map Comment like this:
from sqlalchemy.orm import query_expression
class Comment(Base):
__tablename__ = 'comment'
id = Column(Integer, primary_key=True)
news_id = Column(Integer, ForeignKey(News.id))
is_read = query_expression()
then you need to use options in your query to link the join to your
subquery, as well as the is_read expression, to that object:
from sqlalchemy.orm import contains_eager
comment_read_query = (
session.query(CommentRead).filter(
CommentRead.comment_id == Comment.id,
CommentRead.user_id == 1, # Interested in reads by specific user
).exists().label('is_read')
)
comment_query = session.query(Comment, comment_read_query).subquery()
news = session.query(News).outerjoin(comment_query).options(
contains_eager(News.comments, alias=comment_query).with_expression(
Comment.is_read, comment_query.c.is_read)
).all()
On Fri, May 25, 2018 at 11:28 AM, Marat Sharafutdinov <[email protected]> wrote:
> The news has comments, the comments have readings by users.
> I need to receive all the news with comments and readings of these comments
> by a specific user.
> The query is ok, but I can't get the value of the column `is_read` as an
> attribute of the comment object.
>
> --
> 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
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--
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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