Firebase simultaneous realtime database update (Android)

[Uğur B]

I am developing an android app kinda random chat.

i have users structure in realtime database which is created whenever a new users login with username.

Database structure is as below.

users: {

  user1Id : {

    status: searching,

    username: guest

  }

 .

 .

 .

}

When user click search button the status changes to searching and i am getting all the users whose status are searching at the same time and randomly match 2 of them. Finally change the status of both users to matched and create a room for those users.

But I stucked at this point. For an instance, when 3 users click search their status turns to searching and i randomly match them. But when i read the status as searching, the other user may be matched already.  I can not assure multiple writes to database. 

I also used Google App Engine Servlet but no luck. 

I wonder is there any method to handle multiple updates of the same field in a queue or lock the field for a user who first accessed? 

[Jacob Wenger]

I think you are looking for transactions. You can find docs for them here.

Jacob

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[Uğur B]

thanks men, it seems what i m looking for. i will try it asap. i also wonder if it is possible with write permissions. i.e. auth users can only write if the status field is 'searching'. 

i m trying but i couldnt manage yet. but it must be possible i guess.

9 Haziran 2016 Perşembe 20:47:23 UTC+3 tarihinde Jacob Wenger yazdı: