Re: Queries for Related Objects wonky

[Streamweaver]

"They" are apparently people who read the documentation and understand
better then "me".

Sigh, and I thought I uncovered somethign, ah well.  Simple error and
thanks for clarifying.

On Jul 13, 11:13 pm, Russell Keith-Magee 
wrote:
> On Tue, Jul 14, 2009 at 10:31 AM, Streamweaver wrote:
> >> For example I have a model called Project with a ForeignKey to a
> >> Django User.
>
> >> class Project(models.Model):
> >>    ...
> >>     owner = models.ForeignKey(User)
> >>   ...
>
> >> by the documentation I would expect the following to give me a list of
> >> all Users who are owners of projects but it does not.
>
> >> User.objects.filter(project__owner__isnull=False)
>
> >> Instead it's returning a queryset of all users.
>
> >> Anyone have any insight into this?
> ...
> > Filed a bug report about this.  We'll see if they accept it.
>
> I'm not sure who "they" are supposed to be, but "they" won't accept
> this ticket, because this isn't a bug.
>
> The query:
>
> User.objects.filter(project__owner__isnull=False)
>
> Querying on project__owner is essentially asking Django to traverse to
> the project table so that it can query an attribute that is already
> present on the user table - the ID. Django optimizes this query, and
> doesn't do the join, since it already has the data locally. So, your
> reduces to 'User.objects.filter(id__isnull=False)' - which is the same
> as "User.objects.all()"
>
> What you need to do is query for the non-existence of a project
> associated with a user:
>
> User.objects.filter(project__isnull=False)
>
> Yours,
> Russ Magee %-)
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Re: Queries for Related Objects wonky

[Russell Keith-Magee]

On Tue, Jul 14, 2009 at 10:31 AM, Streamweaver wrote:

>> For example I have a model called Project with a ForeignKey to a
>> Django User.
>>
>> class Project(models.Model):
>>...
>> owner = models.ForeignKey(User)
>>   ...
>>
>> by the documentation I would expect the following to give me a list of
>> all Users who are owners of projects but it does not.
>>
>> User.objects.filter(project__owner__isnull=False)
>>
>> Instead it's returning a queryset of all users.
>>
>> Anyone have any insight into this?
...
> Filed a bug report about this.  We'll see if they accept it.

I'm not sure who "they" are supposed to be, but "they" won't accept
this ticket, because this isn't a bug.

The query:

User.objects.filter(project__owner__isnull=False)

Querying on project__owner is essentially asking Django to traverse to
the project table so that it can query an attribute that is already
present on the user table - the ID. Django optimizes this query, and
doesn't do the join, since it already has the data locally. So, your
reduces to 'User.objects.filter(id__isnull=False)' - which is the same
as "User.objects.all()"

What you need to do is query for the non-existence of a project
associated with a user:

User.objects.filter(project__isnull=False)

Yours,
Russ Magee %-)

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Re: Queries for Related Objects wonky

[Streamweaver]

Filed a bug report about this.  We'll see if they accept it.

On Jul 10, 5:29 pm, Streamweaver  wrote:
> I'm using Django 1.0.2 and having some problems with Related Object
> queries.
>
> For example I have a model called Project with a ForeignKey to a
> Django User.
>
> class Project(models.Model):
>    ...
>     owner = models.ForeignKey(User)
>   ...
>
> by the documentation I would expect the following to give me a list of
> all Users who are owners of projects but it does not.
>
> User.objects.filter(project__owner__isnull=False)
>
> Instead it's returning a queryset of all users.
>
> Anyone have any insight into this?
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Queries for Related Objects wonky

[Streamweaver]

I'm using Django 1.0.2 and having some problems with Related Object
queries.

For example I have a model called Project with a ForeignKey to a
Django User.

class Project(models.Model):
   ...
owner = models.ForeignKey(User)
  ...

by the documentation I would expect the following to give me a list of
all Users who are owners of projects but it does not.

User.objects.filter(project__owner__isnull=False)

Instead it's returning a queryset of all users.

Anyone have any insight into this?


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