I am trying to raise validation error for the entry field in the forms.py
My models.py
class StudBackground(models.Model):
stud_name=models.CharField(max_length=200)
class Student(models.Model):
name=models.CharField(max_length=200)
My forms.py
class StudentForm(forms.ModelForm):
name = forms.CharField(max_length=150, label='',widget= forms.TextInput)
class Meta:
model = Student
fields = ['name',]
where i tried to apply clean method :
def clean_student(self,*args,**kwargs):
name=self.cleaned_data.get("name")
if not studBackground.stud_name in name:
raise forms.ValidationError ( "It is a not valid student")
else: return name
I tried to incorporate stud_name from the StudBackground model to the form but it does not work it raises following error when i try to type student name that is not in DB:
Profiles matching query does not exist
however it supposed to return near the name field "It is a not valid student"
How to make it work? What is the wrong with the code?
You can try like this:
def clean_student(self):
name=self.cleaned_data.get("name")
if not StudBackground.objects.filter(stud_name=name).exists():
raise forms.ValidationError("It is a not valid student")
return name
I am using filter(...) function from queryset to check if a name exists in StudBackground. I am also running exists() to check if entry exists in DB.
Update
I think your indentations are not correct for the view. But, you can try like this:
def home(request):
form = StudentForm(request.POST or None)
if request.method == "POST":
if form.is_valid():
instance = form.save()
name = instance.name
class_background=StudBackground.objects.get(stud_name=name)
context={'back':class_background}
return render(request, 'class10/background.html', context)
# Now let us handle if request type is GET or the form is not validated for some reason
# Sending the form instance to template where student form is rendered. If form is not validated, then form.errors should render the errors.
# How to show form error: https://docs.djangoproject.com/en/3.0/topics/forms/#rendering-form-error-messages
return render(request, 'your_student_form_template.html', context={'form':form})
Related
Hello is there a way to get 'value' attribute from HTML template into views.py and use it there??
HTML:
<form class="card__delete" method="POST"> {% csrf_token %}
<button value="{{item.id}}" class="card__delete__button" name="delete" type="submit">✘</button>
</form>
views.py
class TodoView(UserPassesTestMixin, CreateView):
model = Item
template_name = 'home/todo.html'
form_class = ItemCreationForm
def test_func(self):
return self.request.user.username in self.request.path
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context['card'] = Card.objects.get(user=self.request.user, pk=self.kwargs.get('pk'))
return context
def post(self, request, pk, username):
if 'delete' in self.request.POST:
Item.objects.get(id=pk).delete()
print('deleted')
return redirect('home-page')
The value is in request.POST, so you should be able to access it with
value = self.request.POST.get('delete', None)
Take care to validate that value before using the id of an object to do anything catastrophic to it (such as .delete()). It's not being validated through a form, and a random hacker on the internet might try posting back random numbers which might be the id of other objects
Added after reading comment:
Data pulled out of request.POST is raw data. I don't think CSRF token can protect against a person who uses inspect object in his browser and changes the value of that button before clicking it. I may be wrong.
Anyway, if you can check the value using a queryset of the object type with a filter for objects that this user is permitted to delete, then do. For example,
value = request.POST.get("delete", None)
if value:
obj = Card.objects.filter(
user=self.request.user ).get( pk=value)
# will raise CardDoesNotExist if value isn't one of user's objects,
# because it's been filtered out
obj.delete()
I'm trying to call an attribute from my model into my HTML template using Django. There is something strange going on as I am only able to call one of my two models into the template. Both models are working perfectly fine as far as I can tell by looking into my database. This is what my models.py looks like
class Respondez(models.Model):
responder = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='scores')
score = models.IntegerField(default=0)
post_time = models.DateTimeField(default=timezone.now)
class Meta:
ordering = ['post_time']
def __str__(self):
return self.score
class Profilez(models.Model):
newuser = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, blank=True,null=True)
preference = models.CharField(max_length=30)
def __str__(self):
return self.newuser
I am trying to call Profilez. However, only Respondez can be called. This is the view I'm calling from, which I simplified.
#login_required
def add(request):
p = Profilez()
z = Respondez()
context = {
'p' : p,
'z' : z
}
return render(request, 'rating/add.html', context)
To test whether I can call my models, I have simple header tags in HTML for my template, add.html:
{% extends "rating/base.html" %}
{% block content%}
<h3> {{user.username}} </h3>
<h3> {{ z.post_time }}</h3>
<h3>{{ p.preference }}</h3>
No matter which attribute I call from the models, the line for Respondez works but nothing works for my Profilez model. This is despite the fact that my database has values saved for each attribute from both models.
I am getting inputs for preference from the following view on a separate template (first line won't paste with correct indentation), where users select 1 of 2 choices:
def onboarding2(request):
p = Prof()
p.newuser = request.user
if request.method == 'POST':
selected_opt = (request.POST['ob'])
if selected_opt == 'mood':
p.preference = 'mood'
elif selected_opt == 'productivity':
p.preference = 'productivity'
else:
return HttpResponse(400, 'Invalid form')
p.save()
return redirect('rating-onboarding3')
context = {
'p' : p,
}
return render(request, 'rating/onboard2.html', context)
How can I accurately call my Profilez model? What's wrong here?
Since you have instantiated Profilez with no parameters in the constructor, none of its fields get the initial value. Hence, p.preference also happens to be null. That is why p.preference is not visible in the template.
But, in case of Respondez, though you are still instantiating the object with no parameters, you still have given the default value of current time to z.post_time, so z.post_time is working.
If you want to access p.preference, you need to explicitly assign some value to p.preference, else how will the template show the value for something that doesn't have a value initialized in the first place? For instance, you could do p = Profilez(preference='xyz') while creating the object, and see what happens.
Also, if you want to fetch a specific entry from the database, then you need to do a query, rather than creating a new object. The syntax for creating query would be something like Profilez.objects.get(newuser=some_random_user).
I'm having a problem with django rest framework.
My front is posting data to drf, and one of the fields could be null or an empty string "".
# models.py
class Book(models.Model):
title = models.CharField(max_length=100)
publication_time = models.TimeField(null=True, blank=True)
# serializers.py
from rest_framework import serializers
from .models import Book
class BookSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = ('id', 'title', 'publication_time')
publication_time could either be blank or "".
The blank case works, in fact when I post a json {"title": "yeah a book", "publication_time": none} everything is fine.
When I send {"title": "yeah a book", "publication_time":""} I do get a validation error "Time has wrong format. Use one of these formats instead: hh:mm[:ss[.uuuuuu]]."
I've tried to add a field validator to the serializer class:
def validate_publication_time(self, value):
if not value:
return None
Or even using the extra_kwargs
# ....
def empty_string_to_none(value):
if not value:
return None
# ....
class BookSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = ('id', 'title', 'publication_time')
extra_kwargs = {'publication_time': {'validators' : [empty_string_to_none]} }
What I am trying to do is to transform an empty string to None (that should be accepted by the serializer and the model) before any validation occurs or as the first validation rule.
PROBLEM:
The problem is that the validate_publication_time is never called and I get a validation error before even hitting the function. As I've understood there is a specific order in which the validators run, but now I have no idea how to solve my issue.
QUESTION:
What I want to do is to actually clean the data in order to transform "" into None before any validation is run. Is it possible? How?
EDIT:
This is the representation of my serializer:
# from myapp.serializers import BookSerializer
# serializer = BookSerializer()
# print repr(serializer)
# This is the print result:
BookSerializer():
id = IntegerField(label='ID', read_only=True)
title = CharField(max_length=100)
publication_time = TimeField(allow_null=True, required=False)
So as you can see the publication_time field could be null, isn't it?
I had the same problem and finally found a solution.
In order to deal with '' before the error occurs, you need to override the to_internal_value method:
class BookSerializer(serializers.ModelSerializer):
def to_internal_value(self, data):
if data.get('publication_time', None) == '':
data.pop('publication_time')
return super(BookSerializer, self).to_internal_value(data)
Have you tried to override serialization behavior? What you need is override .to_internal_value(self, data)
the kwarg is allow_null and allow_blank not null and blank.
You can override serializer's save method where you would check if the value is an empty string and if it is then set it to Null.
In your serializer (untested):
def save(self, *args, **kwargs)
if self.publication_time == "":
self.publication_time = Null
super.save(*args, **kwargs)
Or, you can do like that in a view(this is how I do that):
def perform_update(self, serializer):
publication_time = self.kwargs['publication_time']
if publication_time == "":
publication_time = Null
serializer.save(publication_time=publication_time)
only then you'll also need to overwrite perform_create if you also need this when you POST, not only when PUT
Answer of #Ivan Blinov is correct, except you should allow the data to be mutable, otherwise you get this error:
AttributeError: This QueryDict instance is immutable
so the complete answer is:
class BookSerializer(serializers.ModelSerializer):
def to_internal_value(self, data):
if data.get('publication_time', None) == '':
data._mutable = True
data.pop('publication_time')
return super(BookSerializer, self).to_internal_value(data)
I have worked on this for sometime now and I have decided to seek for your help. I have an ongoing project and I am using the django framework to build the site.
I have an html page that requests for user input, I have been able to extract the given data using the form.cleaned_data['']. A
#This is my views.py;
from django.shortcuts import render_to_response
from django.template import RequestContext
from forms import CarloanForm
def index(request):
form = CarloanForm()
if request.POST:
form = CarloanForm(request.POST)
if form.is_valid():
form.save()
else:
form = CarloanForm()
return render_to_response('carloan/index.html', {'form': form},
context_instance=RequestContext(request))
#I am extracting the user inputs using;
amount_of_vehicle = form.cleaned_data['cost_of_vehicle_Naira']
tenure = form.cleaned_data['loan_repayment_tenure_Months']
interest_rate = form.cleaned_data['interest_rate_Percentage']
equity = form.cleaned_data['equity_contrib_rate_Percentage']
depreciation_rate = form.cleaned_data['depreciation_rate_Percentage']
What I need to do and don't know how to go about it are;
Carry out some operations on the data (extracted using form.cleaned_data['']) and I have written some lines of code to that effect;
class LoanCalc:
def __init__(self,amount_of_vehicle,tenure,interest_rate,equity,depreciation_rate):
self.amount_of_vehicle = float(amount_of_vehicle)
self.tenure = float(tenure)
self.interest_rate = float(interest_rate)
self.equity = float(equity)
self.depreciation_rate = float(depreciation_rate)
def interest(self):
return (self.interest_rate/100) * self.amount_of_vehicle *(self.tenure/12)
def management_fee(self):
return 0.01 * (self.amount_of_vehicle + user.interest())
def processing_fee(self):
return 0.0025 *(self.amount_of_vehicle + user.interest())
def legal_fee(self):
return 0.0075 * (self.amount_of_vehicle + user.interest())
def residual_amount(self):
return 0.01 * (self.amount_of_vehicle - ((self.depreciation_rate/100) * self.amount_of_vehicle *(self.tenure/12)))
def equity_contribution(self):
return (self.equity/100) * self.amount_of_vehicle
def LoanPaymentPlan(self):
months = 1
total_amount = self.amount_of_vehicle+user.interest()+user.management_fee()+user.processing_fee()+user.legal_fee()+user.residual_amount()
upfront_payment = user.management_fee()+user.processing_fee()+user.legal_fee()+user.equity_contribution()+user.residual_amount()
opening_balance = total_amount - upfront_payment
balance = opening_balance
while months <= self.tenure:
if balance > 0:
monthly_instalment =(opening_balance/self.tenure)
monthly_interest = (((self.interest_rate/100) * balance)/ 12)
loan_payment = monthly_instalment - monthly_interest
closing_balance = balance - monthly_instalment
print' ',months,' ',round(balance,2),' ', round(monthly_instalment,2),' ',round(monthly_interest,2) \
, ' ',' ',round(loan_payment,2),' ',round(closing_balance,2)
balance = closing_balance
months += 1
return 'Thank you for using the Loan Calculator App'
and i want to carry out the operations in the code above on the extracted data.
I am thinking of doing it in such a way like this;
Create an empty dictionary;
user = {}
user = LoanCalc(amount_of_vehicle,tenure,interest_rate,equity,depreciation_rate)
result= user.interest()
result1 = user.management_fee()
. .
. .
. .
result10 = user.LoanPaymentPlan()
Pass the result(s) obtained from (question 2) to the same template that generated the form.
Please help me out guys, i am still very new to django. Thanks
This is the full stack of the referenced error am getting:
Environment:
Request Method: GET
Request URL: http://127.0.0.1:9000/result/
Django Version: 1.4.1
Python Version: 2.5.4
Installed Applications:
('django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.admin',
'carloan')
Installed Middleware:
('django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware')
Traceback:
File "C:\Python25\Lib\site-packages\django\core\handlers\base.py" in get_response
111. response = callback(request, *callback_args, **callback_kwargs)
File "C:\Users\AJIBIKE\Documents\Circuit Atlantic\calculator\carloan\views.py" in result_page
226. 'carloan': instance,
def result_page(request):
if request.POST:
form = Carloan_formForm(request.POST)
if form.is_valid():
instance = form.save(commit=False)
instance.interest = (instance.interest_rate/100) * instance.amount_of_vehicle * (instance.tenure/12)
instance.save()
else:
form = Carloan_formForm()
return render_to_response('carloan/result.html', {'carloan': instance,'form': form},
context_instance=RequestContext(request))
Exception Type: UnboundLocalError at /result/
Exception Value: local variable 'instance' referenced before assignment
Latest
from django.shortcuts import render_to_response
from django.template import RequestContext
from django.http import HttpResponseRedirect, HttpResponse
from forms import Carloan_formForm
def index(request):
if request.POST:
form = Carloan_formForm(request.POST)
if form.is_valid():
instance = form.save()
return HttpResponseRedirect ('/result/')
form = Carloan_formForm()
kwvars = {
'form': form,
}
return render_to_response('carloan/index.html', kwvars,
context_instance=RequestContext(request))
def result_page(request):
instance = None
if request.POST:
form = Carloan_formForm(request.POST)
if form.is_valid():
instance = form.save(commit=False)
instance.interest = (instance.interest_rate_Percentage/100) * instance.cost_of_vehicle_Naira * (instance.loan_repayment_tenure_Months/12)
instance.management_fee = 0.01 * (instance.cost_of_vehicle_Naira + instance.interest)
instance.processing_fee = 0.0025 * (instance.cost_of_vehicle_Naira + instance.interest)
instance.legal_fee = 0.0075 * (instance.cost_of_vehicle_Naira + instance.interest)
#i get syntax error starting from this line, and when i comment it out and the lines below, there is no syntax error.
instance.residual_amount = 0.01 * ((instance.cost_of_vehicle_Naira - ((instance.depreciation_rate_Percentage/100) * instance.cost_of_vehicle_Naira * (instance.tenure/12)))
instance.equity_contribution = (instance.equity_contrib_rate_Percentage/100) * instance.cost_of_vehicle_Naira)
instance.save()
else:
form = Carloan_formForm()
return render_to_response('carloan/result.html', {'instance': instance, 'form': form},
context_instance=RequestContext(request))
forms.py
from django import forms
from django.forms import ModelForm
from models import Carloan_form
class Carloan_formForm(ModelForm):
class Meta:
model = Carloan_form
exclude = ('interest', 'management_fee', 'processing_fee', 'legal_fee', \
'residual_amount', 'equity_contribution')
1 Save the result of the operations carried out on the extracted data in the Django Administration. (N.B: I already know how to save the user input)
Create a model to save the user's entries. app/models.py
class Carloan(models.Model) :
# In addition to your model fields add the functions that are part of your LoanCalc
...
Then create a ModelForm: app/forms.py
class CarLoanForm(forms.ModelForm) :
class Meta:
model = Carloan
Use CarLoanForm the same way you normally would except: app/views.py
if request.POST:
form = CarloanForm(request.POST)
if form.is_valid():
carloan = form.save()
#pass carloan (the instance) to the template and
#call its functions(from LoanCalc) instead of
#passing all of the values separately
Lastly, register this Model so it appears in the admin section app/admin.py
from django.contrib import admin
from app.models import Carloan
admin.sites.register(Carloan)
2 I have divided the page into two(one for the form and the other for
the result) and i want to pass the result to one-half of the page to
enable the user to see it.
Using the steps above, carloan will be passed to the view. go ahead and render its values.
Additionally:
Refactor index
your index definition should be refactored slightly, or your POST bound form will never make it to the template:
def index(request):
if request.POST:
form = CarloanForm(request.POST)
if form.is_valid():
instance = form.save()
else :
form = CarloanForm()
return render_to_response('carloan/index.html', {'form': form},
context_instance=RequestContext(request))
Refactor your ModelForm
Carry out some operations on the data (extracted using form.cleaned_data['']) and I have written some lines of code to that effect; - using a ModelForm instead of a regular django form you will get an instance of the model with the user's values already filled in, you reference them with instance.field.
and i want to carry out the operations in the code above on the extracted data. - the fields that you plan to calculate values for are listed in exclude they will not factor into form validation.
class CarLoanForm(forms.ModelForm) :
class Meta:
model = Carloan
# exclude fields that are calculated from user input
# NOTE: these fields must be in your model
exclude = ('interest', 'management_fee'...)
Refactor result page
Carry out some operations on the data (extracted using form.cleaned_data['']) and I have written some lines of code to that effect;
in results_page under the form.is_valid check, ther is a line: instance = form.save(commit=False) this gets all of the values that the user submitted in a instance of the Carloan Model that has NOT been saved yet.
further down: instance.interest = (instance.interest_rate/100) * instance.amount_of_vehicle *(instance.tenure/12) in this line I am calculating one of the excluded fields values (this calculation is a copy of your code).
lastly (after all of the operations on the data have been completed) I save the instance of the model.
then pass the instance to the template for display.
code:
def result_page(request):
if request.POST:
form = CarloanForm(request.POST)
if form.is_valid():
# get an instance from the form but don't save it
instance = form.save(commit=False)
# calculate excluded field values
instance.interest = (instance.interest_rate/100) * instance.amount_of_vehicle *(instance.tenure/12)
...
# after you have calculated all of the excluded fields save the instance
instance.save()
else :
form = CarloanForm()
return render_to_response('carloan/result.html', {'carloan' : instance, 'form' : form},
context_instance=RequestContext(request))
Error:
reference before error assignment - What does it say was referenced before assignment? Paste the entire stack trace please.
One of the simpler ways would be to store the data in the session in one view, retrieve it in the next. The docs will help.1
Having said that - there are a few other ways to approach the problem. It has been discussed more than once on SO:
Django Passing data between views
How do you pass or share variables between django views?
how to pass a list between views in django
I defined some WTForms forms in an application that uses SQLALchemy to manage database operations.
For example, a form for managing Categories:
class CategoryForm(Form):
name = TextField(u'name', [validators.Required()])
And here's the corresponding SQLAlchemy model:
class Category(Base):
__tablename__= 'category'
id = Column(Integer, primary_key=True)
name = Column(Unicode(255))
def __repr__(self):
return '<Category %i>'% self.id
def __unicode__(self):
return self.name
I would like to add a unique constraint on the form validation (not on the model itself).
Reading the WTForms documentation, I found a way to do it with a simple class:
class Unique(object):
""" validator that checks field uniqueness """
def __init__(self, model, field, message=None):
self.model = model
self.field = field
if not message:
message = u'this element already exists'
self.message = message
def __call__(self, form, field):
check = self.model.query.filter(self.field == field.data).first()
if check:
raise ValidationError(self.message)
Now I can add that validator to the CategoryForm like this:
name = TextField(u'name', [validators.Required(), Unique(Category, Category.name)])
This check works great when the user tries to add a category that already exists \o/
BUT it won't work when the user tries to update an existing category (without changing the name attribute).
When you want to update an existing category : you'll instantiate the form with the category attribute to edit:
def category_update(category_id):
""" update the given category """
category = Category.query.get(category_id)
form = CategoryForm(request.form, category)
The main problem is I don't know how to access the existing category object in the validator which would let me exclude the edited object from the query.
Is there a way to do it? Thanks.
In the validation phase, you will have access to all the fields. So the trick here is to pass in the primary key into your edit form, e.g.
class CategoryEditForm(CategoryForm):
id = IntegerField(widget=HiddenInput())
Then, in the Unique validator, change the if-condition to:
check = self.model.query.filter(self.field == field.data).first()
if 'id' in form:
id = form.id.data
else:
id = None
if check and (id is None or id != check.id):
Although this is not a direct answer I am adding it because this question is flirting with being an XY Problem. WTForms primary job is to validate that the content of a form submission. While a decent case could be made that verifying that a field's uniqueness could be considered the responsibility of the form validator, a better case could be made that this is the responsibility of the storage engine.
In cases where I have be presented with this problem I have treated uniqueness as an optimistic case, allowed it to pass form submission and fail on a database constraint. I then catch the failure and add the error to the form.
The advantages are several. First it greatly simplifies your WTForms code because you do not have to write complex validation schemes. Secondly, it could improve your application's performance. This is because you do not have to dispatch a SELECT before you attempt to INSERT effectively doubling your database traffic.
The unique validator needs to use the new and the old data to compare first before checking if the data is unique.
class Unique(object):
...
def __call__(self, form, field):
if field.object_data == field.data:
return
check = DBSession.query(model).filter(field == data).first()
if check:
raise ValidationError(self.message)
Additionally, you may want to squash nulls too. Depending on if your truly unique or unique but allow nulls.
I use WTForms 1.0.5 and SQLAlchemy 0.9.1.
Declaration
from wtforms.validators import ValidationError
class Unique(object):
def __init__(self, model=None, pk="id", get_session=None, message=None,ignoreif=None):
self.pk = pk
self.model = model
self.message = message
self.get_session = get_session
self.ignoreif = ignoreif
if not self.ignoreif:
self.ignoreif = lambda field: not field.data
#property
def query(self):
self._check_for_session(self.model)
if self.get_session:
return self.get_session().query(self.model)
elif hasattr(self.model, 'query'):
return getattr(self.model, 'query')
else:
raise Exception(
'Validator requires either get_session or Flask-SQLAlchemy'
' styled query parameter'
)
def _check_for_session(self, model):
if not hasattr(model, 'query') and not self.get_session:
raise Exception('Could not obtain SQLAlchemy session.')
def __call__(self, form, field):
if self.ignoreif(field):
return True
query = self.query
query = query.filter(getattr(self.model,field.id)== form[field.id].data)
if form[self.pk].data:
query = query.filter(getattr(self.model,self.pk)!=form[self.pk].data)
obj = query.first()
if obj:
if self.message is None:
self.message = field.gettext(u'Already exists.')
raise ValidationError(self.message)
To use it
class ProductForm(Form):
id = HiddenField()
code = TextField("Code",validators=[DataRequired()],render_kw={"required": "required"})
name = TextField("Name",validators=[DataRequired()],render_kw={"required": "required"})
barcode = TextField("Barcode",
validators=[Unique(model= Product, get_session=lambda : db)],
render_kw={})
Looks like what you are looking for can easily be achieved with ModelForm which is built to handle forms that are strongly coupled with models (the category model in your case).
To use it:
...
from wtforms_components import Unique
from wtforms_alchemy import ModelForm
class CategoryForm(ModelForm):
name = TextField(u'name', [validators.Required(), Unique(Category, Category.name)])
It will verify unique values while considering the current value in the model. You can use the original Unique validator with it.
This worked for me, simple and easy:
Make sure that every time when a new row created in DB it must have unique name in colomn_name_in_db otherwise it will not work.
class SomeForm(FlaskForm):
id = IntegerField(widget=HiddenInput())
fieldname = StringField('Field name', validators=[DataRequired()])
...
def validate_fieldname(self, fieldname):
names_in_db = dict(Model.query.with_entities(Model.id,
Model.colomn_name_in_db).filter_by(some_filtes_if_needed).all())
if fieldname.data in names_in_db.values() and names_in_db[int(self.id)] != fieldname.data:
raise ValidationError('Name must be unique')