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Django Validation Error raised but not displayed for shopping cart app

I am running Django 2.2 and have written a simple shopping cart. I wish to validate two fields at the same time in such a way that both cannot be empty at the same time. In my forms.py,
from django import forms
class CartAddProductForm(forms.Form):
cc_handle = forms.CharField(required=False, label='CC Handle', empty_value='')
lc_handle = forms.CharField(required=False, label='LC Handle', empty_value='')
def clean(self):
cleaned_data = super().clean()
if cleaned_data.get('cc_handle') == '' and cleaned_data.get('lc_handle') == '':
print("issue detected")
raise forms.ValidationError('Either cc or lc handle is required.')
return cleaned_data
This is following the official Django docs on cleaning and validating fields that depend on each other. The print() statement above lets me know that the issue has been detected, i.e. both fields are empty. Running the Django server, I see that the issue was indeed detected but no validation error message was displayed on top of the originating page. The originating page is the product page that contains the product and a link to add the product to the shopping cart. Normally the validation error message is displayed at the top of the page.
According to the docs, the validation is done when is_valid() is called. So I put a diagnostic print of my views.py
from django.shortcuts import render, redirect, get_object_or_404
from django.views.decorators.http import require_POST
from shop.models import Product
from .cart import Cart
from .forms import CartAddProductForm
#require_POST
def cart_add(request, product_id):
cart = Cart(request)
product = get_object_or_404(Product, id=product_id)
form = CartAddProductForm(request.POST)
if form.is_valid():
cd = form.cleaned_data
cart.add(product=product,
cc_handle=cd['cc_handle'],
lc_handle=cd['lc_handle'])
else:
print('invalid form')
return redirect('cart:cart_detail')
And indeed the words 'invalid form' popped up. The code then takes me to the shopping cart. Instead, what I want is to be at the product page and show the validation error informing the reader that both fields cannot be empty. Is there a simple way of doing it?
For required=True fields in the forms, if I leave it blank, there will be a message popping up saying that I need to fill it in. So I want to do something similar except the validation requires that both fields cannot be empty.
This is different from this Stackoverflow answer because that is a registration form. You can redirect it to the same form whereas for this case, the CartAddProductForm is embedded in all the products page on the site. If possible, I want the validation to occur at the same stage as the field with required=True option.
The product/detail.html template looks like the following.
{% extends "shop/base.html" %}
{% load static %}
{% block title %}
{{ product.name }}
{% endblock %}
{% block content %}
<div class="product-detail">
<img src="{% if product.image %}{{ product.image.url }}{% else %}{% static "img/no_image.png" %}{% endif %}">
<h1>{{ product.name }}</h1>
<h2>{{ product.category }}</h2>
<p class="price">${{ product.price }}</p>
<form action="{% url "cart:cart_add" product.id %}" method="post">
{{ cart_product_form }}
{% csrf_token %}
<input type="submit" value="Add to cart">
</form>
{{ product.description|linebreaks }}
</div>
{% endblock %}

Adding this line in form template has cleared your issue.
{{ cart_product_form.non_field_errors }}
product/detail.html:
{% extends "shop/base.html" %}
{% load static %}
{% block title %}
{{ product.name }}
{% endblock %}
{% block content %}
<div class="product-detail">
<img src="{% if product.image %}{{ product.image.url }}{% else %}{% static "img/no_image.png" %}{% endif %}">
<h1>{{ product.name }}</h1>
<h2>{{ product.category }}</h2>
<p class="price">${{ product.price }}</p>
<form action="{% url "cart:cart_add" product.id %}" method="post">
{{ cart_product_form }}
{% csrf_token %}
{{ cart_product_form.non_field_errors }} // This line will raise validation errors
<input type="submit" value="Add to cart">
</form>
{{ product.description|linebreaks }}
</div>
{% endblock %}
Doc:(Copied from official documentation)
Note that any errors raised by your Form.clean() override will not be
associated with any field in particular. They go into a special
“field” (called all), which you can access via the
non_field_errors() method if you need to. If you want to attach errors
to a specific field in the form, you need to call add_error().

Your view is inconditionnally redirecting to cart_details so no surprise you don't see the validation errors - you'd have to render the invalid form for this. You should only redirect when the post succeeded.

Django: can't access OneToOneField after rendering TemplateView Form

I am new to Django and don't understand what really is causing this:
I have a Model Company which has an OneToOneField, creator.
# models.py
class Company(models.Model):
class Meta:
verbose_name = 'Company'
verbose_name_plural = 'Companies'
creator = models.OneToOneField(User, related_name="company", on_delete=models.CASCADE, unique=False, null=True)
name = models.CharField(max_length=50)
I have a TemplateView class to handle get and post requests for creating a Company model:
# views.py
class create_company(TemplateView):
def get(self, request):
form = CompanyCreateForm()
title = "Some form"
return render(request, "form.html", {"form": form, "title": title})
def post(self, request):
form = CompanyCreateForm(request.POST)
if form.is_valid():
comp = form.save(commit=False)
comp.creator = request.user
comp.save()
return redirect('index')
The form is showing correctly also storing when I submit, the problem I am facing is with base.html where I show {% user.company %}; the form template extends it like:
{% extends "account/base.html" %}
{% load crispy_forms_tags %}
{% block content %}
<div class="container">
<form method="post" action="">
{% csrf_token %}
{{form|crispy}}
<button class="btn btn-success" type="submit">Save</button>
</form>
<br>
</div>
<br>
{% endblock %}
and in base.html I access
{% if user.is_authenticated %}
{% user.company %}
{% endif %}
But user.company is not showing even it is set; it shows only when I redirect to index but not when I render the form.
Can someone help me understand what causes this?

{% if request.user.is_authenticated %}
{% request.user.company %}
{% endif %}
you are not sending any context to the base.html, thus only user wont work.

This was the error when I simulated your code.
Error during template rendering
In template /home/user/django/drf_tutorial/snippets/templates/base.html, error at line 2
Invalid block tag on line 2: 'user.company', expected 'elif', 'else' or 'endif'. Did you forget to register or load this tag?
1 {% if user.is_authenticated %}
2 {% user.company %}
3 {% endif %}
4 {% block content %}{% endblock %}
It gives hint that the code to show company should be variable {{ }} instead of tag {% %}. So the base.html template should be as below.
{% if user.is_authenticated %}
{{ user.company }}
{% endif %}
{% block content %}{% endblock %}

In Django, form isn't rendered on browser

I have started learning django, but I can't understand how to render form.
This is form.py I have made.
from django import forms
class TweetForm(forms.Form):
text = forms.CharField(widget = forms.Textarea(attrs = {'rows' : 1, 'cols' : 85}), max_length = 160)
country = forms.CharField(widget = forms.HiddenInput())
This is code snippet in views.py.
from .forms import TweetForm
class Profile(View):
def get(self, request, username):
params = dict()
user = User.objects.get(username = username)
tweets = Tweet.objects.filter(user = user)
params["user"] = user
params["tweets"] = tweets
form = TweetForm
return render(request, 'profile.html', {'params' : params, 'form' : form})
This is html file and it must render form I have made.
{% extends "base.html" %}
{% block content %}
<div class="row clearfix">
<div class="col-md-12 column">
<form method="post" action="post/">
{% csrf_token %}
<div class="col-md-8 col-md-offset-2 fieldWrapper">
{{ form.text.errors }}
{{ form.text }}
</div>
{{ form.country.as_hidden }}
<div>
<input type="submit" value="post">
</div>
</form>
</div>
<h3> </h3>
<div class="col-md-12 column">
{% for tweet in tweets %}
<div class="well">
<span>{{ tweet.text }}</span>
</div>
{% endfor %}
</div>
</div>
{% endblock %}
When I issue command(run server), browser don't render form without any exception.
I think there is a problem in views.py file, But I can't find it.
How can I send form parameter to Template(.html file) and render form in result?

You didn't instantiate the form.
You need to instantiate the form, for rendering in a template, like this,
form = TweetForm()
Note:
The params variable is already a dict(), you could just add form into the params like this,
params['form'] = form
Then, render the template with context as params,
render(request, 'profile.html', params)

is_paginated not working for django Generic Views

I've been using django built-in pagination (is_paginated) in few of my pages. They are all working fine. Except for the search page where the pagination should only appear based on the filtered queryset.
I've checked through few other thread but it ain't helping much.
How do I use pagination with Django class based generic ListViews?
Django template tag exception
Here's a mini version of what I have so far:-
1)views.py
class SearchBookView(ListView):
template_name = 'books/search_book.html'
paginate_by = '2'
context_object_name = 'book'
form_class = SearchBookForm
def get(self, request):
form = self.form_class(request.GET or None)
if form.is_valid():
filtered_books = self.get_queryset(form)
context = {
'form' : form,
'book' : filtered_books,
}
else:
context = {'form': form}
return render(request, self.template_name, context)
def get_queryset(self, form):
filtered_books = Book.objects.all()
if form.cleaned_data['title'] != "":
filtered_books = filtered_books.filter(
title__icontains=form.cleaned_data['title'])
return filtered_books
def get_context_data(self):
context = super(SearchBookView, self).get_context_data()
return context
2) search_book.html (template)
{% crispy form %}
{% if book %}
<p>Found {{ book|length }} book{{ book|pluralize }}.</p>
{% for book in book %}
<div class="card">
<div style="height:170px; border:solid #111111;" class="col-md-3">
Ima
</div>
<div class="whole-card col-md-9">
<div class="title">"{{ book.title }}"</div>
<div>{{ book.description }}</div>
Read More
</div>
</div>
{% endfor %}
{% else %}
<p>No book matched your searching criteria.</p>
{% endif %}
{% if is_paginated %}
<div class="pagination">
<span class="page-links">
{% if page_obj.has_previous %}
previous
{% endif %}
<span class="page-current">
Page {{ page_obj.number }} of {{ page_obj.paginator.num_pages }}.
</span>
{% if page_obj.has_next %}
next
{% endif %}
</span>
</div>
{% endif %}
forms.py
class SearchBookForm(forms.Form):
title = forms.CharField(max_length=20)
def __init__(self, *args, **kwargs):
self.helper = FormHelper()
self.helper.add_input(Submit('search', 'Search', css_class='btn'))
self.helper.form_method = 'GET'
self.helper.layout = Layout('title')
super(SearchBookForm, self).__init__(*args, **kwargs)
------------------UPDATE------------------
Though I understand Daniel Roseman's answer but as I am fairly new to django, I am not sure how to implement the whole thing, hitting plenty of "X not accessible, X is not attribute of Y" and etc. After much digging, I found some other useful posts on this same matter.
Django: Search form in Class Based ListView
Updating context data in FormView form_valid method?
Django CBV: Easy access to url parameters in get_context_data()?
Django class based view ListView with form
URL-parameters and logic in Django class-based views (TemplateView)
Another problem I encounter is I am unable to access the parameters in URL using self.kwargs as what suggested in most of the posts. In the final link I posted above, Ngenator mentioned that URL parameters has to be accessed using request.GET.get('parameter'). I used that and it's working fine for me.
By combining everything, here's the revised piece of coding I have. Just in case anyone is having the same problem as me.
1) views.py
class SearchBookView(ListView):
template_name = 'books/search_book.html'
paginate_by = '3'
context_object_name = 'book_found'
form_class = SearchBookForm
model = Book
def get_queryset(self):
object_list = self.model.objects.all()
title = self.request.GET.get('title', None)
if title is not None and title != "":
object_list = object_list.filter(title__icontains=title)
else:
object_list = []
return object_list
def get_context_data(self):
context = super(SearchBookView, self).get_context_data()
form = self.form_class(self.request.GET or None)
context.update({
'form': form,
})
return context
2) search_book.html (template)
{% extends "base.html" %}
{% load crispy_forms_tags %}
{% load staticfiles %}
{% load bootstrap_pagination %}
{% block title %}Search Page{% endblock %}
{% block content %}
<div class="container">
{% if form.errors %}
<p style="color: red;">
Please correct the error{{ form.errors|pluralize }} below.
</p>
{% endif %}
{% crispy form %}
{% if book_found %}
<p>Found {{ paginator.count }} book{{ book_found_no|pluralize }}.</p>
{% for book in book_found %}
<div class="wholecard">
<div style="height:170px; border:solid #111111;" class="col-md-3">
Image
</div>
<div class="card col-md-9">
<div class="card-title">"{{ book.title }}"</div>
<div>{{ book.description }}</div>
Read More
</div>
</div>
{% endfor %}
{% else %}
<p>No book matched your searching criteria.</p>
{% endif %}
{% bootstrap_paginate page_obj %}
</div>
{% endblock %}
And I ended up using jmcclell's bootstrap-pagination also for pagination. Saved me lots of time! Good stuff...

You've specifically overridden the get method so that it defines its own context, and never calls the default methods, so naturally none of the default context bars are available.
Don't do that; you should almost never be overriding the get and post methods. You should probably move all the form stuff directly into get_queryset.

It's working
views.py
class UserListView(ListView):
model = User
template_name = 'user_list.html'
context_object_name = 'users'
paginate_by = 10
def get_queryset(self):
return User.objects.all()
templates/user_list.html
{% if is_paginated %}
<nav aria-label="Page navigation conatiner">
<ul class="pagination justify-content-center">
{% if page_obj.has_previous %}
<li>« PREV </li>
{% else %}
<li class="disabled page-item"><a class="page-link">PREV !</a></li>
{% endif %}
{% for i in %}
{{ i }}
{% endfor %}
{% if page_obj.has_next %}
<li> NEXT »</li>
{% else %}
<li class="disabled page-item"><a class="page-link">NEXT !</a></li>
{% endif %}
</ul>
</nav>
</div>
{% endif %}

Django - Have a class based view and Crispy form parrallell to each other on same page

Using Django, I am making a site that displays tickets. On the login page, I want it to where there is a preview area of existing tickets to the left of the login form. I am able to make both pages seperately, but I can not figure out how to make them co-exist side by side. I am also using jinja2 templating. I've been trying at this for 2 days, and I have read the tutorials over and over. Here is how I have it:
url.py:
urlpatterns = patterns('',
url(r'', include('ticket_app.urls')),
url(r'^accounts/login/$', login, {'authentication_form': forms.LoginForm}, name='login'),
)
views.py Note: Request is the database table object:
class PreviewList(ListView):
model = Request
form.py:
class LoginForm(AuthenticationForm):
def __init__(self, *args, **kwargs):
super(LoginForm, self).__init__(*args, **kwargs)
self.helper = FormHelper()
self.helper.form_class = 'form-horizontal'
self.helper.label_class = 'col-lg-2'
self.helper.field_class = 'col-lg-8'
self.helper.form_tag = False
self.helper.layout = Layout(
Field('username', placeholder="Username", css_class='input-xlarge'),
Field('password', placeholder="Password", css_class='input-xlarge'),
FormActions(
Submit('login', 'Login', css_class="btn-primary"),
)
base.html(short version):
<h1>{% block page_title %}Preview of tickets{% endblock page_title %}</h1>
{% block preview %}
{% endblock preview %}
{% block login %}
{% endblock login %}
preview.html:
{% extends 'base.html'%}
{% block preview %}
<div class="span6">
<ul class="list-group">
{% if object_list %}
{% for item in object_list %}
<li class="list-group-item">{{item.date_due}} - {{item.desctription}}
<span class="badge">
{% if item.user_assigned %}
<span class="badge"style="color:green"> assigned </span>
{% else %}<span class="badge" style="color:red">unassigned</span>
{% endif %}
</li>
{% endfor %}
{% else %}
<p>Yay! No ticket requests found!</p>
{% endif %}
</div>
{% endblock preview %}
login.html:
{% extends 'base.html' %}
{% load crispy_forms_tags %}
{% block login %}
<div class="container" style="padding-bottom: 70px;">
<div class='row'>
<div class='col-md-6 col-md-offset-3'>
<div class="well">
<legend>Sign in to Site</legend>
<form method="post" action="{% url 'django.contrib.auth.views.login' %}" class="form-horizontal">
{% crispy form %}
<input type="hidden" name="next" value="{{ next }}"/>
</form>
</div>
</div>
</div>
</div>
{% endblock login %}

There are multiple ways to accomplish this. For example, you could create your own login view that 'extends' the one from django.contrib.auth:
from django.contrib.auth.views import login
def login_with_preview(request, extra_context=None, *args, **kwargs):
if extra_context is None:
extra_context = {}
extra_context['object_list'] = Request.objects.all()
return login(request, authentication_form=LoginForm, extra_context=extra_context, *args, **kwargs)
And then use login_with_preview in your url conf and merge your two templates.
Another possibility is to create a custom template tag. This is especially nice if you want to show this preview list in different places:
#register.inclusion_tag("yourapp/preview_list.html")
def ticket_preview_list():
return {'object_list': Request.objects.all()}
preview_list.html should only contain the template code that, right now, is in your preview template block. You need to make sure that template doesn't extend base.html; that would mess things up. The usual template tag setup steps apply.

You could create one view that renders the login form and the preview data