CODEWITHSUNDEEP
firebasefirebase-realtime-database
Thalatta
Thalatta

Reputation: 4578

firebase database equivalent of MySQL transaction

I'm seeking something where I can thread through multiple updates to multiple firebase.database.References (before performing a commit) a single object and then commit that at the end and if it is unsuccessful no changes are made to any of my Firebase References.

Does this exist? the firebase.database.Transaction I thought would be similar since it is an atomic update and it does involve a callback which says if it has been committed or not, but the update function, I believe, is only for a single object, and the function doesn't seem to return a transactionId or something I could pass to other firebase.database.Transactionss or something.

UPDATE This transaction's update seems to return a Transaction which would lend itself to perhaps chaining: https://firebase.google.com/docs/reference/js/firebase.firestore.Transaction

however this is different from the other Transaction:

Upvotes: 0

Views: 193

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 599766

Firebase Database transactions perform an update to a single location based on the current value of that same location. They explicitly do not work across multiple locations, since that would limit their scalability. Sometimes developers work around this by performing a transaction higher up in their JSON tree (at the first common point of the locations). I'd recommend against that, as that would limit the scalability even further.

The only way to efficiently update multiple locations with one API call, is with a multiple location update. This does however not have reading of the current value built-in.

So if you want to update multiple locations based on their current value, you'll have to perform the read operation in your application code, turn that into a multi-location update, and then use security rules to ensure all of those updates follow your application rules. This is a quite non-trivial approach, so I hardly see it being done in practice. See my answer here for an example: Is the way the Firebase database quickstart handles counts secure?

Upvotes: 1

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