if request.method == "POST":
    form = ConnexionForm(request.POST)
    if form.is_valid():
        username = form.cleaned_data["Username"]
        user = authenticate(username=username, password=username)
        if user:
            login(request, user)
            UserAuthentified = True
        else:
            Error = True
    else:
        Error = True
else:
    form = ConnexionForm()

request.user.username