For writing data in Firebase Database I use setValue() in my android app.
My question is: can a value of a variable change, if at the same time I change the value using the Admin API?
All writes to the database from all clients are ordered. It doesn't matter if its from a client app or the admin SDK. If there are two database clients trying to write different values to the same location in the database, the last writer in the order overwrites the previous value, which is then what all the other clients will eventually see.
If you want to decide what to do in the event of a conflict like this, you can use a transaction to make sure that each client gets to know exactly what the prior data was, and what the new data will be. This is how you make things like a counter safe to increment when there are lots of writers trying to increment it.
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I have been working on a arduino project based on firebase real time database. My task is to monitor change in values of KEYS . I am able to read KEYS from arduino but to do this I am reading KEYS in a loop but this increases my data traffic, which I dont want to do( Google gives 10 GB of free data for RTDB).
I want this process in such a way that whenever there will be change in KEY'S value firebase should inform my controller that values have been changed . By doing this I can avoid reading KEY again and again and this way I can save Data traffic.
Please help me if there is any efficient way to get to know change in KEYs values.
Since you use the Firebase-ESP8266 library, you need to use the technique described in the "Server Data Changes Listener with Server-Sent Events or HTTP Streaming" section of the documentation.
I am saving some data to firebase, I am using golang admin sdk. My problem is when I push object to firebase it generates an ID which is good for some use cases, but I don't need that what need is a custom integer key like 1,3,4.....
The object may look like this after pushing.
I know I can set it by fetching all data then count them and create next id and add my object under that ID but I don't want this. Is there any way to achieve this in firebase automatically.
You can technically do this but it requires some additional setup.
You will have to maintain the current index in a 'global' position and increment it
there is a risk of write failure if there is a race condition between 2 or more users. to minimize this, you can look at using transactions and rules to control the flow of data.
Additionally, you can use cloud functions to process this if you don't want the client to handle the transaction and updating of the global counter.
Sources:
Cloud Functions
Server side increment
Rules for existing vs new data
I'm writing a small game for Android in Unity. Basically the person have to guess whats on the photo. Now my boss wants me to add an additional function-> after successful/unsuccessful guess the player will get the panel to rate the photo (basically like or dislike), because we want to track which photos are not good/remove the photos after a couple of successful guesses.
My understanding is that if we want to add +1 to the variable in Firebase first I have to make the call and get it then we have to make a separate call with adding 1 to the value we got. I was wandering if there is a more efficient way to do it?
Thanks for any suggestions!
Instead of requesting firebase when you want to add ,you can request firebase in the beginning (onCreate like method) and save the object and then use it when you want to update it.
thanks
Well, one thing you can do is to store your data temporarily in some object, but NOT send it to Firebase right away. Instead, you can send the data to Firebase in times when the app/game is about to get paused/minimized; hence, reducing potential lags and increasing player satisfaction. OnApplicationPause(bool) is one of such functions that gets called when the game is minimized.
To do what you want, I would recommend using a Transaction instead of just doing a SetValueAsync. This lets you change values in your large shared database atomically, by first running your transaction against the local cache and later against the server data if it differs (see this question/answer).
This gets into some larger interesting bits of the Firebase Unity plugin. Reads/writes will run against your local cache, so you can do things like attach a listener to the "likes" node of a picture. As your cache syncs online and your transaction runs, this callback will be asynchronously triggered letting you keep the value up to date without worrying about syncing during app launch/shutdown/doing your own caching logic. This also means that generally, you don't have to worry too much about your online/offline state throughout your game.
I have two different nodes in database.
all posts
users
As per the fan-out model when a user adds a post , it gets updated at both all posts and users/uid/posts.
Each post consists of a like button which displays the number of likes.
When a user clicks on it the like should increase by +1.
According to the docs, we use transactionfor this kind of process.
But the problem with using transaction is that it updates only one node as far as i know
But my problem is how shall i update this transaction in both the nodes as mentioned above
Shall i use update method
What is the way to use transaction that gets updated at both the nodes
You can push all your logic for updating the database onto the server side with Cloud Functions for Firebase. Use can use a database trigger to respond to data being written in the database, then execute some JavaScript to make sure the fan-out finishes correctly. It will have the advantage of making sure all the changes happen without depending on the client.
Transactions can't modify data at two different locations at once, but you will still probably want to use them in your client and Cloud Functions to make sure concurrent writes will not have problems.
Lets say I'm making an app with firebase where the user can create permanent lobbies in which they can send permanent dated messages to. The lobby's name is a key in my data structure. What I want to do is that each time a new lobby is created, an index is automatically created on the server side to sort the messages of that lobby by date.
That can probably be done if I have another server listening in to the creation of new lobbies but is there a way to do this without having an additional server? Just through the client? Without compromising the security of the app?
(Note: I'm using the Unity sdk)
There is no way to programmatically add an index, short from updating a rules.json file and uploading it with the Firebase tools/CLI, which I'd highly recommend against.
If you find you need to dynamically add indexes, you've probably structured your data wrong. But without seeing a minimal sample of the JSON (as text, no screenshots please) that reproduces the problem, it is impossible to say more than that.
You can use the Push() function on a database reference. This will create a unique key based on the timestamp so all values can easily be sorted chronologically.
Use Push() anytime you need to generate a new unique key on your database. You can use this for the lobby itself and even the conversations within the lobby.
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