Re: [sqlalchemy] Re: Register function example (perhaps) to remove tab, newline or carriage return from column.

[Jonathan Vanasco]

On Wednesday, February 14, 2018 at 6:49:47 AM UTC-5, Simon King wrote:
 

> For what it's worth, I would do it something like this:  
>

that's elegant. I'd rather do that now too. 

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
Example.  See  http://stackoverflow.com/help/mcve for a full description.
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Re: [sqlalchemy] How right use session/scoped_session in web app?

[Simon King]

I think there are a couple of problems with this.

1. You are calling scoped_session and sessionmaker every time the
decorated function is called, which is unnecessary. sessionmaker
returns a factory function for creating sessions, so you typically
only have one sessionmaker() call in your application. You could
either make it a module-global, or do it during application
configuration.

2. You are never calling session.close(). This means that the
transaction started by a web request will stay open after the request
ends. Since you are using scoped_session as well, the session is
maintained as a thread-local object, so when the thread handles
another web request, it will use the same session and the same
transaction. Your long-running transactions are probably the reason
why you are getting blocked requests.

You might like to read
http://docs.sqlalchemy.org/en/latest/orm/session_basics.html#session-frequently-asked-questions.

I was going to say that you need to add a "finally" section to your
session_decorator that calls session.close(), but if you ever have one
decorated function calling another decorated function, they are going
to interfere with each other. If you are *absolutely certain* that
will never happen, adding the "finally" section will probably improve
things, but I would recommend that you try to structure your app a
little differently, so that the session creation and teardown happen
at the beginning and end of the web request.

Hope that helps,

Simon


On Wed, Feb 14, 2018 at 2:14 PM,   wrote:
> Decorator like this
>
> engine = create_engine(
>
> 'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}={TIMEOUT}'.format(**DATABASE),
> isolation_level='READ COMMITTED'
> )
>
>
> def decorator_with_args(decorator_to_enhance):
> """
> https://habrahabr.ru/post/141501/
> """
> def decorator_maker(*args, **kwargs):
> def decorator_wrapper(func):
> return decorator_to_enhance(func, *args, **kwargs)
> return decorator_wrapper
> return decorator_maker
>
>
> def scope_func():
> return scoped_session(sessionmaker(bind=engine, autocommit=True))()
>
>
> @decorator_with_args
> def session_decorator(func, default=None, **kwargs):
> def wrapper(*a, **kw):
> session = scope_func()
> if 'session' not in kw:
> kw['session'] = session
> try:
> return func(*a, **kw)
> except Exception as e:
> session.rollback()
>
> print('#FUNCTION NAME: {}'.format(func.__name__))
>
> print(e)
> logging.error(e)
> return default
> return wrapper
>
>
>
>
> среда, 14 февраля 2018 г., 17:06:54 UTC+3 пользователь Simon King написал:
>>
>> The pattern you should be aiming for is one in which a fresh
>> transaction is started for every web request that touches the
>> database, and that the transaction is closed at the end of the
>> request. How are you ensuring that at the moment?
>>
>> Simon
>>
>> On Wed, Feb 14, 2018 at 12:51 PM,   wrote:
>> > If I run tests where all functions run one-by-one - all tests passed.
>> > But when i run web app and functions can call almost in parallel then i
>> > have
>> > a problem, then there are problems - transactions can block each other.
>> > I tried to set the isolation level of SNAPSHOT and READ COMMITTED, but
>> > it
>> > did not help.
>> >
>> > среда, 14 февраля 2018 г., 14:58:37 UTC+3 пользователь
>> > eugene...@gmail.com
>> > написал:
>> >>
>> >> Hello, Mike!
>> >> In my web app i have many selects like
>> >> session.execute(select([table1]).where(condition))
>> >> and not so much updates, inserts and deletes like
>> >> session.execute(update(table1).where(condition).values(**values))
>> >> session.execute(insert(table1).values(**values))
>> >> session.execute(delete(table1).where(condition))
>> >>
>> >> What better way to create session for web application?
>> >> Without additional components like flask-sqlalchemy.
>> >>
>> >> суббота, 27 января 2018 г., 20:23:05 UTC+3 пользователь Mike Bayer
>> >> написал:
>> >>>
>> >>> On Sat, Jan 27, 2018 at 5:49 AM, Евгений Рымарев
>> >>>  wrote:
>> >>> > I receive this error:
>> >>> > This result object does not return rows. It has been closed
>> >>> > automatically.
>> >>>
>> >>> there's a lot of weird situations which can cause that error, usually
>> >>> when using a connection that has had some failure condition occur upon
>> >>> it which renders the connection unusable until either a transaction is
>> >>> rolled back or sometimes the connection needs to be discarded.  We
>> >>> can't diagnose it without a full example that reproduces it as well as
>> >>> the complete stack trace.
>> >>>
>> >>>
>> >>> >
>> >>> >
>> >>> >
>> >>> > суббота, 27 января 2018 г., 1:09:53 UTC+3 пользователь Mike Bayer
>> >>> > написал:
>> >>> >>
>> >>> >> On Fri, Jan 26, 2018 at 4:21 PM, Евгений Рымарев

Re: [sqlalchemy] How right use session/scoped_session in web app?

[eugene . deneb]

Decorator like this

engine = create_engine(

'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}={TIMEOUT}'.format(**DATABASE),
isolation_level='READ COMMITTED'
)


def decorator_with_args(decorator_to_enhance):
"""
https://habrahabr.ru/post/141501/
"""
def decorator_maker(*args, **kwargs):
def decorator_wrapper(func):
return decorator_to_enhance(func, *args, **kwargs)
return decorator_wrapper
return decorator_maker


def scope_func():
return scoped_session(sessionmaker(bind=engine, autocommit=True))()


@decorator_with_args
def session_decorator(func, default=None, **kwargs):
def wrapper(*a, **kw):
session = scope_func()
if 'session' not in kw:
kw['session'] = session
try:
return func(*a, **kw)
except Exception as e:
session.rollback()

print('#FUNCTION NAME: {}'.format(func.__name__))

   print(e)
logging.error(e)
return default
return wrapper




среда, 14 февраля 2018 г., 17:06:54 UTC+3 пользователь Simon King написал:
>
> The pattern you should be aiming for is one in which a fresh 
> transaction is started for every web request that touches the 
> database, and that the transaction is closed at the end of the 
> request. How are you ensuring that at the moment? 
>
> Simon 
>
> On Wed, Feb 14, 2018 at 12:51 PM,   
> wrote: 
> > If I run tests where all functions run one-by-one - all tests passed. 
> > But when i run web app and functions can call almost in parallel then i 
> have 
> > a problem, then there are problems - transactions can block each other. 
> > I tried to set the isolation level of SNAPSHOT and READ COMMITTED, but 
> it 
> > did not help. 
> > 
> > среда, 14 февраля 2018 г., 14:58:37 UTC+3 пользователь 
> eugene...@gmail.com 
> > написал: 
> >> 
> >> Hello, Mike! 
> >> In my web app i have many selects like 
> >> session.execute(select([table1]).where(condition)) 
> >> and not so much updates, inserts and deletes like 
> >> session.execute(update(table1).where(condition).values(**values)) 
> >> session.execute(insert(table1).values(**values)) 
> >> session.execute(delete(table1).where(condition)) 
> >> 
> >> What better way to create session for web application? 
> >> Without additional components like flask-sqlalchemy. 
> >> 
> >> суббота, 27 января 2018 г., 20:23:05 UTC+3 пользователь Mike Bayer 
> >> написал: 
> >>> 
> >>> On Sat, Jan 27, 2018 at 5:49 AM, Евгений Рымарев 
> >>>  wrote: 
> >>> > I receive this error: 
> >>> > This result object does not return rows. It has been closed 
> >>> > automatically. 
> >>> 
> >>> there's a lot of weird situations which can cause that error, usually 
> >>> when using a connection that has had some failure condition occur upon 
> >>> it which renders the connection unusable until either a transaction is 
> >>> rolled back or sometimes the connection needs to be discarded.  We 
> >>> can't diagnose it without a full example that reproduces it as well as 
> >>> the complete stack trace. 
> >>> 
> >>> 
> >>> > 
> >>> > 
> >>> > 
> >>> > суббота, 27 января 2018 г., 1:09:53 UTC+3 пользователь Mike Bayer 
> >>> > написал: 
> >>> >> 
> >>> >> On Fri, Jan 26, 2018 at 4:21 PM, Евгений Рымарев 
> >>> >>  wrote: 
> >>> >> > Hello, everyone! 
> >>> >> > Engine: 
> >>> >> > engine = create_engine( 
> >>> >> > 
> >>> >> > 
> >>> >> > 
> >>> >> > 
> 'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}'.format(**DATABASE),
>  
>
> >>> >> > isolation_level='READ COMMITTED' 
> >>> >> > ) 
> >>> >> > 
> >>> >> > 
> >>> >> > My first decorator for session: 
> >>> >> > @decorator_with_args 
> >>> >> > def session_decorator(func, default=None): 
> >>> >> >def wrapper(*a, **kw): 
> >>> >> >s = Session(engine) 
> >>> >> >kw['session'] = s 
> >>> >> >try: 
> >>> >> >return func(*a, **kw) 
> >>> >> >except Exception as e: 
> >>> >> >func(*a, **kw) 
> >>> >> >s.rollback() 
> >>> >> >s.close() 
> >>> >> >logging.error(e) 
> >>> >> >return default 
> >>> >> >finally: 
> >>> >> >s.commit() 
> >>> >> >s.close() 
> >>> >> >return wrapper 
> >>> >> > 
> >>> >> > My second decorator for session: 
> >>> >> > session = scoped_session(sessionmaker(bind=engine)) 
> >>> >> > 
> >>> >> > 
> >>> >> > @decorator_with_args 
> >>> >> > def session_decorator(func, default=None): 
> >>> >> >def wrapper(*a, **kw): 
> >>> >> >kw['session'] = session 
> >>> >> >try: 
> >>> >> >return func(*a, **kw) 
> >>> >> >except Exception as e: 
> >>> >> >session.remove() 
> >>> >> >logging.error(e) 
> >>> >> >return default 
> >>> >> >finally: 
> >>> >> >session.remove() 
> 

Re: [sqlalchemy] How right use session/scoped_session in web app?

[Simon King]

The pattern you should be aiming for is one in which a fresh
transaction is started for every web request that touches the
database, and that the transaction is closed at the end of the
request. How are you ensuring that at the moment?

Simon

On Wed, Feb 14, 2018 at 12:51 PM,   wrote:
> If I run tests where all functions run one-by-one - all tests passed.
> But when i run web app and functions can call almost in parallel then i have
> a problem, then there are problems - transactions can block each other.
> I tried to set the isolation level of SNAPSHOT and READ COMMITTED, but it
> did not help.
>
> среда, 14 февраля 2018 г., 14:58:37 UTC+3 пользователь eugene...@gmail.com
> написал:
>>
>> Hello, Mike!
>> In my web app i have many selects like
>> session.execute(select([table1]).where(condition))
>> and not so much updates, inserts and deletes like
>> session.execute(update(table1).where(condition).values(**values))
>> session.execute(insert(table1).values(**values))
>> session.execute(delete(table1).where(condition))
>>
>> What better way to create session for web application?
>> Without additional components like flask-sqlalchemy.
>>
>> суббота, 27 января 2018 г., 20:23:05 UTC+3 пользователь Mike Bayer
>> написал:
>>>
>>> On Sat, Jan 27, 2018 at 5:49 AM, Евгений Рымарев
>>>  wrote:
>>> > I receive this error:
>>> > This result object does not return rows. It has been closed
>>> > automatically.
>>>
>>> there's a lot of weird situations which can cause that error, usually
>>> when using a connection that has had some failure condition occur upon
>>> it which renders the connection unusable until either a transaction is
>>> rolled back or sometimes the connection needs to be discarded.  We
>>> can't diagnose it without a full example that reproduces it as well as
>>> the complete stack trace.
>>>
>>>
>>> >
>>> >
>>> >
>>> > суббота, 27 января 2018 г., 1:09:53 UTC+3 пользователь Mike Bayer
>>> > написал:
>>> >>
>>> >> On Fri, Jan 26, 2018 at 4:21 PM, Евгений Рымарев
>>> >>  wrote:
>>> >> > Hello, everyone!
>>> >> > Engine:
>>> >> > engine = create_engine(
>>> >> >
>>> >> >
>>> >> >
>>> >> > 'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}'.format(**DATABASE),
>>> >> > isolation_level='READ COMMITTED'
>>> >> > )
>>> >> >
>>> >> >
>>> >> > My first decorator for session:
>>> >> > @decorator_with_args
>>> >> > def session_decorator(func, default=None):
>>> >> >def wrapper(*a, **kw):
>>> >> >s = Session(engine)
>>> >> >kw['session'] = s
>>> >> >try:
>>> >> >return func(*a, **kw)
>>> >> >except Exception as e:
>>> >> >func(*a, **kw)
>>> >> >s.rollback()
>>> >> >s.close()
>>> >> >logging.error(e)
>>> >> >return default
>>> >> >finally:
>>> >> >s.commit()
>>> >> >s.close()
>>> >> >return wrapper
>>> >> >
>>> >> > My second decorator for session:
>>> >> > session = scoped_session(sessionmaker(bind=engine))
>>> >> >
>>> >> >
>>> >> > @decorator_with_args
>>> >> > def session_decorator(func, default=None):
>>> >> >def wrapper(*a, **kw):
>>> >> >kw['session'] = session
>>> >> >try:
>>> >> >return func(*a, **kw)
>>> >> >except Exception as e:
>>> >> >session.remove()
>>> >> >logging.error(e)
>>> >> >return default
>>> >> >finally:
>>> >> >session.remove()
>>> >> >return wrapper
>>> >> >
>>> >> > In both attempts, I came to the conclusion that sessions can block
>>> >> > other
>>> >> > sessions.
>>> >> > How correctly to create a session once, so that it can be used
>>> >> > throughout
>>> >> > the web application and no locks were created?
>>> >>
>>> >> The Session doesn't create locks, transactions and your database does.
>>> >>
>>> >> What is the nature of these "blocks", are they deadlocks between
>>> >> tables or rows?  What operations are prevented from proceeding?  Are
>>> >> the locks timing out?   SQL Server has graphical consoles that can
>>> >> show you this.
>>> >>
>>> >> What version of SQL Server is this?   Do you have
>>> >> ALLOW_SNAPSHOT_ISOLATION and READ_COMMITTED_SNAPSHOT turned on?
>>> >>
>>> >>
>>> >> >
>>> >> > --
>>> >> > SQLAlchemy -
>>> >> > The Python SQL Toolkit and Object Relational Mapper
>>> >> >
>>> >> > http://www.sqlalchemy.org/
>>> >> >
>>> >> > To post example code, please provide an MCVE: Minimal, Complete, and
>>> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a
>>> >> > full
>>> >> > description.
>>> >> > ---
>>> >> > 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.
>>> >> > To post to this group, send email to 

Re: [sqlalchemy] How right use session/scoped_session in web app?

[eugene . deneb]

If I run tests where all functions run one-by-one - all tests passed.
But when i run web app and functions can call almost in parallel then i 
have a problem, then there are problems - transactions can block each other.
I tried to set the isolation level of SNAPSHOT and READ COMMITTED, but it 
did not help.

среда, 14 февраля 2018 г., 14:58:37 UTC+3 пользователь eugene...@gmail.com 
написал:
>
> Hello, Mike!
> In my web app i have many selects like
> session.execute(select([table1]).where(condition))
> and not so much updates, inserts and deletes like
> session.execute(update(table1).where(condition).values(**values))
> session.execute(insert(table1).values(**values))
> session.execute(delete(table1).where(condition))
>
> What better way to create session for web application?
> Without additional components like flask-sqlalchemy.
>
> суббота, 27 января 2018 г., 20:23:05 UTC+3 пользователь Mike Bayer написал:
>>
>> On Sat, Jan 27, 2018 at 5:49 AM, Евгений Рымарев 
>>  wrote: 
>> > I receive this error: 
>> > This result object does not return rows. It has been closed 
>> automatically. 
>>
>> there's a lot of weird situations which can cause that error, usually 
>> when using a connection that has had some failure condition occur upon 
>> it which renders the connection unusable until either a transaction is 
>> rolled back or sometimes the connection needs to be discarded.  We 
>> can't diagnose it without a full example that reproduces it as well as 
>> the complete stack trace. 
>>
>>
>> > 
>> > 
>> > 
>> > суббота, 27 января 2018 г., 1:09:53 UTC+3 пользователь Mike Bayer 
>> написал: 
>> >> 
>> >> On Fri, Jan 26, 2018 at 4:21 PM, Евгений Рымарев 
>> >>  wrote: 
>> >> > Hello, everyone! 
>> >> > Engine: 
>> >> > engine = create_engine( 
>> >> > 
>> >> > 
>> >> > 
>> 'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}'.format(**DATABASE),
>>  
>>
>> >> > isolation_level='READ COMMITTED' 
>> >> > ) 
>> >> > 
>> >> > 
>> >> > My first decorator for session: 
>> >> > @decorator_with_args 
>> >> > def session_decorator(func, default=None): 
>> >> >def wrapper(*a, **kw): 
>> >> >s = Session(engine) 
>> >> >kw['session'] = s 
>> >> >try: 
>> >> >return func(*a, **kw) 
>> >> >except Exception as e: 
>> >> >func(*a, **kw) 
>> >> >s.rollback() 
>> >> >s.close() 
>> >> >logging.error(e) 
>> >> >return default 
>> >> >finally: 
>> >> >s.commit() 
>> >> >s.close() 
>> >> >return wrapper 
>> >> > 
>> >> > My second decorator for session: 
>> >> > session = scoped_session(sessionmaker(bind=engine)) 
>> >> > 
>> >> > 
>> >> > @decorator_with_args 
>> >> > def session_decorator(func, default=None): 
>> >> >def wrapper(*a, **kw): 
>> >> >kw['session'] = session 
>> >> >try: 
>> >> >return func(*a, **kw) 
>> >> >except Exception as e: 
>> >> >session.remove() 
>> >> >logging.error(e) 
>> >> >return default 
>> >> >finally: 
>> >> >session.remove() 
>> >> >return wrapper 
>> >> > 
>> >> > In both attempts, I came to the conclusion that sessions can block 
>> other 
>> >> > sessions. 
>> >> > How correctly to create a session once, so that it can be used 
>> >> > throughout 
>> >> > the web application and no locks were created? 
>> >> 
>> >> The Session doesn't create locks, transactions and your database does. 
>> >> 
>> >> What is the nature of these "blocks", are they deadlocks between 
>> >> tables or rows?  What operations are prevented from proceeding?  Are 
>> >> the locks timing out?   SQL Server has graphical consoles that can 
>> >> show you this. 
>> >> 
>> >> What version of SQL Server is this?   Do you have 
>> >> ALLOW_SNAPSHOT_ISOLATION and READ_COMMITTED_SNAPSHOT turned on? 
>> >> 
>> >> 
>> >> > 
>> >> > -- 
>> >> > SQLAlchemy - 
>> >> > The Python SQL Toolkit and Object Relational Mapper 
>> >> > 
>> >> > http://www.sqlalchemy.org/ 
>> >> > 
>> >> > To post example code, please provide an MCVE: Minimal, Complete, and 
>> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a 
>> full 
>> >> > description. 
>> >> > --- 
>> >> > 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. 
>> >> > To post to this group, send email to sqlal...@googlegroups.com. 
>> >> > Visit this group at https://groups.google.com/group/sqlalchemy. 
>> >> > For more options, visit https://groups.google.com/d/optout. 
>> > 
>> > -- 
>> > SQLAlchemy - 
>> > The Python SQL Toolkit and Object Relational Mapper 
>> > 
>> > http://www.sqlalchemy.org/ 
>> > 
>> > To post example code, please provide an MCVE: 

Re: [sqlalchemy] running py.test

[Simon King]

The error is coming from here:

https://github.com/zzzeek/sqlalchemy/blob/master/lib/sqlalchemy/testing/mock.py

So I guess you could start by adding some print statements in that
file to see where the exception is being raised. Perhaps you have a
different "mock.py" somewhere on the PYTHONPATH that is being imported
instead of the real library?

Simon


On Tue, Feb 13, 2018 at 3:58 PM, su-sa  wrote:
> Hi Simon,
>
> I installed both pytest and mock using pip install py.test mock in the
> virtualenv. I am using anaconda python. Both the libraries are surely
> installed.
>
>
> On Friday, 9 February 2018 12:36:26 UTC+1, Simon King wrote:
>>
>> On Wed, Feb 7, 2018 at 2:23 PM, su-sa  wrote:
>> > Hallo everyone,
>> >
>> > I am trying to run all the pytest of sqlalchemy. But I always get the
>> > error
>> > - SQLAlchemy requires Mock as of version 0.8.2. I already have the mock
>> > library installed. Could somebody please help me to solve the problem.
>> >
>>
>> How have you installed these libraries? Are you using virtualenv? If
>> so, are pytest and mock both installed in the virtualenv?
>>
>> Simon
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> 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 https://groups.google.com/group/sqlalchemy.
> For more options, visit https://groups.google.com/d/optout.

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
Example.  See  http://stackoverflow.com/help/mcve for a full description.
--- 
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 https://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.

Re: [sqlalchemy] How right use session/scoped_session in web app?

[eugene . deneb]

Hello, Mike!
In my web app i have many selects like
session.execute(select([table1]).where(condition))
and not so much updates, inserts and deletes like
session.execute(update(table1).where(condition).values(**values))
session.execute(insert(table1).values(**values))
session.execute(delete(table1).where(condition))

What better way to create session for web application?
Without additional components like flask-sqlalchemy.

суббота, 27 января 2018 г., 20:23:05 UTC+3 пользователь Mike Bayer написал:
>
> On Sat, Jan 27, 2018 at 5:49 AM, Евгений Рымарев 
>  wrote: 
> > I receive this error: 
> > This result object does not return rows. It has been closed 
> automatically. 
>
> there's a lot of weird situations which can cause that error, usually 
> when using a connection that has had some failure condition occur upon 
> it which renders the connection unusable until either a transaction is 
> rolled back or sometimes the connection needs to be discarded.  We 
> can't diagnose it without a full example that reproduces it as well as 
> the complete stack trace. 
>
>
> > 
> > 
> > 
> > суббота, 27 января 2018 г., 1:09:53 UTC+3 пользователь Mike Bayer 
> написал: 
> >> 
> >> On Fri, Jan 26, 2018 at 4:21 PM, Евгений Рымарев 
> >>  wrote: 
> >> > Hello, everyone! 
> >> > Engine: 
> >> > engine = create_engine( 
> >> > 
> >> > 
> >> > 
> 'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}'.format(**DATABASE),
>  
>
> >> > isolation_level='READ COMMITTED' 
> >> > ) 
> >> > 
> >> > 
> >> > My first decorator for session: 
> >> > @decorator_with_args 
> >> > def session_decorator(func, default=None): 
> >> >def wrapper(*a, **kw): 
> >> >s = Session(engine) 
> >> >kw['session'] = s 
> >> >try: 
> >> >return func(*a, **kw) 
> >> >except Exception as e: 
> >> >func(*a, **kw) 
> >> >s.rollback() 
> >> >s.close() 
> >> >logging.error(e) 
> >> >return default 
> >> >finally: 
> >> >s.commit() 
> >> >s.close() 
> >> >return wrapper 
> >> > 
> >> > My second decorator for session: 
> >> > session = scoped_session(sessionmaker(bind=engine)) 
> >> > 
> >> > 
> >> > @decorator_with_args 
> >> > def session_decorator(func, default=None): 
> >> >def wrapper(*a, **kw): 
> >> >kw['session'] = session 
> >> >try: 
> >> >return func(*a, **kw) 
> >> >except Exception as e: 
> >> >session.remove() 
> >> >logging.error(e) 
> >> >return default 
> >> >finally: 
> >> >session.remove() 
> >> >return wrapper 
> >> > 
> >> > In both attempts, I came to the conclusion that sessions can block 
> other 
> >> > sessions. 
> >> > How correctly to create a session once, so that it can be used 
> >> > throughout 
> >> > the web application and no locks were created? 
> >> 
> >> The Session doesn't create locks, transactions and your database does. 
> >> 
> >> What is the nature of these "blocks", are they deadlocks between 
> >> tables or rows?  What operations are prevented from proceeding?  Are 
> >> the locks timing out?   SQL Server has graphical consoles that can 
> >> show you this. 
> >> 
> >> What version of SQL Server is this?   Do you have 
> >> ALLOW_SNAPSHOT_ISOLATION and READ_COMMITTED_SNAPSHOT turned on? 
> >> 
> >> 
> >> > 
> >> > -- 
> >> > SQLAlchemy - 
> >> > The Python SQL Toolkit and Object Relational Mapper 
> >> > 
> >> > http://www.sqlalchemy.org/ 
> >> > 
> >> > To post example code, please provide an MCVE: Minimal, Complete, and 
> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a 
> full 
> >> > description. 
> >> > --- 
> >> > 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. 
> >> > To post to this group, send email to sqlal...@googlegroups.com. 
> >> > Visit this group at https://groups.google.com/group/sqlalchemy. 
> >> > For more options, visit https://groups.google.com/d/optout. 
> > 
> > -- 
> > SQLAlchemy - 
> > The Python SQL Toolkit and Object Relational Mapper 
> > 
> > http://www.sqlalchemy.org/ 
> > 
> > To post example code, please provide an MCVE: Minimal, Complete, and 
> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
> > description. 
> > --- 
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> > For more options, visit 

Re: [sqlalchemy] Re: Register function example (perhaps) to remove tab, newline or carriage return from column.

[Simon King]

On Fri, Feb 9, 2018 at 7:38 PM, Jeremy Flowers
 wrote:
> And I do want to use this functionality repeatedly on many columns, hence
> the idea of registering a function.
>

For what it's worth, I would do it something like this:

def removechars(col, chars):
for c in chars:
col = sa.func.REPLACE(col, c, '')
return col

def removewhitespace(col):
return removechars(col, '\t\r\n')

print removewhitespace(Jobdtl.jobdtl_cmd)

Hope that helps,

Simon

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
Example.  See  http://stackoverflow.com/help/mcve for a full description.
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