How to dispaly dependaent dropdown list in django Python

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Django

how to dispaly data in dropdown when i click on first dropdown item ,means related or filtered data suppose i click on city dropdown all the city related devices from same table will be displayed for perticular city  in python django 

What I have tried:

-----views.py---------
def show3(request):
employees = Employee.objects.all().values('city').distinct()
if 'nameEmployees' in request.GET:
nameEmployees = 'nameEmployees' in request.POST and request.POST['nameEmployees']
employees = Employee.objects.filter(Q(city__contains='nameEmployees'))
return render(request, 'testapp/show3.html', {'employees':employees })


---------------show3.html------------

<form class="form" method="POST" action="show3">
                                <select id="nameEmployees" name="nameEmployees" class="form-control" onchange="get_host_name(this.value)">
                                        <option value="%">---------</option>
                                        {% for employee in employees %}
                                            <option value="{{ employee.id }}">{{ employee.city }}</option>
                                        {% endfor %}<br>
                                        
                                </select>
                            </form>

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{% for employee in employees %}

{{ employee.host_name }}


{% endfor %}