this is my first model
class DipPegawai(models.Model):
PegID = models.AutoField(primary_key=True)
PegNamaLengkap = models.CharField(max_length=100, blank=True, null=True)
PegUnitKerja = models.IntegerField(null=True,blank=True)
and this is my second model
class DipHonorKegiatanPeg(models.Model):
KegID = models.AutoField(primary_key=True)
PegID = models.ForeignKey(DipPegawai, blank=True,null=True)
KegNama = models.Charfield(max_length=100,null=True,blank=True)
i want to make left join with this model, something like this in mysql query
SELECT PegNamaLengkap, KegNama_id
FROM karyawan_dippegawai AS k LEFT JOIN honorkegiatanpeg_diphonorkegiatanpeg AS h ON k.PegID = h.PegID_id
WHERE PegUnitKerja = 3
GROUP BY k.PegID
how to make left join with django orm same like mysql query above?
Should be something like:
DipPegawai.objects.filter(PegUnitKerja=3).values_list.('pegnamalengkap', 'diphonorkegiatanpeg_kegnama')
Tell me if that worked for you.
You can print your raw query using print(your_var_here.query). Remember put your query into a var
DipHonorKegiatanPeg.objects.filter(PegID__PegUnitKerja=3).values('PegID__PegNamaLengkap', 'KegNama_id')
Related
I have the following models:
class Shelf(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=200, db_index=True)
slug = models.SlugField(max_length=200, editable=False)
games = models.ManyToManyField(Game, blank=True, through='SortedShelfGames')
objects = ShelfManager()
description = models.TextField(blank=True, null=True)
class SortedShelfGames(models.Model):
game = models.ForeignKey(Game, on_delete=models.CASCADE)
shelf = models.ForeignKey(Shelf, on_delete=models.CASCADE)
date_added = models.DateTimeField()
order = models.IntegerField(blank=True, null=True)
releases = models.ManyToManyField(Release)
objects = SortedShelfGamesManager.as_manager()
class Game(models.Model):
name = models.CharField(max_length=300, db_index=True)
sort_name = models.CharField(max_length=300, db_index=True)
...
I have a view where I want to get all of a user's SortedShelfGames, distinct on the Game relationship. I then want to be able to sort that list of SortedShelfGames on a few different fields. So right now, I'm doing the following inside of the SortedShelfGamesManager (which inherits from models.QuerySet) to get the list:
games = self.filter(
pk__in=Subquery(
self.filter(shelf__user=user).distinct('game').order_by('game', 'date_added').values('pk') # The order_by statement in here is to get the earliest date_added field for display
)
)
That works the way it's supposed to. However, whenever I try and do an order_by('game__sort_name'), the query takes forever in my python. When I'm actually trying to use it on my site, it just times out. If I take the generated SQL and just run it on my database, it returns all of my results in a fraction of a second. I can't figure out what I'm doing wrong here. The SortedShelfGames table has millions of records in it if that matters.
This is the generated SQL:
SELECT
"collection_sortedshelfgames"."id", "collection_sortedshelfgames"."game_id", "collection_sortedshelfgames"."shelf_id", "collection_sortedshelfgames"."date_added", "collection_sortedshelfgames"."order",
(SELECT U0."rating" FROM "reviews_review" U0 WHERE (U0."game_id" = "collection_sortedshelfgames"."game_id" AND U0."user_id" = 1 AND U0."main") LIMIT 1) AS "score",
"games_game"."id", "games_game"."created", "games_game"."last_updated", "games_game"."exact", "games_game"."date", "games_game"."year", "games_game"."quarter", "games_game"."month", "games_game"."name", "games_game"."sort_name", "games_game"."rating_id", "games_game"."box_art", "games_game"."description", "games_game"."slug", "games_game"."giantbomb_id", "games_game"."ignore_giantbomb", "games_game"."ignore_front_page", "games_game"."approved", "games_game"."user_id", "games_game"."last_edited_by_id", "games_game"."dlc", "games_game"."parent_game_id"
FROM
"collection_sortedshelfgames"
INNER JOIN
"games_game"
ON
("collection_sortedshelfgames"."game_id" = "games_game"."id")
WHERE
"collection_sortedshelfgames"."id"
IN (
SELECT
DISTINCT ON (U0."game_id") U0."id"
FROM
"collection_sortedshelfgames" U0
INNER JOIN
"collection_shelf" U1 ON (U0."shelf_id" = U1."id")
WHERE
U1."user_id" = 1
ORDER
BY U0."game_id" ASC, U0."date_added" ASC
)
ORDER BY
"games_game"."sort_name" ASC
I think you don't need a Subquery for this.
Here's what I ended up doing to solve this. Instead of using a Subquery, I created a list of primary keys by evaluating what I was using as the Subquery in, then feeding that into my query. It looks like this:
pks = list(self.filter(shelf__user=user).distinct('game').values_list('pk', flat=True))
games = self.filter(
pk__in=pks)
)
games = games.order_by('game__sort_name')
This ended up being pretty fast. This is essentially the same thing as the Subquery method, but whatever was going on underneath the hood in python/Django was slowing this way down.
i am using django(3.1.5). and i am trying to get parent model to child model by filter query
i have model like -
class Product(models.Model):
product_name = models.CharField(max_length=255, unique=True)
is_feature = models.BooleanField(default=False)
is_approved = models.BooleanField(default=False)
created_at = models.DateTimeField(auto_now_add=True)
class ProductGalleryImage(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE)
product_gallery_image = models.FileField(upload_to='path')
is_feature = models.BooleanField(default=False)
i am getting data from SELECT * FROM products_product AS pp INNER JOIN products_productgalleryimage AS ppgi ON ppgi.product_id = pp.id WHERE ppgi.is_feature=1 AND pp.is_feature=1 AND is_approved=1 ORDER BY pp.created_at LIMIT 4 mysql query.
so how can i get data like this query in django filter query
Firstly you can add related_name to ProductGalleryImage for better query support like this
product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name='product_images')
Then your query should be like this
products=Product.objects.filter(is_approved=True, is_feature=True, product_images__is_feature=True).order_by('created_at')[:4]
You can simply loop over the other related model like so:
for product_gallery_image in product_instance.productgalleryimage_set.all():
print(product_gallery_image.product_gallery_image)
The productgalleryimage_set here is simply the related model name in lowercase with _set appended. You can change this by setting the related_name attribute on the foreign key.
Note: This will perform a query to fetch each of the product_gallery_image objects of some product instance.
If you want to get the first object only:
product_gallery_image = product_instance.productgalleryimage_set.first()
If you want to perform a join as in your example which will perform only one query you can use select_related (this will only work in forward direction for reverse direction look at prefetch_related):
product_gallery_images = ProductGalleryImage.objects.all().select_related('product')
for product_gallery_image in product_gallery_images:
print(product_gallery_image.product.product_name)
print(product_gallery_image.product_gallery_image)
there are two tables:
class TBLUserProfile(models.Model):
userid = models.IntegerField(primary_key=True)
relmusicuid = models.IntegerField()
fansnum = models.IntegerField()
class TSinger(models.Model):
fsinger_id = models.IntegerField()
ftbl_user_profile = models.ForeignKey(TBLUserProfile, db_column='Fsinger_id')
I want to get Tsinger info and then order by TBLUserProfile.fansnum, I know how to write sql query: select * from t_singer INNER JOIN tbl_user_profile ON (tbl_user_profile.relmusicuid=t_singer.Fsinger_id) order by tbl_user_profile.fansnum, but I don't want to use model raw function. relmusicuid is not primary key otherwise I can use ForeignKey to let it work. How can I use django model to achieve this？
You can do like this :
Tsinger.objects.all().order_by('ftbl_user_profile__fansnum')
For information about Django JOIN :
https://docs.djangoproject.com/en/1.8/topics/db/examples/many_to_one/
I want to make query works as follow sql:
sql_str = '''
select * from luckydraw_winner W
inner join luckydraw_prizeverificationcodesmslog L on W.id =L.winner_id
where W.lucky_draw_id = %s
limit 10
'''
models:
class Winner(models.Model):
lucky_draw = models.ForeignKey(LuckyDraw)
participation = models.ForeignKey(Participation)
prize = models.ForeignKey(Prize)
mobile_number = models.CharField(max_length=15, null=True, default = None)
class PrizeVerificationCodeSMSLog(models.Model):
winner = models.ForeignKey(Winner)
mobile_number = models.CharField(max_length=15, db_index=True)
created_on = models.DateTimeField(auto_now_add=True)
because mobile_number isn't always filled in Winner model,what I want is a winner who has mobile number or who get the sms.So must join PrizeVerificationCodeSMSLog to make my purpose.
Only get winner is simple:
winners = models.Winner.objects.filter(lucky_draw_id=id).order_by('-created_on')[:10]
But I have no idea what filter can be added to join PrizeVerificationCodeSMSLog.
I have finally understood how to retrieve data I want in django.
If you want to get model A restricted by another model B which has a Foreign Key to A, do not try to use filter(). Because A don't know B,but B know A!Just retrieve A base B.
Try
logs = PrizeVerificationCodeSMSLog.objects.filter(winner__lucky_draw_id=id).order_by('-created_on')
winners = logs.select_related("winner")[:10]
This generates following query
SELECT "prizeverificationcodesmslog"."id", "prizeverificationcodesmslog"."winner_id",
"prizeverificationcodesmslog"."mobile_number", "prizeverificationcodesmslog"."created_on",
"winner"."id", "winner"."lucky_draw_id", "winner"."participation_id",
"winner"."prize_id", "winner"."mobile_number"
FROM "prizeverificationcodesmslog"
INNER JOIN "winner" ON ("prizeverificationcodesmslog"."winner_id" = "winner"."id")
WHERE "winner"."lucky_draw_id" = 1
ORDER BY "prizeverificationcodesmslog"."created_on"
DESC LIMIT 10;
I am not sure what are your requirements but you may want to agregate by Max PrizeVerificationCodeSMSLog
see https://docs.djangoproject.com/en/1.5/topics/db/aggregation/
Sorry for probably simple question but I'm a newby in Django and really confused.
I have an ugly legacy tables that I can not change.
It has 2 tables:
class Salespersons(models.Model):
id = models.IntegerField(unique=True, primary_key=True)
xsin = models.IntegerField()
name = models.CharField(max_length=200)
surname = models.CharField(max_length=200)
class Store(models.Model):
id = models.IntegerField(unique=True, primary_key=True)
xsin = models.IntegerField()
brand = models.CharField(max_length=200)
So I suppose I can not add Foreign keys in class definitions because they change the tables.
I need to execute such sql request:
SELECT * FROM Salespersons, Store INNER JOIN Store ON (Salespersons.xsin = Store.xsin);
How can I achieve it using Django ORM?
Or I'm allowed to get Salespersons and Store separately i.e.
stores = Store.objects.filter(xsin = 1000)
salespersons = Salespersons.objects.filter(xsin = 1000)
Given your example query, are your tables actually named Salespersons/Store?
Anyway, something like this should work:
results = Salespersons.objects.extra(tables=["Store"],
where=["""Salespersons.xsin = Store.xsin"""])
However, given the names of the tables/models it doesn't seem to me that an inner join would be logically correct. Unless you always have just 1 salesperson per store with same xsin.
If you can make one of the xsin fields unique, you can use a ForeignKey with to_field to generate the inner join like this:
class Salespersons(models.Model):
xsin = models.IntegerField(unique=True)
class Store(models.Model):
xsin = models.ForeignKey(Salespersons, db_column='xsin', to_field='xsin')
>>> Store.objects.selected_related('xsin')
I don't see why you can't use the models.ForeignKey fields even if the database lacks the constraints -- if you don't explicitly execute the SQL to change the database then the tables won't change. If you use a ForeignKey then you can use Salespersons.objects.select_related('xsin') to request that the related objects are fetched at the same time.