Fixes to the .key_up() method to make it usable for a dynamic dropdown autocomplete

[abidlabs]

This PR makes two changes:

1. In the Dropdown component, we were resetting the value when the choices were updated. It is somewhat debatable whether we should do this or not. For example, in Dropdown doesn't retain value if choice name is changed #6853, users asked for this behavior. However, it makes it impossible to use for the use case in which the Dropdown component's choices are being updated based on the value of the Dropdown itself.

The way I've implemented it here is that iff when allow_custom_value=True, the Dropdown's values are not reset, which I think is the desired behavior for users in either case. I've also added a test for this.

2. Since .key_up() is an event that is expected to be fired continuously, I've set the default trigger_mode for the .key_up() event to be always_last, just like for .change().

Test the new behavior with this demo:

import gradio as gr
import time

def f(x, k: gr.KeyUpData):
    time.sleep(1)
    return gr.update(choices=[f"{k.input_value} {i}" for i in range(int(5))])    


with gr.Blocks() as demo:
    t = gr.Dropdown(interactive=True, allow_custom_value=True)
    t.key_up(f, t, t, show_progress="hidden", trigger_mode="always_last")
    
demo.launch()

cc @apolinario (see internal thread)

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	ready!	Website preview
	Storybook	ready!	Storybook preview
🦄	Changes	detected!	Details

---

Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/cc8bf9e1d4502c3bd36baf226b868f1574c37e3e/gradio-4.19.0-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@cc8bf9e1d4502c3bd36baf226b868f1574c37e3e#subdirectory=client/python"

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/dropdown	patch
gradio	patch

• Maintainers can select this checkbox to manually select packages to update.

With the following changelog entry.

Fixes to the .key_up() method to make it usable for a dynamic dropdown autocomplete

Maintainers or the PR author can modify the PR title to modify this entry.

Something isn't right?

• Maintainers can change the version label to modify the version bump.
• If the bot has failed to detect any changes, or if this pull request needs to update multiple packages to different versions or requires a more comprehensive changelog entry, maintainers can update the changelog file directly.

[pngwn]

Isn't this a breaking change?

[abidlabs]

Both of the changes are technically breaking changes but the original changes were both made in 4.19.0 (the first one was changed in 4.19.0 and the KeyUp event was introduced in 4.19.0) so I think its ok but I should mark it as such

[pngwn]

I wouldnt list them as breaking changes if we aren't doing a major bump :p that's just confusing. I'd just put it through as a fix.

[abidlabs]

The python test is failing due to a typecheck issue on files that I haven't touched, something strange is happening on CI. Will investigate but that should be independent of this PR

[hannahblair]

Nice @abidlabs, works great!

[abidlabs]

Thanks @hannahblair for reviewing! Merging in changes from main to fix the typechecks. And then will merge this in.