Re: Primary key in queryset even when using only()
Thank you very much, this works perfectly!
On Mar 22, 12:01 pm, bruno desthuilliers
wrote:
> On 22 mar, 11:08, Kevin Renskers wrote:
>
> > Hi,
>
> > I am using a combination of the only() and distinct() functions on a
> > model to get the unique values of one column. Sadly, the only()
> > function also includes the primary key (even though I only give one
> > column name), which has the effect that all rows are seen as unique.
>
> only() is only (no pun) a complement to defer() - it still loads the
> Model instances, so you'll indeed have the primary key included.
>
> The method you want is values_list:
>
>
>
>
>
> >> results = YourModel.objects.values_list('power_meter',
> >> flat=True).distinct()
> > This is the result I want:
> > power_meter
> > 1
> > 2
> > 3
>
> > This is the result I get:
> > id power_meter
> > 80 1
> > 81 1
> > 82 1
> > 83 2
> > 84 2
> > 85 3
> > 86 3
>
> > So I am wondering why the primary key is included in the query, even
> > though I used only('power_meter') in my query.
>
> cf above. Querysets default behaviour is to yield Model instances -
> not raw data -, and Model instances neeed to have their primary key
> loaded to work correctly. If you want raw data, use either values() or
> values_list()
>
> HTH
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Re: Primary key in queryset even when using only()
On 22 mar, 11:08, Kevin Renskers wrote:
> Hi,
>
> I am using a combination of the only() and distinct() functions on a
> model to get the unique values of one column. Sadly, the only()
> function also includes the primary key (even though I only give one
> column name), which has the effect that all rows are seen as unique.
only() is only (no pun) a complement to defer() - it still loads the
Model instances, so you'll indeed have the primary key included.
The method you want is values_list:
>> results = YourModel.objects.values_list('power_meter', flat=True).distinct()
> This is the result I want:
> power_meter
> 1
> 2
> 3
>
> This is the result I get:
> id power_meter
> 80 1
> 81 1
> 82 1
> 83 2
> 84 2
> 85 3
> 86 3
>
> So I am wondering why the primary key is included in the query, even
> though I used only('power_meter') in my query.
cf above. Querysets default behaviour is to yield Model instances -
not raw data -, and Model instances neeed to have their primary key
loaded to work correctly. If you want raw data, use either values() or
values_list()
HTH
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Primary key in queryset even when using only()
Hi,
I am using a combination of the only() and distinct() functions on a
model to get the unique values of one column. Sadly, the only()
function also includes the primary key (even though I only give one
column name), which has the effect that all rows are seen as unique.
This is the result I want:
power_meter
1
2
3
This is the result I get:
id power_meter
80 1
81 1
82 1
83 2
84 2
85 3
86 3
So I am wondering why the primary key is included in the query, even
though I used only('power_meter') in my query. I could just do a GROUP
BY, but alas, that's impossible with the ORM...
I am not using an ORDER BY, so that should not be the reason the
primary key is included.
Thanks,
Kevin Renskers
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