Datastore - Changing Schema Breaks Query

[fjnoyp]

Describe the bug

For Amplify iOS - Datastore, if a user saves a model instance, then modifies its modelSchema to add another field, then runs amplify codegen models, a crash happens:

Query API failed. Error = DataStoreError: The operation couldn't be completed. (SQLite.Result error 0.)
Recovery suggestion: The operation couldn't be completed. (SQLite.Result error 0.)

To Reproduce
Steps to reproduce the behavior:

1. Create the following schema:

type Note @model {
id: ID!
content: String!
}

2. Save the model and then query. Observe no error.

3. Update the schema:

type Note @model {
id: ID!
content: String!
name: String
}

4. Run query. Don't save. Observe the error:

Query API failed. Error = DataStoreError: The operation couldn't be completed. (SQLite.Result error 0.)
Recovery suggestion: The operation couldn't be completed. (SQLite.Result error 0.)

Expected behavior
No error after changing the modelschema and running query

Screenshots
Here is the local DB on the phone. As you can see it's updated to include the extra fields:

Also on the AWS Amplify console you can see the extra fields as well:

Device Information (please complete the following information):

• Device: Simulator
• iOS Version: 14.2

[palpatim]

@fjnoyp Thanks for reporting this.

Right now we don't have a mechanism for supporting local migrations, but I wouldn't expect a crash--the documented behavior is that we remove local items and re-sync from the cloud.

[ruiguoamz]

Hi, @fjnoyp

Are you talking about the usage with sync enabled or disabled?
For whichever use case, I don't see a crash. But I do see subscription fails to be established for one case which I explain below

No matter for sync enabled or not, as long as there is a schema change, the local database will be cleared as @palpatim mentioned: we don't support for local data migration and we don't have control over customer's change of schema.

In this case the difference is the sync part:

If sync is enabled, when you change your schema, you should do a amplify push and then amplify codegen models, in this case, no error will be returned and thus no crash with the schema you provided. The sync will still be kicked off and when you do a query, the following result should be returned:

Note(id: "uuid********whatever", content: "note7", name: nil)

but if you skip doing amplify push, it fails to set up subscription, and since local database is cleared, you will get an empty array.

Maybe please provide more detailed reproduction steps that we can help out. Thanks

[github-actions]

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