Live Query

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    Description — Working with Couchbase Lite’s data model  — Querying database data using live queries
    Related Content — Predictive Queries | Indexes | Queries

    A live query stays active and monitors the database for changes. A live query is a great way to build reactive user interfaces, especially table/list views, that keep themselves up to date. For example, as the replicator runs and pulls new data from the server, a live query-driven UI will automatically update to show the data without the user having to manually refresh. This helps your app feel quick and responsive.

    Query query = QueryBuilder
        .select(SelectResult.all())
        .from(DataSource.database(database));
    
    // Adds a query change listener.
    // Changes will be posted on the main queue.
    ListenerToken token = query.addChangeListener(change -> {
        for (Result result : change.getResults()) {
            Log.d(TAG, "results: " + result.getKeys());
            /* Update UI */
        }
    });
    
    // Start live query.
    query.execute(); (1)
    1 To start a live query, you must call query.execute(). This will immediately execute the query and post the result to the change listener. When there’s a change it re-runs itself automatically, and posts the new query result to any observers (change listeners).

    The following example stops the live query with the token from the previous example.

    query.removeChangeListener(token);