Wonderfull
(ps :sorry, I should have put the model)
On Friday, May 20, 2016 at 2:40:33 AM UTC-4, James Schneider wrote:
>
> On Wed, May 18, 2016 at 9:54 PM, stunaz <stu...@gmail.com <javascript:>>
> wrote:
>
>> Hi,
>> I would like to write the following query using django orm.
>>
>> select * ,
>> (select image_url from blog_image bi where bi.blog_id = b.id and bi.
>> principal=1) as blog_main_imange
>> from blog b
>>
>>
>> Any idea, how to write the queryset ?
>>
>
> Without Django models, not with much accuracy.
>
> Assuming that your models are named Blog and BlogImage, with an FK from
> Blog to BlogImage named 'image', I think you can do something like this:
>
>
> from django.db.models import Prefetch
>
> Blog.objects.all().prefetch_related(
> Prefetch('image',
> queryset=BlogImage.objects.filter(principal=1),
> to_attr='blog_main_image'
> )
> )
>
>
> References:
>
>
> https://docs.djangoproject.com/en/1.9/ref/models/querysets/#prefetch-related
>
> https://docs.djangoproject.com/en/1.9/ref/models/querysets/#prefetch-objects
>
> Completely untested and written off the top of my head using a model
> structure I deduced from your query, so YMMV, but I hope that at least
> points you in the right direction.
>
> -James
>
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