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D6 feat(core): support listening to outputs on dynamically-created compo… · angular/angular@be44cc8 · GitHub
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crisbetommalerba
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feat(core): support listening to outputs on dynamically-created components (#60137)
Adds the new `outputBinding` function that allows users to listen to outputs on dynamically-created components in a similar way to templates. For example, here we create an instance of `MyCheckbox` and listen to its `onChange` event: ```ts interface CheckboxChange { value: string; } createComponent(MyCheckbox, { bindings: [ outputBinding<CheckboxChange>('onChange', event => console.log(event.value)) ], }); ``` Note that while it has always been possible to listen to events like this by getting a hold of of the instance and subscribing to it, there are a few key differences: 1. `outputBinding` behaves in the same way as if the event was bound in a template which comes with some behaviors like forwarding errors to the `ErrorHandler` and marking the view as dirty. 2. With `outputBinding` the listeners will be cleaned up automatically when the component is destroyed. 3. `outputBinding` accounts for host directive outputs by binding to them through the host. E.g. if the `onChange` event above was coming from a host directive, `outputBinding` would bind to it automatically. Currently `outputBinding` is available only in `createComponent`, `ViewContainerRef.createComponent` and `ComponentFactory.create`, but it will serve as a base for APIs in the future. PR Close #60137
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-5
lines changed

17 files changed

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‎goldens/public-api/core/index.api.md

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@@ -1363,6 +1363,9 @@ export const Output: OutputDecorator;
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// @public
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export function output<T = void>(opts?: OutputOptions): OutputEmitterRef<T>;
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1366+
// @public
1367+
export function outputBinding<T>(eventName: string, listener: (event: T) => unknown): Binding;
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// @public
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export interface OutputDecorator {
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(alias?: string): any;

‎goldens/size-tracking/integration-payloads.json

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@@ -1,7 +1,7 @@
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{
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"cli-hello-world": {
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"uncompressed": {
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"main": 132425,
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"main": 137893,
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"polyfills": 33792
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}
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},

‎packages/core/src/core.ts

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Original file line numberDiff line numberDiff line change
@@ -112,7 +112,7 @@ export {
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afterNextRender,
113113
ɵFirstAvailable,
114114
} from './render3/after_render/hooks';
115-
export {inputBinding} from './render3/dynamic_bindings';
115+
export {inputBinding, outputBinding} from './render3/dynamic_bindings';
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export {ApplicationConfig, mergeApplicationConfig} from './application/application_config';
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export {makeStateKey, StateKey, TransferState} from './transfer_state';
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export {booleanAttribute, numberAttribute} from './util/coercion';

‎packages/core/src/render3/dynamic_bindings.ts

Lines changed: 70 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -9,9 +9,11 @@
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import {RuntimeError, RuntimeErrorCode} from '../errors';
1010
import {Type} from '../interface/type';
1111
import {bindingUpdated} from './bindings';
12+
import {listenToDirectiveOutput, wrapListener} from './instructions/listener';
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import {setDirectiveInput, storePropertyBindingMetadata} from './instructions/shared';
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import {DirectiveDef} from './interfaces/definition';
14-
import {getLView, getSelectedTNode, getTView, nextBindingIndex} from './state';
15+
import {CONTEXT} from './interfaces/view';
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import {getCurrentTNode, getLView, getSelectedTNode, getTView, nextBindingIndex} from './state';
1517

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/** Symbol used to store and retrieve metadata about a binding. */
1719
export const BINDING = /* @__PURE__ */ Symbol('BINDING');
@@ -47,8 +49,9 @@ export interface DirectiveWithBindings<T> {
4749
bindings: Binding[];
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}
4951

50-
// This is constant between all the bindings so we can reuse the object.
52+
// These are constant between all the bindings so we can reuse the objects.
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const INPUT_BINDING_METADATA: Binding[typeof BINDING] = {kind: 'input', requiredVars: 1};
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const OUTPUT_BINDING_METADATA: Binding[typeof BINDING] = {kind: 'output', requiredVars: 0};
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5356
class InputBinding<T> implements Binding {
5457
readonly target!: DirectiveDef<T>;
@@ -89,6 +92,46 @@ class InputBinding<T> implements Binding {
8992
}
9093
}
9194

95+
class OutputBinding<T> implements Binding {
96+
readonly target!: DirectiveDef<unknown>;
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readonly [BINDING] = OUTPUT_BINDING_METADATA;
98+
99+
constructor(
100+
private readonly eventName: string,
101+
private readonly listener: (event: T) => unknown,
102+
) {}
103+
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create(): void {
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if (!this.target && ngDevMode) {
106+
throw new RuntimeError(
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RuntimeErrorCode.NO_BINDING_TARGET,
108+
`Output binding to "${this.eventName}" does not have a target.`,
109+
);
110+
}
111+
112+
const lView = getLView<{} | null>();
113+
const tView = getTView();
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const tNode = getCurrentTNode()!;
115+
const context = lView[CONTEXT];
116+
const wrappedListener = wrapListener(tNode, lView, context, this.listener);
117+
const hasBound = listenToDirectiveOutput(
118+
tNode,
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tView,
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lView,
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this.target,
122+
this.eventName,
123+
wrappedListener,
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);
125+
126+
if (!hasBound && ngDevMode) {
127+
throw new RuntimeError(
128+
RuntimeErrorCode.INVALID_BINDING_TARGET,
129+
`${this.target.type.name} does not have an output with a public name of "${this.eventName}".`,
130+
);
131+
}
132+
}
133+
}
134+
92135
/**
93136
* Creates an input binding.
94137
* @param publicName Public name of the input to bind to.
@@ -110,3 +153,28 @@ class InputBinding<T> implements Binding {
110153
export function inputBinding<T>(publicName: string, value: () => unknown): Binding {
111154
return new InputBinding<T>(publicName, value);
112155
}
156+
157+
/**
158+
* Creates an output binding.
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* @param eventName Public name of the output to listen to.
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* @param listener Function to be called when the output emits.
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*
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* ### Usage example
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* In this example we create an instance of the `MyCheckbox` component and listen
164+
* to its `onChange` event.
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*
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* ```
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* interface CheckboxChange {
168+
* value: string;
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* }
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*
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* createComponent(MyCheckbox, {
172+
* bindings: [
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* outputBinding<CheckboxChange>('onChange', event => console.log(event.value))
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* ],
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* });
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* ```
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*/
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export function outputBinding<T>(eventName: string, listener: (event: T) => unknown): Binding {
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return new OutputBinding<T>(eventName, listener);
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}

‎packages/core/src/render3/instructions/listener.ts

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Original file line numberDiff line numberDiff line change
@@ -328,7 +328,7 @@ function executeListenerWithErrorHandling(
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* @param wrapWithPreventDefault Whether or not to prevent default behavior
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* (the procedural renderer does this already, so in those cases, we should skip)
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*/
331-
function wrapListener(
331+
export function wrapListener(
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tNode: TNode,
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lView: LView<{} | null>,
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context: {} | null,
@@ -378,3 +378,80 @@ function isOutputSubscribable(value: unknown): value is SubscribableOutput<unkno
378378
value != null && typeof (value as Partial<SubscribableOutput<unknown>>).subscribe === 'function'
379379
);
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}
381+
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/** Listens to an output on a specific directive. */
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export function listenToDirectiveOutput(
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tNode: TNode,
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tView: TView,
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lView: LView,
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target: DirectiveDef<unknown>,
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eventName: string,
389+
listenerFn: (e?: any) => any,
390+
): boolean {
391+
const tCleanup = tView.firstCreatePass ? getOrCreateTViewCleanup(tView) : null;
392+
const lCleanup = getOrCreateLViewCleanup(lView);
393+
let hostIndex: number | null = null;
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let hostDirectivesStart: number | null = null;
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let hostDirectivesEnd: number | null = null;
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let hasOutput = false;
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398+
if (ngDevMode && !tNode.directiveToIndex?.has(target.type)) {
399+
throw new Error(`Node does not have a directive with type ${target.type.name}`);
400+
}
401+
402+
const data = tNode.directiveToIndex!.get(target.type)!;
403+
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if (typeof data === 'number') {
405+
hostIndex = data;
406+
} else {
407+
[hostIndex, hostDirectivesStart, hostDirectivesEnd] = data;
408+
}
409+
410+
if (
411+
hostDirectivesStart !== null &&
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hostDirectivesEnd !== null &&
413+
tNode.hostDirectiveOutputs?.hasOwnProperty(eventName)
414+
) {
415+
const hostDirectiveOutputs = tNode.hostDirectiveOutputs[eventName];
416+
417+
for (let i = 0; i < hostDirectiveOutputs.length; i += 2) {
418+
const index = hostDirectiveOutputs[i] as number;
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420+
if (index >= hostDirectivesStart && index <= hostDirectivesEnd) {
421+
ngDevMode && assertIndexInRange(lView, index);
422+
hasOutput = true;
423+
listenToOutput(
424+
tNode,
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tView,
426+
lView,
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index,
428+
hostDirectiveOutputs[i + 1] as string,
429+
eventName,
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listenerFn,
431+
lCleanup,
432+
tCleanup,
433+
);
434+
} else if (index > hostDirectivesEnd) {
435+
break;
436+
}
437+
}
438+
}
439+
440+
if (hostIndex !== null && target.outputs.hasOwnProperty(eventName)) {
441+
ngDevMode && assertIndexInRange(lView, hostIndex);
442+
hasOutput = true;
443+
listenToOutput(
444+
tNode,
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tView,
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lView,
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hostIndex,
448+
eventName,
449+
eventName,
450+
listenerFn,
451+
lCleanup,
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tCleanup,
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);
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}
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return hasOutput;
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}

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