409 'Document update conflict' on couchbase lite 2.0 iOS

Mobile Couchbase Lite
1

Hi,
I am using couchbase lite 2.0 in iOS i am getting this error. CouchbaseLite Sync ERROR: {Repl#1} Got error response: HTTP 409 ‘Document update conflict’

I used following code for save or update the document.

 do {
            if try database.saveDocument(doc, concurrencyControl: .lastWriteWins) {
                // save was a success. docToSave is the new saved revision. Proceed as usual
            }
            else {
                // Failure on save with failOnConflict mode
                // Handle conflict appropriately
                print("Document failed with conflicts......")
                if let currDoc = database.document(withID: doc.id) {
                    // Option 2: Examine contents of current saved version of doc
                    // Force write of document
                    try database.saveDocument(doc)
                }
                else {
                    // Doc was deleted.
                    // Option 2: Attempt to do a force write of document to override the delete
                    try database.saveDocument(doc)
                }
            }
        }
        catch {
            print("Some other error in saving \(error)")
        }

Here is my sync config file. which is supports auto conflicts fix as well

{
        "log": ["*"],
        "databases": {
                "stores": {
                        "server": "http://localhost:8091",
                        "bucket": "stores",
                        "username": "admin",
                        "password": "admin@123",
                        "allow_conflicts":false,
                        "users": {
                                "GUEST": {
                                        "disabled": false,
                                        "admin_channels": ["*"]
                                }
                        }

                }
        }
}

Can you please tell me, how to perform lastWriteWins always on sycn gateway and in couchbase lite?

2

That’s just a log message. It shouldn’t affect your app. Is anything actually going wrong in your app’s behavior?

3

Seems sometimes, the otherside app local DB not updating. But i thought following is the issue for conflicts. Because when i get new updated record, i will do some operation again.

database.addChangeListener { [weak self](change) in
            guard let `self` = self else {
                return
            }
            
            for docId in change.documentIDs   {
                let doc = self.database.document(withID: docId)
                print("Doc id is \(docId) and doc is \(doc?.toDictionary()) and \(doc?.sequence)")
                if let _doc = doc{
                    documentlistener?(_doc)
                }
            }
        }

Still didn’t understand why addChangeListener block calling multiple times for same documentid. even when i update a single document one time at a time.

Do we have any other lister to identify what are records changed recently without any duplicated like above. or shall we use liver query for this?

4

@jens Any update, even sometimes my latest revision is not updated to server.
Here i attached my sync log and admin portal. i didnt understand the root cause.

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5

The Couchbase Lite logs would be the most useful thing to see here. Also, you should specify what document ID is involved.

And please don’t attach logs as screenshots – they’re hard to read and unsearchable. Copy the text and paste it into a gist on Github, and post a link to that.

6

Sure, i will upload synch gateway config logs.