foos(self, foo_id=, foo_firstname=,
 foo_lastname=):

 foos = session.query(Foo).filter_by(foo_id=foo_id,
 foo_firstname=foo_firstname, foo_lastname=foo_lastname)



 return foos



 Now, the thing I'm struggling with is how to make all those
 attributes optional. Because at the moment I call that method like
 so:



 get_foos(foo_id=2)



 I get no results returned because SQLAlchemy is looking for records
 that not only have an id of 2 but also have a first and last name
 which is an empty string.



 What I would ideally like to do is only have it filter by the
 arguments for getfoos() which are not empty strings. This would
 allow me to build a more reusable query method.



 Is this possible? And how would one achieve it?



 Cheers,



 Heston


 


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[sqlalchemy] Re: Filter by optional attributes.

2008-07-15 Thread Heston James - Cold Beans 

Hi Svil:

 use keywordargs as dictionary, i.e.
...query.filter( **kwargs)
 where the kwargs are a dict made by u containing only the required 
 fields. e.g. 

 kwargs={}
 if foo_id: kwargs['fooid']=fooid

That sounds like a fair enough solution to me, seems safer than the more
generic version.

Thanks for the tip mate, sounds really great. I'll play around with that
concept.

Heston


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[sqlalchemy] Re: Filter by optional attributes.

2008-07-15 Thread Heston James - Cold Beans 

Hello Again Svil:

 That sounds like a fair enough solution to me, seems safer than the more
 generic version.

 Thanks for the tip mate, sounds really great. I'll play around with that
 concept.

 Heston

I've tested this little concept and it works really nicely :-D thanks.

One quick question I'd like to pick your brain on. With filter(), is that
filter applied at the SQL level? Or are _all_ records returned from the
database and then SQLAlchemy applies the filter?

I'm just trying to get an idea of performance when we have many records, I'd
hate to be pulling them _all_ from the database with each query.

Heston


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[sqlalchemy] Re: Filter by optional attributes.

2008-07-15 Thread Heston James - Cold Beans 

Hi,

 pass an echo=True to the create_engine() (or whereever else u could 
 pass that) and u'll see the sql.

Ok, I see! Perfect!

I've just configured logging on this so I can keep track, looks excellent.

Heston


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[sqlalchemy] Injecting business objects into constructor

2008-07-15 Thread Heston James - Cold Beans 
Afternoon Guys,

 

In my classic non-orm based applications I would usually inject other
business object instances into my classes for such things as logging,
emailing and all manner of other things. For instance:

 

class foo:



def __init__(self, logger, email_service, foo_id=, foo_firstname=):

self.logger = logger

self.email_service = email_service

self.foo_id = foo_id

self.foo_firstname = foo_firstname

 

Now that I'm using the ORM I ask the ORM for these objects, however, it
obviously just hands me back an instance with all its properties loaded from
the database, what is essentially a glorified dict or 'dumb' object.

 

How would you go about getting these business objects into the objects
returned by the ORM? Would you have your service layer set them before
returning the object? Or can we somehow configure the ORM to do it for us?

 

Thanks guys, I'm really enjoying this.

 

Heston


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[sqlalchemy] Re: unexpected behavior with relation and filter_by

2008-07-15 Thread Michael Bayer 


On Jul 14, 2008, at 7:19 PM, Jon wrote:

 I've encountered some weird stuff. I'm probably doing it wrong, but I
 don't understand *why*.

 The following code:


 s = Session()
 # returns all accounts, the .licenses param
 # not taken into consideration
 accts = s.query(Account).filter(Account.licenses==[])
 print accts
 print

 accts = s.query(Account).filter(Account.licenses.any())
 print accts
 print

 # returns the correct list of accounts.
 accts = s.query(Account).filter(Account.licenses==None)
 print accts
 print

 print accts[0].licenses # prints [] not None.

Comparison to lists is currently taken to mean return objects whos  
collection contains these elements, i.e. its like a mass  
Account.licenses.contains() operator.  So if you compare to an empty  
list that would return all parent elements.  Comparison to None  
returns items using a NOT EXISTS clause, i.e. parent items with no  
child items.  any() returns items where any of them meet the given  
criterion -since the criteiron is blank here, all child items match.
any() is the best operator to use when asking for parents with no  
child items, using ~Account.licenses.any() (I think theres a tutorial  
example to this effect).

Once loaded, all collection-based attributes default to the empty  
collection if no elements are present, which is by default a list. 
  

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[sqlalchemy] Bug in 0.4.6/0.5 ?

2008-07-15 Thread Stefano Bartaletti 

Hello list,

I recently installed 0.4.6 to check the news, and with horror I saw this dump:

Traceback (most recent call last):
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/login.py, line 85, 
in onCheckUtente
self.checkUtente(self.inputUser.GetValue().lower())
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/login.py, line 64, 
in checkUtente
user = mapperFunctions.getUtente(user)
  File 
/media/userdata/stefano/Documenti/projects/Tosi/erp/dyemagic2/mapperFunctions.py,
 line 19, in getUtente
rep = mappers.Reparto.query.first() #Per inizializzare la sessione
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/scoping.py,
 line 144, in __getattr__
return getattr(self.context.registry().query(class_), key)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/session.py,
 line 895, in query
return self._query_cls(entities, self, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/query.py,
 line 97, in __init__
self.__setup_aliasizers(self._entities)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/query.py,
 line 111, in __setup_aliasizers
mapper, selectable, is_aliased_class = _entity_info(entity, ent.entity_name)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/util.py,
 line 398, in _entity_info
mapper = class_mapper(entity, entity_name, compile)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/util.py,
 line 488, in class_mapper
mapper = mapper.compile()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/mapper.py,
 line 368, in compile
mapper.__initialize_properties()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/mapper.py,
 line 389, in __initialize_properties
prop.init(key, self)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/interfaces.py,
 line 378, in init
self.do_init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/properties.py,
 line 514, in do_init
self._post_init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/properties.py,
 line 750, in _post_init
super(PropertyLoader, self).do_init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/interfaces.py,
 line 548, in do_init
self.strategy = self.__init_strategy(self.strategy_class)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/interfaces.py,
 line 537, in __init_strategy
strategy.init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/strategies.py,
 line 339, in init
self.logger.info(%s lazy loading clause %s % (self, self.__lazywhere))
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/expression.py,
 line 1155, in __str__
return unicode(self.compile()).encode('ascii', 'backslashreplace')
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/expression.py,
 line 1151, in compile
compiler.compile()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 175, in compile
self.string = self.process(self.statement)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 183, in process
return meth(obj, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 377, in visit_binary
return self.process(binary.left) +   + op +   + 
self.process(binary.right)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 183, in process
return meth(obj, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 227, in visit_grouping
return ( + self.process(grouping.element) + )
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 183, in process
return meth(obj, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 507, in visit_select
for co in select.inner_columns
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 463, in label_select_column
return column.label(column.anon_label)
AttributeError: '_BindParamClause' object has no attribute 'anon_label'

After some helpless googling for version upgrade errors, I read the code and I 
added _BindParamClause in function label_select_column:
elif not isinstance(column, (sql._UnaryExpression, sql._TextClause)) 
and (not

[sqlalchemy] Bug in 0.4.6/0.5 ?

2008-07-15 Thread Stefano Bartaletti 

I recently installed 0.4.6 to check the news, and with horror I saw this dump:

Traceback (most recent call last):
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/login.py, line 85, 
in onCheckUtente
self.checkUtente(self.inputUser.GetValue().lower())
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/login.py, line 64, 
in checkUtente
user = mapperFunctions.getUtente(user)
  File 
/media/userdata/stefano/Documenti/projects/Tosi/erp/dyemagic2/mapperFunctions.py,
 line 19, in getUtente
rep = mappers.Reparto.query.first() #Per inizializzare la sessione
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/scoping.py,
 line 144, in __getattr__
return getattr(self.context.registry().query(class_), key)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/session.py,
 line 895, in query
return self._query_cls(entities, self, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/query.py,
 line 97, in __init__
self.__setup_aliasizers(self._entities)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/query.py,
 line 111, in __setup_aliasizers
mapper, selectable, is_aliased_class = _entity_info(entity, ent.entity_name)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/util.py,
 line 398, in _entity_info
mapper = class_mapper(entity, entity_name, compile)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/util.py,
 line 488, in class_mapper
mapper = mapper.compile()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/mapper.py,
 line 368, in compile
mapper.__initialize_properties()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/mapper.py,
 line 389, in __initialize_properties
prop.init(key, self)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/interfaces.py,
 line 378, in init
self.do_init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/properties.py,
 line 514, in do_init
self._post_init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/properties.py,
 line 750, in _post_init
super(PropertyLoader, self).do_init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/interfaces.py,
 line 548, in do_init
self.strategy = self.__init_strategy(self.strategy_class)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/interfaces.py,
 line 537, in __init_strategy
strategy.init()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/orm/strategies.py,
 line 339, in init
self.logger.info(%s lazy loading clause %s % (self, self.__lazywhere))
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/expression.py,
 line 1155, in __str__
return unicode(self.compile()).encode('ascii', 'backslashreplace')
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/expression.py,
 line 1151, in compile
compiler.compile()
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 175, in compile
self.string = self.process(self.statement)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 183, in process
return meth(obj, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 377, in visit_binary
return self.process(binary.left) +   + op +   + 
self.process(binary.right)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 183, in process
return meth(obj, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 227, in visit_grouping
return ( + self.process(grouping.element) + )
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 183, in process
return meth(obj, **kwargs)
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 507, in visit_select
for co in select.inner_columns
  File 
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2-py2.5.egg/sqlalchemy/sql/compiler.py,
 line 463, in label_select_column
return column.label(column.anon_label)
AttributeError: '_BindParamClause' object has no attribute 'anon_label'

After some helpless googling for version upgrade errors, I read the code and I 
added _BindParamClause in function label_select_column:
elif not isinstance(column, (sql._UnaryExpression, sql._TextClause)) 
and (not hasattr(column,

[sqlalchemy] Re: Bug in 0.4.6/0.5 ?

2008-07-15 Thread Michael Bayer 

Did you call something like select([literal('foo')]) ?If you use  
straight Python literals in the columns clause (i.e. select(['foo'])),  
they will be rendered directly, which is probably what you want here.

This is fixed in r4933 / r4934 0.5 trunk/ 0.4 branch.


On Jul 15, 2008, at 10:52 AM, Stefano Bartaletti wrote:


 I recently installed 0.4.6 to check the news, and with horror I saw  
 this dump:

 Traceback (most recent call last):
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/ 
 login.py, line 85, in onCheckUtente
self.checkUtente(self.inputUser.GetValue().lower())
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/ 
 login.py, line 64, in checkUtente
user = mapperFunctions.getUtente(user)
  File /media/userdata/stefano/Documenti/projects/Tosi/erp/dyemagic2/ 
 mapperFunctions.py, line 19, in getUtente
rep = mappers.Reparto.query.first() #Per inizializzare la sessione
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/scoping.py, line 144, in __getattr__
return getattr(self.context.registry().query(class_), key)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/session.py, line 895, in query
return self._query_cls(entities, self, **kwargs)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/query.py, line 97, in __init__
self.__setup_aliasizers(self._entities)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/query.py, line 111, in __setup_aliasizers
mapper, selectable, is_aliased_class = _entity_info(entity,  
 ent.entity_name)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/util.py, line 398, in _entity_info
mapper = class_mapper(entity, entity_name, compile)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/util.py, line 488, in class_mapper
mapper = mapper.compile()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/mapper.py, line 368, in compile
mapper.__initialize_properties()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/mapper.py, line 389, in  
 __initialize_properties
prop.init(key, self)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/interfaces.py, line 378, in init
self.do_init()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/properties.py, line 514, in do_init
self._post_init()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/properties.py, line 750, in _post_init
super(PropertyLoader, self).do_init()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/interfaces.py, line 548, in do_init
self.strategy = self.__init_strategy(self.strategy_class)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/interfaces.py, line 537, in __init_strategy
strategy.init()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/orm/strategies.py, line 339, in init
self.logger.info(%s lazy loading clause %s % (self,  
 self.__lazywhere))
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/expression.py, line 1155, in __str__
return unicode(self.compile()).encode('ascii', 'backslashreplace')
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/expression.py, line 1151, in compile
compiler.compile()
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 175, in compile
self.string = self.process(self.statement)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 183, in process
return meth(obj, **kwargs)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 377, in visit_binary
return self.process(binary.left) +   + op +   +  
 self.process(binary.right)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 183, in process
return meth(obj, **kwargs)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 227, in visit_grouping
return ( + self.process(grouping.element) + )
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 183, in process
return meth(obj, **kwargs)
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 507, in visit_select
for co in select.inner_columns
  File /usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta2- 
 py2.5.egg/sqlalchemy/sql/compiler.py, line 463, in

[sqlalchemy] Re: session.dirty but not session.is_modified....

2008-07-15 Thread Michael Bayer 

popping from dirty() wont change anything since its a set thats  
generated each time it's called.

this is from the doc for dirty():

 Note that this 'dirty' calculation is 'optimistic'; most
 attribute-setting or collection modification operations will  
mark an
 instance as 'dirty' and place it in this set, even if there  
is no net
 change to the attribute's value.  At flush time, the value of  
each
 attribute is compared to its previously saved value, and if  
there's no
 net change, no SQL operation will occur (this is a more  
expensive
 operation so it's only done at flush time).

 To check if an instance has actionable net changes to its  
attributes,
 use the is_modified() method.





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[sqlalchemy] Re: srid autodiscovery mechanism

2008-07-15 Thread jason kirtland 

Michael Bayer wrote:
 
 On Jul 13, 2008, at 5:42 PM, Eric Lemoine wrote:
 
 So far, so good; user can do:

 wifi_table = Table('wifi', metadata,
Column('the_geom', Geometry(4326)),
autoload=True)

 But ultimately I'd like that my users can do:

 wifi_table = Table('wifi', metadata, autoload=True)

 I tried this:

 from sqlalchemy.databases import postgres
 postgres.ischema_names['geometry'] = Geometry

 This is ok, but during reflection, when SQLA creates Geometry objects,
 it obviously passes no srid argument to the Geometry constructor, so
 the Geometry objects all end up with the srid property set to -1.
 The proper srid value to pass to the Geometry constructor is
 actually in a PostGIS table (geometry_columns). So if a geometry
 column is discovered, the table's srid value could be read from that
 table and passed to the Geometry constructor. I thought about doing
 something like that:

 from sqlalchemy.databases import postgres
 def geometry_factory():
// go read srid associated with table from geometry_columns
srid =
return Geometry(srid)
 postgres.ischema_names['geometry'] = geometry_factory

 but geometry_factory doesn't have any connection object to go read the
 srid value.

 My question is simple: do you see solutions to my problem?
 
 like before with asdecimal=False, we dont have a standard API for the  
 ischema_names dict and again here is a place where you're looking  
 for one.   Such an API might look like:
 
   def create_postgis_type(table, connection):
   srid = connection.execute(select whatever you need to figure 
 out  
 SRID value).scalar()
   return Geometry(srid=srid)
 
   engine = create_engine('postgres://...', type_reflectors={
   'numeric':PGFloat,
   'PostGIS':create_postgis_type
   })
 
 where reflecttable() distinguishes between a TypeEngine class and a  
 plain callable, which is assumed to implement a particular API.   But  
 thats just a guess.   I wouldn't implement such an API casually since  
 while its very easy to add little features like this, its much harder  
 to change them or take them away after you've observed they're a bad  
 idea or were not well thought out (additionally this one's a pretty  
 big job to implement across every dialect).   Any opinions from Jason/ 
 Rick/other ?

Would be pretty useful.  Would the mapping have to go deeper, and
control the resolution of (e.g.) String - PGString across the board for
the dialect?

The reflection factories would probably want some *args and **kw to pass
along column/type metadata snarfed up in the first phase of reflection.


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[sqlalchemy] Re: Injecting business objects into constructor

2008-07-15 Thread Rick Morrison 
I'm not sure where this is going with the 0.5 version, but I believe that
MappedClass.__int__ is still not called when objects are loaded from the DB.


If that's the case, and there isn't some alternate that SA provides like
MappedClass.__onload__, You can look into Mapper Extensions to provide this.
Check out the 'create_instance' method.

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[sqlalchemy] Load capabilities with default pool_size and max_overflow

2008-07-15 Thread Fotinakis 

Hello SQLAlchemists,

What is (or what do you think is) the load that SQLAlchemy can handle
with the default engine options of pool_size=5 and max_overflow=10?
The application I'm working on has the potential for bursts of
thousands of requests in a few seconds, so I am concerned about load.

Is it appropriate to increase these values to some arbitrary number? I
see that you can set max_overflow to -1 so that it creates as many
connections as needed, but do you think that would be necessary (or
bad practice)? Thanks for any advice about this, I'm trying to
understand the nature of connections and the QueuePool implementation
to avoid load problems when we go live. Any simple way to script
exceeding the QueuePool limit quickly for load testing?


Thanks for the help, much appreciated.

And also, I've wanted to throw out a huge thank you to the
developers ... on top of SQLAlchemy being extremely robust and
powerful, the SQLAlchemy documentation is impeccable. Better than most
all other open source software ... *awesome* ... so, thank you.

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[sqlalchemy] Re: Load capabilities with default pool_size and max_overflow

2008-07-15 Thread Andreas Jung 



--On 15. Juli 2008 22:32:35 -0700 Fotinakis [EMAIL PROTECTED] wrote:



Hello SQLAlchemists,

What is (or what do you think is) the load that SQLAlchemy can handle
with the default engine options of pool_size=5 and max_overflow=10?
The application I'm working on has the potential for bursts of
thousands of requests in a few seconds, so I am concerned about load.


Default settings are called that way because they make sense to possibly
80% of all use-cases. Don't expect that a high-traffic environment works 
without tuning. So the answer is basically: unlikely.




Is it appropriate to increase these values to some arbitrary number?


Those parameters are exposed as part of the API for performing such a 
tuning?!




-aj

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