Re: [pylons-discuss] pyramid_tm - is there an acceptable way to unjoin the transaction and use explicit commits?

[Michael Merickel]

It’s not recommended. But it’s there for you to use if you want. When you
do a commit you’re crossing transaction boundaries to continue the request
and all of the checks you did early on are not guaranteed any longer to be
valid.

Using a separate connection is the best and most generally sound way to go
for recording data not specific to the resource-level goals of processing
the request.

On Sun, Feb 9, 2020 at 12:37 Mike Orr  wrote:

> I sometimes use explicit commits to log usage stats, which I want to
> succeed even if the request later aborts. I use a separate database
> connection not attached to the transaction. I tried to use pyramid_tm
> commit multiple times but it seemed it could only be used once. So
> you're supposed to use transaction.commint/abort followed immediately
> by transaction.begin? That wasn't clear in the docs.
>
> I've also used a custom transaction adapter to get a Redis session
> attached to the transaction. Since Redis is non-transactinal, t saves
> its pending work in the object, and on commit it writes it to the
> database.
>
> On Fri, Feb 7, 2020 at 9:04 AM Michael Merickel 
> wrote:
> >
> > pyramid_tm does have a configurable activate_hook that you can use to
> turn off the TM for certain endpoints. You would need to coordinate that
> with something else that managed the transaction. If I were doing it myself
> I'd probably configure my activate hook to return true/false based on an
> custom attribute on the request like `request.activate_tm`. I'd then set
> this to False in a tween mounted over pyramid_tm. The reason I'd do it this
> way is because if you're turning off pyramid_tm then you probably still
> need to do something to manage the connection - and a tween would be a good
> spot to do this.
> >
> > That being said, I'd ask why you would want to turn it off instead of
> just committing multiple times? You just need to use `request.tm.commit()`,
> `request.tm.abort()` and `request.tm.begin()` instead of
> `request.dbsession.commit()`. Make sure to always call begin after
> commit/abort and things should work fine - whether it's a good idea or not
> in general (see Mikko's comments) is a separate question.
> >
> > - Michael
> >
> > On Thu, Feb 6, 2020 at 7:03 PM Jonathan Vanasco 
> wrote:
> >>
> >> one of my apps uses pyramid_tm, but has reached a point where one
> (possibly two) views (out of dozens) need to make explicit commits with the
> SqlAlchemy session.
> >>
> >> does anyone know if it's currently possible to handle this?  i have a
> few apps that only integrate pyramid_tm on a small subset of views, but i
> haven't tried to bypass it on a single view in many years.  I'm trying to
> avoid a secondary database connection, because this app can support a
> sqlite database and I've had problems with too many connections and sqlite
> in the past.
> >>
> >> --
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> .
> >
> >
> >
> > --
> >
> > Michael
> >
> > --
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>
>
>
> --
> Mike Orr 
>
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>
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Michael

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Re: [pylons-discuss] pyramid_tm - is there an acceptable way to unjoin the transaction and use explicit commits?

[Mike Orr]

I sometimes use explicit commits to log usage stats, which I want to
succeed even if the request later aborts. I use a separate database
connection not attached to the transaction. I tried to use pyramid_tm
commit multiple times but it seemed it could only be used once. So
you're supposed to use transaction.commint/abort followed immediately
by transaction.begin? That wasn't clear in the docs.

I've also used a custom transaction adapter to get a Redis session
attached to the transaction. Since Redis is non-transactinal, t saves
its pending work in the object, and on commit it writes it to the
database.

On Fri, Feb 7, 2020 at 9:04 AM Michael Merickel  wrote:
>
> pyramid_tm does have a configurable activate_hook that you can use to turn 
> off the TM for certain endpoints. You would need to coordinate that with 
> something else that managed the transaction. If I were doing it myself I'd 
> probably configure my activate hook to return true/false based on an custom 
> attribute on the request like `request.activate_tm`. I'd then set this to 
> False in a tween mounted over pyramid_tm. The reason I'd do it this way is 
> because if you're turning off pyramid_tm then you probably still need to do 
> something to manage the connection - and a tween would be a good spot to do 
> this.
>
> That being said, I'd ask why you would want to turn it off instead of just 
> committing multiple times? You just need to use `request.tm.commit()`, 
> `request.tm.abort()` and `request.tm.begin()` instead of 
> `request.dbsession.commit()`. Make sure to always call begin after 
> commit/abort and things should work fine - whether it's a good idea or not in 
> general (see Mikko's comments) is a separate question.
>
> - Michael
>
> On Thu, Feb 6, 2020 at 7:03 PM Jonathan Vanasco  wrote:
>>
>> one of my apps uses pyramid_tm, but has reached a point where one (possibly 
>> two) views (out of dozens) need to make explicit commits with the SqlAlchemy 
>> session.
>>
>> does anyone know if it's currently possible to handle this?  i have a few 
>> apps that only integrate pyramid_tm on a small subset of views, but i 
>> haven't tried to bypass it on a single view in many years.  I'm trying to 
>> avoid a secondary database connection, because this app can support a sqlite 
>> database and I've had problems with too many connections and sqlite in the 
>> past.
>>
>> --
>> You received this message because you are subscribed to the Google Groups 
>> "pylons-discuss" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to pylons-discuss+unsubscr...@googlegroups.com.
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/pylons-discuss/c3d3f561-8bcc-4c20-b1e8-f2aa147483f0%40googlegroups.com.
>
>
>
> --
>
> Michael
>
> --
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-- 
Mike Orr 

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Re: [pylons-discuss] pyramid_tm - is there an acceptable way to unjoin the transaction and use explicit commits?

[Michael Merickel]

pyramid_tm does have a configurable activate_hook that you can use to turn
off the TM for certain endpoints. You would need to coordinate that with
something else that managed the transaction. If I were doing it myself I'd
probably configure my activate hook to return true/false based on an custom
attribute on the request like `request.activate_tm`. I'd then set this to
False in a tween mounted over pyramid_tm. The reason I'd do it this way is
because if you're turning off pyramid_tm then you probably still need to do
something to manage the connection - and a tween would be a good spot to do
this.

That being said, I'd ask why you would want to turn it off instead of just
committing multiple times? You just need to use `request.tm.commit()`,
`request.tm.abort()` and `request.tm.begin()` instead of
`request.dbsession.commit()`. Make sure to always call begin after
commit/abort and things should work fine - whether it's a good idea or not
in general (see Mikko's comments) is a separate question.

- Michael

On Thu, Feb 6, 2020 at 7:03 PM Jonathan Vanasco 
wrote:

> one of my apps uses pyramid_tm, but has reached a point where one
> (possibly two) views (out of dozens) need to make explicit commits with the
> SqlAlchemy session.
>
> does anyone know if it's currently possible to handle this?  i have a few
> apps that only integrate pyramid_tm on a small subset of views, but i
> haven't tried to bypass it on a single view in many years.  I'm trying to
> avoid a secondary database connection, because this app can support a
> sqlite database and I've had problems with too many connections and sqlite
> in the past.
>
> --
> You received this message because you are subscribed to the Google Groups
> "pylons-discuss" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to pylons-discuss+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pylons-discuss/c3d3f561-8bcc-4c20-b1e8-f2aa147483f0%40googlegroups.com
> 
> .
>


-- 

Michael

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Re: [pylons-discuss] pyramid_tm - is there an acceptable way to unjoin the transaction and use explicit commits?

[Mikko Ohtamaa]

one of my apps uses pyramid_tm, but has reached a point where one (possibly
> two) views (out of dozens) need to make explicit commits with the
> SqlAlchemy session.
>

Because this does not fit well in the view/request model, I would usually
try to offload these tasks to a worker processes (Celery) where it is much
easier to have a explicit control over the transaction cycle. A request
would only serve as a trigger for the background process. It does not work
for all kind of use cases, though.

-Mikko

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[pylons-discuss] pyramid_tm - is there an acceptable way to unjoin the transaction and use explicit commits?

[Jonathan Vanasco]

one of my apps uses pyramid_tm, but has reached a point where one (possibly 
two) views (out of dozens) need to make explicit commits with the 
SqlAlchemy session.  

does anyone know if it's currently possible to handle this?  i have a few 
apps that only integrate pyramid_tm on a small subset of views, but i 
haven't tried to bypass it on a single view in many years.  I'm trying to 
avoid a secondary database connection, because this app can support a 
sqlite database and I've had problems with too many connections and sqlite 
in the past.

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