mirror of
https://github.com/DioxusLabs/dioxus
synced 2024-12-24 03:23:11 +00:00
122 lines
2.8 KiB
Markdown
122 lines
2.8 KiB
Markdown
# Dioxus Signals
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Dioxus Signals is an ergonomic Copy runtime for data with local subscriptions.
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## Copy Data
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All signals implement Copy, even if the inner value does not implement copy. This makes it easy to move any data into futures or children.
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```rust
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use dioxus::prelude::*;
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use dioxus_signals::*;
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fn app(cx: Scope) -> Element {
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let signal = use_signal(cx, || "hello world".to_string());
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spawn(async move {
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// signal is Copy even though String is not copy
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print!("{signal}");
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});
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render! {
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"{signal}"
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}
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}
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```
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## Local Subscriptions
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Signals will only subscribe to components when you read from the signal in that component. It will never subscribe to a component when reading data in a future or event handler.
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```rust
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use dioxus::prelude::*;
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use dioxus_signals::*;
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fn app(cx: Scope) -> Element {
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// Because signal is never read in this component, this component will not rerun when the signal changes
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let signal = use_signal(cx, || 0);
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render! {
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button {
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onclick: move |_| {
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*signal.write() += 1;
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},
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"Increase"
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}
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for id in 0..10 {
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Child {
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signal: signal,
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}
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}
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}
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}
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#[derive(Props, Clone, PartialEq)]
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struct ChildProps {
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signal: Signal<usize>,
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}
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fn Child(cx: Scope<ChildProps>) -> Element {
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// This component does read from the signal, so when the signal changes it will rerun
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render! {
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"{cx.props.signal}"
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}
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}
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```
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Because subscriptions happen when you read from (not create) the data, you can provide signals through the normal context API:
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```rust
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use dioxus::prelude::*;
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use dioxus_signals::*;
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fn app(cx: Scope) -> Element {
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// Because signal is never read in this component, this component will not rerun when the signal changes
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use_context_provider(cx, || Signal::new(0));
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render! {
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Child {}
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}
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}
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fn Child(cx: Scope) -> Element {
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let signal: Signal<i32> = *use_context(cx).unwrap();
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// This component does read from the signal, so when the signal changes it will rerun
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render! {
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"{signal}"
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}
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}
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```
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## Computed Data
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In addition to local subscriptions in components, `dioxus-signals` provides a way to derive data with local subscriptions.
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The use_selector hook will only rerun when any signals inside of the hook change:
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```rust
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use dioxus::prelude::*;
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use dioxus_signals::*;
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fn app(cx: Scope) -> Element {
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let signal = use_signal(cx, || 0);
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let doubled = use_selector(cx, || signal * 2);
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render! {
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button {
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onclick: move |_| *signal.write() += 1,
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"Increase"
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}
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Child {
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signal: signal
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}
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}
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}
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#[inline_props]
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fn Child(cx: Scope, signal: ReadOnlySignal<usize>) -> Element {
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render! {
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"{signal}"
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}
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}
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```
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