On 3/7/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]
> wrote:
At present, there isn't an 'exists' operation for queries - although it sounds like a good addition. It would probably end up as part of aggregate functionality, so it might be worth adding a note to ticket 1435 so your idea doesn't get forgotten.
However, in the interim, something like:
Topic.objects.filter(article_set__id__notnull=True).distinct()
might do the trick. It's a slightly roundabout way of getting it done - the article_set__id__notnull is there to deliberately select every row of the article_set; by putting this query in the Topic filter, it forces an inner join from Topic to Article, which contains every member of article; because the query is over Topic, only topic columns are returned, so enabling distinct should give you one result for every Topic that has at least one Article.
Glad you're enjoying it. Feedback like this is always nice to hear.
Russ Magee %-)
Bit of newbie question I guess, but I can't seem to find the answer in
the documentation or the group archive, so sorry if it's been asked
before.
I'm currently running the magic-removal branch and have two models
looking something like this:
class Topic (models.Model ):
parent = models.ForeignKey('self', null=True, blank=True,
related_name='child')
title = models.CharField(maxlength=128)
description = models.TextField()
class Article (models.Model ):
topic = models.ManyToManyField(Topic)
title = models.CharField(maxlength=255)
body = models.TextField()
Is it possible in a single line to retrieve all Topics that have at
least 1 related article without manually iterating through the Topics
to find out?
At present, there isn't an 'exists' operation for queries - although it sounds like a good addition. It would probably end up as part of aggregate functionality, so it might be worth adding a note to ticket 1435 so your idea doesn't get forgotten.
However, in the interim, something like:
Topic.objects.filter(article_set__id__notnull=True).distinct()
might do the trick. It's a slightly roundabout way of getting it done - the article_set__id__notnull is there to deliberately select every row of the article_set; by putting this query in the Topic filter, it forces an inner join from Topic to Article, which contains every member of article; because the query is over Topic, only topic columns are returned, so enabling distinct should give you one result for every Topic that has at least one Article.
Thanks in advance and thanks for an amazing framework, I'm having great
fun with it and it's soooo much faster and sooo much nicer than the bad
old days of PHP :)
Glad you're enjoying it. Feedback like this is always nice to hear.
Russ Magee %-)
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