New properties in Storage.Pickers - SuggestedDefaultFolder, SuggestedFolder, FileTypeChoices by DinahK-2SO · Pull Request #5772 · microsoft/WindowsAppSDK

DinahK-2SO · 2025-08-29T08:06:37Z

An implementation of

API review for new properties in Storage.Pickers - SuggestedDefaultFolder, FileTypeChoices #5771

This pull request introduces new experimental features to the Windows Storage Pickers API, specifically enabling support for suggested folders and enhanced file type choices. These changes are gated behind a new feature flag, Feature_StoragePickers2, and are only available in the experimental channel. The updates affect the FileOpenPicker, FileSavePicker, and FolderPicker classes, as well as related internal data structures and the public API contract.

Feature flag and API contract updates:

Added the new feature definition and flag for Feature_StoragePickers2, including its XML specification and auto-generated header (TerminalVelocityFeatures-StoragePickers2.xml, TerminalVelocityFeatures-StoragePickers2.h). The feature is always enabled in the experimental channel and disabled in preview/stable channels. [1] [2]
Updated the IDL contract to version 2.0 and added new properties (SuggestedFolder, SuggestedStartFolder, FileTypeChoices) to the pickers, gated by the new feature flag. [1] [2] [3] [4]

New properties and API surface:

Added support for SuggestedFolder and SuggestedStartFolder properties to FileOpenPicker, FileSavePicker, and FolderPicker, with validation and feature gating. Also added the FileTypeChoices property to FileOpenPicker. [1] [2] [3] [4] [5] [6] [7] [8] [9]

Internal data structure changes:

Updated constructors and usage of FileTypeChoicesMap and FileTypeFilterVector to support feature gating and picker-specific logic. [1] [2] [3] [4]

Parameter handling and validation:

Modified parameter capture logic in pickers to include the new suggested folder properties and file type choices, and updated validation to use a unified folder path validation method. [1] [2] [3]

Miscellaneous:

Minor includes and code hygiene improvements, such as new headers for string handling.

Saharsh979 · 2025-10-01T07:12:57Z

dev/Interop/StoragePickers/PickerCommon.cpp

    }

-    void ValidateSuggestedFolder(winrt::hstring const& path)
+    void ValidateFolderPath(winrt::hstring const& path, std::string const& propertyName)


In ValidateFolderPath, how does the implementation handle edge cases like relative paths (e.g., .\folder, ..\parent), standard UNC paths (e.g., \server\share), and non-existent folders (e.g., C:\NonExistent)? The code doesn’t seem to reject relative paths or check folder existence, which could lead to runtime errors?

Can you clarify the intended behavior for these cases and share how they were tested!

Thanks @Saharsh979 for joining the review.

All path strings in the storage pickers are full path.
The relative path are not supported yet.

Saharsh979 · 2025-10-01T07:13:44Z

dev/Interop/StoragePickers/FileTypeChoicesMap.h

    {
-        FileTypeChoicesMap();
+        FileTypeChoicesMap(bool forSavePicker = true);
+


Curiosity - Can you explain the rationale behind this update?

Yes, this is for velocity. The FileSavePicker already has FileTypeChoices, so it doesn't need an velocity check.
This PR is adding FileTypeChoices property to the FileOpenPicker, meaning that we need a velocity check when this customized map type is used for in the FIleOpenPicker.

In future when we remove this velocity, we can remove the forSavePicker flag too.
Note that this is an internal class, it should not impact the public API contract.

dev/Interop/StoragePickers/FileTypeFilterVector.cpp

Saharsh979 · 2025-10-01T07:18:40Z

dev/Interop/StoragePickers/FileOpenPicker.cpp

    {
        return m_fileTypeFilter;
    }
+    winrt::hstring FileOpenPicker::SuggestedFolder()


Curiosity: Maybe it might be worthwhile to test performance as well? Could complex or large FileTypeChoices lists slow down picker init?

Should be ok. It is the same property logic existing in FileSavePicker.

Saharsh979 · 2025-10-01T07:21:30Z

dev/Interop/StoragePickers/FileSavePicker.h

        hstring SuggestedFolder();
        void SuggestedFolder(hstring const& value);

+        hstring SuggestedStartFolder();


Nit - Is there a possibility to move common logic to a base class?

Thanks, this is a good point. We might do some refactoring in future.

dev/Interop/StoragePickers/PickerCommon.cpp

codendone

DinahK-2SO · 2025-10-03T02:43:32Z

/azp run

azure-pipelines · 2025-10-03T02:43:48Z

Azure Pipelines successfully started running 1 pipeline(s).

DinahK-2SO · 2025-10-03T12:34:09Z

/azp run

azure-pipelines · 2025-10-03T12:34:26Z

Azure Pipelines successfully started running 1 pipeline(s).

DinahK-2SO · 2025-10-03T13:11:48Z

Thanks @codendone and @Saharsh979 for reviewing this PR. The pipeline build failed last night - caused by the missing head file of velocity. So I pushed a fix in the last iteration. Please review the updates when you have a moment.

DinahK-2SO · 2025-10-03T13:12:31Z

/azp run

azure-pipelines · 2025-10-03T13:12:48Z

Azure Pipelines successfully started running 1 pipeline(s).

…lder, FileTypeChoices (#5771) This is a design spec for adding new functionality to the Microsoft.Windows.Storage.Pickers APIs, including 2 main changes: - the SuggestedFolder and SuggestedStartFolder properties for all three picker types, - the new FileTypeChoices property for FileOpenPicker. Code implementation details can be found in (#5772)

…uggestedFolder, FileTypeChoices (#5772)" This reverts commit 4774aae.

microsoft-github-policy-service bot added the needs-triage label Aug 29, 2025

This was referenced Sep 15, 2025

SuggestedStartLocation not working correctly in File/Folder pickers #5836

Closed

[Request] Update MainLandingPage UI to WinUI Gallery one + Template fix + Questions ghost1372/DevWinUI#96

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new functionalities

52e0974

DinahK-2SO force-pushed the user/DinahK-2SO/storage_pickers_new_functionality branch from 9a2af4e to 52e0974 Compare September 29, 2025 18:18

DinahK-2SO marked this pull request as ready for review September 29, 2025 18:19

DinahK-2SO changed the title ~~New properties in Storage.Pickers - SuggestedDefaultFolder, FileTypeChoices~~ New properties in Storage.Pickers - SuggestedDefaultFolder, SuggestedFolder, FileTypeChoices Sep 29, 2025

DinahK-2SO requested review from Hong-Xiang, Scottj1s, codendone, kmahone and yeelam-gordon September 30, 2025 05:42

ghost1372 referenced this pull request in ghost1372/DevWinUI Sep 30, 2025

Remove Obsolete Classes/Methods

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Saharsh979 reviewed Oct 1, 2025

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DinahK-2SO added 2 commits October 2, 2025 10:48

fix errors

1534dd9

ForFeature_StoragePickers2

3f0a1dd

codendone approved these changes Oct 2, 2025

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Saharsh979 approved these changes Oct 3, 2025

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fix build error: fix the missing velocity head includes; graceful

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DinahK-2SO force-pushed the user/DinahK-2SO/storage_pickers_new_functionality branch from 550d668 to 0618e5b Compare October 3, 2025 13:00

codendone approved these changes Oct 3, 2025

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Scottj1s approved these changes Oct 3, 2025

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DinahK-2SO merged commit 4774aae into main Oct 4, 2025
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DinahK-2SO deleted the user/DinahK-2SO/storage_pickers_new_functionality branch October 4, 2025 04:14

guimafelipe added a commit that referenced this pull request Oct 4, 2025

Revert "New properties in Storage.Pickers - SuggestedDefaultFolder, S…

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…uggestedFolder, FileTypeChoices (#5772)" This reverts commit 4774aae.

DinahK-2SO added a commit that referenced this pull request Oct 10, 2025

Revert "New properties in Storage.Pickers - SuggestedDefaultFolder, S…

1389870

…uggestedFolder, FileTypeChoices (#5772)" This reverts commit 4774aae.

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