Thanks a lot Rajes, now I understand the situation better
On Fri, Jan 23, 2009 at 7:05 PM, Rajesh Dhawan <rajesh.dha...@gmail.com> wrote:
>
>>
>> class Tag(models.Model):
>> name = models.CharField(max_length=100)
>> related = models.ManyToManyField('self', symmetrical=False,
>> through='TagCorrelation', blank=True)
>>
>> class TagCorrelation(models.Model):
>> from_tag = models.ForeignKey(Tag, related_name='related_source')
>> to_tag = models.ForeignKey(Tag, related_name='related_target')
>> common_posts = models.IntegerField(blank=True, null=True)
>>
>> You see, it is a slightly denormalized way to store relation between tags.
>>
>> Now, after reading the docs
>> athttp://docs.djangoproject.com/en/dev/topics/db/models/, following this
>> esample:
>>
>> # Find all the members of the Beatles that joined after 1 Jan 1961>>>
>> Person.objects.filter(
>>
>> ... group__name='The Beatles',
>> ... membership__date_joined__gt=date(1961,1,1))
>> [<Person: Ringo Starr]
>>
>> it seems that it should be possible to query the using attributes of
>> the intermediate model. So I tried with:
>>
>> Tag.objects.filter(tagcorrelation__common_posts_gt=1)
>>
>> but tt does not work, gives this error:
>>
>> FieldError: Cannot resolve keyword 'tagcorrelation' into field.
>> Choices are: id, name, post, related, related_source, related_target,
>> source, tag
>>
>> Am i missing something?
>
> Yes. TagCorrelation has two Foreign Keys back to Tag. So
> tagcorrelation__* is ambiguous and therefore not supported. Try:
>
> Tag.objects.filter(related_source__common_posts_gt=1)
>
> Or
>
> Tag.objects.filter(related_target__common_posts_gt=1)
>
> -Rajesh D
>
> >
>
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