Error boundary with different error types

[fprasx]

Hi All,

I'm having some trouble with the ErrorBoundary type. I think I'm missing something about which types can be errors because I get an error whenever I deviate from the example. Here's an example (based on the example from the book):

#[component]
fn NumericInput(cx: Scope) -> impl IntoView {
    let (value, set_value) = create_signal(cx, Ok(0));

    - let on_input = move |ev| set_value(event_target_value(&ev).parse::<i32>());
    + // Changing the error type
    + let on_input = move |ev| set_value(event_target_value(&ev).parse::<i32>().map_err(|_| "error"));
    view! { cx,
        <h1>"Error Handling"</h1>
        <label>
            "Type a number (or something that's not a number!)"
            <input on:input=on_input/>
            <ErrorBoundary
                // the fallback receives a signal containing current errors
                fallback=|cx, errors| view! { cx,
                    <div class="error">
                        <p>"Not a number! Errors: "</p>
                        // we can render a list of errors as strings, if we'd like
                        <ul>
                            {move || errors.get()
                                .into_iter()
                                .map(|(_, e)| view! { cx, <li>{e.to_string()}</li>})
                                .collect_view(cx)
                            }
                        </ul>
                    </div>
                }
            >
                <p>"You entered " <strong>{value}</strong></p>
            </ErrorBoundary>
        </label>
    }
}

Changing the error type to someting like &'static str or another integer type causes compile errors like:

the trait `leptos::IntoView` is not implemented for `(leptos::Scope, ReadSignal<Result<i32, &str>>)

Thank you for the help!

[gbj]

IntoView is implemented for Result<T, E> if T implements IntoView and E implements Error. &'static str doesn't implement Error.

[fprasx]

Hmm, I thought this might be the case, but this doesn't compile due to a similar error:

#[derive(Debug, Error)]
enum MyError {
    #[error("I'm an error")]
    Error,
}

// Compiles
fn impls_into_error() -> leptos::error::Error {
    MyError::Error.into()
}


#[component]
fn NumericInput(cx: Scope) -> impl IntoView {
    let (value, set_value) = create_signal(cx, Ok(0));
    
    // Added a map_err on this line
    let on_input = move |ev| set_value.set(event_target_value(&ev).parse::<i32>().map_err(|_| MyError::Error));
    view! { cx,
        <h1>"Error Handling"</h1>
        <label>
            "Type a number (or something that's not a number!)"
            <input on:input=on_input/>
            <ErrorBoundary
                // the fallback receives a signal containing current errors
                fallback=|cx, errors| view! { cx,
                    <div class="error">
                        <p>"Not a number! Errors: "</p>
                        // we can render a list of errors as strings, if we'd like
                        <ul>
                            {move || errors.get()
                                .into_iter()
                                .map(|(_, e)| view! { cx, <li>{e.to_string()}</li>})
                                .collect_view(cx)
                            }
                        </ul>
                    </div>
                }
            >
                <p>"You entered " <strong>{value}</strong></p>
            </ErrorBoundary>
        </label>
    }
}

[gbj]

Ah okay in this case it's actually because MyError doesn't implement Clone, so ReadSignal<Result<_, MyError>> doesn't implement Fn(), so can't be used directly in the view.

If you just add a Clone derived on your error type it compiles fine.

[fprasx]

Ahh ok, thank you!