On Wed, May 15, 2019 at 6:10 PM Tony Cao <t...@benchling.com> wrote:
>
> I mean query.update().
>
> Ah our goal was to make it so the update in question happened automatically
> without the developer having to explicitly specify it - in that case both
> obj.attr = x and obj_class.query.update({obj.attr: x}) should both trigger an
> update to obj.attr_modified. That's why I initially asked about onupdate, as
> it is triggered for both cases.
for query.update() you can use the before_compile_update() and modify
the context.values dictionary in place to affect the UPDATE statement
generated by query.update(). See
https://docs.sqlalchemy.org/en/13/orm/events.html?highlight=before_compile_update#sqlalchemy.orm.events.QueryEvents.before_compile_update.
Additional detail regarding .values will be up within 30 minutes.
>
>
> On Wednesday, May 15, 2019 at 2:38:19 PM UTC-7, Mike Bayer wrote:
>>
>> Bulk query updates, you mean, query.update() ? Or
>> session.bulk_update_mappings() ? In both cases you are
>> programatically providing the VALUES clause, so you know from your own
>> data what the UPDATE statement will be.
>>
>>
>>
>> On Wed, May 15, 2019 at 4:14 PM Tony Cao <to...@benchling.com> wrote:
>> >
>> > Ah but it also looks like the before_update event isn't triggered when
>> > doing bulk query updates, which we'd like to also update on. Is there a
>> > way to track those?
>> >
>> > On Wednesday, May 15, 2019 at 10:38:24 AM UTC-7, Mike Bayer wrote:
>> >>
>> >> you can inspect() the object and look at
>> >> inspect(obj).attrs['some_attr'].history
>> >>
>> >> https://docs.sqlalchemy.org/en/13/orm/internals.html#sqlalchemy.orm.state.AttributeState
>> >>
>> >>
>> >> On Wed, May 15, 2019 at 1:14 PM Tony Cao <to...@benchling.com> wrote:
>> >> >
>> >> > Hi,
>> >> >
>> >> > Thanks for the response! I also tried looking into before_update, but
>> >> > is there a recommended way to figure out what columns are being updated
>> >> > from that event? I had found this post
>> >> > (https://stackoverflow.com/questions/15642286/how-can-i-get-a-sqlalchemy-orm-objects-previous-state-after-a-db-update)
>> >> > that suggests looking at the history of the attribute state - is there
>> >> > a better way?
>> >> >
>> >> > On Wednesday, May 15, 2019 at 7:55:44 AM UTC-7, Mike Bayer wrote:
>> >> >>
>> >> >> On Mon, May 13, 2019 at 4:18 PM Tony Cao <to...@benchling.com> wrote:
>> >> >> >
>> >> >> > Hi all,
>> >> >> >
>> >> >> > Is there way to use Column.onupdate conditionally? For example, say
>> >> >> > I have:
>> >> >> >
>> >> >> > class A(Base):
>> >> >> > foo = Column(String)
>> >> >> > bar = Column(String)
>> >> >> > foo_updated = Column(DateTime, onupdate=update_fn) # Should only
>> >> >> > update when foo is updated
>> >> >> >
>> >> >> > def update_fn(context):
>> >> >> > if ...: # How can I check if only foo was updated?
>> >> >> > return datetime.now()
>> >> >> > else:
>> >> >> > return ... # How can I say to not update?
>> >> >> >
>> >> >> > Is there a way to define update_fn to only update foo_updated when
>> >> >> > foo changes? I can look at context.get_current_parameters() to see
>> >> >> > what columns are being used in the compiled statement, but it
>> >> >> > doesn't explicitly say which columns are the ones actually being
>> >> >> > updated; for example, if I have
>> >> >> >
>> >> >> > A.query.filter(A.bar == 'test').update({A.foo: 'new'},
>> >> >> > synchronize_session=False)
>> >> >> >
>> >> >> > then context.get_current_parameters will return a dict with keys for
>> >> >> > both 'bar' and 'foo', although it looks like it suffixes the filter
>> >> >> > param with a '_1' - is that something I can rely on to know if a
>> >> >> > column is used as a filter instead of an update? And beyond that, is
>> >> >> > there a way I can specify to not update the column?
>> >> >> >
>> >> >> > Alternatively, is there another approach recommended to doing this?
>> >> >>
>> >> >> the most common way is to use the ORM level before_update event:
>> >> >>
>> >> >> https://docs.sqlalchemy.org/en/13/orm/events.html?highlight=before_update#sqlalchemy.orm.events.MapperEvents.before_update
>> >> >>
>> >> >> there's also before_execute() at the Core level, but before the UPDATE
>> >> >> statement is even written, e.g. at the ORM level, is the best way.
>> >> >> Once you are in the onupdate Python function, you have to return a
>> >> >> value, as this occurs well after the UPDATE statement has been
>> >> >> compiled.
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >> >
>> >> >> > Thanks!
>> >> >> >
>> >> >> > --
>> >> >> > 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 sqlal...@googlegroups.com.
>> >> >> > To post to this group, send email to sqlal...@googlegroups.com.
>> >> >> > Visit this group at https://groups.google.com/group/sqlalchemy.
>> >> >> > To view this discussion on the web visit
>> >> >> > https://groups.google.com/d/msgid/sqlalchemy/b66e89c9-6618-4600-9381-182fa101f5b6%40googlegroups.com.
>> >> >> > 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 sqlal...@googlegroups.com.
>> >> > To post to this group, send email to sqlal...@googlegroups.com.
>> >> > Visit this group at https://groups.google.com/group/sqlalchemy.
>> >> > To view this discussion on the web visit
>> >> > https://groups.google.com/d/msgid/sqlalchemy/f13c4205-1df5-49c5-8c91-3c97cd8d9b05%40googlegroups.com.
>> >> > 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 sqlal...@googlegroups.com.
>> > To post to this group, send email to sqlal...@googlegroups.com.
>> > Visit this group at https://groups.google.com/group/sqlalchemy.
>> > To view this discussion on the web visit
>> > https://groups.google.com/d/msgid/sqlalchemy/38b1162d-1204-41b7-9649-3938775eeef8%40googlegroups.com.
>> > 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.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sqlalchemy/6dfe0cd9-c55c-486a-94b0-85eb222bdb55%40googlegroups.com.
> 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.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sqlalchemy/CA%2BRjkXFDV_e0jP0QWKrcXrF23XLDt%3DV_ppWNtY1TFzLSmQqe7A%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.
