On 23 May 2006 at 21:01, Luís Bruno wrote:
> > class DatabaseMiddleware(object):
> >
> > def __init__(self, application, global_conf,
> > db_uri=None, echo=False, **kw):
>
> This looks very much like the paste.filter_app_factory protocol, don't
> you agree? You might as well move the assert in the factory method
> here, I guess.
It does, but paste deploy looks for a function, not a class.. So the factory
has to
be a function.
>
> > class Manager(object):
> >
> > def __init__(self, *args, **kw):
> > self.aborted = False
> > global_connect(*args, **kw )
> > self.engine = schema.default_engine.get_engine()
> > self.engine.begin()
>
> This is where you've lost me; does this connect to the database on
> every request? Since you've global_connect()'ed in the middleware's
> __init__(), I thought you wouldn't need to do anything else than a
> begin().
I'm using scgi, so default_engine.get_engine() looks in thread_local storage
for the db connection. The first webrequest is running in a different thread
than
main, so without the global_connect() call, get_engine() dies with a key error.
anyway, global_connect() caches engines by uri, so it's not too bad.
> Maybe I'm not getting it, but wouldn't you need to provide each
> Table() or Mapper() to the response generator? I *think* the MetaData
> in the -schema branch has a list of tables, so I don't need to provide
> anything else; <del>but I don't think you can get away with just an
> engine.</del> ah, yes; you can use engine.tables[name]. Never mind.
In my case, the table meta data is generated w/o any engine being specified, so
the proxy engine is used then..
The filter just puts the manager instance into the environment, lower down
app code does whatever it needs to do with sqlalchemy.
In my case, I don't yet need the objectstore access in my app, but I will.
So, here's an example app with REST exposure of some data. Module dbtables
has my table meta-data
(still a work inprogress)
def __call__(self, environ, start_response):
"""Generate the response"""
transaction_manager = environ['p2pserver.transaction_manager']
table_name = request.path_info_pop(environ)
table = table_name and getattr(dbtables, table_name, None) or None
if not table:
return httpexceptions.HTTPBadRequest(detail="Invalid tablename %r"
% table_name)(environ, start_response)
request_method = environ['REQUEST_METHOD']
if request_method == 'GET':
form = variable_decode(request.parse_formvars(environ))
print "form", form
id = form.get('id')
criteria = form.get('criteria', {})
print "criteria", criteria
if id:
# expect a single record
record = table.get(int(id))
results = {
'table_name':table_name,
'id':id,
'record':record or None,
}
else:
args = []
if criteria:
for k, v in criteria.items():
args.append(table.c[k] == v)
records = table.select(*args).data
results = {
'table_name':table_name,
'records':records,
'criteria':criteria or None,
}
results['columns'] = table.c.keys()
else:
form = {}
results = {
'error':'no request',
}
response = xml_string(object=results, name="results",
policy=self.policy)
response = DataApp(response, content_type='text/xml')
return response(environ, start_response)
--
Brad Clements, [EMAIL PROTECTED] (315)268-1000
http://www.murkworks.com
AOL-IM or SKYPE: BKClements
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