how to create a autocomplete input field in a form using Django

I am pretty new to django and its ways. I am trying to create an autocomplete field for a form. My code is as below

forms.py

from django import forms

class LeaveForm(forms.Form):
    leave_list = (
        ('Casual Leave', 'Casual Leave'),
        ('Sick Leave', 'Sick Leave')
    )
    from_email = forms.EmailField(required=True, widget=forms.TextInput(attrs={'style': 'width: 400px'}))
    start_date = end_date = forms.CharField(widget=forms.TextInput(attrs={'type': 'date', 'style': 'width: 175px'}))
    leave_type = forms.ChoiceField(choices=leave_list, widget=forms.Select(attrs={'style': 'width: 400px'}))
    comments = forms.CharField(required=True, widget=forms.Textarea(attrs={'style': 'width: 400px; height: 247px'}))

    def clean_from_email(self):
        data = self.cleaned_data['from_email']
        if "@testdomain.com" not in data:
            raise forms.ValidationError("Must be @testdomain.com")
        return data

What I want to achieve is that when an user types words into the "From Email" field the list of emails I have stored in an external DB should appear in the autocomplete list option.

models.py

from django.db import models


class ListOfUsers(models.Model):
    emp_number = models.CharField(db_column='Emp_Number', primary_key=True, max_length=50, unique=True)  # Field name made lowercase.
    name = models.CharField(db_column='Name', max_length=40)  # Field name made lowercase.
    supervisor = models.CharField(db_column='Supervisor', max_length=40)  # Field name made lowercase.
    email = models.CharField(db_column='Email', max_length=50, blank=False, null=False, unique=True)  # Field name made lowercase.


    class Meta:
        managed = False
        db_table = 'List of users'

Any idea how this can be done ?

Update :

I started messing around with django-autocomplete-light and now able to get a reply from the autocomplete url. It looks like this

{"results": [{"id": "[e-mail]", "text": "[e-mail]"}, {"id": "[e-mail]", "text": "[e-mail]"}, {"id": "[e-mail]", "text": "[e-mail]"}]}

views.py

class EmailAutocomplete(autocomplete.Select2ListView):
    def get_list(self):
        qs = ListOfUsers.objects.using('legacy')

        if self.q:
            qs = qs.filter(email__icontains=self.q).values_list('email', flat=True)

        return qs

I still do not know how to get this data to appear in the field "from_email"

Answer

I finally got the autocomplete search working using the instructions found here

https://github.com/xcash/bootstrap-autocomplete
https://bootstrap-autocomplete.readthedocs.io/en/latest/

It is very simple to use and does not need to install any app in settings.py and it works for both bootstrap 3 and bootstrap 4

There are lot of other packages available but this was simple and easy for my need.

I am going to explain the code I used

page.html

{% block script %}
    <script src="https://cdn.rawgit.com/xcash/bootstrap-autocomplete/3de7ad37/dist/latest/bootstrap-autocomplete.js"></script>
    <script>
        $('.basicAutoComplete').autoComplete(
            {minLength: 1}
        );
        $('.dropdown-menu').css({'top': 'auto', 'left': 'auto'})

    </script>
{% endblock %}
.
.
.
.
.
{% if field.name == "from_email" %}
   {% render_field field class="basicAutoComplete form-control" %}
{% else %}
   {% render_field field class="form-control" %}
{% endif %}

autoComplete is the function called to perform the action and minLength specifies the minimum length of the text before performing the fetch action I added an extra CSS to fix the autocomplete dropdown otherwise it was weird.

The Jinja render kept overwriting the class definition from views so I added an if check for it.

urls.py

from . import views

urlpatterns = [
    .
    .
    .
    path('email_autocomplete/', views.email_autocomplete, name='email_autocomplete')
]

Added this line to urls.py

forms.py

class LeaveForm(forms.Form):
    from_email = forms.EmailField(required=True, widget=forms.TextInput(
        attrs={
            'style': 'width: 400px',
            'class': 'basicAutoComplete',
            'data-url': "/domain/email_autocomplete/"
        }))

The above is the code for the input field in forms.py. data-url points to where the JSON result would be generated.

views.py

from django.http import HttpResponse, HttpResponseRedirect, JsonResponse
from .models import model
        
def email_autocomplete(request):
    if request.GET.get('q'):
        q = request.GET['q']
        data = model.objects.using('legacy').filter(email__startswith=q).values_list('email',flat=True)
        json = list(data)
        return JsonResponse(json, safe=False)
    else:
        HttpResponse("No cookies")
            

This was the most confusing part for me. The GET request is easy to understand but it took a while to convert the data from model.objects into a JSON formatted object. The trick was to use

values_list('columnName',flat=True)

when filtering the data from the database, then converting to a list using list(data) and finally use JsonResponse to convert it to JSON.

Hope this will help any one who wants a simple autocomplete