Made Watch return a Task, which completes after it has finished initializing.

Author: Chriztiaan

PowerSync/PowerSync.Common/Client/PowerSyncDatabase.cs

@@ -451,6 +451,7 @@ await Database.WriteTransaction(async tx =>
 
             if (txId == null)
             {
+
                 all = [CrudEntry.FromRow(first)];
             }
             else
@@ -573,8 +574,9 @@ public async Task<T> WriteTransaction<T>(Func<ITransaction, Task<T>> fn, DBLockO
     /// Use <see cref="SQLWatchOptions.ThrottleMs"/> to specify the minimum interval between queries.
     /// Source tables are automatically detected using <c>EXPLAIN QUERY PLAN</c>.
     /// </summary>
-    public void Watch<T>(string query, object[]? parameters, WatchHandler<T> handler, SQLWatchOptions? options = null)
+    public Task Watch<T>(string query, object[]? parameters, WatchHandler<T> handler, SQLWatchOptions? options = null)
     {
+        var tcs = new TaskCompletionSource();
         Task.Run(async () =>
         {
             try
@@ -604,12 +606,14 @@ public void Watch<T>(string query, object[]? parameters, WatchHandler<T> handler
                     Signal = options?.Signal,
                     ThrottleMs = options?.ThrottleMs
                 });
+                tcs.SetResult();
             }
             catch (Exception ex)
             {
                 handler.OnError?.Invoke(ex);
             }
         });
+        return tcs.Task;
     }
 
     private record ExplainedResult(string opcode, int p2, int p3);

PowerSync/PowerSync.Common/README.md

@@ -24,12 +24,12 @@ static async Task Main() {
 
 ```
 
-
 ### Watched queries
-Watched queries will automatically update when a dependant table is updated.
+Watched queries will automatically update when a dependant table is updated. 
+Awaiting `Watch()` ensures the watcher is fully initialized and ready to monitor database changes.
 
 ```csharp
-db.Watch("select * from lists", null, new WatchHandler<ListResult>
+await db.Watch("select * from lists", null, new WatchHandler<ListResult>
 {
     OnResult = (results) =>
     {

Tests/PowerSync/PowerSync.Common.Tests/Client/PowerSyncDatabaseTransactionTests.cs

@@ -265,7 +265,7 @@ public async Task ReflectWriteTransactionUpdatesOnReadConnectionsTest()
         var watched = new TaskCompletionSource();
 
         var cts = new CancellationTokenSource();
-        db.Watch("SELECT COUNT(*) as count FROM assets", null, new WatchHandler<CountResult>
+        await db.Watch("SELECT COUNT(*) as count FROM assets", null, new WatchHandler<CountResult>
         {
             OnResult = (x) =>
             {
@@ -277,7 +277,6 @@ public async Task ReflectWriteTransactionUpdatesOnReadConnectionsTest()
             }
         }, new SQLWatchOptions
         {
-
             Signal = cts.Token
         });
 
@@ -297,7 +296,7 @@ public async Task ReflectWriteLockUpdatesOnReadConnectionsTest()
         var watched = new TaskCompletionSource();
 
         var cts = new CancellationTokenSource();
-        db.Watch("SELECT COUNT(*) as count FROM assets", null, new WatchHandler<CountResult>
+        await db.Watch("SELECT COUNT(*) as count FROM assets", null, new WatchHandler<CountResult>
         {
             OnResult = (x) =>
             {

demos/CommandLine/Demo.cs

@@ -31,7 +31,7 @@ static async Task Main()
 
         bool running = true;
 
-        db.Watch("select * from lists", null, new WatchHandler<ListResult>
+        await db.Watch("select * from lists", null, new WatchHandler<ListResult>
         {
             OnResult = (results) =>
             {