On 02/06/2017 11:02 AM, Евгений Иванов wrote:
I need a dynamically calculated column for my model. column_property
looks great for that, but problem here that it's compiled at time when
model is mapped and I need to provide some value for filtering at time
the request is executed. I thought that bindparam can solve that problem
for me, but found that topic:
https://bitbucket.org/zzzeek/sqlalchemy/issues/3620/new-query-doesnt-expire-column_property
this is not really a great way to use column_property as it is
treated like any other persisted attribute, and is not reloaded
unnecessarily.
you can use column_property with a bound parameter it just wont normally
be refreshed if you query for the same object again when it's already
loaded. it depends on what you want things to do.
|
User:
id
name
Book:
id
name
UserFavoriteBooks:
user_id
book_id
|
So I have many-to-many relation between users and books to represent
list of favorite books for a user. Then some user queries a book from DB
and want to know if it's in his favorite list, so I need to query the
Book entry for db with some fake bool column "favorite" which is checked
over the current user (who performed the request). Is it possible to do
that in SQLAlchemy so the "favorite" fields is automatically filled with
correct value once I do a query for a Book?
what's a "fake" column? if "favorite" is a column in UserFavoriteBooks
you'd use the association object pattern, i dont see where the
column_property/bind thing is used there.
BR, Evgeny
--
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
<mailto:sqlalchemy+unsubscr...@googlegroups.com>.
To post to this group, send email to sqlalchemy@googlegroups.com
<mailto: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.
