Unable to assign to Option<String> and Option<Cow<'static, str>>

[ctron]

Problem

In Yew 0.17 the following code worked:

#[cfg(test)]
mod test {
    use super::*;
    use crate::{html, ComponentLink, Html};
    use crate::html::Properties;

    #[derive(Properties, Clone)]
    pub struct MockProps {
        #[prop_or_default]
        string: String,
        string_opt: Option<String>,
    }

    pub struct MockComponent;

    impl Component for MockComponent {
        type Message = ();
        type Properties = MockProps;

        fn create(_props: Self::Properties, _link: ComponentLink<Self>) -> Self {
            unimplemented!()
        }

        fn update(&mut self, _msg: Self::Message) -> bool {
            unimplemented!()
        }

        fn change(&mut self, _props: Self::Properties) -> bool {
            unimplemented!()
        }

        fn view(&self) -> Html {
            unimplemented!()
        }
    }

    #[test]
    fn test_str() {
        html!{
            <MockComponent
                string="foo"
                string_opt="foo"
                />
        };
    }
}

With Yew 0.18, this fails with:

error[E0277]: the trait bound `&str: conversion::IntoPropValue<std::option::Option<std::string::String>>` is not satisfied
   --> packages/yew/src/html/conversion.rs:138:28
    |
138 |                 string_opt="foo"
    |                            ^^^^^ the trait `conversion::IntoPropValue<std::option::Option<std::string::String>>` is not implemented for `&str`
    |
    = help: the following implementations were found:
              <&'static str as conversion::IntoPropValue<std::borrow::Cow<'static, str>>>
              <&'static str as conversion::IntoPropValue<std::string::String>>

Steps To Reproduce
Steps to reproduce the behavior:

1. Compile the code above

Expected behavior

I would expect to have a simple way to assign T to Option using the macro.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment:

• Yew version: 0.18, master
• Rust version: 0.51.0

Questionnaire

• I'm interested in fixing this myself but don't know where to start
• I would like to fix and I have a solution
• I don't have time to fix this right now, but maybe later

[ctron]

I have the same issue when switching from String to Cow<'static, str>.

[gzeronet]

@ctron, same issue when assign value to properties like (input) 'max', I just use 'value.to_string()', and it works now. Hope that can help.

[ctron]

Yea, that works. But also clones. And doesn't work with Cow.

I played around a little bit with the Yew code, and it looks to me the problem is the concept of IntoOptPropValue<T>. That doesn't work properly.

Removing this in favor of IntoPropValue<Option<T>> seems to bring the same functionality, but removes the problem. So you can properly assign &str to Option<Cow<static, str>>and&strtoOption` too.

[ctron]

I created a PR (#1895) which works fine for me, and doesn't seem to have any negative effects.

[christianfosli]

I'm also experiencing this issue updating from yew 0.17 to 0.18.
Would be amazing if the fix from #1895 could be ported to 0.18 and released on crates.io 👼

[ctron]

Yea, I was hoping for a release of this too. Either 0.18 or 0.19.