I would like to create and save model instances with Django.
These are my models:
class Customer(models.Model):
id = models.IntegerField(primary_key=True, unique=True)
user = models.OneToOneField(User, on_delete=models.CASCADE)
first_name = models.CharField(max_length=255)
last_name = models.CharField(max_length=255)
...
class Order(models.Model):
id = models.IntegerField(primary_key=True, unique=True)
customer = models.ForeignKey(Customer, on_delete=models.CASCADE)
comment = models.TextField()
...
I create an order like this:
def store_storage_space_order(cleaned_data):
try:
user = User.objects.create_user(
cleaned_data["customer_email"],
cleaned_data["customer_email"],
1234
)
customer = Customer.objects.create(
user=user,
first_name=cleaned_data["customer_firstname"],
last_name=cleaned_data["customer_lastname"],
email=cleaned_data["customer_email"],
phone_number=cleaned_data["customer_phone"]
)
StorageSpaceOrder.objects.create(
customer=customer,
order_price=Decimal(cleaned_data["order_price"])
)
except Exception as exc:
logger.exception("Couldn't store any order information", exc, cleaned_data)
As far as I've learned, Django will save the object on calling create as well.
Trying to save the order, I get the following error message:
save() prohibited to prevent data loss due to unsaved related customer
What I don't get; customer is already there and saved in the database. There are no changes on the customer in between.
Also, I've tried customer_id=customer.id/pk, - but both ID and PK return None.
Why is this and what do I need to change? Loading the object again is not the preferred way, as I only got the ID which marks it as unique.
Thanks for your input :)
ID fields have to be auto-generated by Django, so you don't need to declare them in your models.
If you do, you override the default behaviour called when an instance of this model is created/saved.
Related
I have a Django model which has relationship with user model. Where user are assigned to groups. especially "Admin", "Teacher","Student". So I want to make a foreign key relationship in such a way that it will show only The users that have been assigned to Teacher groups for Teacher_details model, And Similar for Student_Details Model. I have made the models Teacher_Details , Student_Details and established foreign key relation with User model. But the problem is that its showing all the user when I am filling Student_Details or Teacher_Details. Hope you got my problem.
I am hoping positive response.
The code looks like this:
class Student_Details(models.Model):
user = models.OneToOneField(User,on_delete=models.CASCADE)
image = models.ImageField(default='none', upload_to='img/')
details_updated = models.DateTimeField(auto_now_add=True)
address = models.CharField(max_length=150)
admission_date = models.DateField()
previous_college = models.CharField(max_length=150)
course_enrolled = models.ForeignKey(ModelUniversity,on_delete=models.CASCADE)
semester = models.CharField(max_length=20,choices=semester,default=None)
def __str__(self):
return self.user.first_name
class Teacher_Details(models.Model):
address = models.CharField(max_length=150)
image = models.ImageField(default='none', upload_to='img/')
details_updated = models.DateTimeField(auto_now_add=True)
subject_taught = models.ManyToManyField(to='Student.stu_subject')
user = models.OneToOneField(User,on_delete=models.CASCADE)
def __str__(self):
return self.user.first_name
def subject_teacher_teaches(self):
return [str(s) for s in self.subject_taught.all()]
Since both models have a user_id reference, you could use that info to search both models based on the request and fetch the necessary instance. Make a view which checks the user_id in the request, search both models and return the results (I assume a user cannot belong to both groups...)
I have two models. One is for UserProfile and the other is for Company.
class UserProfile(models.Model):
company_name = models.ForeignKey(Company, on_delete = models.CASCADE, related_name = 'company')
class Company(models.Model):
name = models.CharField(max_length = 100)
I am using Django Rest Framework for user creation. What I want to achieve is when I create a new user, I want to assign a company_name to that user. And if that company_name is not present in the db, then I want to create it on the go. But it is throwing an error. "Invalid hyperlink - No URL match."
You can use python's #property to tackle this problem in a clean and simple way. It works well for creating and for updating the object aswell. Note that the UserPorifle's field is renamed to company. Here is how you do it:
class Company(models.Model):
name = models.CharField(max_length=100)
class UserProfile(models.Model):
company = models.ForeignKey(Company, on_delete=models.CASCADE, related_name='company')
#property
def company_name(self):
return self.company.name
#company_name.setter
def company_name(self, value):
self.company, _ = Company.objects.get_or_create(name=value)
Now you can create objects using:
UserProfile.objects.create(company_name='Some name')
First you need to link your UserProfile Model with the user. It should be a OnetoOne Relationship because a User should only have one company I guess.
In your serializer you should add in the Company model and save the company name from the input in the API and then connect it to the new user that is being created.
I have a model like this:
class CreateDeal(models.Model):
name = models.CharField(max_length=100)
fuel = models.CharField(max_length=15)
mileage = models.PositiveIntegerField(db_index=True)
phone_number = models.CharField(max_length=17)
location = models.CharField(max_length=100, db_index=True)
car_picture = models.ImageField(upload_to='car_picture')
description = models.TextField()
price = models.PositiveSmallIntegerField(db_index=True)
available = models.BooleanField(default=True)
created_on = models.DateTimeField(default=timezone.now)
user = models.ForeignKey(User, on_delete=models.CASCADE)
def __str__(self):
return self.name
and I have a test class to test the model above like this:
class CreateDealTest(TestCase):
def setUp(self):
self.user = User.objects.create_user(
username='alfa', email='alfa#hotmail.com', password='top_secret'
)
self.deal = CreateDeal.objects.create(
name='deal1', mileage=100, price=25, user=self.user
)
def test_deal_name(self):
deal = CreateDeal.objects.get(name='deal1')
expected_deal_name = f'{self.deal.name}'
self.assertAlmostEqual(expected_deal_name, str(deal))
if I run the test I have:
Ran 1 test in 0.166s
OK
My question is why django don't raise an exception since almost all fields in my model are required. And what I don't understand is if I remove one field of Createdeal in my setUp (like mileage, price, user or name) I have an error.
For instance if I remove mileage, I have this error:
raise utils.IntegrityError(*tuple(e.args))
django.db.utils.IntegrityError: (1048, "Column 'mileage' cannot be null")
Charfield, Imagefield and Textfield can be empty string which is valid at the database level, some of your fields have default values so they will be written if not set so that makes them also valid at the database level.
PositiveIntegerField and Foreign key cannot be set to empty string, just to value or null so they will fail since null=False by default.
The default blank=False option is only applied at the validation level, not at the database level. This means if you call full_clean() on your model, it will raise a ValidationError. But nothing stops you from saving an invalid model (save() does not call full_clean() as explained here).
Basically, I have two models: User and Event. An event is always associated with one user.
class User(models.Model):
user_id = models.AutoField(primary_key=True)
username = models.CharField(max_length=255, unique=True)
hashed_password = models.CharField(max_length=255)
class Event(models.Model):
event_id = models.AutoField(primary_key=True)
title = models.CharField(max_length=255)
description = models.TextField(max_length=255, blank=True, default='')
user = models.ForeignKey(User)
And then I have the following form for Event.
class EventForm(forms.ModelForm):
class Meta:
model = Event
fields = ['title', 'description', 'user']
I can succesfully show this form in my template to create an event. I can also associate a user to a form successfully with Select field when the users number are still few.
Now the problem is, when I have 1M users in database, my browser crashes when loading the template. Any idea how to solve this one? I was thinking about using AJAX and then search user that matches the username, but I'd like to hear other better approaches. Thanks!
I'm trying to make own form adding object Announcement
models.py:
class Announcement(models.Model):
person = models.ForeignKey('Person')
source = models.CharField(max_length=30)
date = models.DateField(default=datetime.now())
valid_date = models.DateField(null=True,blank=True)
class Person(models.Model):
names = models.ManyToManyField('Name')
birth_date = models.DateField(null=True, blank=True)
class Name(models.Model):
first_name = models.CharField(max_length=50,blank=True)
middle_name = models.CharField(max_length=50, blank=True)
last_name = models.CharField(max_length=50, blank=True)
(It maybe loos weird, but in my concept each Person can have more than one Name, and also the same Name can be assigned to different Persons)
forms.py
from django import forms
from backoffice.models import Announcement
class AnnouncementForm(forms.ModelForm):
class Meta:
model = Announcement
fields = ('person','signature','organisation','source', 'date')
And everything works perfectly but I have to choose Person from selectbox. And it is expected behaviour.
But in my case i'm definetely sure, that person doesn't exists in base (all announcements are for different person for very long time - so i want to change person select box to three fields, and create new person (with new names) everytime I save the announcement.
I think I know how to save many to many, that's why i don't put the views.py, but I don't know how to set the forms.py to get fields.
I tried
class AnnouncementForm(forms.ModelForm):
class Meta:
model = Announcement
fields = ('person__names__first_name','signature','organisation','source', 'date')
but got Unknown field(s) (person__names__first_name) specified for Announcement
person__name__first_name will not really work in the forms, that only works for the django admin
you have to create a custom field for the first name and then create a logic for saving on either
def clean(self):
// logic here
or
def save(self, commit=True):
// put clean data here
announcement_form = super(AnnouncementForm, self).save(commit=False)
announcement_form.save()