Develop Reference

Django + Python Reference related data from Q Object

I have two models and a Q object.
How can I retrieve the related data (the field called GROUP) and add it into my serialized result set shown below?
Thank you in advance!
Model A
class WaiverAdult(models.Model):
first_name = models.CharField(max_length=50)
middle_initial = models.CharField(max_length=50, blank=True)
last_name = models.CharField(max_length=50, blank=True)
Model B
class CheckIns(models.Model):
adult = models.ForeignKey(
WaiverAdult, on_delete=models.CASCADE, blank=True, null=True, related_name='adult_checkin')
checkin = models.DateTimeField(blank=True, null=True)
checkout = models.DateTimeField(blank=True, null=True)
group = models.IntegerField(blank=True, null=True)
Query
group_adults = serializers.serialize('jsonl', WaiverAdult.objects.filter(
Q(adult_checkin__checkin__gte=today()) & Q(adult_checkin__group__exact=group)), fields=('first_name', 'last_name'))

You can annotate this, with:
from django.db.models import Value
group_adults = serializers.serialize(
'jsonl',
WaiverAdult.objects.filter(
adult_checkin__checkin__gte=today(), adult_checkin__group=group
).annotate(group=Value(group)),
fields=('first_name', 'last_name', 'group'),
)

How to join 3 or more than 3 models in one single query ORM?

I am having 4 models linked with a foreign key,
class CustomUser(AbstractUser):
username = None
email = models.EmailField(('email address'), unique=True)
phone_no = models.CharField(max_length=255, unique=True)
USERNAME_FIELD = 'email'
REQUIRED_FIELDS = []
objects = CustomUserManager()
def __str__(self):
return self.email
class personal_profile(models.Model):
custom_user = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
picture = models.ImageField(default='profile_image/pro.png', upload_to='profile_image', blank=True)
role = models.CharField(max_length=255, blank=True, null=True)
gender = models.CharField(max_length=255, blank=True, null=True)
date_of_birth = models.DateField(blank=True, null=True)
def __str__(self):
return str(self.pk)
class academia_profile(models.Model):
custom_user = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
education_or_certificate = models.CharField(max_length=255, blank=True, null=True)
university = models.CharField(max_length=255, blank=True, null=True)
def __str__(self):
return str(self.pk)
class contact_profile(models.Model):
custom_user = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
country = models.CharField(max_length=255, blank=True, null=True)
state = models.CharField(max_length=255, blank=True, null=True)
city = models.CharField(max_length=255, blank=True, null=True)
def __str__(self):
return str(self.pk)
For extracting the data of those four models, I need to extract it by querying 4 times differently and then by passsing for different variables to HTML templates it something a hectic plus would be reducing the performance speed (I am sure!)
My current queries be like
user_base = CustomUser.objects.get(id=user_id)
user_personal = personal_profile.objects.get(custom_user=user_id)
academia = academia_profile.objects.get(custom_user=user_id)
contact = contact_profile.objects.get(custom_user=user_id)
Is it possible to get all of the four queries values in a single variable by hitting a single join query in ORM ?
also, I want to extract just the country from contact_profile and picture from personal_profile in the join query.
Select_related() can able to work here but how? that's what I am not getting.

You are looking for prefetch_related:
Returns a QuerySet that will automatically retrieve, in a single batch, related objects for each of the specified lookups.
user_base = (
CustomUser
.objects
.prefetch_related( #<-- THIS!
"personal_profile_set",
"academia_profile_set",
"contact_profile_set")
.get(id=user_id))
personal_profile = user_base.personal_profile_set.all()[0]
academia_profile = user_base.academia_profile_set.all()[0]
contact_profile = user_base.contact_profile_set.all()[0]
Btw, if you have only one personal_profile, academia_profile, contact_profile per CustomUser, consider changing ForeignKey by OneToOneField and use select_related.

Django multiple foreign key to a same table

I need to log the transaction of the item movement in a warehouse. I've 3 tables as shown in the below image. However Django response error:
ERRORS:
chemstore.ItemTransaction: (models.E007) Field 'outbin' has column name 'bin_code_id' that is used by another field.
which is complaining of multiple uses of the same foreign key. Is my table design problem? or is it not allowed under Django? How can I achieve this under Django? thankyou
DB design
[Models]
class BinLocation(models.Model):
bin_code = models.CharField(max_length=10, unique=True)
desc = models.CharField(max_length=50)
def __str__(self):
return f"{self.bin_code}"
class Meta:
indexes = [models.Index(fields=['bin_code'])]
class ItemMaster(models.Model):
item_code = models.CharField(max_length=20, unique=True)
desc = models.CharField(max_length=50)
long_desc = models.CharField(max_length=150, blank=True)
helper_qty = models.DecimalField(max_digits=10, decimal_places=4)
unit = models.CharField(max_length=10, blank=False)
def __str__(self):
return f"{self.item_code}"
class Meta:
verbose_name = "Item"
verbose_name_plural = "Items"
indexes = [models.Index(fields=['item_code'])]
class ItemTransaction(models.Model):
trace_code = models.CharField(max_length=20, unique=False)
item_code = models.ForeignKey(
ItemMaster, related_name='trans', on_delete=models.CASCADE, null=False)
datetime = models.DateTimeField(auto_now=False, auto_now_add=False)
qty = models.DecimalField(max_digits=10, decimal_places=4)
unit = models.CharField(max_length=10, blank=False)
action = models.CharField(
max_length=1, choices=ACTION, blank=False, null=False)
in_bin = models.ForeignKey(
BinLocation, related_name='in_logs', db_column='bin_code_id', on_delete=models.CASCADE, null=False)
out_bin = models.ForeignKey(
BinLocation, related_name='out_logs', db_column='bin_code_id', on_delete=models.CASCADE, null=False)
remarks = models.TextField(blank=True)
def __str__(self):
return f"{self.trace_code} {self.datetime} {self.item_code} {dict(ACTION)[self.action]} {self.qty} {self.unit} {self.in_bin} {self.out_bin}"

you have same db_column in two fields so change it
in_bin = models.ForeignKey(
BinLocation, related_name='in_logs', db_column='bin_code_id', on_delete=models.CASCADE, null=False)
out_bin = models.ForeignKey(
BinLocation, related_name='out_logs', db_column='other_bin_code', on_delete=models.CASCADE, null=False) /*change db_column whatever you want but it should be unique*/

If are linked to the same model name, You should use different related_name for each foreign_key filed . here is the exemple :
address1 = models.ForeignKey(Address, verbose_name=_("Address1"),related_name="Address1", null=True, blank=True,on_delete=models.SET_NULL)
address2 = models.ForeignKey(Address, verbose_name=_("Address2"),related_name="Address2", null=True, blank=True,on_delete=models.SET_NULL)

thank you for everyone helped. According to Aleksei and Tabaane, it is my DB design issue (broken the RDBMS rule) rather than Django issue. I searched online and find something similar: ONE-TO-MANY DB design pattern
In my case, I should store in bin and out bin as separated transaction instead of both in and out in a single transaction. This is my solution. thankyou.
p.s. alternative solution: I keep in bin and out bin as single transaction, but I don't use foreign key for bins, query both in bin and out bin for the bin selection by client application.

How to make an inner join query with same table using Django's ORM

The query to be implemented with ORM is as follows,
SELECT t2.*
FROM sub_menu AS t1
INNER JOIN sub_menu AS t2 ON (t1.sub_menu_id = t2.parent_sub_menu_id)
WHERE t1.sub_menu_id = 1;
The model is as follows,
class SubMenu(models.Model):
sub_menu_id = models.AutoField(primary_key=True)
menu = models.ForeignKey('commons.MainMenu', related_name='sub_menus', on_delete=models.CASCADE)
parent_sub_menu_id = models.IntegerField(blank=True, null=True)
name = models.CharField(max_length=50)
en_name = models.CharField(max_length=50, blank=True)
ord = models.IntegerField()
api = models.CharField(max_length=255, blank=True)
api_method = models.CharField(max_length=7, blank=True)
api_detail = models.CharField(max_length=255, blank=True)
menu_type_cd = models.CharField(max_length=5, blank=True)
menu_auth_type_cd = models.CharField(max_length=5)
is_common = models.BooleanField(default=False)
is_ns = models.BooleanField(default=False)
spc_auth = models.BooleanField(default=False)
spc_auth_cd = models.CharField(max_length=5, blank=True)
create_dt = models.DateTimeField(auto_now_add=True)
update_dt = models.DateTimeField(auto_now=True)
class Meta:
db_table = 'sub_menu'
unique_together = ('api', 'api_method',)
Not using a raw method, Is it possible to implement with Django's ORM?
Thank you.

You should do the relationship correctly on your model: https://docs.djangoproject.com/en/3.0/ref/models/fields/#module-django.db.models.fields.related. Then the parent_sub_menu should be:
class Submenu:
parent_sub_menu = models.ForeignKey('self', null=True, blank=True, on_delete=models.CASCADE)
Then run generate & DB migration. The query below should work.
And never declare relationship like you are doing right now, use Model instead via the documentation I sent.
Django does it for you already. You can just filter the related field.
https://docs.djangoproject.com/en/3.0/topics/db/queries/#lookups-that-span-relationships
SubMenu.objects.filter(parent_sub_menu__sub_menu_id=1)

Django Tastypie ToOneField error

I'm trying to create a one-to-one relationship matching a table with property billing records to another with physical addresses, but I keep getting this error. When I search for the error, nothing shows that is relevant to this situation.
I've no idea what "[<PropertyRecord: 242811400004>]" is referencing since it isn't a PIN number and doesn't exist in any tables.
Also, I've been through the data and there are no null values on the pin in either table.
Getting this error:
{
error: "The object '[<PropertyRecord: 242811400004>]' has an empty attribute 'pin' and doesn't allow a default or null value."
}
Models:
class PropertyRecord(models.Model):
pin = models.BigIntegerField(db_index=True, max_length=20)
date_added = models.DateField(null=True)
last_chgdte = models.DateField()
name = models.CharField(db_index=True, max_length=30, null=True)
address1 = models.CharField(max_length=100, null=True)
address2 = models.CharField(max_length=100, null=True)
city = models.CharField(max_length=50, null=True)
state = models.CharField(max_length=2, null=True)
zip = models.CharField(max_length=10, null=True)
class Meta:
unique_together = ("pin", "last_chgdte")
select_on_save = True
def __str__(self):
return str(self.pin)
class PropertyAddress(models.Model):
pin = models.BigIntegerField(db_index=True, max_length=20, unique=True)
street_address = models.CharField(max_length=50, null=True)
city_name = models.CharField(max_length=50, null=True)
zip_code = models.IntegerField(max_length=5, null=True)
class Meta:
select_on_save = True
def __str__(self):
return str(self.pin)
Resources:
class PropertyAddressResource(ModelResource):
class Meta:
queryset = PropertyAddress.objects.all()
class PropertyRecordResource(ModelResource):
full_address = fields.ToOneField(
PropertyAddressResource,
attribute=lambda bundle: PropertyRecord.objects.filter(pin=bundle.obj.pin),
full=True,
null=True
)
class Meta:
queryset = PropertyRecord.objects.all()
resource_name = 'propertyrecords'

I can't imagine that joining tables wouldn't be a common need, so it should have a simple solution.
Rather, I was able to get around the issue by using dehydrate, which feels overly complicated but works. +1 to this being a PITA with the extra step to serialize the data.
def dehydrate(self, bundle):
query_data = PropertyAddress.objects.filter(pin=bundle.obj.pin)
results = serialize('json', query_data, fields=('street_address', 'city_name', 'zip_code'))
bundle.data['full_address'] = json.loads(results)
return bundle