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fix: allow Option<T> and &T as VNode children in html! macro #4005

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Merged
Madoshakalaka merged 3 commits into from
Feb 27, 2026
Merged

fix: allow Option<T> and &T as VNode children in html! macro #4005

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2b996c2
fix: allow Option<String> and Option<AttrValue> as VNode children in …
Madoshakalaka Feb 26, 2026
6331a01
fix: allow &T references as VNode children in html! macro
Madoshakalaka Feb 26, 2026
cdb6993
fix: website snippet affected by the regression
Madoshakalaka Feb 26, 2026
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8 changes: 4 additions & 4 deletions Cargo.lock
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38 changes: 19 additions & 19 deletions packages/yew-macro/tests/html_macro/component-fail.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -488,14 +488,14 @@ error[E0277]: the trait bound `{integer}: IntoPropValue<String>` is not satisfie
| required by a bound introduced by this call
|
= help: the following other types implement trait `IntoPropValue<T>`:
f32
f64
i128
i16
i32
i64
i8
isize
&f32
&f64
&i128
&i16
&i32
&i64
&i8
&isize
and $N others
note: required by a bound in `ChildPropertiesBuilder::string`
--> tests/html_macro/component-fail.rs:4:17
Expand All @@ -516,14 +516,14 @@ error[E0277]: the trait bound `{integer}: IntoPropValue<String>` is not satisfie
| required by a bound introduced by this call
|
= help: the following other types implement trait `IntoPropValue<T>`:
f32
f64
i128
i16
i32
i64
i8
isize
&f32
&f64
&i128
&i16
&i32
&i64
&i8
&isize
and $N others
note: required by a bound in `ChildPropertiesBuilder::string`
--> tests/html_macro/component-fail.rs:4:17
Expand Down Expand Up @@ -560,9 +560,9 @@ error[E0277]: the trait bound `u32: IntoPropValue<i32>` is not satisfied
| |
| required by a bound introduced by this call
|
= help: the trait `IntoPropValue<i32>` is not implemented for `u32`
but trait `IntoPropValue<VNode>` is implemented for it
= help: for that trait implementation, expected `VNode`, found `i32`
= help: the following other types implement trait `IntoPropValue<T>`:
&u32
u32
note: required by a bound in `ChildPropertiesBuilder::int`
--> tests/html_macro/component-fail.rs:4:17
|
Expand Down
14 changes: 7 additions & 7 deletions packages/yew-macro/tests/html_macro/element-fail.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -465,14 +465,14 @@ error[E0277]: the trait bound `NotToString: IntoPropValue<Option<implicit_clone:
| ^^^^^^^^^^^ the trait `IntoPropValue<Option<implicit_clone::unsync::string::IString>>` is not implemented for `NotToString`
|
= help: the following other types implement trait `IntoPropValue<T>`:
`&&String` implements `IntoPropValue<VNode>`
`&&str` implements `IntoPropValue<VNode>`
`&'static [(K, V)]` implements `IntoPropValue<implicit_clone::unsync::map::IMap<K, V>>`
`&'static [T]` implements `IntoPropValue<implicit_clone::unsync::array::IArray<T>>`
`&'static str` implements `IntoPropValue<Classes>`
`&'static str` implements `IntoPropValue<Option<String>>`
`&'static str` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`&'static str` implements `IntoPropValue<String>`
`&'static str` implements `IntoPropValue<implicit_clone::unsync::string::IString>`
`&ChildrenRenderer<VNode>` implements `IntoPropValue<VNode>`
and $N others

error[E0277]: the trait bound `Option<NotToString>: IntoPropValue<Option<implicit_clone::unsync::string::IString>>` is not satisfied
Expand All @@ -491,8 +491,8 @@ error[E0277]: the trait bound `Option<NotToString>: IntoPropValue<Option<implici
`Option<F>` implements `IntoPropValue<Option<yew::Callback<I, O>>>`
`Option<Rc<str>>` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`Option<String>` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`Option<T>` implements `IntoPropValue<VNode>`
`Option<VChild<T>>` implements `IntoPropValue<Option<ChildrenRenderer<C>>>`
`Option<VNode>` implements `IntoPropValue<VNode>`

error[E0277]: the trait bound `Option<{integer}>: IntoPropValue<Option<implicit_clone::unsync::string::IString>>` is not satisfied
--> tests/html_macro/element-fail.rs:48:22
Expand All @@ -510,8 +510,8 @@ error[E0277]: the trait bound `Option<{integer}>: IntoPropValue<Option<implicit_
`Option<F>` implements `IntoPropValue<Option<yew::Callback<I, O>>>`
`Option<Rc<str>>` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`Option<String>` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`Option<T>` implements `IntoPropValue<VNode>`
`Option<VChild<T>>` implements `IntoPropValue<Option<ChildrenRenderer<C>>>`
`Option<VNode>` implements `IntoPropValue<VNode>`

error[E0277]: the trait bound `{integer}: IntoEventCallback<MouseEvent>` is not satisfied
--> tests/html_macro/element-fail.rs:51:28
Expand Down Expand Up @@ -627,8 +627,8 @@ error[E0277]: the trait bound `Option<yew::NodeRef>: IntoPropValue<yew::NodeRef>
`Option<F>` implements `IntoPropValue<Option<yew::Callback<I, O>>>`
`Option<Rc<str>>` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`Option<String>` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`Option<T>` implements `IntoPropValue<VNode>`
`Option<VChild<T>>` implements `IntoPropValue<Option<ChildrenRenderer<C>>>`
`Option<VNode>` implements `IntoPropValue<VNode>`

error[E0277]: the trait bound `yew::Callback<String>: IntoEventCallback<MouseEvent>` is not satisfied
--> tests/html_macro/element-fail.rs:58:29
Expand Down Expand Up @@ -665,14 +665,14 @@ error[E0277]: the trait bound `NotToString: IntoPropValue<Option<implicit_clone:
| ^^^^^^^^^^^ the trait `IntoPropValue<Option<implicit_clone::unsync::string::IString>>` is not implemented for `NotToString`
|
= help: the following other types implement trait `IntoPropValue<T>`:
`&&String` implements `IntoPropValue<VNode>`
`&&str` implements `IntoPropValue<VNode>`
`&'static [(K, V)]` implements `IntoPropValue<implicit_clone::unsync::map::IMap<K, V>>`
`&'static [T]` implements `IntoPropValue<implicit_clone::unsync::array::IArray<T>>`
`&'static str` implements `IntoPropValue<Classes>`
`&'static str` implements `IntoPropValue<Option<String>>`
`&'static str` implements `IntoPropValue<Option<implicit_clone::unsync::string::IString>>`
`&'static str` implements `IntoPropValue<String>`
`&'static str` implements `IntoPropValue<implicit_clone::unsync::string::IString>`
`&ChildrenRenderer<VNode>` implements `IntoPropValue<VNode>`
and $N others

error[E0277]: the trait bound `(): IntoPropValue<yew::NodeRef>` is not satisfied
Expand Down
20 changes: 20 additions & 0 deletions packages/yew-macro/tests/html_macro/html-element-pass.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,26 @@ fn compile_pass() {

let option_vnode = ::std::option::Option::Some(::yew::html! {});
_ = ::yew::html! { <div>{option_vnode}</div> };

let opt_string: ::std::option::Option<::std::string::String> =
::std::option::Option::Some(::std::convert::From::from("hello"));
_ = ::yew::html! { <div>{opt_string}</div> };

let opt_attr: ::std::option::Option<::yew::AttrValue> =
::std::option::Option::Some(::yew::AttrValue::Static("hello"));
_ = ::yew::html! { <div>{opt_attr}</div> };

let opt_none: ::std::option::Option<::std::string::String> = ::std::option::Option::None;
_ = ::yew::html! { <div>{opt_none}</div> };

let num = 42i32;
_ = ::yew::html! { <div>{&num}</div> };

let text = ::std::string::String::new();
_ = ::yew::html! { <div>{&text}</div> };

let sr: &::core::primitive::str = "hello";
_ = ::yew::html! { <div>{&sr}</div> };
}

fn main() {}
35 changes: 33 additions & 2 deletions packages/yew/src/html/conversion/into_prop_value.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -214,10 +214,10 @@ impl IntoPropValue<VNode> for Vec<VNode> {
}
}

impl IntoPropValue<VNode> for Option<VNode> {
impl<T: IntoPropValue<VNode>> IntoPropValue<VNode> for Option<T> {
#[inline]
fn into_prop_value(self) -> VNode {
self.unwrap_or_default()
self.map(IntoPropValue::into_prop_value).unwrap_or_default()
}
}

Expand Down Expand Up @@ -292,6 +292,12 @@ macro_rules! impl_into_prop_value_via_display {
VText::from(self).into()
}
}
impl IntoPropValue<VNode> for &$from_ty {
#[inline(always)]
fn into_prop_value(self) -> VNode {
self.clone().into_prop_value()
}
}
};
}

Expand Down Expand Up @@ -350,6 +356,31 @@ mod test {
let _: Option<AttrValue> = Cow::Borrowed("foo").into_prop_value();
}

#[test]
fn test_option_to_vnode() {
let _: VNode = Some(String::from("hello")).into_prop_value();
let _: VNode = Some(AttrValue::Static("hello")).into_prop_value();
let _: VNode = Option::<String>::None.into_prop_value();
let _: VNode = Option::<AttrValue>::None.into_prop_value();
let _: VNode = Some(VNode::default()).into_prop_value();
let _: VNode = Option::<VNode>::None.into_prop_value();
let _: VNode = Some(42u32).into_prop_value();
let _: VNode = Some(true).into_prop_value();
}

#[test]
fn test_ref_to_vnode() {
let _: VNode = (&42i32).into_prop_value();
let _: VNode = (&true).into_prop_value();
let _: VNode = (&1.5f64).into_prop_value();
let s = String::from("hello");
let _: VNode = (&s).into_prop_value();
let a = AttrValue::Static("hello");
let _: VNode = (&a).into_prop_value();
let sr: &str = "hello";
let _: VNode = (&sr).into_prop_value();
}

#[test]
fn test_callback() {
let _: Callback<String> = (|_: String| ()).into_prop_value();
Expand Down
2 changes: 1 addition & 1 deletion website/docs/advanced-topics/children.mdx
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Original file line number Diff line number Diff line change
Expand Up @@ -287,7 +287,7 @@ impl Component for Page {
fn view(&self, ctx: &Context<Self>) -> Html {
html! {
<div class="page">
{ ctx.props().sidebar.clone().map(Html::from).unwrap_or_default() }
{ ctx.props().sidebar.clone() }
// ... page content
</div>
}
Expand Down
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