I am trying to write this raw SQL query,
info_model = list(InfoModel.objects.raw('SELECT *,
max(date),
count(postid) AS freq,
count(DISTINCT author) AS contributors FROM
crudapp_infomodel GROUP BY topicid ORDER BY date DESC'))
as a django query. The following attempt does not work as I can't get related fields for 'author' and 'post'.
info_model = InfoModel.objects.values('topic')
.annotate( max=Max('date'),
freq=Count('postid'),
contributors=Count('author',
distinct=True))
.order_by('-max')
With raw SQL I can use SELECT * but how can I do the equivalent with the Django query?
The model is,
class InfoModel(models.Model):
topicid = models.IntegerField(default=0)
postid = models.IntegerField(default=0)
author = models.CharField(max_length=30)
post = models.CharField(max_length=30)
date = models.DateTimeField('date published')
I did previously post this problem here Django Using order_by with .annotate() and getting related field
I guess you want to order by the maximum date so:
InfoModel.objects.values('topic')
.annotate(
max=Max('date'), freq=Count('postid'),
contributors=Count('author', distinct=True))
.order_by('max')
The following view amalgamates two queries to solve the problem,
def info(request):
info_model = InfoModel.objects.values('topic')
.annotate( max=Max('date'),
freq=Count('postid'),
contributors=Count('author', distinct=True))
.order_by('-max')
info2 = InfoModel.objects.all()
columnlist = []
for item in info2:
columnlist.append([item])
for item in info_model:
for i in range(len(columnlist)):
if item['max'] == columnlist[i][0].date:
item['author'] = columnlist[i][0].author
item['post'] = columnlist[i][0].post
return render(request, 'info.html', {'info_model': info_model})
Related
I am writing a Django query to filter a list of teams which the user is a part of.
(The Team and UserTeams models I am querying):
class Team(models.Model)
name = models.CharField(max_length=100)
venue = models.CharField(max_length=100)
countryID = models.ForeignKey(Countries, on_delete=models.CASCADE)
owner = models.ForeignKey(User)
class UserTeams(models.Model):
userID = models.ForeignKey(User,on_delete=models.CASCADE)
teamID = models.ForeignKey(Team,on_delete=models.CASCADE)
I'm struggling to make two queries:
Query 1:
The first query (teamquery) filters the Teams by checking if the owner=request.user, and I then display a list of these teams in my template.
Query 2: I then want to display a list of teams where the UserTeams UserID = request.user (userteamquery)
Problem:
Some teams are appearing in both query results. Is there a 'not equal' query I can use where it will exclude all UserTeams in the userteamquery where the teamID is a result of teamquery? so teamID=teamquery
#login_required
def teamsview(request):
teamquery = Team.objects.filter(owner=request.user)
userteamquery = UserTeams.objects.filter(userID=request.user)
return render(request, 'teammanager/teams.html', {
"teams": teamquery, "userteams": userteamquery})
Tried to exclude() (pretty sure this isn't even valid use)
userteamquery =
UserTeams.objects.exclude(teamID=teamquery).filter(userID=request.user)
This didnt change anything at all in my output
Also tried ~Q but didnt change anything either:
userteamquery = UserTeams.objects.filter(Q(userID=request.user),
~Q(teamID=teamquery))
*Edit -
Added __in to my parameter, this works:
userteamquery = UserTeams.objects.filter(Q(userID=request.user),
~Q(teamID__in=teamquery))
In model.py, I create class Order has a field 'order_date' with DateTimeField.
In views.py, I am using this query:
orders = Order.objects.filter(order_date__date__gte = date_from, order_date__date__lte = date_to)
The Query doesn't return any data, although in the database, there are many records between date_from and date_to.
You can do that like this:
orders = Order.objects.filter(order_date__gte = date_from, order_date__lte = date_to)
You have an extra __date that you don't need, since order_date is a DateTimeField.
I am trying to filter in view my queryset based on relation between 2 fields .
however always getting the error that my field is not defined .
My Model has several calculated columns and I want to get only the records where values of field A are greater than field B.
So this is my model
class Material(models.Model):
version = IntegerVersionField( )
code = models.CharField(max_length=30)
name = models.CharField(max_length=30)
min_quantity = models.DecimalField(max_digits=19, decimal_places=10)
max_quantity = models.DecimalField(max_digits=19, decimal_places=10)
is_active = models.BooleanField(default=True)
def _get_totalinventory(self):
from inventory.models import Inventory
return Inventory.objects.filter(warehouse_Bin__material_UOM__UOM__material=self.id, is_active = true ).aggregate(Sum('quantity'))
totalinventory = property(_get_totalinventory)
def _get_totalpo(self):
from purchase.models import POmaterial
return POmaterial.objects.filter(material=self.id, is_active = true).aggregate(Sum('quantity'))
totalpo = property(_get_totalpo)
def _get_totalso(self):
from sales.models import SOproduct
return SOproduct.objects.filter(product__material=self.id , is_active=true ).aggregate(Sum('quantity'))
totalso = property(_get_totalpo)
#property
def _get_total(self):
return (totalinventory + totalpo - totalso)
total = property(_get_total)
And this is line in my view where I try to get the conditional queryset
po_list = MaterialFilter(request.GET, queryset=Material.objects.filter( total__lte = min_quantity ))
But I am getting the error that min_quantity is not defined
What could be the problem ?
EDIT:
My problem got solved thank you #Moses Koledoye but in the same code I have different issue now
Cannot resolve keyword 'total' into field.Choices are: am, author, author_id, bom, bomversion, code, creation_time, description, id, inventory, is_active, is_production, itemgroup, itemgroup_id, keywords, materialuom, max_quantity, min_quantity, name, pomaterial, produce, product, slug, trigger_quantity, uom, updated_by, updated_by_id, valid_from, valid_to, version, warehousebin
Basically it doesn't show any of my calculated fields I have in my model.
Django cannot write a query which is conditioned on a field whose value is unknown. You need to use a F expression for this:
from django.db.models import F
queryset = Material.objects.filter(total__lte = F('min_quantity'))
And your FilterSet becomes:
po_list = MaterialFilter(request.GET, queryset = Material.objects.filter(total__lte=F('min_quantity')))
From the docs:
An F() object represents the value of a model field or annotated
column. It makes it possible to refer to model field values and
perform database operations using them without actually having to pull
them out of the database into Python memory
I am using the following model:
class Topping(models.Model):
name = models.CharField(max_length=30)
class Pizza(models.Model):
name = models.CharField(max_length=50)
toppings = models.ManyToManyField(Topping)
def __str__(self): # __unicode__ on Python 2
return "%s (%s)" % (self.name, ", ".join(topping.name
for topping in self.toppings.all()))
And now I want only the elements for vegetarian menu, filtered by tomatoes
pizza_item = Pizza.objects.filter(toppings__name='tomatoes')
My select is:
SELECT `pizza`.`id`, `pizza`.`name`
FROM `pizza`
INNER JOIN `pizza_toppings` ON (
`pizza`.`id` = `pizza_toppings`.`pizza_id` )
INNER JOIN `web_topping` ON (
`pizza_toppings`.`topping_id` = `topping`.`id` )
WHERE `topping`.`name` = azucar
but i want get:
SELECT `pizza`.`id`, `pizza`.`name`, `topping`.`name`
FROM `pizza`
INNER JOIN `pizza_toppings` ON (
`pizza`.`id` = `pizza_toppings`.`pizza_id` )
INNER JOIN `web_topping` ON (
`pizza_toppings`.`topping_id` = `topping`.`id` )
WHERE `topping`.`name` = azucar
This last query works fine in mysql db. And works using pizza.objects.raw but i want get using django ORM
Is a select with topping.name i try it using prefetch_select('toppings'). but i cant get the same select.
Have you tried using the values method for Queryset ?
Something like :
pizza_item = Pizza.objects.filter(toppings__name='tomatoes').values("id", "name", "toppings__name")
I am not sure if that's doable. Because when you use Pizza.objects... you are limited to the fields that are in the Pizza model. Since the Pizza model does not contain toppings' name field. You cannot retrieve it. You can only retrieve toppings' id field:
pizza_item = Pizza.objects.filter(toppings__name='tomatoes').values('id', 'name', 'toppings')
Which will provide "toppings"."topping_id" in SELECT.
Also, since you have specified that toppings__name='tomatoes, all of toppings' name will be tomatoes in this queryset, so what is the point of having topping.name in your result?
EDIT:
It turns out the real question is - how do I get select_related to follow the m2m relationships I have defined? Those are the ones that are taxing my system. Any ideas?
I have two classes for my django app. The first (Item class) describes an item along with some functions that return information about the item. The second class (Itemlist class) takes a list of these items and then does some processing on them to return different values. The problem I'm having is that returning a list of items from Itemlist is taking a ton of queries, and I'm not sure where they're coming from.
class Item(models.Model):
# for archiving purposes
archive_id = models.IntegerField()
users = models.ManyToManyField(User, through='User_item_rel',
related_name='users_set')
# for many to one relationship (tags)
tag = models.ForeignKey(Tag)
sub_tag = models.CharField(default='',max_length=40)
name = models.CharField(max_length=40)
purch_date = models.DateField(default=datetime.datetime.now())
date_edited = models.DateTimeField(auto_now_add=True)
price = models.DecimalField(max_digits=6, decimal_places=2)
buyer = models.ManyToManyField(User, through='Buyer_item_rel',
related_name='buyers_set')
comments = models.CharField(default='',max_length=400)
house_id = models.IntegerField()
class Meta:
ordering = ['-purch_date']
def shortDisplayBuyers(self):
if len(self.buyer_item_rel_set.all()) != 1:
return "multiple buyers"
else:
return self.buyer_item_rel_set.all()[0].buyer.name
def listBuyers(self):
return self.buyer_item_rel_set.all()
def listUsers(self):
return self.user_item_rel_set.all()
def tag_name(self):
return self.tag
def sub_tag_name(self):
return self.sub_tag
def __unicode__(self):
return self.name
and the second class:
class Item_list:
def __init__(self, list = None, house_id = None, user_id = None,
archive_id = None, houseMode = 0):
self.list = list
self.house_id = house_id
self.uid = int(user_id)
self.archive_id = archive_id
self.gen_balancing_transactions()
self.houseMode = houseMode
def ret_list(self):
return self.list
So after I construct Itemlist with a large list of items, Itemlist.ret_list() takes up to 800 queries for 25 items. What can I do to fix this?
Try using select_related
As per a question I asked here
Dan is right in telling you to use select_related.
select_related can be read about here.
What it does is return in the same query data for the main object in your queryset and the model or fields specified in the select_related clause.
So, instead of a query like:
select * from item
followed by several queries like this every time you access one of the item_list objects:
select * from item_list where item_id = <one of the items for the query above>
the ORM will generate a query like:
select item.*, item_list.*
from item a join item_list b
where item a.id = b.item_id
In other words: it will hit the database once for all the data.
You probably want to use prefetch_related
Works similarly to select_related, but can deal with relations selected_related cannot. The join happens in python, but I've found it to be more efficient for this kind of work than the large # of queries.
Related reading on the subject