Multiselectdropdown: Control selectedTextFormat

[yahiakala]

Is your feature request related to a problem? Please describe.
I want to control the selectedTextFormat option as described here:

https://developer.snapappointments.com/bootstrap-select/options/
https://developer.snapappointments.com/bootstrap-select/examples/#selected-text-format

This shows up as data-selected-text-format="count" in the HTML part of the existing Anvil component.

The gist is that I want to display the placeholder text and otherwise control the text that is displayed on the component.

Describe the solution you'd like
Ideally this would be a component property.

Describe alternatives you've considered
For now, I have duplicated the component in my own project and hardcoded "static" which is my preferred option.

`

<select class="select-picker" 
        multiple 
        data-container="body"
        data-icon-base="fa"
        data-tick-icon="fa-check"
        data-show-subtext="true"
        data-selected-text-format="static"
></select>
<script type="module">
import {DesignerMultiSelectDropDown} from "https://deno.land/x/[email protected]/js/designer_components/bundle.min.js";
DesignerMultiSelectDropDown.init();
</script>

`

Additional context
Add any other context or screenshots about the feature request here.

I am considering making a PR for this issue
I am hesitant. Although it is a small change to hardcode, making it a property seems like I'd have to navigate a lot of abstractions. There's some code on deno.land, a bunch of helper functions, etc. If I get a little guidance I can take a stab at it.

It would be nice to understand this code more as I have created a component with choices-js but didn't have to use any of the stuff I see in your repo - I'd like to know what I'm missing

[s-cork]

don't worry about any of the deno.land stuff
that's obsolete since anvil updated custom components to be live in the designer

It should hopefully be a case of:
updating a property setter/getter in python
adding the property to the custom component dialogue, or equivalently editing the yaml
I'd expect it to be a 1 line diff in the yaml and 1 line diff in the python.

[s-cork]

looking at the docs - this is already somewhat supported

https://anvil-extras.readthedocs.io/en/latest/guides/components/multi_select_dropdown.html#format_selected_text

[yahiakala]

Ah yes I must have missed that in the docs - that works when multiple items are selected. That override doesn't work when only one option is selected (the selected text is whatever is selected).

I'll take a stab at a PR then and see how it goes

[yahiakala]

Turned out to be remarkably simple! Just needed to create a new property (and default)

  data_selected_text_format = _component_property("data_selected_text_format", "data-selected-text-format")

I'll get around to a PR when I have the energy to update the docs.