[sqlalchemy] Re: Reload mapper column definition
*Addition:* This is a *relationship* -- 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] Reload mapper column definition
On my project, i use __getattr__ for adding column deifinition to object class Such as: def __getattr__(self,attr): ... my_load_function(...) session.refresh(self) ... return getattr(self,attr) It works, but refresh loses changes on this object. I cannot flush, because it used for another function. I found solution session.refresh(self, attribute_names=['attr_name']) But it will raise exception sqlalchemy.exc.InvalidRequestError: No column-based properties specified for refresh operation. Use session.expire() to reload collections and related items.] I already tried use session.expire(self) and session.expire(self, attribute_names=['attr_name'])) before and after refresh, but nothing changed Can someone help me with this eror? -- 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] Re: Dynamically change table name to select from for query
Thank you very much, your answer is very detailed as always. I think that
this approach may fit to me, because this tables are read-only, because it
is kind of datawarehouse.
Thanks!
суббота, 3 марта 2018 г., 10:45:45 UTC+3 пользователь Stanislav Lobanov
написал:
>
> Hello!
>
> I have a database with 10 tables with same structure. This structure of a
> tables are always the same.
>
> I want to be able to query this tables using one declarative mapper
> instead of 10 similar mappers, but to do so i need a way to change table
> name somehow.
>
> Desired code:
>
> class T(Base):
>some_column = Column(Integer) # just an example
>
> table_a_results =
> session.query(T).select_from_table('table_a').filter(T.some_column >
> 10).count()
> table_b_results =
> session.query(T).select_from_table('table_b').filter(T.some_column >
> 10).count()
>
>
> Are there any possibility to implement such query feature? Are there any
> alternative variants to this feature?
>
> 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 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.
