Provide method to clear and full sync specific models

[PS-MS]

Before opening, please confirm:

• I have searched for duplicate or closed issues and discussions.

Language and Async Model

Kotlin

Amplify Categories

DataStore

Gradle script dependencies

    def amplify_version = "1.32.1"
    def amplify_kotlin_version = "0.16.0"

    implementation "com.amplifyframework:core-kotlin:$amplify_kotlin_version"
    implementation "com.amplifyframework:aws-storage-s3:$amplify_version"
    implementation "com.amplifyframework:aws-auth-cognito:$amplify_version"
    implementation "com.amplifyframework:aws-api:$amplify_version"
    implementation "com.amplifyframework:aws-datastore:$amplify_version"

Please include any relevant guides or documentation you're referencing

https://docs.amplify.aws/lib/datastore/sync/q/platform/android/#clear-local-data
https://docs.amplify.aws/lib/datastore/sync/q/platform/android/#reevaluate-expressions-at-runtime

Describe the feature request

I'm currently working on a feature to allow set roles and permissions and cannot clear or full sync a specific model if needed at runtime.

var syncPosts: Boolean = false

fun initialize() {
    Amplify.addPlugin(AWSDataStorePlugin.builder().dataStoreConfiguration(
        DataStoreConfiguration.builder()
            .syncExpression(Post::class.java) {
                                if (syncPosts) {
                                    QueryPredicates.all()
                                } else QueryPredicates.none()
                            }
            .build())
        .build())
}

fun changeSync() {
    syncPosts = true;
    Amplify.DataStore.stop(
        {
            Amplify.DataStore.start(
                { Log.i("MyAmplifyApp", "DataStore started") },
                { Log.e("MyAmplifyApp", "Error starting DataStore", it) }
            )
        },
        { Log.e("MyAmplifyApp", "Error stopping DataStore", it) }
    )
}

To use the documentation examples, initially this user isn't allowed to use any Posts. The app will start up, full sync Posts (giving nothing) and sets the LastSyncMetadata saying this model has been synced.

A GraphQL mutation is observed and the user is now allowed to view Posts, so changeSync() is called setting the syncPosts flag and restarting datastore (stop & start, not clear).

I would expect the Post model to retrieve all of the posts, as that is now the predicate, not just the posts that were updated since the last sync attempt.

A GraphQL mutation is observed and the user is now NOT allowed to view Posts again, unfortunately the only way to remove all Post from the local data is a DataStore.clear() but this clears the whole database, which contains wanted information and would require a complete database sync again.

Summary:

• I would like a way to perform a full sync on a specific model
• I would like a way to clear a specific model

[PS-MS]

Is it correct that changing the syncExpression from none() to all() should only sync the changes since the expression update?