I am using django to create an inventory management system. There are two models store and retailer. Each retailer can only work in one store, but each store can have many retailer s.
Therefore, store is a ForeignKey in my retailer model. I have registered models in django admin. When I add a retailer I can choose a store.
When I add a store, I would like to be able to add a retailer to a store in the same page I add a store.
class Retailer(models.Model):
user = models.OneToOneField(User,on_delete=models.CASCADE)
phone_number = models.IntegerField(default=00000000000)
store = models.ForeignKey(Store,null=True,on_delete=models.CASCADE)
class Store(models.Model):
name = models.CharField(max_length=200)
serial = models.CharField(max_length=200)
number_of_visitors = models.IntegerField(default=0)
it is called inline models:
https://books.agiliq.com/projects/django-admin-cookbook/en/latest/edit_multiple_models.html
https://docs.djangoproject.com/en/dev/ref/contrib/admin/#inlinemodeladmin-objects
And you can find a lot of material about,
But you need something like this:
on your admin.py
#Create a class for inline display:
class RetailerINLINE(admin.TabularInline): #or stacked inline
model = Retailer
extra = 1
class StoreAdmin(admin.ModelAdmin):
.....
inlines = RetailerINLINE,
Related
I am creating an ecommerce website using Django-rest-framework and react. I am trying to add items to cart. I am able to add items to the cart on the frontend but I want to store the cart data to the backend (Django) database so that whenever the user add items to cart and reloads the page the items should still be in his cart like any other ecommerce site. Here is my Code for django models, serializers, viewset.
class Products(models.Model):
title = models.CharField(max_length=100)
image = models.URLField()
description = models.TextField(max_length=500, blank=True, null=True)
category = models.CharField(max_length=50, blank=True, null=True)
rating = models.IntegerField(blank=True, null=True)
price = models.FloatField()
def __str__(self):
return f"{self.id}"
class Cart(models.Model):
product = models.ManyToManyField(
Products, related_name="cart")
buyer = models.ForeignKey(
User, on_delete=models.CASCADE, related_name="cart")
def __str__(self) -> str:
return f"{self.buyer}"
class ProductsSerializer(serializers.ModelSerializer):
class Meta:
model = Products
fields = '__all__'
class CartSerializer(serializers.ModelSerializer):
class Meta:
model = Cart
fields = '__all__'
class ProductsViewSet(viewsets.ModelViewSet):
queryset = Products.objects.all()
serializer_class = ProductsSerializer
class CartViewSet(viewsets.ModelViewSet):
queryset = Cart.objects.all()
authentication_classes = [JWTAuthentication]
permission_classes = [
permissions.IsAuthenticated
]
serializer_class = CartSerializer
router = routers.DefaultRouter()
router.register('products', ProductsViewSet, 'products')
router.register('cart', CartViewSet, 'cart')
I am using postman to post the cart items. I am able to add more than one products for a single buyer.
but the problem is when i again add another product to the same user using postman i added before, it creates another row for the same user.
I do not want that. I want a single instance or row of a user in cart table and add as many products as i want. when i post other products for the same user, that product should also get added up in the single user row or instance. What is the best way to achieve my goal.
Here is the issue, Django can't automatically do that because it doesn't know which behaviour is expected. If you look at the code to add a product and look at the code to add a cart, it's exactly the same. So behaviour will also be the same.
For the behaviour that you want, you will have to override the create method of your ModelViewSet.
Here are the steps to achieve what you want -
Check whether or not the user with that id already has a cart.
If they have a cart, then you'll need to fetch the cart object belonging to that user and add products to it.
If they don't, then you'll have to create a new cart object and do the default thing.
class CartViewSet(viewsets.ModelViewSet):
queryset = Cart.objects.all()
authentication_classes = [JWTAuthentication]
permission_classes = [
permissions.IsAuthenticated
]
serializer_class = CartSerializer
def create(self, request):
# Checking whether the Cart object already exists for the buyer
cart = Cart.objects.filter(buyer_id = request.data.get("buyer"))
if len(cart)=1:
#If cart exists, we loop through the list of product ids and add them
for product_id in request.data.get("product"):
cart[0].product.add(get_object_or_404(Product, id = product_id ))
if len(cart)=0:
# Doing what normally happens.
return super().create(request)
if len(cart)>1:
#Error in database. One person having multiple carts. Custom error message.
To check out how to add data to many-to-many fields, check this out.
I have a main table
Slideshow
then a site specific table that captures a few extra details for that site.
Site1_Slideshow
In a web app (specific to a site) i want a single model i.e. Slideshow that combines the 2 tables above.
Currently i have the code below, but i dont think this is correct. I cant do things like
s = Slideshow.objects.get(slideshowId=1) as Slideshows only has the properties featurecategory and slideshow. So how can i have an model called Slideshow that is composed of these 2 tables but looks like it was a single db table.
class SlideshowAbstract(models.Model):
slideshowid = models.IntegerField(primary_key=True, db_column=u'SlideshowId') # Field name made lowercase.
headline = models.TextField(db_column=u'Headline') # Field name made lowercase.
class Meta:
db_table = u'Slideshow'
class Slideshow(models.Model):
slideshow = models.OneToOneField(SlideshowAbstract, primary_key=True,db_column=u'SlideshowId')
def __unicode__(self):
return self.slideshow.headline
class Meta:
db_table = u'Site1_Slideshow'
Think i found the solution.
On the Site1_Slideshow you need to add a column for django to use, that i presume is always the same as primary key value.
Its name is SlideshowAbstract_ptr_id
Once that is added you can change the Slideshow model to be
class Slideshow(SlideshowAbstract):
featureCategory = models.ForeignKey(Featurecategory,db_column=u'FeatureCategoryId')
def __unicode__(self):
return self.headline
class Meta:
db_table = u'Site1_Slideshow'
So doable but not the nicest if you are not doing "model first" and already have the schema. Would be good to be able to override the name of the _ptr_id column.
I did try adding the following to Slideshow too see if i could map this ptr col to the primary key
slideshowabstract_ptr_id = models.IntegerField(primary_key=True, db_column=u'SlideshowId')
but no cigar.
I havent tested inserts either but ...objects.all() works
Hi I have a lot of users in my system who are classified into different types. I want to store the address details of all those users. For instance the user could be a student, a school or a franchisee. All the users here could have an address information associated with them.
from django.db import models
from django.contrib.auth.Models import User
class Address(models.Model):
user = models.OneToOneField(User)
address = models.TextField()
class Student(models.Model):
user_id = models.ForeignKey(User)
address = models.ForeignKey(Address)
class School(models.Model):
user_id = models.ForeignKey(User)
address = models.ForeignKey(Address)
contact_person_name = models.CharField(max_length=50)
In this scenario there are 2 references to the User model - one through user_id and another through address.user though they should be referring to the same instance. Is it a bad practice to have duplicate references?
I thought of leaving out the 'user' foreignkey in Address, but I think that the address can't exist without a user. How to better model this?
As you already mentioned in question duplication of same field in
a model is not a good Idea.
If these are your actual models, I would suggest you using abstract
models:
from django.db import models
from django.contrib.auth.Models import User
class Profile(models.Model):
user = models.OneToOneField(User, related_name="%(app_label)s_%(class)s_related")
address = models.TextField()
class Meta:
abstract = True
class Student(Profile):
pass
class School(Profile):
contact_person_name = models.CharField(max_length=50)
This will generate two tables: students, schools with fields
user, address and user, address, contact_person_name
respectively.
I have Guest model in my app:
class Guest(models.Model):
event = models.ForeignKey(Event, related_name='guests')
contact = models.ForeignKey(Contact, related_name='guests')
attending_status = models.CharField(max_length=32, choices=ATTENDING_CHOICES, default='no_rsvp')
number_of_guests = models.SmallIntegerField(default=0)
comment = models.CharField(max_length=255, blank=True, default='')
updated = models.DateTimeField(blank=True, null=True)
Event and Contact I fill up by myself in Admin when creating a guest. On the site all I want is a guest to fill up the form where he refreshes his attending status, points out number of guests and leaves a comment.
class RSVPForm(forms.Form):
attending = forms.ChoiceField(choices=VISIBLE_ATTENDING_CHOICES, initial='yes', widget=forms.RadioSelect)
number_of_guests = forms.IntegerField(initial=0)
comment = forms.CharField(max_length=255, required=False, widget=forms.Textarea)
How can I save the changes to the Guest model instance? How can I access the guest's id when saving the changes to his profile?
You are probably looking for Django's ModelForms. Instead of subclassing forms.Form in your RSVPForm class, you should subclass forms.ModelForm. Then you can use the features of the model form class to help you achieve what you want (hide some fields, etc). An example is below:
class RSVPForm(forms.ModelForm):
class Meta:
model = Guest
fields = ('attending_status', 'number_of_guests', 'comment')
This will do essentially what you want, but you will need to remember to provide an instance keyword argument to the form constructor in your view function. This argument is the instance of the Guest model you will be updating with the form.
form = RSVPForm(instance=guest_object)
Now calls to the form.save() method will automatically save the new data to this Guest object instance. You just need to make sure that you always pass the instance keyword argument, even when using request.POST:
form = RSVPForm(request.POST, instance=guest_object)
I have a course catalogue and am trying to include pre-requisits.
A course has 0 to n pre-requisits and a course can be the pre-quesit for 0 to n courses.
The course class is as follows
class Course(models.Model):
class Meta:
ordering = ['course_code', 'title']
course_id = models.AutoField(primary_key=True)
course_code = models.SlugField(max_length=20, null=False, blank=False)
....
....
class Pre_requisit(models.Model)
course = models.ForeignKey(Course, course_id')
pre_req = ???????
I have tried the pre_req field as a ForeginKey and MamyToManyField but cant find a solution.
Django will not allow 2 ForeignKeys from Pre_requisit class to the Course class.
With the ManyToMany field evn through another table I still get errors.
Can anyone let me know how to acheive this relationship.
I wish to ensure the pre-requisit course exists and be able to link to it so it can be displayed.
Many thanks.
class Course(models.Model):
....
pre_req = models.ManyToManyField("self")
read more at http://docs.djangoproject.com/en/dev/ref/models/fields/#manytomanyfield
If you wish to store extra info you can specify a "through" table also ( info at http://docs.djangoproject.com/en/dev/topics/db/models/#intermediary-manytomany) such as hard pre-requisite or recommended etc.