Here is my models:
enter code here
class Room_Type(models.Model):
"""Django data model Room_Type"""
ROOM_CATEGORIES={
('Elt','Elite'),
('Lux','Luxury'),
('Sig','Signature')
}
image = models.ImageField(upload_to="pics")
roomtype = models.CharField(choices=ROOM_CATEGORIES,max_length=20)
price = models.CharField(blank=True, max_length=100)
def __str__(self):
return f'{self.roomtype}
I want Id with any one of the detail given in model,Help me solve geeks
when you create a model id is automatically created in django if you want to access that id you can access like this in your view
room_type = Room_Type.objects.get(name='John')
print(room_type.id)
Related
I have two models, Product and Price. I have used the ForeignKey association of the Django models to define the association between product and price. the scenario is, one product can have multiple prices according to size. On the home page, I have to fetch all the products with their prices and need to show their price(probably base price).
Following is the code that I tried.
class Product(BaseModel):
name = models.CharField(max_length=50)
category = models.ForeignKey(Category, null=True, on_delete=models.SET_NULL, help_text='Please add new category if not given.')
image = models.ImageField(upload_to='images/')
tag = models.ManyToManyField(Tag, help_text='You can add multiple tags')
slug = models.SlugField(unique=True, null=True)
time = models.TimeField(verbose_name='Time Required')
class Price(BaseModel):
product = models.ForeignKey(Product, on_delete=models.CASCADE)
size = models.FloatField(validators=[MinValueValidator(0)])
amount = models.FloatField(validators=[MinValueValidator(0)])
Then in the view.py file
class ProductListView(ListView):
model = Product
context_object_name = 'products'
paginate_by = 32
def get_context_data(self,*args, **kwargs):
object = super(ProductListView, self).get_context_data(*args, **kwargs)
object['categories'] = Category.objects.order_by('name')
return object
def get_queryset(self):
return Product.objects.order_by('name')
In the template, I am able to get and loop through the categories and products but I am not able to access the related prices of each product.
If I tried something in the get_context_data, will it cause N+1 queries to fetch prices for every product?
In the template I tried to use something like {{ product.price_set }} but it returns order.Price.None.
use {{ product.price_set.all }}.
To avoid N+1 queries in your filter, use prefetch_related so it looks something like.
Product.objects.all().prefetch_related('price_set')
See prefetch_related in the Django documentation.
See also select related vs prefetch related
I Have a Invoice system where employee or staff can create invoice and can add multiple product and quantity for the specific customer . as i am using mysql i cant take json data or an array data .so i was taking the quantity and price( after discount and other modificaion) as a string and then when showing or printing the invoice i used regex to find the quantity and price .i added product ids in a manytomay field from where i am getting the product name and selling price. while showing the data on printing page in when i use zip the products are showing as the id of the product so i want to retrive the data the way it is being saved . or could you tell me any way to do it more easier way?
Here is my models.py
class Invoice(models.Model):
customers = models.ForeignKey(Customer, on_delete=models.CASCADE)
products = models.ManyToManyField(Product)
total = models.FloatField()
date = models.DateField(auto_now_add=True)
amounts = models.CharField(max_length=500, default="00")
quantity = models.CharField(max_length=500, blank=True)
def save(self, *args, **kwargs):
if not Invoice.objects.count():
self.id = 20210001
else:
self.id = Invoice.objects.last().id + 1
super(Invoice, self).save(*args, **kwargs)
Here is my views.py of printing page function
def final_billing(request, id=None):
pk = id
obj = Invoice.objects.get(id=pk)
products = obj.products.all()
customer = Customer.objects.get(id=obj.customers.id)
amn = obj.amounts
qt = obj.quantity
list_of_comma = re.findall("[\d+.+\d]+", amn)
amnts = [float(n) for n in list_of_comma]
list_of_quantity = re.findall('[0-9]+', qt)
qty = [int(n) for n in list_of_quantity if n.isdigit()]
products = list(products)
both = zip(products,amnts,qty)
return render(request, 'finalbill.html',{'bills': obj, "due": customer, "both": both})
I want it to be retrieved the product objects in the sequence of it was saved
The query can only be sorted with a specific field, Django cannot guess otherwise, so in your case the best case is to sort your products by the date they were created, for example :
obj.products.all().order_by("created")
This suppose that you have a "created" field that is added each time a product is save in your database.
Another way of doing it is to specify the through option, from the documentation :
you can use the through option to specify the Django model that represents the intermediate table that you want to use.
The most common use for this option is when you want to associate extra data with a many-to-many relationship.
The through table contains an the primary key of the relation, you can use that to retrieve the sequence in which your objects were added.
for example :
from django.db import models
class Person(models.Model):
name = models.CharField(max_length=50)
class Group(models.Model):
name = models.CharField(max_length=128)
members = models.ManyToManyField(
Person,
through='Membership',
through_fields=('group', 'person'),
)
class Membership(models.Model):
group = models.ForeignKey(Group, on_delete=models.CASCADE)
person = models.ForeignKey(Person, on_delete=models.CASCADE)
inviter = models.ForeignKey(
Person,
on_delete=models.CASCADE,
related_name="membership_invites",
)
invite_reason = models.CharField(max_length=64)
Through Field
I want to create a method that copies an object of the BlogPost model. my models looks like this:
class BlogPost(models.Model):
title = models.CharField(max_length=250)
body = models.TextField()
author = models.ForeignKey(Author, on_delete=models.CASCADE)
date_created = models.DateTimeField(auto_now_add=True)
def copy(self):
pass
class Comment(models.Model):
blog_post = models.ForeignKey(
BlogPost, on_delete=models.CASCADE, related_name="comments"
)
text = models.CharField(max_length=500)
my challenge is implementing the copy method. The copy method should copy the current object with all the comments related to that and I don't have any idea how to do it.
Do you mean you want to save a copy to the database. If so you can do this:
class MyModel(models.Model):
...
def copy(self):
self.id = None
self.save()
The way this works is that if a model instance doesn't have an id, then when you call it's save method, django adds one and creates a new row in your table.
I have two different models: Trainer and User. I'm pulling in the trainer_price field from Trainer into my form in User. Please note that I'm also not using a foreign key.
The problem I'm having is that the trainer_price is not getting inserted and the default value of 0 is there, which is not what I want.
The way the User form works is they fill out their name, address, email and the trainer_price is automatically populated once they selected a trainer. It's also a read-only field.
Here's what I've tried so far:
user views.py
def buyer(request):
user_form = UserForm()
trainer_listing = Trainer.objects.get(id=15).trainer_price
context = {'user_form':user_form, 'trainer_listing':trainer_listing}
if request.method == "POST":
user_form = UserForm(request.POST)
if user_form.is_valid():
user_form.save()
return redirect("/success_page")
return render(request, "user/user_form.html", context)
forms.py
class UserForm(forms.ModelForm):
Fullname = forms.CharField(widget=forms.TextInput(attrs={'placeholder': 'John Doe'}))
Email = forms.CharField(widget=forms.TextInput(attrs={'placeholder': 'Email'}))
Mobile = forms.CharField(widget=forms.TextInput(attrs={'placeholder': '312-222-2222'}))
Address = forms.CharField(widget=forms.TextInput(attrs={'placeholder': '1234 Main St'}))
City = forms.CharField()
State = forms.ChoiceField(choices=STATES)
zipcode = forms.CharField()
trainer_price = forms.DecimalField(label="Trainer Price", required=False, widget=forms.TextInput(attrs={'readonly':'readonly'}))
class Meta:
model = User
fields = ['Fullname','Email', 'Mobile', 'Address', 'City',
'State', 'zipcode', 'trainer_price']
Any help in the right direction would be great!
Basically, we can set default values for the form field using the initial argument.
def buyer(request):
trainer = Trainer.objects.get(id=15)
user_form = UserForm(initial={"trainer_price": trainer.trainer_price})
# etc
PS. Make sure that you do not populate the value from the trainer_price with the results from the request.POST. Smart users could use this to get very cheap deals. In stead, always re-query the actual value.
I have recently come to know about fastAPI and worked my way through the tutorial and other docs. Although fastAPI is pretty well documented, I couldn't find information about how to process a nested input when working with a database.
For testing, I wrote a very small family API with two models:
class Member(Base):
__tablename__ = 'members'
id = Column(Integer, primary_key=True, server_default=text("nextval('members_id_seq'::regclass)"))
name = Column(String(128), nullable=False)
age = Column(Integer, nullable=True)
family_id = Column(Integer, ForeignKey('families.id', deferrable=True, initially='DEFERRED'), nullable=False, index=True)
family = relationship("Family", back_populates="members")
class Family(Base):
__tablename__ = 'families'
id = Column(Integer, primary_key=True, server_default=text("nextval('families_id_seq'::regclass)"))
family_name = Column(String(128), nullable=False)
members = relationship("Member", back_populates="family")
and I created a Postgres database with two tables and the relations described here. With schema definitions and a crud file as in the fastAPI tutorial, I can create individual families and members and view them in a nested fashion with a get request. Here is the nested schema:
class Family(FamilyBase):
id: int
members: List[Member]
class Config:
orm_mode = True
So far, so good. Now, I would like to add a post view which accepts the nested structure as input and populates the database accordingly. The documentation at https://fastapi.tiangolo.com/tutorial/body-nested-models/ shows how to do this in principle, but it misses the database (i.e. crud) part.
As the input will not have id fields and obviously doesn't need to specify family_id, I have a MemberStub schema and the NestedFamilyCreate schema as follows:
class MemberStub(BaseModel):
name: str
age: int
class NestedFamilyCreate(BaseModel):
family_name: str
members: List[MemberStub]
In my routing routine families.py I have:
#app.post('/nested-families/', response_model=schemas.Family)
def create_family(family: schemas.NestedFamilyCreate, db: Session = Depends(get_db)):
# no check for previous existence as names can be duplicates
return crud.create_nested_family(db=db, family=family)
(the response_model points to the nested view of a family with all members including all ids; see above).
What I cannot figure out is how to write the crud.create_nested_family routine. Based on the simple create as in the tutorial, this looks like:
def create_nested_family(db: Session, family: schemas.NestedFamilyCreate):
# split information in family and members
members = family.members
core_family = None # ??? This is where I get stuck
db_family = models.Family(**family.dict()) # This fails
db.add(db_family)
db.commit()
db.refresh(db_family)
return db_family
So, I can extract the members and can loop through them, but I would first need to create a new db_family record which must not contain the members. Then, with db.refresh, I would get the new family_id back, which I could add to each record of members. But how can I do this? If I understand what is required here, I would need to achieve some mapping of my nested schema onto a plain schema for FamilyCreate (which works by itself) and a plain schema for MemberCreate (which also works by itself). But how can I do this?
I found a solution after re-reading about Pydantic models and their mapping to dict.
in crud.py:
def create_nested_family(db: Session, family: schemas.NestedFamilyCreate):
# split information in family and members
family_data = family.dict()
member_data = family_data.pop('members', None) # ToDo: handle error if no members
db_family = models.Family(**family_data)
db.add(db_family)
db.commit()
db.refresh(db_family)
# get family_id
family_id = db_family.id
# add members
for m in member_data:
m['family_id'] = family_id
db_member = models.Member(**m)
db.add(db_member)
db.commit()
db.refresh(db_member)
return db_family
Hope, this may be useful to someone else.