Re: [sqlalchemy] inspect a scalar relationship property when it is loaded

2016-10-28 Thread mike bayer 



On 10/28/2016 11:55 AM, Kent Bower wrote:

The load() event would also capture if it were subqueryload()ed, right?


any eagerload.




And overriding Query.__iter__ wouldn't catch the cases where the scalar
is a "use_get" lookup that was already in session.identity_map...


right, would need to catch that too.

 No

good way to intercept attributes.set_committed() for that, is there?


there's not events for that because setting attribute values for loads 
is usually done using more direct paths than that and speed is extremely 
critical.  that's why there's not a lot of "load" events.new events 
that are local to relationship loading are feasible though.





On Fri, Oct 28, 2016 at 11:21 AM, mike bayer > wrote:



On 10/28/2016 10:48 AM, Kent wrote:

@validates and 'set' attribute events will only fire when the /user/
sets a property (setattr), not when initially loaded by the orm.

Is there a way to intercept (for inspection) a scalar relationship
property instance when it is loaded?  I don't think the 'load' event
will work because I won't know if the current instance is being
loaded
in the context of setting an instrumented attribute.

For example:

If I have a parent object, I want to know when parent.childobj is
populated by the orm framework (whether on a lazy load or joined
load).

Is that possible?

Thanks in advance!


based on the laws of twos, being that any random issue that has
never been asked ever for ten years will suddenly be asked for twice
within two days, the answer is no!   the event proposed would be
collection_populate, at the same time we'd add scalar_populate, see
https://groups.google.com/d/msg/sqlalchemy/IfuUwUgKwW0/5ZgPmpAvBAAJ
 .

Interim solution is to subclass Query and override __iter__.   The
load() event will get you eagerly-loaded attributes though, set it
on "parent"'s class and then inspect "childobj".





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Re: [sqlalchemy] inspect a scalar relationship property when it is loaded

2016-10-28 Thread Kent Bower 
The load() event would also capture if it were subqueryload()ed, right?

And overriding Query.__iter__ wouldn't catch the cases where the scalar is
a "use_get" lookup that was already in session.identity_map...  No good way
to intercept attributes.set_committed() for that, is there?

On Fri, Oct 28, 2016 at 11:21 AM, mike bayer 
wrote:

>
>
> On 10/28/2016 10:48 AM, Kent wrote:
>
>> @validates and 'set' attribute events will only fire when the /user/
>> sets a property (setattr), not when initially loaded by the orm.
>>
>> Is there a way to intercept (for inspection) a scalar relationship
>> property instance when it is loaded?  I don't think the 'load' event
>> will work because I won't know if the current instance is being loaded
>> in the context of setting an instrumented attribute.
>>
>> For example:
>>
>> If I have a parent object, I want to know when parent.childobj is
>> populated by the orm framework (whether on a lazy load or joined load).
>>
>> Is that possible?
>>
>> Thanks in advance!
>>
>
> based on the laws of twos, being that any random issue that has never been
> asked ever for ten years will suddenly be asked for twice within two days,
> the answer is no!   the event proposed would be collection_populate, at the
> same time we'd add scalar_populate, see https://groups.google.com/d/ms
> g/sqlalchemy/IfuUwUgKwW0/5ZgPmpAvBAAJ .
>
> Interim solution is to subclass Query and override __iter__.   The load()
> event will get you eagerly-loaded attributes though, set it on "parent"'s
> class and then inspect "childobj".
>
>
>
>
>
>> --
>> 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
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>> .
>> 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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Re: [sqlalchemy] inspect a scalar relationship property when it is loaded

2016-10-28 Thread mike bayer 



On 10/28/2016 10:48 AM, Kent wrote:

@validates and 'set' attribute events will only fire when the /user/
sets a property (setattr), not when initially loaded by the orm.

Is there a way to intercept (for inspection) a scalar relationship
property instance when it is loaded?  I don't think the 'load' event
will work because I won't know if the current instance is being loaded
in the context of setting an instrumented attribute.

For example:

If I have a parent object, I want to know when parent.childobj is
populated by the orm framework (whether on a lazy load or joined load).

Is that possible?

Thanks in advance!


based on the laws of twos, being that any random issue that has never 
been asked ever for ten years will suddenly be asked for twice within 
two days, the answer is no!   the event proposed would be 
collection_populate, at the same time we'd add scalar_populate, see 
https://groups.google.com/d/msg/sqlalchemy/IfuUwUgKwW0/5ZgPmpAvBAAJ .


Interim solution is to subclass Query and override __iter__.   The 
load() event will get you eagerly-loaded attributes though, set it on 
"parent"'s class and then inspect "childobj".







--
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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[sqlalchemy] inspect a scalar relationship property when it is loaded

2016-10-28 Thread Kent 
@validates and 'set' attribute events will only fire when the *user* sets a 
property (setattr), not when initially loaded by the orm.

Is there a way to intercept (for inspection) a scalar relationship property 
instance when it is loaded?  I don't think the 'load' event will work 
because I won't know if the current instance is being loaded in the context 
of setting an instrumented attribute.

For example:

If I have a parent object, I want to know when parent.childobj is populated 
by the orm framework (whether on a lazy load or joined load).

Is that possible?

Thanks in advance!

-- 
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 
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