def login_view(request):
    if request.method == 'GET':
        #display login form
        template_name = 'login.html'
        login_form = LoginForm()
    elif request.method == 'POST':
        #process the form data
        login_form = LoginForm(request.POST)
        if login_form.is_valid():
            #validation successful
            username = login_form.cleaned_data['username']
            password = login_form.cleaned_data['password']
            #read data from db
            user = UserModel.objects.filter(username=username).first()
            if user:
                #compare password
                if check_password(password, user.password):
                    #login successful
                    template_name = 'login_success.html'
                    return render(request, 'login_success.html', {'login_form': login_form})

                # else:
                #     #login failed.
                #     template_name = 'login_fail.html'
                #     return render(request, template_name, {'login_form': login_form})

            else:
                  #user does not exist in db.
                  template_name = 'login_fail.html'

    return render(request, template_name, {'login_form':login_form})