Consider these pseudo models:
class Category(models.Model):
name = models.CharField()
class Product(models.Model):
name = models.CharField()
code = models.CharField()
category = models.ForeignKey(Category)
price = models.DecimalField()
stock = models.IntegerField()
class AlternativeProduct(Product):
original_product = models.ForeignKey(Product, related_name="alternative", editable=False)
I want to use inlines to be able to quickly add a product and its alternative option without typing duplicate data (ONLY code, stock and price differentiate).
admin.py
class AlternativeProductInline(admin.TabularInline):
model = AlternativeProduct
formset = AlternativeProductInlineFormset
fk_name = "original_product"
fields = ["code", "price", "in_stock"]
max_num = 1
extra = 0
class ProductAdmin(admin.ModelAdmin):
form = ProductAdminForm
inlines = [AlternativeProductInline]
Ofcourse this will raise ValidationError, because AlternativeProduct is missing a category.
Now I could setup a default value to fix that:
class Product(models.Model):
name = models.CharField()
code = models.CharField()
category = models.ForeignKey(Category, default=1)
price = models.DecimalField()
stock = models.IntegerField()
But besides the fact this id might not exist it still needs to be corrected. Is there any other way (besides Javascript) to copy the category value of the genuine product to the alternative inline product 'under the hood'
I have tried to change the admin_view, but it gets hackish, perhaps a custom view would be a nice solution although javascript is a less time consuming approach.
Javascript does seem to be the easy approach to achieve this.
$(document).ready(function(){
$('#alternative-group thead th:nth-child(2)').hide();
$('#alternative-group tbody td:nth-child(1) p').hide();
$('#alternative-group tbody td:nth-child(3)').hide();
$('#id_alternative-0-category').hide();
var product_category = $('#id_category option:selected').val();
$('#id_alternative-0-category').val(product_category);
$("#id_category").change(function() {
product_category = $('#id_category option:selected').val();
$('#id_alternative-0-category').val(product_category);
});
});
Related
models.py
class products(models.Model):
name = models.CharField(max_length=100)
sku = models.CharField(max_length=50)
vendor = models.CharField(max_length=50)
brand = models.CharField(max_length=50)
price = models.FloatField()
product_status = models.BooleanField()
quantity = models.IntegerField()
def __str__(self):
return self.name
# categories
class categories(models.Model):
category_name = models.CharField(max_length=50)
parent_id = models.IntegerField()
# product categories
class product_categories(models.Model):
product = models.ForeignKey(products, on_delete=models.CASCADE)
category = models.ForeignKey(categories, on_delete=models.CASCADE)
def __str__(self):
return self.category
I can access 'category' table data(inside django shell) using
data = products.objects.all()
data.values('product_categories__category__category_name')
output: <QuerySet [{'product_categories__category__category_name': 'xxxx'}}]>
If I put this(inside django shell)
data.product_categories.category
output: 'QuerySet' object has no attribute 'product_categories'
How do I get a queryset(can be passed to html) which includes data from "categories" table along with the data of "products" table
There are a couple of issues happening here. First, data is a queryset, which is kind of like a list of objects, even though here there's just one object in the list. What you want is to get an attribute off of the item in the list, so you need something like a data.first() to get to that object before you start dotting into its attributes.
Secondly, the way Django handles reverse FK relationships requires that you refer to the FK by the standard name of, in your case, product_categories_set, OR you set your own related_name attribute on the FK. Something like:
# product categories
class product_categories(models.Model):
product = models.ForeignKey(products, on_delete=models.CASCADE, related_name='product_categories')
category = models.ForeignKey(categories, on_delete=models.CASCADE, related_name='product_categories')
def __str__(self):
return self.category
so that you can refer to your product_categories model from both the product and categories using just data.product_categories.
Thirdly, when accessing a reverse FK relationship, just like in point (1) above, you will get a related manager, from which you can get a queryset of items. Thus, to get the category name, you need to indicate which item you want the category name for. Assuming it's just the first item for everything, it would look something like:
data = products.objects.all()
product_category = data.product_categories.all()
category_name = product_category.category.category_name
Of course once you have more data, you'll not always want to just pick the first item, so you'll need to add filtering logic into the query to make sure you get the item you're looking for.
ETA, I do agree with the comment by Jorge above - a MTM would make this a bit simpler and would, in essence, create your product_categories table for you.
Hello Guys I am working on a restaurant project which allow user to select food item and book an order but i am getting this error as i try to book an order
"Django Cannot assign "'Pizza'": "Order.Food_Name" must be a "Foods" instance."
I am using drop down menu to select food items i am using django version 2.1.5 . Please Help
views.py
def place_order(request):
name = request.POST["user"]
food_items = request.POST['food_item']
qty = request.POST['qty']
rating = request.POST['ratings']
price = Foods.Food_Price
order = Order(Date=datetime.date, Name_of_Person=name,Food_Name=food_items, Qty=qty, Total=price, Ratings=rating)
order.save()
return render(request, "index.html")
model.py
from django.db import models
class Foods(models.Model):
Food_Number = models.IntegerField(null=False,)
Food_Name = models.CharField(max_length=30, primary_key=True, null=False)
Food_Qty = models.CharField(max_length=10)
Food_Price = models.IntegerField()
def __str__(self):
return f"{self.Food_Number} - {self.Food_Name} {self.Food_Price}"
class Order(models.Model):
Order_id = models.AutoField(null=False, primary_key=True)
Date = models.DateField()
Name_of_Person = models.CharField(null=False, max_length=40)
Food_Name = models.ForeignKey(Foods, on_delete=models.CASCADE)
Qty = models.CharField(max_length=10)
Total = models.IntegerField()
Ratings = models.IntegerField()
def __str__(self):
return f"{self.Order_id} - {self.Name_of_Person} |{self.Food_Name} |{self.Total}"
What can i do solve this error
Problem is in your Order model Food_Name is foreign-key field. So you need to assign model-instance which is Food in this case to this field. But you are assigning food_items = request.POST['food_item'] which is suppose to be food_name string i guess. That is why this error raise. I don't think your model is properly design. Food_Name is not an unique id field in Food model rather in your Order table you would like to have Food not Food_name.
I'm very confused about this right now,
so I know when there's a simple code like the below
def text_detail(request ,course_pk, step_pk):
step = get_object_or_404(Text, course_id = course_pk, pk=step_pk)
course_pk and step_pk from the url, and those requests are set equal to course_id and pk here. but what I don't understand is what is course_id and pk here? I mean, course_id is from Course model which is foreignkey to step. so it's self.Course.id so it's course_id. But then, how about the next one pk? shouldn't it be step_id = step_pk? when it's just pk how does django know which pk it is?
Sorry if the question is very confusing, I'm very confused right now.
Edit
class Step(models.Model):
title = models.CharField(max_length=200)
description = models.CharField()
order = models.IntegerField(default=0)
course = models.ForeignKey(Course)
class Meta:
abstract = True
ordering = ['order',]
def __str__(self):
self.title
class Text(Step):
content = models.TextField(blank=True, default="")
Actually the get_or_404() method doing a similar/exact job as below,
try:
return Text.object.get(pk=step_pk,course_id = course_pk)
except Text.DoesNotExist:
raise Http404
You can read the source code of the same here
What is course_id and pk ?
Both are attributes of your Text model, as the name indicates pk is your Primary Key of Text model and course_id is the id/pk of course field which is a FK.
EDIT
Text is inherited from Step model so, it will show properties of usual python class.Hence, the Text model be like this internally (not-exact)
class Text(models.Model):
content = models.TextField(blank=True, default="")
title = models.CharField(max_length=200)
description = models.CharField()
order = models.IntegerField(default=0)
course = models.ForeignKey(Course)
class Meta:
ordering = ['order', ]
def __str__(self):
return self.title
Example
text = Text.objects.get(id=1) # text instance with id=1
text.course_id # will hold the id of "course" instance which is related to the particular "text" instance
URL assignment and all those stuffs are entirely depends on your choice and logic. So If you need to get a Text instance in your view, do as below,
text = get_object_or_404(Text, pk = pk_of_TEXT_instance)
I'm working now on my first Django project. I want to render results table which contains all fields from Priekabos model and one custom column from Grafikas which should contain something similar to:
SELECT max(kada_moketi) FROM grafikas WHERE priekabos_id = ?
Whatever I try from examples nothing works. Should I write another view function with that custom query:
(Grafikas.objects.filter(priekabos_id=1)
neither with:
.aggregate(Max('kada_moketi')
neither with:
.latest('kada_moketi')
worked for me I created a new table class in tables.py which later PriekabosTable will inherit? That didn't work for me too.
Here's my code:
models.py
class Grafikas(models.Model):
id = models.AutoField(primary_key=True)
mokejimo_nr = models.IntegerField()
kada_moketi = models.DateField()
priekabos = models.ForeignKey('Priekabos', models.DO_NOTHING)
class Priekabos(models.Model):
id = models.AutoField(primary_key=True)
sutarties_nr = models.CharField(unique=True, max_length=45, verbose_name='Sut. Nr.')
nuomos_pradz = models.DateField()
sutarties_trukme = models.IntegerField()
views.py
def priekabos_table(request):
table = PriekabosTable(Priekabos.objects.all())
RequestConfig(request, paginate={'per_page': 20}).configure(table)
return render(request, 'isperkamoji_nuoma/priekabos_table.html', {'table': table})
tables.py
class PriekabosTable(tables.Table):
class Meta:
model = Priekabos
attrs = {"class": "paleblue"}
fields = ('id', 'sutarties_nr', 'nuomos_pradz')
For better understanding, here's 'grafikas' table:
MySQL 'grafikas' table
It sounds like you might be able to fetch the extra field using annotate.
from django.db.models import Max
queryset = Priekabos.objects.annotate(max_kada_moketi=Max('grafikas__kada_moketi'))
table = PriekabosTable(queryset)
Remember to add the field to your table.
class PriekabosTable(tables.Table):
class Meta:
model = Priekabos
attrs = {"class": "paleblue"}
fields = ('id', 'sutarties_nr', 'nuomos_pradz', 'max_kada_moketi')
I'm making a program that helps log missions in a game. In each of these missions I would like to be able to select a number of astronauts that will go along with it out of the astronauts table. This is fine when I only need one, but how could I approach multiple foreign keys in a field?
I currently use a 'binary' string that specifies which astronauts are to be associated with the mission (1 refers to Jeb, but not Bill, Bob, or Val and 0001 means only Val), with the first digit specifying the astronaut with id 1 and so forth. This works, but it feels quite clunky.
Here's the model.py for the two tables in question.
class astronauts(models.Model):
name = models.CharField(max_length=200)
adddate = models.IntegerField(default=0)
experience = models.IntegerField(default=0)
career = models.CharField(max_length=9, blank=True, null=True)
alive = models.BooleanField(default=True)
def __str__(self):
return self.name
class Meta:
verbose_name_plural = "Kerbals"
class missions(models.Model):
# mission details
programid = models.ForeignKey(programs, on_delete=models.SET("Unknown"))
missionid = models.IntegerField(default=0)
status = models.ForeignKey(
missionstatuses, on_delete=models.SET("Unknown"))
plan = models.CharField(max_length=1000)
# launch
launchdate = models.IntegerField(default=0)
crewmembers = models.IntegerField(default=0)
# recovery
summary = models.CharField(max_length=1000, blank=True)
recdate = models.IntegerField(default=0)
def __str__(self):
return str(self.programid) + '-' + str(self.missionid)
class Meta:
verbose_name_plural = "Missions"
I saw a post about an 'intermediate linking table' to store the crew list but that also isn't ideal.
Thanks!
This is the use case for Django's ManyToManyField. Change the appropriate field on the missions:
class missions(models.Model):
crewmembers = models.ManyToManyField('astronauts')
You can access this from the Astronaut model side like so:
jeb = astronaut.objects.get(name='Jebediah Kerman')
crewed_missions = jeb.missions_set.all()
Or from the mission side like so:
mission = missions.objects.order_by('?')[0]
crew = mission.crewmembers.all()
This creates another table in the database, in case that is somehow a problem for you.