I'm trying to create a new Topic and the category id is dynamically determined in javascript on the client side. The problem i'm having is I pass the category id and I want to lookup the correct category object, but using a model form, it checks if the category is an instance of Category before I can assign it and save it.
--model.py--
class Topic(models.Model):
category = models.ForeignKey(Category)
--form.py--
class TopicForm(ModelForm):
category = forms.IntegerField(widget=forms.HiddenInput())
class Meta:
model = Topic
fields = ('category')
--view.py--
form = TopicForm(request.POST)
if form.is_valid():
form.save(commit=False) # throws exception category is not a Category instance
form.category = Category.objects.get(pk=form.cleaned_data.get('category'))
form.save()
Use a ModelChoiceField instead of the IntegerField in your form. See the built-in fields reference
Following Oggy's suggestion, I changed it to a ModelChoiceField and now Django does all the magic behind the scenes.
category = forms.ModelChoiceField(Category.objects.all(), widget=forms.HiddenInput())
Now I hope the queryset doesn't get evaluated, since it's not necessary and there are 90,000 records. :)
Related
relative to this answer: How to make follower-following system with django model
I will like to know how to get all the post of the user that I'm following just in case I'll want to add that extra functionality in the future.
You will have an another Model Post associated with User.
class Post(models.Model):
description = models.TextField()
user = models.ForeignKey("User", related_name="posts")
Getting all posts of following_user_id, you can achieve by below query
following_user_ids = request.user.followers.all().values_list("following_user_id", flat=True)
posts = Post.objects.filter(user__in=following_user_ids)
request.user is the logged-in user, related_name="followers" is used get all associated records from UserFollowing Model. values_list() will return the following_user_id in list form than pass the returned list in Post
In my Django Rest Framework project, I have a ForeignKey relationship between two models:
class Book(models.Model):
...
category = models.ForeignKey(Category, on_delete=models.CASCADE, blank=True, null=True)
...
class Category(models.Model):
name = models.CharField(max_length=100, blank=False)
As you can see, a Book can belong to a Category but it does not have to. That means the 'category' field could be null.
So, in my views.py, any Book instance can be updated/patched if the user wants to assign a certain Book to a particular Category. That views.py update method looks like this:
class UpdateBooksCategory(generics.GenericAPIView):
'''
Class-based view to update the 'category' field of a Book instance.
'''
serializer_class = BookSerializer
permission_classes = [IsAuthenticated]
def patch(self, request,*args, **kwargs):
# get the Book instance first
book = Book.objects.get(pk=request.data.get('bookId'))
# if it is not assigned to a Category, then assign it
if book and not book.category:
book.category = Category.objects.get(name=request.data.get('categoryName'))
book.save()
serializer = self.get_serializer(book, context={"request": request})
return Response(serializer.data)
# otherwise, return a generic response
return Response({'response': "You have already put the selected Book in a Category."})
If you can see, first I get the Book instance that the user wants to update by using the Book's ID. If its Category field is not already filled, I get a Category instance using the given category name and assign it.
For the sake of completeness, here are my serializer classes:
class CategorySerializer(serializers.ModelSerializer):
class Meta:
model = Category
fields = ['id', 'name']
class BookSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = ['id', /*some other fields*/,..., 'category']
So, finally my question: I wanted to know if this is the preferred way of updating a ForeingKey field like this? I mean looking at the UpdateBooksCategory class-based view, is this the right way of doing it? The code works ( I tested it with PostMan) but since I am new to DRF I wanted to know if such an updating process is correct.
You can change your BookSerializer:
class BookSerializer(serializers.ModelSerializer):
category_id = serializers.IntegerField(write_only=True)
category = CategorySerializer(read_only=True)
class Meta:
model = Book
fields = [
'id',
# some other fields,
'category',
'category_id',
]
category will be a nested data that is read only, then setting the category will be by including the category_id in your requests.
I have a table of employees when I click a row it will get the Id of the row and pass it to django sql query.
This is my raw sql query in django
class GetEmployeeDetailsApi(ListAPIView):
queryset = EmployeeTb.objects.raw('SELECT *
FROM EmployeTable
WHERE EmployeeId = %s', [id])
serializer_class = GetEmployeeDetailsSerializer
I already tried another a way to do this by fetching all records then filter it in front-end and it worked, but I do not want to do this because of security reasons, it exposes the whole table when I only need one record.
I think you want a view that extends ModelViewSet. This provides a full object list, plus the ability to retrieve individual objects.
http://www.django-rest-framework.org/api-guide/viewsets/#modelviewset
class EmployeeDetailsViewSet(viewsets.ModelViewSet):
queryset = EmployeeTb.objects.all()
serializer_class = GetEmployeeDetailsSerializer
I suggest you work through the DRF tutorial, which covers basic concepts like this:
http://www.django-rest-framework.org/tutorial/quickstart/
I have 2 models
class Parent(models.Model):
name = models.CharField(max_length=50)
class Child(models.Model):
parent = models.ForeignKey(Parent,related_name='child')
child_name = models.CharField(max_length=80)
type = models.BooleanField()
I want to fetch result from parent model and related records from child
Parent.objects.all()
it returns me all records form parent and child IN django rest framework but I want only that child which type is ture, how can i add condition
Please let me know
In your Parent generic list api view override the get_queryset method:
def get_queryset(self):
return (Parent.objects.all()
.prefetch_related(Prefetch('child', queryset=Child.objects.filter(type=True))))
Also on a side note I suggest you not to name the field type on child model since it conflicts with the python keyword type. And another suggestion is to use the related_name value as children.
I have two models for store and city:
class City(models.Model):
name = models.CharField()
slug = models.SlugField()
class Store(models.Model):
name = models.CharField()
slug = models.SlugField()
city = models.ForeignKey(City)
If I have my Add Store url designed as
r^'mysite.com/city/(?[-\w]+)/venue/add$'
where the represents the City.slug field can I initialize a StoreForm that automatically populates the Store.city field from the url data?
In your template, define your link as follows.
{%url somename relevant_slug_text%}
Or :
href='/mysite.com/city/{{slug_text}}/venue/add'
In your url conf, define your url like:
url(r^'mysite.com/city/(?P<slug_text>\w+)/venue/add$', 'func_name', name='somename')
So, you can pass the value of relelvant_slug_text variable to your url as slug_text, and in your function definiton:
def func_name(request, slug_text):
So , you can pass text value to your funcrtion with slug_text parameter...
EDIT:
There are tow ways...
One:
Crete your city selection form using ModelForm..., then inthe second step, use posted data to populate your form again like:
form = StoreForm(request.POST)
then you can render this form to your template...
But if it is not possible o use this, yo ucan do the following...
Since you are using ModelForm to create your forms:
class StoreForm(forms.ModelForm):
# your form field definitions are here
im your function, just override city field, but at this point, since you use modelform, your form thml will be created as
<select>
<option value="id of record">"unicode value of record"</option>
So, you have record id's as option values. And you have slug_field values to initialize your field. So you have to get related city to use it...
my_city = City.objects.get(slug=<your_slug_value>)
Now you can override the form, but you must do it before you pass your form to a variable to render to your template...
StoreForm.base_fields['city'] = forms.ModelChoiceField(queryset=City.objects.all(), initial=my_city)
form = StoreForm()