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I am looking into migrating a large application written in Xamarin and moving to Flutter with Cloud Firestore as the backend. Since Cloud Firestore is still in beta there appears to be very few concrete examples demonstrating best practices when called from a Flutter client.

In particular - there seems to be no direct approach to checking whether a TX has failed or whether it succeeds.

So taking the standard 'Delete' operation as an example - what is the best approach to rolling your own transactions within both online/offline mode including providing appropriate error handling in Flutter ?

I have expanded on my solution below (in the remove method) and you can see that two network calls are being made, one to get the latest document reference and another to perform the delete.

However, since we use a StreamBuilder that gets updates to when any documents change , can we not positively assume that widget.documents[index].reference will hold the latest document reference and therefore do away with :

var snapshot=await tx.get(docReference)
if (snapshot.exists)
 await tx.delete(snapshot.reference)

and just use :

 var docReference = widget.documents[index].reference;
 await tx.delete(docReference);

Note

Both of the approaches above work - i am after an approach that conforms 100% to ACID test in relation to transactions as well as offering best performance.

Example use case

Streambuilder subscription:

In the FirestoreListView a ListView.Builder is created that adds delete/edit button that allows any item to be deleted or added , thus we have something like this :

Listview:

Behind the delete button, we perform the delete as :

Delete code: