*Edit* Graphql Update Appending Data to Arrays instead of overwriting

[Rafcin]

I noticed a bug today, while I was working on an editor. When running the update mutation, my properties that use arrays are duplicated leaving me with the original array and the new array stored together. How the editor works is I get the data for x object, set the state and then with the same state if the user modified it and confirms it then it updates. I was under the impression it would override the values

[Rafcin]

Another issue that goes with this is that when I set the values to be null or empty the action goes through but never actually makes the arrays empty or null.

    await API.graphql(graphqlOperation(mutations.updateRestaurant, { input: {
      id: this.state.restaurantData.id,
      restaurantPaymentOptions: [],
      restaurantOpeningHours: [],
      restaurantImageHeaders: [],
    } }))

[Rafcin]

Would using AWSJSON be appropriate for this case?

[Rafcin]

Also I should note that looking at other issues online I noticed some people had issues because of @versioned and I have the version stamps on my DynamoDB items and yet I never added the version tag to my schema....

[Rafcin]

Fixed it. The issue is caused by the conflict detection. Although I removed the conflict detection through the CLI I had to manually remove

        "project": {
            "ConflictHandler": "AUTOMERGE",
            "ConflictDetection": "VERSION"
        },

[ondojo]

Hi, we are actually facing the same problems, using DataStore (which requires us to use conflict detection) and hence removing that is not a probable solution for us.
The symptoms are, that occasionally an update of a model having an array attribute leads to a duplication of the array items.

I hope that description is somewhat understandable, if not, please let me know and I will try to elaborate in more detail.

[ammarkarachi]

@ondojo do you mean the items are concatenated even though they are the same? Also could you share your tranform.conf file?

[stale]

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[stale]

This issue has been automatically closed because of inactivity. Please open a new issue if you are still encountering problems.

[CarbnJacob]

I have this same problem too! With automerge the data objects concatenate every time rather than replace, which leads to huge issues.

[crolly]

I have this same problem too! With automerge the data objects concatenate every time rather than replace, which leads to huge issues.

after some more digging into the docs of app sync, i have found this: https://docs.aws.amazon.com/appsync/latest/devguide/conflict-detection-and-sync.html

the leads me to believe, that everything works as it is supposed to.

Conflict on a list: GraphQL type and database type are lists. Concatenate the incoming list with the existing list in the server. The list values in the incoming mutation will be appended to the end of the list in the server. Duplicate values will be retained.

What we did, was to change the conflict resolution to Optimistic Concurrency and implementing our own conflict resolution.
@CarbnJacob you could e.g. use lodash's isEqual and then replace items in the list or the entire list. I guess it all depends on your data model.

[CarbnJacob]

@CarbnJacob you could e.g. use lodash's isEqual and then replace items in the list or the entire list. I guess it all depends on your data model.

Thanks for getting back to me so fast @crolly!

I'm new to conflict resolution - would this conflict resolution need to be done in the callback from failed GraphQL mutations made by the client?

I'm doing most of the saves through Amplify DataStore so it's largely a black box to me :(

[crolly]

@CarbnJacob yes. take a look here: https://docs.amplify.aws/lib/datastore/conflict/q/platform/js#custom-configuration

you can specify your own conflictHandler with DataStore.configure.

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