Re: Building correct queryset

[Горобец Дмитрий]

Score field is on Brand model.

пятница, 26 мая 2017 г., 3:19:56 UTC+5 пользователь Melvyn Sopacua написал:
>
> On Monday 22 May 2017 15:26:59 Todor Velichkov wrote:
>
> > Hello, Дмитрий,
>
> > you can try this one, but w/o further optimizations it may be a very
>
> > slow query.
>
> > 
>
> > qs = Product.objects.filter(
>
> > #Where score is greater or equal
>
> > #to the 4th max score from its group
>
> > score__gte=Subquery(
>
> > (Product.objects
>
> > .filter(brand=OuterRef('brand'))
>
> > .values('score')
>
> > .order_by('-score')[3:4]
>
> > )
>
> > )
>
> > ).order_by('-score')
>
>  
>
> Yeah, that's how I read it too. But the code says score is on Brand model, 
> not Product. Which is correct?
>
> -- 
>
> Melvyn Sopacua
>

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Re: Building correct queryset

[Melvyn Sopacua]

On Monday 22 May 2017 15:26:59 Todor Velichkov wrote:
> Hello, Дмитрий,
> you can try this one, but w/o further optimizations it may be a very
> slow query.
> 
> qs = Product.objects.filter(
> #Where score is greater or equal
> #to the 4th max score from its group
> score__gte=Subquery(
> (Product.objects
> .filter(brand=OuterRef('brand'))
> .values('score')
> .order_by('-score')[3:4]
> )
> )
> ).order_by('-score')

Yeah, that's how I read it too. But the code says score is on Brand model, not 
Product. 
Which is correct?
-- 
Melvyn Sopacua

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Re: Building correct queryset

[Горобец Дмитрий]

Thank you, Todor. I'll try.

вторник, 23 мая 2017 г., 3:27:00 UTC+5 пользователь Todor Velichkov написал:
>
> Hello, Дмитрий,
> you can try this one, but w/o further optimizations it may be a very slow 
> query.
>
> qs = Product.objects.filter(
> #Where score is greater or equal
> #to the 4th max score from its group
> score__gte=Subquery(
> (Product.objects
> .filter(brand=OuterRef('brand'))
> .values('score')
> .order_by('-score')[3:4]
> )
> )
> ).order_by('-score')
>
>
>
>
>  
>
> On Friday, May 19, 2017 at 12:32:49 PM UTC+3, Горобец Дмитрий wrote:
>>
>> Hello. I have these two models. I have to show 4 or less products on a page 
>> for each brand ordered by score. Please, help construct correct queryset.
>>
>>
>>
>> class Brand(models.Model):
>> title = models.CharField(
>> verbose_name='Название бренда',
>> max_length=64,
>> unique=True,
>> db_index=True,
>> error_messages={
>> 'unique': 'Бренд с таким именем уже существует.'
>> }
>> )
>>
>> slug = AutoSlugField(
>> verbose_name='Адрес страницы бренда',
>> populate_from='title',
>> editable=True,
>> unique=True,
>> slugify=custom_slugify,
>> db_index=True
>> )
>>
>> owner = models.OneToOneField(
>> to=settings.AUTH_USER_MODEL,
>> verbose_name='Владелец',
>> on_delete=models.PROTECT,
>> )
>>
>>
>> score = models.DecimalField(
>> verbose_name='Рейтинг бренда',
>> blank=True,
>> null=True,
>> max_digits=19,
>> decimal_places=18,
>> )
>>
>>
>>
>> class Product(models.Model):
>> title = models.CharField(
>> verbose_name='Название изделия',
>> max_length=255,
>> db_index=True,
>> )
>>
>> slug = AutoSlugField(
>> verbose_name='Адрес страницы изделия',
>> populate_from='title',
>> editable=False,
>> unique_with='brand',
>> slugify=custom_slugify,
>> db_index=True,
>> )
>>
>> brand = models.ForeignKey(
>> to=Brand,
>> verbose_name='Бренд',
>> related_name='products',
>> on_delete=models.CASCADE,
>> )
>>
>>
>>

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Re: Building correct queryset

[Todor Velichkov]

Hello, Дмитрий,
you can try this one, but w/o further optimizations it may be a very slow 
query.

qs = Product.objects.filter(
#Where score is greater or equal
#to the 4th max score from its group
score__gte=Subquery(
(Product.objects
.filter(brand=OuterRef('brand'))
.values('score')
.order_by('-score')[3:4]
)
)
).order_by('-score')




 

On Friday, May 19, 2017 at 12:32:49 PM UTC+3, Горобец Дмитрий wrote:
>
> Hello. I have these two models. I have to show 4 or less products on a page 
> for each brand ordered by score. Please, help construct correct queryset.
>
>
>
> class Brand(models.Model):
> title = models.CharField(
> verbose_name='Название бренда',
> max_length=64,
> unique=True,
> db_index=True,
> error_messages={
> 'unique': 'Бренд с таким именем уже существует.'
> }
> )
>
> slug = AutoSlugField(
> verbose_name='Адрес страницы бренда',
> populate_from='title',
> editable=True,
> unique=True,
> slugify=custom_slugify,
> db_index=True
> )
>
> owner = models.OneToOneField(
> to=settings.AUTH_USER_MODEL,
> verbose_name='Владелец',
> on_delete=models.PROTECT,
> )
>
>
> score = models.DecimalField(
> verbose_name='Рейтинг бренда',
> blank=True,
> null=True,
> max_digits=19,
> decimal_places=18,
> )
>
>
>
> class Product(models.Model):
> title = models.CharField(
> verbose_name='Название изделия',
> max_length=255,
> db_index=True,
> )
>
> slug = AutoSlugField(
> verbose_name='Адрес страницы изделия',
> populate_from='title',
> editable=False,
> unique_with='brand',
> slugify=custom_slugify,
> db_index=True,
> )
>
> brand = models.ForeignKey(
> to=Brand,
> verbose_name='Бренд',
> related_name='products',
> on_delete=models.CASCADE,
> )
>
>
>

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Re: Building correct queryset

[Горобец Дмитрий]

Andrew, your solution works great for one brand. But I have more than one.

суббота, 20 мая 2017 г., 0:20:18 UTC+5 пользователь Andrew Beales написал:
>
> brand = Brand.objects.get(title='mybrand')
> products = Product.objects.filter(brand=brand).order_by('-score')[:4]
>
> ...gets you the top 4 products in order for the brand
>
> On Friday, May 19, 2017 at 10:32:49 AM UTC+1, Горобец Дмитрий wrote:
>>
>> Hello. I have these two models. I have to show 4 or less products on a page 
>> for each brand ordered by score. Please, help construct correct queryset.
>>
>>
>>
>> class Brand(models.Model):
>> title = models.CharField(
>> verbose_name='Название бренда',
>> max_length=64,
>> unique=True,
>> db_index=True,
>> error_messages={
>> 'unique': 'Бренд с таким именем уже существует.'
>> }
>> )
>>
>> slug = AutoSlugField(
>> verbose_name='Адрес страницы бренда',
>> populate_from='title',
>> editable=True,
>> unique=True,
>> slugify=custom_slugify,
>> db_index=True
>> )
>>
>> owner = models.OneToOneField(
>> to=settings.AUTH_USER_MODEL,
>> verbose_name='Владелец',
>> on_delete=models.PROTECT,
>> )
>>
>>
>> score = models.DecimalField(
>> verbose_name='Рейтинг бренда',
>> blank=True,
>> null=True,
>> max_digits=19,
>> decimal_places=18,
>> )
>>
>>
>>
>> class Product(models.Model):
>> title = models.CharField(
>> verbose_name='Название изделия',
>> max_length=255,
>> db_index=True,
>> )
>>
>> slug = AutoSlugField(
>> verbose_name='Адрес страницы изделия',
>> populate_from='title',
>> editable=False,
>> unique_with='brand',
>> slugify=custom_slugify,
>> db_index=True,
>> )
>>
>> brand = models.ForeignKey(
>> to=Brand,
>> verbose_name='Бренд',
>> related_name='products',
>> on_delete=models.CASCADE,
>> )
>>
>>
>>

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Re: Building correct queryset

[Andrew Beales]

brand = Brand.objects.get(title='mybrand')
products = Product.objects.filter(brand=brand).order_by('-score')[:4]

...gets you the top 4 products in order for the brand

On Friday, May 19, 2017 at 10:32:49 AM UTC+1, Горобец Дмитрий wrote:
>
> Hello. I have these two models. I have to show 4 or less products on a page 
> for each brand ordered by score. Please, help construct correct queryset.
>
>
>
> class Brand(models.Model):
> title = models.CharField(
> verbose_name='Название бренда',
> max_length=64,
> unique=True,
> db_index=True,
> error_messages={
> 'unique': 'Бренд с таким именем уже существует.'
> }
> )
>
> slug = AutoSlugField(
> verbose_name='Адрес страницы бренда',
> populate_from='title',
> editable=True,
> unique=True,
> slugify=custom_slugify,
> db_index=True
> )
>
> owner = models.OneToOneField(
> to=settings.AUTH_USER_MODEL,
> verbose_name='Владелец',
> on_delete=models.PROTECT,
> )
>
>
> score = models.DecimalField(
> verbose_name='Рейтинг бренда',
> blank=True,
> null=True,
> max_digits=19,
> decimal_places=18,
> )
>
>
>
> class Product(models.Model):
> title = models.CharField(
> verbose_name='Название изделия',
> max_length=255,
> db_index=True,
> )
>
> slug = AutoSlugField(
> verbose_name='Адрес страницы изделия',
> populate_from='title',
> editable=False,
> unique_with='brand',
> slugify=custom_slugify,
> db_index=True,
> )
>
> brand = models.ForeignKey(
> to=Brand,
> verbose_name='Бренд',
> related_name='products',
> on_delete=models.CASCADE,
> )
>
>
>

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Building correct queryset

[Горобец Дмитрий]

Hello. I have these two models. I have to show 4 or less products on a page for 
each brand ordered by score. Please, help construct correct queryset.



class Brand(models.Model):
title = models.CharField(
verbose_name='Название бренда',
max_length=64,
unique=True,
db_index=True,
error_messages={
'unique': 'Бренд с таким именем уже существует.'
}
)

slug = AutoSlugField(
verbose_name='Адрес страницы бренда',
populate_from='title',
editable=True,
unique=True,
slugify=custom_slugify,
db_index=True
)

owner = models.OneToOneField(
to=settings.AUTH_USER_MODEL,
verbose_name='Владелец',
on_delete=models.PROTECT,
)


score = models.DecimalField(
verbose_name='Рейтинг бренда',
blank=True,
null=True,
max_digits=19,
decimal_places=18,
)



class Product(models.Model):
title = models.CharField(
verbose_name='Название изделия',
max_length=255,
db_index=True,
)

slug = AutoSlugField(
verbose_name='Адрес страницы изделия',
populate_from='title',
editable=False,
unique_with='brand',
slugify=custom_slugify,
db_index=True,
)

brand = models.ForeignKey(
to=Brand,
verbose_name='Бренд',
related_name='products',
on_delete=models.CASCADE,
)


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