raise


Definition
The keyword return with the argument in the case condition is not fulfilled.

Syntax
raise

Parameters
N/A

Examples
Here, in this example, the IntegerField validated number entered should be in record and before the Field vale is passed on HttpResponseRedirect in views.py and index.html files.
Steps for creating virtual environment, startproject, startapps, & running server:
  • virtualenv myvirtualenv
  • cd  mysite
  • .\Scripts\activate
  • pip install django
  • python .\Scripts\django-admin.py startproject mysite
  • cd mysite
  • python manage.py startapp myapphttp
  • python manage.py runserver 



setting.py

INSTALLED_APPS = (
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles','myapphttp',
)

urls.py

from django.conf.urls import include, url

from myapphttp.views import response

urlpatterns = [
      url(r'^', response),
]

myapphttp/forms.py

from django import forms



def Validate(value):
    pin=[1101,2945,3635,5550,3334,5553,2822,4624,3221,6453,2223,4456,5462]
    if value not in pin:
        raise ValidationError('%s : The pin number is not in our record.'% value)

class IntegerField(forms.Form):
    number=forms.IntegerField(label='Number' ,validators=[Validate])

myapphttp/views.py

from django.shortcuts import render

from .forms import IntegerField

def response(request):
    if request.method == 'POST':
        form=IntegerField(request.POST)
        if form.is_valid():
            return HttpResponseRedirect('/Thanks-for-submitting-your-request/')
    else:
        form = IntegerField()

    return render(request, 'myapphttp\index.html', {'form':form})


myapphttp/index.html

<!DOCTYPE html>
<html>
<title> </title>
<body>

<form action="/pin-not-found/" method="post">
    {% csrf_token %}
    {{ form }}
    <input type="submit" value="Submit" />
</form>

</body>
</html>






Here, in this examples, the form validation is processed through the calling the function in the forms.EmailField(). The  function validated the list items after the form is submitted through POST method.
 Steps for creating virtual environment, startproject, startapps, & running server:
  • virtualenv myenv
  • cd  myenv
  • .\Scripts\activate
  • .\Scripts\deactivate
  • pip install django
  • python .\Scripts\django-admin.py startproject mysite
  • cd mysite
  • python manage.py startapp myapp
  • python manage.py runserver

Files


setting.py

INSTALLED_APPS = (
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles', 'myapp', 
)

urls.py

from myapp.views import submit

urlpatterns = [
    url(r'^', submit),
]

myapp/forms.py

from django import forms
from django.core.exceptions import ValidationError

def Validate(email):
    list=['adil@adilwaseem.com', 'adil@pythonlake.com','contact@adilwaseem.com']
    if email not in list:
        raise ValidationError("%s is not in our record."% email )

class AccessForm(forms.Form):
    email=forms.EmailField(label='Email',validators=[Validate])

myapp/views.py

from django.shortcuts import render

from .forms import AccessForm

def submit(request):
    if request.method == 'POST':
        form=AccessForm(request.POST)
        if form.is_valid():
            return HttpResponseRedirect('/thanks/')
    else:
        form = AccessForm()

    return render(request, 'myapp\index.html', {'form':form})

myapp/index.html

<!DOCTYPE html>
<html>
<title> </title>
<body>

<form action="/Response/" method="post">
    {% csrf_token %}
    {{ form }}
    <input type="submit" value="Submit" />
</form>

</body>
</html>

view at localhost:8000/






The method raise the error exception if the condition is not fulfilled.
x ="Python"

if x=="P":
    print("Welcome")

    raise ValueError(print("not allowed"))

>>> 
not allowed
>>>
        

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