fix: Move HandlePlatformFileDrop to window._wails internal API by leaanthony · Pull Request #4616 · wailsapp/wails

leaanthony · 2025-10-02T01:55:09Z

Summary

Fixes #4489 - Drag-and-drop broken with npm package @wailsio/runtime

The npm package @wailsio/runtime doesn't work for drag-and-drop because the Go backend calls window.wails.Window.HandlePlatformFileDrop(), but the npm package doesn't populate window.wails (by design for encapsulation).

Root Cause

PR #3295 (March 2024) intentionally removed window.wails assignment from the npm package to improve encapsulation. However, this broke platform handlers that the Go backend relies on.

Solution

Move HandlePlatformFileDrop from public API (window.wails) to internal API (window._wails), following the existing pattern used by other internal methods:

window._wails.invoke
window._wails.environment
window._wails.flags

Changes

Register handlePlatformFileDrop in window._wails namespace (index.ts:61)
Update Go backend to call window._wails.handlePlatformFileDrop() (webview_window.go:1501)
Use camelCase naming for consistency with other internal API methods
Rebuild bundled runtime with changes

Benefits

✅ npm package works without window.wails pollution
✅ Maintains encapsulation of public API
✅ Platform handlers clearly separated as internal
✅ Follows existing internal API conventions
✅ Multi-window support preserved via .bind()

Test plan

Test drag-and-drop with bundled runtime
Test drag-and-drop with npm package @wailsio/runtime
Test multi-window applications
Verify dropzone functionality works correctly

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Improved reliability of file drag-and-drop on desktop windows, ensuring correct registration and fewer errors across platforms.
Refactor
- Updated runtime bindings and aligned public exports without changing the external API or behavior.
Chores
- Adjusted frontend namespace for file-drop handling to use a more stable internal hook, with no user-facing impact.

Fixes #4489 ## Problem The npm package @wailsio/runtime doesn't work for drag-and-drop because Go backend calls window.wails.Window.HandlePlatformFileDrop(), but the npm package doesn't populate window.wails (by design for encapsulation). ## Root Cause PR #3295 (March 2024) intentionally removed window.wails assignment from the npm package to improve encapsulation. However, this broke platform handlers that Go backend relies on. ## Solution Move HandlePlatformFileDrop from public API (window.wails) to internal API (window._wails), following the existing pattern: - window._wails.invoke - window._wails.environment - window._wails.flags ## Changes - Register handlePlatformFileDrop in window._wails namespace - Update Go backend to call window._wails.handlePlatformFileDrop() - Use camelCase naming for consistency with other internal API methods - Rebuild bundled runtime with changes ## Benefits ✅ npm package works without window.wails pollution ✅ Maintains encapsulation of public API ✅ Platform handlers clearly separated as internal ✅ Follows existing internal API conventions 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>

cloudflare-workers-and-pages · 2025-10-02T01:55:16Z

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coderabbitai · 2025-10-02T01:55:16Z

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Reviewing files that changed from the base of the PR and between 20660de and 8ddb029.

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v3/UNRELEASED_CHANGELOG.md (1 hunks)

Walkthrough

Updates internal runtime exports, binds a platform file-drop handler to window._wails.handlePlatformFileDrop, and redirects the Go-side invocation to the new global. Adjusts mapped symbols for CancelError, CancellablePromise, and Window in the bundled runtime.

Changes

Cohort / File(s)	Summary
Bundled runtime export remaps `v3/internal/assetserver/bundledassets/runtime.js`	Remaps public exports: CancelError k→F, CancellablePromise B→H, Window G→S. No API shape changes indicated.
Internal runtime binding `v3/internal/runtime/desktop/@wailsio/runtime/src/index.ts`	Binds Window.HandlePlatformFileDrop to window._wails.handlePlatformFileDrop with correct this context; retains System.invoke("wails:runtime:ready") and window._wails.invoke.
Go WebView callsite update `v3/pkg/application/webview_window.go`	Switches call from window.wails.Window.HandlePlatformFileDrop(...) to window._wails.handlePlatformFileDrop(...).

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant OS as OS/Platform (Drop)
  participant WV as WebView Window (Go)
  participant JS as Frontend JS (window._wails)
  participant RT as Runtime Window Handler

  OS->>WV: File(s) dropped
  WV->>JS: window._wails.handlePlatformFileDrop(files)
  JS->>RT: Invoke bound Window.HandlePlatformFileDrop(files)
  RT-->>WV: Process/dispatch to Go-side handlers
  note over JS,RT: Binding established in runtime src/index.ts

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

fix: compute dropped file path before css handling #3595 — Adjusts drag-and-drop onDrop logic; intersects with platform file-drop handling path updated here.

Suggested labels

Bug, Javascript, Windows, runtime, v3-alpha, size:M

Suggested reviewers

Alpa-1

Poem

A file took a hop, a skip, a plop—drop!
I twitched my ears: “Bind the handle at the top!”
From _wails to Window, the path is clear,
No more lost parcels in midair.
Thump-thump—drag ‘n’ drop, my dear! 🐇📦

Pre-merge checks and finishing touches

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description Check	⚠️ Warning	The pull request description does not follow the repository’s required template headings and lacks sections for type of change, test configuration details, and the checklist items specified in the template.	Please update the description to use the template’s "# Description" heading, include the "## Type of change" section with the appropriate checkbox, provide the "How Has This Been Tested?" and test configuration details, and complete the checklist at the end.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The pull request title clearly and concisely describes the key change of moving the HandlePlatformFileDrop method to window._wails and uses a standard "fix:" prefix, so it accurately reflects the primary intent of the changeset.
Linked Issues Check	✅ Passed	The changes properly move HandlePlatformFileDrop to window._wails and update the Go backend invocation as required by issue #4489, which restores the broken drag-and-drop functionality on Windows based on the linked issue’s objectives.
Out of Scope Changes Check	✅ Passed	All modified files—including the rebuilt runtime.js, index.ts, and webview_window.go—are directly related to the intended fix and runtime rebuild, and no unrelated or extraneous changes are present.

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github-actions · 2025-10-02T01:55:27Z

⚠️ Missing Changelog Update

Hi @leaanthony, please update v3/UNRELEASED_CHANGELOG.md with a description of your changes.

This helps us keep track of changes for the next release.

Updates UNRELEASED_CHANGELOG.md with the fix for #4489. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>

…form-file-drop

sonarqubecloud · 2025-10-02T02:02:43Z

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

…app#4616) * fix: Move HandlePlatformFileDrop to window._wails internal API Fixes wailsapp#4489 ## Problem The npm package @wailsio/runtime doesn't work for drag-and-drop because Go backend calls window.wails.Window.HandlePlatformFileDrop(), but the npm package doesn't populate window.wails (by design for encapsulation). ## Root Cause PR wailsapp#3295 (March 2024) intentionally removed window.wails assignment from the npm package to improve encapsulation. However, this broke platform handlers that Go backend relies on. ## Solution Move HandlePlatformFileDrop from public API (window.wails) to internal API (window._wails), following the existing pattern: - window._wails.invoke - window._wails.environment - window._wails.flags ## Changes - Register handlePlatformFileDrop in window._wails namespace - Update Go backend to call window._wails.handlePlatformFileDrop() - Use camelCase naming for consistency with other internal API methods - Rebuild bundled runtime with changes ## Benefits ✅ npm package works without window.wails pollution ✅ Maintains encapsulation of public API ✅ Platform handlers clearly separated as internal ✅ Follows existing internal API conventions 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> * chore: Add changelog entry for drag-and-drop fix Updates UNRELEASED_CHANGELOG.md with the fix for wailsapp#4489. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: Claude <noreply@anthropic.com>

github-actions Bot added v3-alpha runtime labels Oct 2, 2025

chore: Add changelog entry for drag-and-drop fix

9aad5db

Updates UNRELEASED_CHANGELOG.md with the fix for #4489. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>

github-actions Bot added the Documentation Improvements or additions to documentation label Oct 2, 2025

Merge branch 'v3-alpha' into v3-alpha-bugfix/4489-invalid-handle-plat…

8ddb029

…form-file-drop

leaanthony merged commit 6665a3a into v3-alpha Oct 2, 2025
10 of 12 checks passed

leaanthony deleted the v3-alpha-bugfix/4489-invalid-handle-platform-file-drop branch October 2, 2025 02:01

coderabbitai Bot mentioned this pull request Oct 5, 2025

[v3] fix: (Windows OS) DnD dropzone detection failing at non-100% display scaling #4632

Open

15 tasks

This was referenced Dec 11, 2025

[v3] Fix not enough memory error when initialising drag and drop on Windows #4765

Merged

fix(macos): fix print dialog not opening and add Window.Print() to runtime #4789

Merged

coderabbitai Bot mentioned this pull request Feb 3, 2026

fix(runtime): file drop not working with @wailsio/runtime npm module #4953

Merged

This was referenced May 8, 2026

fix(v3,linux): enable frameless resize edge detection on Linux (#4680) #5366

Merged

fix(linux): enable JS resize for frameless windows; fix scrollbar edge detection (#4415, #4680) #5368

Merged

coderabbitai Bot mentioned this pull request Jun 11, 2026

fix(v3/runtime): make @wailsio/runtime importable without a DOM #5571

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fix: Move HandlePlatformFileDrop to window._wails internal API#4616

fix: Move HandlePlatformFileDrop to window._wails internal API#4616
leaanthony merged 3 commits into
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v3-alpha-bugfix/4489-invalid-handle-platform-file-drop

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