Saving Current State when Redirected to Login Fragment in Open Event Android

Some features in Open Event Android requires the user to be logged in, for example, buying tickets or viewing bought tickets. If the user selects to buy tickets for an event and he/she is not logged in, the user will be redirected to login fragment and on successful login, the user will return to the last state. This blog post will help you understand how its done in Open Event Android we will be taking the example of buying tickets without logged in.

To give you an overview once a user selects to buy tickets he is taken to a Tickets Fragment which contains different tickets and allows the user to pick their respective quantity. After selecting the right quantities the user can select on the register and he/she will be taken to Attendee Fragment which requires the user to be logged in, if not he will be redirected to login fragment and on successful login he can continue from attendee fragment without losing the selected tickets and their quantity information

To do this when redirecting from Attendee Fragment to the AuthActivity we modify the redirect method and send additional information with the intent such as even id and list of ticket id and quantity selected by the user. Following is how it can be done.

val intent = Intent(activity,
       val bundle = Bundle()
       bundle.putLong(EVENT_ID, id.toLong())
       if (ticketIdAndQty != null)
           bundle.putSerializable(TICKET_ID_AND_QTY, ticketIdAndQty as ArrayList)

Now that we have sent additional information with intent we will also have to modify the login fragment to use this information.

The above-discussed method will redirect the user to AuthActivity which handles all the authentication part. The user can either select to log in with an existing account or he may sign up with a new account. For existing accounts login fragment is shown and similarly for new sign up sign up fragment is shown.

The AuthActivity simply takes the bundle it received using intent.getExtras and passes the same to the fragment it is rendering. The load fragment function in Auth Activity looks like below. Whatever fragment is opened (signup/login) it passes the bundle that AuthActivity received as arguments to the fragments. This is done by setting fragment.arguments = bundle

private fun loadFragment(fragment: Fragment) {
       if (bundle != null)
           fragment.arguments = bundle
               .replace(, fragment)

Now we have all the bundle information in our login fragment next what we want is whenever login completes successfully send the user back to Attendee Fragment along with the event and ticket id and selected quantity information.

The following snippet of code takes the user to MainActivity whenever user information is received which means the user has successfully logged in

 loginActivityViewModel.user.observe(this, Observer {

redirectToMain accepts bundle as a parameter this bundle contains the ticket id and quantity list and the event id this is what we received from AuthActivity.

 private fun redirectToMain(bundle: Bundle?) {
       val intent = Intent(activity,
       if (((bundle != null) && !id.equals(-1)) && (ticketIdAndQty != null)) {
           intent.putExtra(LAUNCH_ATTENDEE, true)
       activity?.overridePendingTransition(R.anim.slide_in_left, R.anim.slide_out_right)

The above code snippet shows the redirectToMain function in Login Fragment, this method opens the Main Activity and passes the bundle as a parameter to it along with a trigger LAUNCH_ATTENDEE set. This trigger is responsible for telling MainAcitivty that the login fragment was actually a redirect from attendee fragment and MainActivity uses the bundle information to recreate the Attendee Fragment screen.

The following code handles this part in Main Activity.

if (bundle != null && bundle.getBoolean(LAUNCH_ATTENDEE)) {
           val fragment = AttendeeFragment()
           fragment.arguments = bundle
           openEventsFragment = false

If the bundle information is available and the Launch attendee trigger is set AttendeeFragment is created with arguments as the bundle (fragment.arguments = bundle).


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