fixed ui.download not working in native mode

[Smug246]

Feature request: #2877

[falkoschindler]

Thanks a lot for the pull request, @Smug246!

I just tested this simple test code on macOS:

ui.button('Logo', on_click=lambda: ui.download(b'Hello World', 'hello.txt'))

Unfortunately I get this error:

--- Logging error ---
Traceback (most recent call last):
  File "/Users/falko/.pyenv/versions/3.11.7/lib/python3.11/logging/__init__.py", line 1110, in emit
    msg = self.format(record)
          ^^^^^^^^^^^^^^^^^^^
  File "/Users/falko/.pyenv/versions/3.11.7/lib/python3.11/logging/__init__.py", line 953, in format
    return fmt.format(record)
           ^^^^^^^^^^^^^^^^^^
  File "/Users/falko/.pyenv/versions/3.11.7/lib/python3.11/logging/__init__.py", line 687, in format
    record.message = record.getMessage()
                     ^^^^^^^^^^^^^^^^^^^
  File "/Users/falko/.pyenv/versions/3.11.7/lib/python3.11/logging/__init__.py", line 377, in getMessage
    msg = msg % self.args
          ~~~~^~~~~~~~~~~
TypeError: not all arguments converted during string formatting
Call stack:
  File "/Users/falko/.pyenv/versions/3.11.7/lib/python3.11/site-packages/webview/platforms/cocoa.py", line 283, in download_completionHandler_error_
    logger.error('Download error:', error)
Message: 'Download error:'
Arguments: (Error Domain=NSURLErrorDomain Code=-1002 "unsupported URL" UserInfo={NSLocalizedDescription=unsupported URL, NSErrorFailingURLStringKey=blob:http://127.0.0.1:1234/2c9d12b1-7c39-4d96-8294-1b8a5c8d5db0, NSErrorFailingURLKey=blob:http://127.0.0.1:1234/2c9d12b1-7c39-4d96-8294-1b8a5c8d5db0, _NSURLErrorRelatedURLSessionTaskErrorKey=(
    "LocalDownloadTask <7847E5B6-3828-4AD4-8FEE-E19F85617668>.<1>"
), _NSURLErrorFailingURLSessionTaskErrorKey=LocalDownloadTask <7847E5B6-3828-4AD4-8FEE-E19F85617668>.<1>, NSUnderlyingError=0x12ca33bc0 {Error Domain=kCFErrorDomainCFNetwork Code=-1002 "(null)"}},)

Do you have an idea what's going on? Or do you have a different test to show that your fix is working?

[Smug246]

ah it may be to do with macos. im on windows 11 and dont have a mac to test. im also on python 3.12.2

[Smug246]

uncapped_edit_1713025834898.mp4

no problems for me with ur example

[Smug246]

Could you test this example and see if it works?

import webview

if __name__ == '__main__':
    webview.settings['ALLOW_DOWNLOADS'] = True
    window = webview.create_window('Simple browser', 'https://pywebview.flowrl.com/download')
    webview.start()

[falkoschindler]

Interesting:

• Your plain pywebview example works. And the "ALLOW_DOWNLOADS" flag matters.
• A NiceGUI test with the same URL works, independent of the "ALLOW_DOWNLOADS" flag:

  ui.button('Logo', on_click=lambda: ui.download('https://pywebview.flowrl.com/download/test-data.bin'))

Anyway, enabling this flag seems to help in some cases. But I wonder if we really should enable it by default, since pywebview probably disabled it for a reason. And technically it would be a breaking change.

We could easily make it configurable though: Adding settings to NativeConfig

@dataclass(**KWONLY_SLOTS)
class NativeConfig:
    start_args: Dict[str, Any] = field(default_factory=dict)
    window_args: Dict[str, Any] = field(default_factory=dict)
    settings: Dict[str, Any] = field(default_factory=dict)
    main_window: Optional[WindowProxy] = None

and using them

    webview.settings.update(**core.app.native.settings)

before creating the window. We could even print a warning if the user calls ui.download in native mode without having this flag enabled.

[Smug246]

so although that error occurs on mac you still think it should be default setting. i feel like that would cause numerous issues.

[falkoschindler]

Let me clarify: I think we should make webview.settings configurable with ALLOW_DOWNLOADS being false by default. This way we don't introduce breaking changes and give full control to the user.

[Smug246]

oh right i misunderstood. i'll take my best shot at it

[Smug246]

should i make it configurable through ui.run() parameters?

[falkoschindler]

As mentioned above, I think we should add settings to NativeConfig. Then the user can configure it via

app.native.settings['ALLOW_DOWNLOADS'] = True

like it's already possible for app.native.window_args and app.native.start_args:
https://nicegui.io/documentation/section_configuration_deployment#native_mode

[Smug246]

what do you think?

[Smug246]

had to make a quick revision because i confused myself lol

[falkoschindler]

Thanks, @Smug246!
Looks good to me. 😎