Re: [sqlalchemy] Any recommended approach for creating a new dialect?
Hi Michael, thanks for the prompt response and your directions. This was really helpful. I will start as you've described in your reply. Ralph On Wednesday, April 8, 2015 at 6:19:27 AM UTC+2, Michael Bayer wrote: On 4/7/15 1:59 PM, Ralph Heinkel wrote: Hello dialect experts, what would be the best approach for creating a SqlAlchemy dialect for a new database system? Are there any recipes available for this area, or is the way to go to read code of existing dialects and derive my own dialect from those? I had a first glance at some built-in dialects, and also some in external packages ... it is not always obvious to me why certain classes and methods have been implemented. The obvious thing is to create a subclass of sqlalchemy.enginedefault.DefaultDialect, but how would I know which methods and class attributes to override/implement, except for going through the trial and error approach? And then there are other classes which are implemented in some dialects, like compiler.DDLCompiler, compiler.GenericTypeCompiler, and so on ... where and how would I start best? Any help would be very much appreciated. Start with the README for new dialects: https://bitbucket.org/zzzeek/sqlalchemy/src/44a9820b4e02f65b3884fa2c016efce9663e4910/README.dialects.rst?at=master that will show the guidelines for writing new dialects. Then to see some examples of that layout, take a look at some of the 3rd party dialects listed at: http://docs.sqlalchemy.org/en/latest/dialects/index.html#production-ready Also the sqlalchemy-access dialect is basically something of a demo for the layout, which I basically put there after extracting it from SQLAlchemy main where it had been for many years. It might not be 100% up to date, but mostly follows that guideline and even passed tests at one point, that's at https://bitbucket.org/zzzeek/sqlalchemy-access. The key thing you'll be doing is running the suite tests, which will be part of the test suite within your own dialect. So yes, you start with a fairly plain subclass of DefaultDialect, then you probably want to get a hello world kind of program going where you just see if create_engine and then engine.execute(select * from table) work at all, and then the suite tests should test a lot more. Ciao ciao Ralph -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+...@googlegroups.com javascript:. To post to this group, send email to sqlal...@googlegroups.com javascript:. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Any recommended approach for creating a new dialect?
Mike, I remember an article of yours where you described much of the process of creating a new dialect for SA, for a Java database if I'm not mistaken. I wasn't able to find it, though. :) On 04/08/2015 01:19 AM, Mike Bayer wrote: On 4/7/15 1:59 PM, Ralph Heinkel wrote: Hello dialect experts, what would be the best approach for creating a SqlAlchemy dialect for a new database system? Are there any recipes available for this area, or is the way to go to read code of existing dialects and derive my own dialect from those? I had a first glance at some built-in dialects, and also some in external packages ... it is not always obvious to me why certain classes and methods have been implemented. The obvious thing is to create a subclass of sqlalchemy.enginedefault.DefaultDialect, but how would I know which methods and class attributes to override/implement, except for going through the trial and error approach? And then there are other classes which are implemented in some dialects, like compiler.DDLCompiler, compiler.GenericTypeCompiler, and so on ... where and how would I start best? Any help would be very much appreciated. Start with the README for new dialects: https://bitbucket.org/zzzeek/sqlalchemy/src/44a9820b4e02f65b3884fa2c016efce9663e4910/README.dialects.rst?at=master that will show the guidelines for writing new dialects. Then to see some examples of that layout, take a look at some of the 3rd party dialects listed at: http://docs.sqlalchemy.org/en/latest/dialects/index.html#production-ready Also the sqlalchemy-access dialect is basically something of a demo for the layout, which I basically put there after extracting it from SQLAlchemy main where it had been for many years. It might not be 100% up to date, but mostly follows that guideline and even passed tests at one point, that's at https://bitbucket.org/zzzeek/sqlalchemy-access. The key thing you'll be doing is running the suite tests, which will be part of the test suite within your own dialect. So yes, you start with a fairly plain subclass of DefaultDialect, then you probably want to get a hello world kind of program going where you just see if create_engine and then engine.execute(select * from table) work at all, and then the suite tests should test a lot more. Ciao ciao Ralph -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com mailto:sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com mailto:sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com mailto:sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com mailto:sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
[sqlalchemy] Specifying itersize when streaming_results=True for psycopg2 driver ?
I searched documentation, mailing list, issue-list, code (on github), google, and couldn't find for a way to set the iterszie, the number of rows to get on each batch when streaming results with psycogp2. Is it possible ? In psycopg2 docs: http://initd.org/psycopg/docs/cursor.html#cursor.itersize -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
[sqlalchemy] Eagerly loading backrefs
Hi there -
I'm having trouble working with backrefs of detached objects.
I'm basically working with a extended version of the code below:
class Config(Base):
__tablename__ = 'config'
ID = Column('ID', Integer, primary_key=True)
name = Column('name', String)
last_modified = Column('last_modified', DateTime, default=now, onupdate=
now)
params = relationship('ConfigParam', backref='config', lazy=False)
class ConfigParam(Base):
__tablename__ = 'config_params'
ID = Column('ID', Integer, primary_key=True)
ConfigID = Column('ConfigID', Integer, ForeignKey('config.ID'), nullable
=False)
key = Column('key', String)
value = Column('value', Float)
Now when I load a Config instance I'd have assumed that
Config.params[0].config should be populated - since the eager query
contains all necessary information.
Testing this with a sqlite engine using the following code:
s = Session()
c = Config(name='my_config')
c.params += [ConfigParam(key='a', value=1),
ConfigParam(key='b', value=2)]
s.add(c)
s.commit()
s.close()
del c
# reload from new session:
logging.info('\n\n')
logging.info('Starting with new session:')
s = Session()
c = s.query(Config).filter(Config.name=='my_config').one()
s.close()
for p in c.params:
logging.info('Params:%s = %s' % (p.key, p.value))
for p in c.params:
logging.info('backref: config = %s' % p.config)
however produces (omitting the create_all) the following output:
INFO:sqlalchemy.engine.base.Engine:()
INFO:sqlalchemy.engine.base.Engine:COMMIT
INFO:sqlalchemy.engine.base.Engine:BEGIN (implicit)
INFO:sqlalchemy.engine.base.Engine:INSERT INTO config (name, last_modified)
VALUES (?, ?)
INFO:sqlalchemy.engine.base.Engine:('my_config', '2015-04-08
09:04:16.111000')
INFO:sqlalchemy.engine.base.Engine:INSERT INTO config_params (ConfigID,
key, value) VALUES (?, ?, ?)
INFO:sqlalchemy.engine.base.Engine:(1, 'a', 1.0)
INFO:sqlalchemy.engine.base.Engine:INSERT INTO config_params (ConfigID,
key, value) VALUES (?, ?, ?)
INFO:sqlalchemy.engine.base.Engine:(1, 'b', 2.0)
INFO:sqlalchemy.engine.base.Engine:COMMIT
INFO:root:
INFO:root:Starting with new session:
INFO:sqlalchemy.engine.base.Engine:BEGIN (implicit)
INFO:sqlalchemy.engine.base.Engine:SELECT config.ID AS config_ID,
config.name AS config_name, config.last_modified AS config_last_modified,
config_params_1.ID AS config_params_1_ID, config_params_1.ConfigID AS
config_params_1_ConfigID, config_params_1.key AS config_params_1_key,
config_params_1.value AS config_params_1_value
FROM config LEFT OUTER JOIN config_params AS config_params_1 ON config.ID
= config_params_1.ConfigID
WHERE config.name = ?
INFO:sqlalchemy.engine.base.Engine:('my_config',)
INFO:sqlalchemy.engine.base.Engine:ROLLBACK
INFO:root:Params:a = 1.0
INFO:root:Params:b = 2.0
Traceback (most recent call last):
File D:/Assess/Kiln/assess/scratch/sqla_example.py, line 77, in module
logging.info('backref: config = %s' % p.config)
File
D:\Anaconda\envs\assess\lib\site-packages\sqlalchemy\orm\attributes.py,
line 239, in __get__
return self.impl.get(instance_state(instance), dict_)
File
D:\Anaconda\envs\assess\lib\site-packages\sqlalchemy\orm\attributes.py,
line 591, in get
value = self.callable_(state, passive)
File
D:\Anaconda\envs\assess\lib\site-packages\sqlalchemy\orm\strategies.py,
line 507, in _load_for_state
(orm_util.state_str(state), self.key)
sqlalchemy.orm.exc.DetachedInstanceError: Parent instance ConfigParam at
0x307d898 is not bound to a Session; lazy load operation of attribute
'config' cannot proceed
I'm somewhat new to ORM's -
naively I had assumed the backref should/could be loaded at the same time
the parent is eagerly loaded, since all required information is retrieved
in the above query.
Is there anything I'm missing here?
ps: This is on sqlalchemy 0.9.8 - if that should matter.
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Re: [sqlalchemy] Eagerly loading backrefs
On 4/8/15 3:22 AM, Sebastian Eckweiler wrote:
Hi there -
I'm having trouble working with backrefs of detached objects.
I'm basically working with a extended version of the code below:
|
classConfig(Base):
__tablename__ ='config'
ID =Column('ID',Integer,primary_key=True)
name =Column('name',String)
last_modified
=Column('last_modified',DateTime,default=now,onupdate=now)
params=relationship('ConfigParam',backref='config',lazy=False)
classConfigParam(Base):
__tablename__ ='config_params'
ID =Column('ID',Integer,primary_key=True)
ConfigID=Column('ConfigID',Integer,ForeignKey('config.ID'),nullable=False)
key =Column('key',String)
value =Column('value',Float)
|
Now when I load a Config instance I'd have assumed that
Config.params[0].config should be populated - since the eager query
contains all necessary information.
A load that can be resolved to using the session's identity map instead
of SELECT is still a load nonetheless. You would need a lazy setting on
the backref as well. Since these are many-to-ones and the lazyload
pulls from identity map, I suggest immediate.
Using these settings at the mapping level does mean however that if you
load a ConfigParam object by itself, it will, for a clean session,
immediately issue a second SELECT statement for its Config object.
Testing this with a sqlite engine using the following code:
|
s =Session()
c =Config(name='my_config')
c.params+=[ConfigParam(key='a',value=1),
ConfigParam(key='b',value=2)]
s.add(c)
s.commit()
s.close()
delc
# reload from new session:
logging.info('\n\n')
logging.info('Starting with new session:')
s =Session()
c =s.query(Config).filter(Config.name=='my_config').one()
s.close()
forp inc.params:
logging.info('Params:%s = %s'%(p.key,p.value))
forp inc.params:
logging.info('backref: config = %s'%p.config)
|
however produces (omitting the create_all) the following output:
INFO:sqlalchemy.engine.base.Engine:()
INFO:sqlalchemy.engine.base.Engine:COMMIT
INFO:sqlalchemy.engine.base.Engine:BEGIN (implicit)
INFO:sqlalchemy.engine.base.Engine:INSERT INTO config (name,
last_modified) VALUES (?, ?)
INFO:sqlalchemy.engine.base.Engine:('my_config', '2015-04-08
09:04:16.111000')
INFO:sqlalchemy.engine.base.Engine:INSERT INTO config_params
(ConfigID, key, value) VALUES (?, ?, ?)
INFO:sqlalchemy.engine.base.Engine:(1, 'a', 1.0)
INFO:sqlalchemy.engine.base.Engine:INSERT INTO config_params
(ConfigID, key, value) VALUES (?, ?, ?)
INFO:sqlalchemy.engine.base.Engine:(1, 'b', 2.0)
INFO:sqlalchemy.engine.base.Engine:COMMIT
INFO:root:
INFO:root:Starting with new session:
INFO:sqlalchemy.engine.base.Engine:BEGIN (implicit)
INFO:sqlalchemy.engine.base.Engine:SELECT config.ID AS config_ID,
config.name AS config_name, config.last_modified AS
config_last_modified, config_params_1.ID AS config_params_1_ID,
config_params_1.ConfigID AS config_params_1_ConfigID,
config_params_1.key AS config_params_1_key, config_params_1.value AS
config_params_1_value
FROM config LEFT OUTER JOIN config_params AS config_params_1 ON
config.ID = config_params_1.ConfigID
WHERE config.name = ?
INFO:sqlalchemy.engine.base.Engine:('my_config',)
INFO:sqlalchemy.engine.base.Engine:ROLLBACK
INFO:root:Params:a = 1.0
INFO:root:Params:b = 2.0
Traceback (most recent call last):
File D:/Assess/Kiln/assess/scratch/sqla_example.py, line 77, in
module
logging.info('backref: config = %s' % p.config)
File
D:\Anaconda\envs\assess\lib\site-packages\sqlalchemy\orm\attributes.py,
line 239, in __get__
return self.impl.get(instance_state(instance), dict_)
File
D:\Anaconda\envs\assess\lib\site-packages\sqlalchemy\orm\attributes.py,
line 591, in get
value = self.callable_(state, passive)
File
D:\Anaconda\envs\assess\lib\site-packages\sqlalchemy\orm\strategies.py,
line 507, in _load_for_state
(orm_util.state_str(state), self.key)
sqlalchemy.orm.exc.DetachedInstanceError: Parent instance ConfigParam
at 0x307d898 is not bound to a Session; lazy load operation of
attribute 'config' cannot proceed
I'm somewhat new to ORM's -
naively I had assumed the backref should/could be loaded at the same
time the parent is eagerly loaded, since all required information is
retrieved in the above query.
Is there anything I'm missing here?
ps: This is on sqlalchemy 0.9.8 - if that should matter.
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Re: [sqlalchemy] Specifying itersize when streaming_results=True for psycopg2 driver ?
On 4/8/15 6:43 AM, Dorian Hoxha wrote: I searched documentation, mailing list, issue-list, code (on github), google, and couldn't find for a way to set the iterszie, the number of rows to get on each batch when streaming results with psycogp2. we don't have public API for that attribute at the moment, so unless you want to work with the cursor directly as in http://docs.sqlalchemy.org/en/rel_0_9/core/connections.html#working-with-raw-dbapi-connections, this feature would be an execution_option supported and documented by the psycopg2 dialect. Feel free to open a feature request and/or work up a pull request. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] updating a unicode column
You are good!
The problem was the errant comma!
Thanks
On Wednesday, April 8, 2015 at 7:41:01 PM UTC-6, Michael Bayer wrote:
On 4/8/15 9:38 PM, arash afshar wrote:
I am calling commit, right after updated those two values.
Any suggestion on what else to check?
what is the exact column type given to this column, are there any
event.listen() things going on, and also what does a repr() of the object's
__dict__ look like?
in particular, Python has a really sneaky issue where if you happen to
have an errant comma:
x = foo,
you get:
(foo, )
On Wednesday, April 8, 2015 at 7:33:49 PM UTC-6, Michael Bayer wrote:
On 4/8/15 9:16 PM, arash afshar wrote:
When I try to update a row using ORM in the following way, it shows the
following error:
InterfaceError: (InterfaceError) Error binding parameter 0 - probably
unsupported type. u'UPDATE table_name SET unicode_col=?, int_col=? WHERE
table_name.id = ?' ((u'abcd',), 1, 2)
I suspect the problem is that the value corresponding to unicode_col is
(u'abcd',) as opposed to a simple u'abcd'.
that is the problem.
Here is how I update the database:
1) I first query it and obtain an object representing the row that I need
-- file_row
2) I perform some checks and change the values -- file_row.int_col = 1
followed by file_row.unicode_col = uabcd
3) I call commit on the session
looks fine, so, I'd imagine that somehow that unicode_col = u'abcd' is
not what it seems. Either that's not what's there or something is
interfering with it after the fact.
I am pretty sure the problem is not the original type of value of the
unicode_col since the following succeeds without error:
query(TableName).filter(TableName.id == file_row.id).update({'unicode_col':
uabcd, 'int_col': 1})
Any idea how to fix the error?
Thanks
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Re: [sqlalchemy] listening for events on 'mapper'
On 4/8/15 5:14 PM, Tim Tisdall wrote: I have some code I'm trying to figure out... Here it is: from sqlalchemy import event from colanderalchemy import setup_schema from sqlalchemy.orm import mapper event.listen(mapper, 'mapper_configured', setup_schema) It appears to call `setup_schema` on every ORM class that derives from the `declarative_base()`. All the documentation in SQLAlchemy shows event.listen being called on specific classes or mappers and I'm wondering if this usage is a documented feature. yes, mapper events can be passed the mapper function itself which is recognized as one way to assign an event to all mappers. I found a mention in the 0.7 docs, but no where else: http://docs.sqlalchemy.org/en/rel_0_7/orm/events.html#sqlalchemy.orm.events.MapperEvents that would qualify as documented :) The formatting is cleaner in http://docs.sqlalchemy.org/en/latest/orm/events.html#sqlalchemy.orm.events.MapperEvents. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com mailto:sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com mailto:sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
[sqlalchemy] updating a unicode column
When I try to update a row using ORM in the following way, it shows the
following error:
InterfaceError: (InterfaceError) Error binding parameter 0 - probably
unsupported type. u'UPDATE table_name SET unicode_col=?, int_col=?
WHERE table_name.id = ?' ((u'abcd',), 1, 2)
I suspect the problem is that the value corresponding to unicode_col is
(u'abcd',) as opposed to a simple u'abcd'.
Here is how I update the database:
1) I first query it and obtain an object representing the row that I need
-- file_row
2) I perform some checks and change the values -- file_row.int_col = 1
followed by file_row.unicode_col = uabcd
3) I call commit on the session
I am pretty sure the problem is not the original type of value of the
unicode_col since the following succeeds without error:
query(TableName).filter(TableName.id == file_row.id).update({'unicode_col':
uabcd, 'int_col': 1})
Any idea how to fix the error?
Thanks
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Re: [sqlalchemy] updating a unicode column
On 4/8/15 9:38 PM, arash afshar wrote:
I am calling commit, right after updated those two values.
Any suggestion on what else to check?
what is the exact column type given to this column, are there any
event.listen() things going on, and also what does a repr() of the
object's __dict__ look like?
in particular, Python has a really sneaky issue where if you happen to
have an errant comma:
x = foo,
you get:
(foo, )
On Wednesday, April 8, 2015 at 7:33:49 PM UTC-6, Michael Bayer wrote:
On 4/8/15 9:16 PM, arash afshar wrote:
When I try to update a row using ORM in the following way, it
shows the following error:
InterfaceError: (InterfaceError) Error binding parameter 0 -
probably unsupported type. u'UPDATE table_name SET unicode_col=?,
int_col=? WHERE table_name.id http://table_name.id = ?'
((u'abcd',), 1, 2)
I suspect the problem is that the value corresponding to
unicode_col is (u'abcd',) as opposed to a simple u'abcd'.
that is the problem.
Here is how I update the database:
1) I first query it and obtain an object representing the row
that I need -- file_row
2) I perform some checks and change the values --
file_row.int_col = 1followed by file_row.unicode_col = uabcd
3) I call commit on the session
looks fine, so, I'd imagine that somehow that unicode_col =
u'abcd' is not what it seems. Either that's not what's there or
something is interfering with it after the fact.
I am pretty sure the problem is not the original type of value of
the unicode_col since the following succeeds without error:
query(TableName).filter(TableName.id == file_row.id
http://file_row.id).update({'unicode_col': uabcd, 'int_col': 1})
Any idea how to fix the error?
Thanks
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Re: [sqlalchemy] listening for events on 'mapper'
Sorry, I just saw the the Mapper class itself and the mapper() function indicate listening for all mappers. on the latest docs. Thanks. On Wed, Apr 8, 2015 at 5:27 PM, Mike Bayer mike...@zzzcomputing.com wrote: On 4/8/15 5:14 PM, Tim Tisdall wrote: I have some code I'm trying to figure out... Here it is: from sqlalchemy import event from colanderalchemy import setup_schema from sqlalchemy.orm import mapper event.listen(mapper, 'mapper_configured', setup_schema) It appears to call `setup_schema` on every ORM class that derives from the `declarative_base()`. All the documentation in SQLAlchemy shows event.listen being called on specific classes or mappers and I'm wondering if this usage is a documented feature. yes, mapper events can be passed the mapper function itself which is recognized as one way to assign an event to all mappers. I found a mention in the 0.7 docs, but no where else: http://docs.sqlalchemy.org/en/rel_0_7/orm/events.html#sqlalchemy.orm.events.MapperEvents that would qualify as documented :) The formatting is cleaner in http://docs.sqlalchemy.org/en/latest/orm/events.html#sqlalchemy.orm.events.MapperEvents. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to a topic in the Google Groups sqlalchemy group. To unsubscribe from this topic, visit https://groups.google.com/d/topic/sqlalchemy/bmWUxihSDqY/unsubscribe. To unsubscribe from this group and all its topics, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] updating a unicode column
On 4/8/15 9:16 PM, arash afshar wrote:
When I try to update a row using ORM in the following way, it shows
the following error:
InterfaceError: (InterfaceError) Error binding parameter 0 - probably
unsupported type. u'UPDATE table_name SET unicode_col=?, int_col=?
WHERE table_name.id = ?' ((u'abcd',), 1, 2)
I suspect the problem is that the value corresponding to unicode_col
is (u'abcd',) as opposed to a simple u'abcd'.
that is the problem.
Here is how I update the database:
1) I first query it and obtain an object representing the row that I
need -- file_row
2) I perform some checks and change the values -- file_row.int_col =
1followed by file_row.unicode_col = uabcd
3) I call commit on the session
looks fine, so, I'd imagine that somehow that unicode_col = u'abcd' is
not what it seems. Either that's not what's there or something is
interfering with it after the fact.
I am pretty sure the problem is not the original type of value of the
unicode_col since the following succeeds without error:
query(TableName).filter(TableName.id ==
file_row.id).update({'unicode_col': uabcd, 'int_col': 1})
Any idea how to fix the error?
Thanks
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Re: [sqlalchemy] updating a unicode column
I am calling commit, right after updated those two values.
Any suggestion on what else to check?
On Wednesday, April 8, 2015 at 7:33:49 PM UTC-6, Michael Bayer wrote:
On 4/8/15 9:16 PM, arash afshar wrote:
When I try to update a row using ORM in the following way, it shows the
following error:
InterfaceError: (InterfaceError) Error binding parameter 0 - probably
unsupported type. u'UPDATE table_name SET unicode_col=?, int_col=? WHERE
table_name.id = ?' ((u'abcd',), 1, 2)
I suspect the problem is that the value corresponding to unicode_col is
(u'abcd',) as opposed to a simple u'abcd'.
that is the problem.
Here is how I update the database:
1) I first query it and obtain an object representing the row that I need
-- file_row
2) I perform some checks and change the values -- file_row.int_col = 1
followed by file_row.unicode_col = uabcd
3) I call commit on the session
looks fine, so, I'd imagine that somehow that unicode_col = u'abcd' is not
what it seems. Either that's not what's there or something is interfering
with it after the fact.
I am pretty sure the problem is not the original type of value of the
unicode_col since the following succeeds without error:
query(TableName).filter(TableName.id == file_row.id).update({'unicode_col':
uabcd, 'int_col': 1})
Any idea how to fix the error?
Thanks
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[sqlalchemy] listening for events on 'mapper'
I have some code I'm trying to figure out... Here it is: from sqlalchemy import event from colanderalchemy import setup_schema from sqlalchemy.orm import mapper event.listen(mapper, 'mapper_configured', setup_schema) It appears to call `setup_schema` on every ORM class that derives from the `declarative_base()`. All the documentation in SQLAlchemy shows event.listen being called on specific classes or mappers and I'm wondering if this usage is a documented feature. I found a mention in the 0.7 docs, but no where else: http://docs.sqlalchemy.org/en/rel_0_7/orm/events.html#sqlalchemy.orm.events.MapperEvents -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
