Question: How to synchronize sembast?

[guenth39]

Is there a proven method how to synchronize the sembast database of my flutter app with a backend? Would be nice to have a tutorial for that.

[alextekartik]

Not than I am aware of. Synchronization is a complex algorithm that depends on the backend. Whether you use sembast or any other local database does not make much difference.

One common algorithm:

• Store a server id for each synchronized record
• Store a dirty flag for local changes for each synchronized record.

Full sync:

• Get all server records
• Get server records
• Compare and handle conflict (typically server wins)
• Add local changes

Incremental sync:

• Get all modified/deleted records since xxx
• Add local change/deletion since xxx
• Compare and handle conflict (typically server wins)

[tobinharris]

Is the data modified on both back-end and the phone?

I'm toying with just beaming the entire local JSON .db file up to MongoDb, stored against a user. This is good for a "backup" although there's absolutely no sync logic going on.

For sync, I wonder if CouchDB could be worth a look because it's also a key/value store and works with JSON.

[alextekartik]

Is the data modified on both back-end and the phone?

(I'm assuming If instead of is).
That can happen, that is where you need some resolution strategy (local wins, server wins, last change wins, user prompt...)

I don't recommend storing the whole db file itself. At least save the export using exportDatabase instead of the whole file.