Log user in automatically after sign-up

[yuvipanda]

Right now, when a user signs up, they are then asked to manually go to the login page and log in.

If they don't need explicit admin approval, we should log them in automatically.

[xrdy511623]

I figure it out by reconstructing the code on signup, which looks like this:

class SignUpHandler(LocalBase):
# Render the sign in page.
async def get(self):
if not self.authenticator.enable_signup:
raise web.HTTPError(404)

    self._register_template_path()
    html = self.render_template(
        'signup.html',
        ask_email=self.authenticator.ask_email_on_signup,
        two_factor_auth=self.authenticator.allow_2fa,
    )
    self.finish(html)

def get_result_message(self, user, taken):
    alert = 'alert-info'
    message = 'Your information has been sent to the admin'

    # Always error if username is taken.
    if taken:
        alert = 'alert-danger'
        message = ("Something went wrong. It appears that this "
                   "username is already in use. Please try again "
                   "with a different username.")
    else:
        # Error if user creation was not successful.
        if not user:
            alert = 'alert-danger'
            pw_len = self.authenticator.minimum_password_length
            if pw_len:
                message = ("Something went wrong. Be sure your "
                           "password has at least {} characters, doesn't "
                           "have spaces or commas and is not too "
                           "common.").format(pw_len)
            else:
                message = ("Something went wrong. Be sure your password "
                           "doesn't have spaces or commas and is not too "
                           "common.")

        # If user creation went through & open-signup is enabled, success.
        elif self.authenticator.open_signup:
            alert = 'alert-success'
            message = ('The signup was successful. You can now go to '
                       'home page and log in the system')

    return alert, message

async def post(self):
    if not self.authenticator.enable_signup:
        raise web.HTTPError(404)

    user_info = {
        'username': self.get_body_argument('username', strip=False),
        'pw': self.get_body_argument('pw', strip=False),
        'email': self.get_body_argument('email', '', strip=False),
        'has_2fa': bool(self.get_body_argument('2fa', '', strip=False)),
    }
    taken = self.authenticator.user_exists(user_info['username'])
    user = self.authenticator.create_user(**user_info)

    alert, message = self.get_result_message(user, taken)        

    otp_secret, user_2fa = '', ''
    if user:
        otp_secret = user.otp_secret
        user_2fa = user.has_2fa
        
    # if alert == 'alert-success', enable user to login automatically,
    # otherwise, let them stay at the signup page and show them the error message.
    
    if alert == 'alert-success':
        username = user_info['username']
        password = user_info ['pw']
        data = {'username': username, 'password': password}
        user = await self.login_user(data)
        if user:
            self._jupyterhub_user = user
            self.redirect(self.get_next_url(user))
    
    # In this case,user can signup again according to the result message
    else:
        html = self.render_template(
            'signup.html',
            ask_email=self.authenticator.ask_email_on_signup,
            result_message=message,
            alert=alert,
            two_factor_auth=self.authenticator.allow_2fa,
            two_factor_auth_user=user_2fa,
            two_factor_auth_value=otp_secret,
        )

        self.finish(html)

I have tested the code and got the expected result that user can login automatically after signup.

[xrdy511623]

Forgive me for I really can not edit format of the code correctly.