Live queries and changes - PoolKit

Live queries

let grant = try await pool.authorization.requestAccess(
    AccessRequest(data: [.products], operations: [.query, .observe], purpose: "Keep your wishlist fresh")
)

for try await update in pool.context.observe(ContextQuery(types: [.product]), using: grant) {
    render(update.result.matches)
}

The first update is the current answer. Later updates arrive when the index changes in a way the grant covers.
The grant is checked again before every update. When it is revoked or expires, the stream ends by throwing that error.
Cancel the task to stop observing.

The change log

var cursor = savedCursor  // nil the first time
var page: ChangePage
repeat {
    page = try await pool.context.changes(since: cursor, using: grant)
    for change in page.changes {
        switch change.operation {
        case .upsert: refresh(change.recordID)
        case .delete: remove(change.recordID)
        }
    }
    cursor = page.cursor
} while page.hasMore
save(cursor)

When a photo is deleted, everything derived from it is deleted and the log lists a tombstone for each removed record, with the cause: sourceRemoved, accessRemoved or reset. If you copy anything out of Pool, apply these deletes. The log only lists records your grant covers.