address PR #324 review feedback (#dirkkul)

Two changes from the PR #324 review:

1. Make ExportCreateRequest.FileFormat required.
   Previously defaulted to ExportFileFormat.Parquet. Reviewer flagged
   that adding a new file format later would silently change behaviour
   for callers who relied on the default. Drop the default — callers
   must now pass the format explicitly. Update all 7 call sites
   (4 integration, 3 unit). PublicAPI.Unshipped.txt updated.

2. ExportClient.Cancel returns Task<bool>, no-throw on 409.
   Previously threw WeaviateConflictException when the server responded
   409 (export already in a terminal state — can't cancel). Reviewer
   wanted a true/false pattern: false = could not cancel, throws only
   for genuine errors like 404 Not Found.

   - Rest/Export.cs ExportCancel: returns bool, returns false on 409,
     delegates other status codes to ManageStatusCode.
   - ExportClient.Cancel: signature now Task<bool>.
   - ExportOperationBase: delegate type + public Cancel both return
     Task<bool>, propagating the result.
   - ExportOperation: matching delegate signature.
   - Cancel_StopsRunningExport integration test: replace try/catch on
     WeaviateConflictException with bool assertion.
   - Two new unit tests cover 204→true, 409→false, 404→throws.
   - PublicAPI.Unshipped.txt updated for all three signature changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mpartipilo

src/Weaviate.Client.Tests/Integration/TestExports.cs

@@ -30,6 +30,7 @@ public async Task CreateSync_CompletesSuccessfully()
             new ExportCreateRequest(
                 $"export-sync-{Guid.NewGuid():N}",
                 _backend,
+                ExportFileFormat.Parquet,
                 IncludeCollections: [collection.Name]
             ),
             timeout: TimeSpan.FromMinutes(2),
@@ -50,6 +51,7 @@ public async Task Create_ThenWaitForCompletion()
             new ExportCreateRequest(
                 $"export-async-{Guid.NewGuid():N}",
                 _backend,
+                ExportFileFormat.Parquet,
                 IncludeCollections: [collection.Name]
             ),
             ct
@@ -72,7 +74,12 @@ public async Task GetStatus_ReturnsExportInfo()
         var exportId = $"export-status-{Guid.NewGuid():N}";
 
         await _weaviate.Export.CreateSync(
-            new ExportCreateRequest(exportId, _backend, IncludeCollections: [collection.Name]),
+            new ExportCreateRequest(
+                exportId,
+                _backend,
+                ExportFileFormat.Parquet,
+                IncludeCollections: [collection.Name]
+            ),
             timeout: TimeSpan.FromMinutes(2),
             cancellationToken: ct
         );
@@ -93,35 +100,39 @@ public async Task Cancel_StopsRunningExport()
             new ExportCreateRequest(
                 $"export-cancel-{Guid.NewGuid():N}",
                 _backend,
+                ExportFileFormat.Parquet,
                 IncludeCollections: [collection.Name]
             ),
             ct
         );
 
         // Cancel immediately — may already have completed for small collections.
-        // Server responds with 409 Conflict when the export has already finished,
-        // or 404 Not Found if the record is no longer available.
+        // Cancel returns false when the export has already finished (409 Conflict);
+        // 404 Not Found still throws if the record is no longer available.
+        bool canceled;
         try
         {
-            await _weaviate.Export.Cancel(_backend, operation.Current.Id, ct);
-        }
-        catch (WeaviateConflictException)
-        {
-            // Export already finished — can't cancel a terminal export.
+            canceled = await _weaviate.Export.Cancel(_backend, operation.Current.Id, ct);
         }
         catch (WeaviateNotFoundException)
         {
-            // Export record no longer available.
+            // Export record no longer available — treat as canceled.
+            return;
         }
 
         try
         {
             var status = await _weaviate.Export.GetStatus(_backend, operation.Current.Id, ct);
 
-            Assert.True(
-                status.Status is ExportStatus.Canceled or ExportStatus.Success,
-                $"Expected Canceled or Success but got {status.Status}"
-            );
+            if (canceled)
+            {
+                Assert.Equal(ExportStatus.Canceled, status.Status);
+            }
+            else
+            {
+                // 409: export reached a terminal state before we could cancel.
+                Assert.Equal(ExportStatus.Success, status.Status);
+            }
         }
         catch (WeaviateNotFoundException)
         {

src/Weaviate.Client.Tests/Unit/TestExportClient.cs

@@ -33,7 +33,7 @@ public async Task Create_SendsPostToExportEndpoint()
         );
 
         await using var operation = await client.Export.Create(
-            new ExportCreateRequest("my-export", new FilesystemBackend()),
+            new ExportCreateRequest("my-export", new FilesystemBackend(), ExportFileFormat.Parquet),
             TestContext.Current.CancellationToken
         );
 
@@ -85,7 +85,7 @@ public async Task GetStatus_SendsGetToStatusEndpoint()
     }
 
     /// <summary>
-    /// Cancel must issue a DELETE to /v1/export/filesystem/{id}.
+    /// Cancel must issue a DELETE to /v1/export/filesystem/{id} and return true on 204.
     /// </summary>
     [Fact]
     public async Task Cancel_SendsDeleteToExportEndpoint()
@@ -95,18 +95,60 @@ public async Task Cancel_SendsDeleteToExportEndpoint()
             serverVersion: "1.37.0"
         );
 
-        await client.Export.Cancel(
+        var canceled = await client.Export.Cancel(
             new FilesystemBackend(),
             "my-export",
             TestContext.Current.CancellationToken
         );
 
+        Assert.True(canceled);
         Assert.NotNull(handler.LastRequest);
         handler
             .LastRequest!.ShouldHaveMethod(HttpMethod.Delete)
             .ShouldHavePath("/v1/export/filesystem/my-export");
     }
 
+    /// <summary>
+    /// Cancel returns false (no throw) when the server responds 409 Conflict —
+    /// the export reached a terminal state and cannot be canceled.
+    /// </summary>
+    [Fact]
+    public async Task Cancel_OnConflict_ReturnsFalseWithoutThrowing()
+    {
+        var (client, _) = MockWeaviateClient.CreateWithMockHandler(
+            syncHandler: _ => new HttpResponseMessage(HttpStatusCode.Conflict),
+            serverVersion: "1.37.0"
+        );
+
+        var canceled = await client.Export.Cancel(
+            new FilesystemBackend(),
+            "my-export",
+            TestContext.Current.CancellationToken
+        );
+
+        Assert.False(canceled);
+    }
+
+    /// <summary>
+    /// Cancel still throws on 404 Not Found — the export id is unknown.
+    /// </summary>
+    [Fact]
+    public async Task Cancel_OnNotFound_Throws()
+    {
+        var (client, _) = MockWeaviateClient.CreateWithMockHandler(
+            syncHandler: _ => new HttpResponseMessage(HttpStatusCode.NotFound),
+            serverVersion: "1.37.0"
+        );
+
+        await Assert.ThrowsAsync<WeaviateNotFoundException>(async () =>
+            await client.Export.Cancel(
+                new FilesystemBackend(),
+                "unknown-export",
+                TestContext.Current.CancellationToken
+            )
+        );
+    }
+
     /// <summary>
     /// Status parsing should correctly map all known status strings.
     /// </summary>
@@ -230,6 +272,7 @@ public async Task Create_WithIncludeCollections_SendsCorrectBody()
             new ExportCreateRequest(
                 "my-export",
                 new FilesystemBackend(),
+                ExportFileFormat.Parquet,
                 IncludeCollections: ["Article", "Author"]
             ),
             TestContext.Current.CancellationToken
@@ -262,7 +305,11 @@ public async Task Create_WithS3Backend_UsesCorrectEndpoint()
         );
 
         await using var operation = await client.Export.Create(
-            new ExportCreateRequest("my-export", ObjectStorageBackend.S3()),
+            new ExportCreateRequest(
+                "my-export",
+                ObjectStorageBackend.S3(),
+                ExportFileFormat.Parquet
+            ),
             TestContext.Current.CancellationToken
         );
 

src/Weaviate.Client/ExportClient.cs

@@ -95,18 +95,21 @@ public async Task<Export> GetStatus(
     }
 
     /// <summary>
-    /// Cancel a running export
+    /// Cancel a running export. Returns <c>true</c> if the cancel request was accepted,
+    /// <c>false</c> if the server responded 409 Conflict (export already in a terminal
+    /// state and cannot be canceled). Throws <see cref="WeaviateNotFoundException"/>
+    /// if the export id is unknown.
     /// </summary>
     [RequiresWeaviateVersion(1, 37, 0)]
-    public async Task Cancel(
+    public async Task<bool> Cancel(
         BackupBackend backend,
         string id,
         CancellationToken cancellationToken = default
     )
     {
         await _client.EnsureVersion<ExportClient>();
 
-        await _client.RestClient.ExportCancel(backend.Provider, id, cancellationToken);
+        return await _client.RestClient.ExportCancel(backend.Provider, id, cancellationToken);
     }
 
     private static Rest.Dto.ExportCreateRequest BuildExportCreateRequest(

src/Weaviate.Client/Models/Export.cs

@@ -120,7 +120,7 @@ public record ShardProgress(
 public record ExportCreateRequest(
     string Id,
     BackupBackend Backend,
-    ExportFileFormat FileFormat = ExportFileFormat.Parquet,
+    ExportFileFormat FileFormat,
     AutoArray<string>? IncludeCollections = null,
     AutoArray<string>? ExcludeCollections = null
 );

src/Weaviate.Client/Models/ExportOperation.cs

@@ -8,7 +8,7 @@ public class ExportOperation : ExportOperationBase
     internal ExportOperation(
         Export initial,
         Func<CancellationToken, Task<Export>> statusFetcher,
-        Func<CancellationToken, Task> operationCancel
+        Func<CancellationToken, Task<bool>> operationCancel
     )
         : base(initial, statusFetcher, operationCancel) { }
 }

src/Weaviate.Client/Models/ExportOperationBase.cs

@@ -6,7 +6,7 @@ namespace Weaviate.Client.Models;
 public abstract class ExportOperationBase : IDisposable, IAsyncDisposable
 {
     private readonly Func<CancellationToken, Task<Export>> _statusFetcher;
-    private readonly Func<CancellationToken, Task> _operationCancel;
+    private readonly Func<CancellationToken, Task<bool>> _operationCancel;
     private readonly CancellationTokenSource _cts = new();
     private readonly Task _backgroundRefreshTask;
     private Export _current;
@@ -24,7 +24,7 @@ public abstract class ExportOperationBase : IDisposable, IAsyncDisposable
     protected ExportOperationBase(
         Export initial,
         Func<CancellationToken, Task<Export>> statusFetcher,
-        Func<CancellationToken, Task> operationCancel
+        Func<CancellationToken, Task<bool>> operationCancel
     )
     {
         _current = initial;
@@ -134,13 +134,16 @@ public async Task<Export> WaitForCompletion(
     }
 
     /// <summary>
-    /// Cancels the export operation asynchronously.
+    /// Cancels the export operation asynchronously. Returns <c>true</c> if the server
+    /// accepted the cancel request, <c>false</c> if the export is already in a terminal
+    /// state and cannot be canceled (HTTP 409). Throws if the export id is unknown.
     /// </summary>
     /// <param name="cancellationToken">A cancellation token to observe while canceling.</param>
-    public async Task Cancel(CancellationToken cancellationToken = default)
+    public async Task<bool> Cancel(CancellationToken cancellationToken = default)
     {
-        await _operationCancel(cancellationToken);
+        var canceled = await _operationCancel(cancellationToken);
         await RefreshStatusInternal(cancellationToken);
+        return canceled;
     }
 
     protected virtual void Dispose(bool disposing)

src/Weaviate.Client/PublicAPI.Unshipped.txt

@@ -2936,7 +2936,7 @@ Weaviate.Client.DefaultTokenServiceFactory.CreateAsync(Weaviate.Client.ClientCon
 Weaviate.Client.DefaultTokenServiceFactory.CreateSync(Weaviate.Client.ClientConfiguration! configuration) -> Weaviate.Client.ITokenService?
 Weaviate.Client.DefaultTokenServiceFactory.DefaultTokenServiceFactory() -> void
 Weaviate.Client.ExportClient
-Weaviate.Client.ExportClient.Cancel(Weaviate.Client.Models.BackupBackend! backend, string! id, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task!
+Weaviate.Client.ExportClient.Cancel(Weaviate.Client.Models.BackupBackend! backend, string! id, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<bool>!
 Weaviate.Client.ExportClient.Create(Weaviate.Client.Models.ExportCreateRequest! request, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<Weaviate.Client.Models.ExportOperation!>!
 Weaviate.Client.ExportClient.CreateSync(Weaviate.Client.Models.ExportCreateRequest! request, System.TimeSpan? timeout = null, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<Weaviate.Client.Models.Export!>!
 Weaviate.Client.ExportClient.GetStatus(Weaviate.Client.Models.BackupBackend! backend, string! id, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<Weaviate.Client.Models.Export!>!
@@ -3741,7 +3741,7 @@ Weaviate.Client.Models.ExportCreateRequest.Deconstruct(out string! Id, out Weavi
 Weaviate.Client.Models.ExportCreateRequest.ExcludeCollections.get -> Weaviate.Client.Internal.AutoArray<string!>?
 Weaviate.Client.Models.ExportCreateRequest.ExcludeCollections.init -> void
 Weaviate.Client.Models.ExportCreateRequest.ExportCreateRequest(Weaviate.Client.Models.ExportCreateRequest! original) -> void
-Weaviate.Client.Models.ExportCreateRequest.ExportCreateRequest(string! Id, Weaviate.Client.Models.BackupBackend! Backend, Weaviate.Client.Models.ExportFileFormat FileFormat = Weaviate.Client.Models.ExportFileFormat.Parquet, Weaviate.Client.Internal.AutoArray<string!>? IncludeCollections = null, Weaviate.Client.Internal.AutoArray<string!>? ExcludeCollections = null) -> void
+Weaviate.Client.Models.ExportCreateRequest.ExportCreateRequest(string! Id, Weaviate.Client.Models.BackupBackend! Backend, Weaviate.Client.Models.ExportFileFormat FileFormat, Weaviate.Client.Internal.AutoArray<string!>? IncludeCollections = null, Weaviate.Client.Internal.AutoArray<string!>? ExcludeCollections = null) -> void
 Weaviate.Client.Models.ExportCreateRequest.FileFormat.get -> Weaviate.Client.Models.ExportFileFormat
 Weaviate.Client.Models.ExportCreateRequest.FileFormat.init -> void
 Weaviate.Client.Models.ExportCreateRequest.Id.get -> string!
@@ -3752,11 +3752,11 @@ Weaviate.Client.Models.ExportFileFormat
 Weaviate.Client.Models.ExportFileFormat.Parquet = 0 -> Weaviate.Client.Models.ExportFileFormat
 Weaviate.Client.Models.ExportOperation
 Weaviate.Client.Models.ExportOperationBase
-Weaviate.Client.Models.ExportOperationBase.Cancel(System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task!
+Weaviate.Client.Models.ExportOperationBase.Cancel(System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<bool>!
 Weaviate.Client.Models.ExportOperationBase.Current.get -> Weaviate.Client.Models.Export!
 Weaviate.Client.Models.ExportOperationBase.Dispose() -> void
 Weaviate.Client.Models.ExportOperationBase.DisposeAsync() -> System.Threading.Tasks.ValueTask
-Weaviate.Client.Models.ExportOperationBase.ExportOperationBase(Weaviate.Client.Models.Export! initial, System.Func<System.Threading.CancellationToken, System.Threading.Tasks.Task<Weaviate.Client.Models.Export!>!>! statusFetcher, System.Func<System.Threading.CancellationToken, System.Threading.Tasks.Task!>! operationCancel) -> void
+Weaviate.Client.Models.ExportOperationBase.ExportOperationBase(Weaviate.Client.Models.Export! initial, System.Func<System.Threading.CancellationToken, System.Threading.Tasks.Task<Weaviate.Client.Models.Export!>!>! statusFetcher, System.Func<System.Threading.CancellationToken, System.Threading.Tasks.Task<bool>!>! operationCancel) -> void
 Weaviate.Client.Models.ExportOperationBase.IsCanceled.get -> bool
 Weaviate.Client.Models.ExportOperationBase.IsCompleted.get -> bool
 Weaviate.Client.Models.ExportOperationBase.IsSuccessful.get -> bool

src/Weaviate.Client/Rest/Export.cs

@@ -36,7 +36,7 @@ internal partial class WeaviateRestClient
         return await response.DecodeAsync<Dto.ExportStatusResponse>(cancellationToken);
     }
 
-    internal async Task ExportCancel(
+    internal async Task<bool> ExportCancel(
         BackupStorageProvider backend,
         string id,
         CancellationToken cancellationToken = default
@@ -46,10 +46,15 @@ internal async Task ExportCancel(
             WeaviateEndpoints.ExportStatus(backend.ToEnumMemberString()!, id),
             cancellationToken
         );
+        if (response.StatusCode == HttpStatusCode.Conflict)
+        {
+            return false;
+        }
         await response.ManageStatusCode(
             [HttpStatusCode.OK, HttpStatusCode.NoContent],
             "export cancel",
             ResourceType.Export
         );
+        return true;
     }
 }