ChoiceField - Django Forms - GeeksforGeeks

13 Feb, 2020
ChoiceField in Django Forms is a string field, for selecting a particular choice out of a list of available choices. It is used to implement State, Countries etc. like fields for which information is already defined and user has to choose one. It is used for taking text inputs from the user. The default widget for this input is Select.It Normalizes to: A string.
ChoiceField has one extra required argument :
choices :Either an iterable of 2-tuples to use as choices for this field, or a callable that returns such an iterable. This argument accepts the same formats as the choices argument to a model field.
Syntax
field_name = forms.ChoiceField(**options)
Illustration of ChoiceField using an Example. Consider a project named geeksforgeeks having an app named geeks.
Refer to the following articles to check how to create a project and an app in Django.
How to Create a Basic Project using MVT in Django?
How to Create an App in Django ?
Enter the following code into forms.py file of geeks app.
from django import forms  # iterableGEEKS_CHOICES =(    ("1", "One"),    ("2", "Two"),    ("3", "Three"),    ("4", "Four"),    ("5", "Five"),)  # creating a form class GeeksForm(forms.Form):    geeks_field = forms.ChoiceField(choices = GEEKS_CHOICES)
Add the geeks app to INSTALLED_APPS
# Application definition  INSTALLED_APPS = [    'django.contrib.admin',    'django.contrib.auth',    'django.contrib.contenttypes',    'django.contrib.sessions',    'django.contrib.messages',    'django.contrib.staticfiles',    'geeks',]
Now to render this form into a view we need a view and a URL mapped to that URL. Let’s create a view first in views.py of geeks app,
from django.shortcuts import renderfrom .forms import GeeksForm  # Create your views here.def home_view(request):    context = {}    context['form'] = GeeksForm()    return render( request, "home.html", context)
Here we are importing that particular form from forms.py and creating an object of it in the view so that it can be rendered in a template.Now, to initiate a Django form you need to create home.html where one would be designing the stuff as they like. Let’s create a form in home.html.
<form method = "GET">    {{ form }}    <input type = "submit" value = "Submit"></form>
Finally, a URL to map to this view in urls.py
from django.urls import path  # importing views from views..pyfrom .views import home_view  urlpatterns = [    path('', home_view ),]
Let’s run the server and check what has actually happened, Run
Python manage.py runserver
Thus, an geeks_field ChoiceField is created by replacing “_” with ” “. It is a field to input choices of strings.
ChoiceField is used for input of small-sized strings in the database. One can input state, country, city, etc. Till now we have discussed how to implement ChoiceField but how to use it in the view for performing the logical part. To perform some logic we would need to get the value entered into field into a python string instance.In views.py,
from django.shortcuts import renderfrom .forms import GeeksForm  # Create your views here.def home_view(request):    context ={}    form = GeeksForm()    context['form']= form    if request.GET:        temp = request.GET['geeks_field']        print(temp)    return render(request, "home.html", context)
Now let’s try entering data into the field.
Now this data can be fetched using corresponding request dictionary. If method is GET, data would be available in request.GET and if post, request.POST correspondingly. In above example we have the value in temp which we can use for any purpose.
Core Field arguments are the arguments given to each field for applying some constraint or imparting a particular characteristic to a particular Field. For example, adding an argument required = False to ChoiceField will enable it to be left blank by the user. Each Field class constructor takes at least these arguments. Some Field classes take additional, field-specific arguments, but the following should always be accepted:
NaveenArora
Django-forms
Python Django
Python
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