In my controller I have:
________
query = session.query(Article, Category, User, UserVote)
query = query.outerjoin((UserVote, and_
(Article.id==UserVote.article_id,
UserVote.voter==currently_logged_in_user)))
query = query.outerjoin((Category, Article.category_id ==
Category.id))
query = query.outerjoin((User, Article.submitter_id == User.id))
c.articles = query
________
and then in my template (jinja2) :
________
{% for article, category, submitter, uservote in c.articles %}
{{article.title}} was submitted by {{submitter.name}}, you have voted
for this {{uservote.stars}}
{% endfor %}
________
And this works great. But the problem is that when the user is not
logged in there is obviously no 'currently_logged_in_user'. Looking at
the logger I can see the SQL query ends up like this -
________
LEFT OUTER JOIN uservotes ON articles.id = uservotes.article_id AND
uservotes.voter_id IS NULL
________
So when the user is not logged in, my application trys to select a
uservote where the voter_id is set to null. This will give me the
resulting query I want, because there will never be a uservote record
with the voter_id set to NULL, but it is obviously not the correct way
to do a query. If I was doing the query myself, I would simply not
include the uservote join when the user is not logged in.
If I was to selectively change the query call based on whether the
user is logged in, ie..
________
query = session.query(Article, Category, User, UserVote)
[would become]
query = session.query(Article, Category, User)
________
Then the template, which is expecting 4 items
________
{% for article, category, submitter, uservote in articles %}
________
would get an unpacking error, because it expects the uservote to be
there
So what I am trying to figure out, is if there is a way to have the
query return None in place of the missing UserVote when the user is
not logged in?
I'm hoping there might be some kind of .join_placeholder(UserVote)
method that I have somehow overlooked, or something which can achieve
the same result.
Thanks in advance
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