def register(request):
    """1. register a new user
       2. generate activating code
       3. send validating email
       4. prompt to check activating email.
    """
    if request.method == "GET":
        form = UserForm()
    if request.method == "POST":
        form = UserForm(request.POST)
        print(vars(form))
        if form.is_valid():
            #1. Create User and save to sever
            user = User.objects.create_user(
                      form.cleaned_data['username'],
                      first_name=form.cleaned_data['first_name'],
                      last_name=form.cleaned_data['last_name'],
                      email=form.cleaned_data['email'],
                      password=form.cleaned_data['password'])
            user.is_active = False
            user.save()

            #2. Create activate code and save to server.
            uuid_code = str(uuid.uuid4()).replace("-", '')
            activate_code = ActivateCode(user=user, code=uuid_code)
            activate_code.save()

            #3. Send Validation Email
            activate_link = "http://%s/user/activate/%s" %(request.get_host(), uuid_code)
            activate_message = """
            You're almost done!
            <a href="%s">Click here to complete your registration</a>
            """ % activate_link
            send_mail(subject="Complete Registration With Code Journey",
                      message="Click here to complete your registration: %s" %activate_link,
                      html_message=activate_message,
                      from_email="anexmaple@mail.com",
                      recipient_list=[form.cleaned_data['email'],],
                      fail_silently=False)

           #4. Prompt user to check his email.
            context = {'email': form.cleaned_data['email'],}
            return render(request, "user/validate.html", context)