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crisbetodylhunn
crisbeto
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dylhunn
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feat(core): add API to inject attributes on the host node (#54604)
Angular has the `@Attribute` decorator that allows for attributes to be injected from the host node, but we don't have an equivalent for the `inject` function. These changes introduce the new `HostAttributeToken` class that can be used to inject attributes similarly to `@Attribute`. It can be used as follows: ```typescript import {HostAttributeToken, inject} from '@angular/core'; class MyDir { someAttr = inject(new HostAttributeToken('some-attr')); } ``` The new API works similarly to `@Attribute` with one key exception: it will throw a DI error when the attribute doesn't exist, instead of returning `null` like `@Attribute`. We made this change to align its behavior closer to other injection tokens. PR Close #54604
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‎goldens/public-api/core/index.md‎

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@@ -720,6 +720,13 @@ export interface Host {
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// @public
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export const Host: HostDecorator;
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// @public
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export class HostAttributeToken {
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constructor(attributeName: string);
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// (undocumented)
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toString(): string;
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}
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// @public
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export interface HostBinding {
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hostPropertyName?: string;
@@ -789,6 +796,19 @@ export function inject<T>(token: ProviderToken<T>, options: InjectOptions & {
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// @public (undocumented)
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export function inject<T>(token: ProviderToken<T>, options: InjectOptions): T | null;
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// @public (undocumented)
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export function inject(token: HostAttributeToken): string;
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// @public (undocumented)
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export function inject(token: HostAttributeToken, options: {
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optional: true;
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}): string | null;
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// @public (undocumented)
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export function inject(token: HostAttributeToken, options: {
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optional: false;
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}): string;
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// @public
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export interface Injectable {
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providedIn?: Type<any> | 'root' | 'platform' | 'any' | null;

‎packages/core/src/di/host_attribute_token.ts‎

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@@ -0,0 +1,41 @@
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/*!
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* @license
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* Copyright Google LLC All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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import {ɵɵinjectAttribute} from '../render3/instructions/di_attr';
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/**
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* Creates a token that can be used to inject static attributes of the host node.
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*
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* @usageNotes
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* ### Injecting an attribute that is known to exist
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* ```typescript
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* @Directive()
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* class MyDir {
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* attr: string = inject(new HostAttributeToken('some-attr'));
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* }
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* ```
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*
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* ### Optionally injecting an attribute
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* ```typescript
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* @Directive()
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* class MyDir {
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* attr: string | null = inject(new HostAttributeToken('some-attr'), {optional: true});
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* }
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* ```
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* @publicApi
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*/
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export class HostAttributeToken {
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constructor(private attributeName: string) {}
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/** @internal */
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__NG_ELEMENT_ID__ = () => ɵɵinjectAttribute(this.attributeName);
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toString(): string {
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return `HostAttributeToken ${this.attributeName}`;
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}
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}

‎packages/core/src/di/index.ts‎

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@@ -28,3 +28,4 @@ export {InjectOptions} from './interface/injector';
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export {INJECTOR} from './injector_token';
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export {ClassProvider, ModuleWithProviders, ClassSansProvider, ImportedNgModuleProviders, ConstructorProvider, EnvironmentProviders, ConstructorSansProvider, ExistingProvider, ExistingSansProvider, FactoryProvider, FactorySansProvider, Provider, StaticClassProvider, StaticClassSansProvider, StaticProvider, TypeProvider, ValueProvider, ValueSansProvider} from './interface/provider';
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export {InjectionToken} from './injection_token';
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export {HostAttributeToken} from './host_attribute_token';

‎packages/core/src/di/injector_compatibility.ts‎

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@@ -18,6 +18,7 @@ import {getInjectImplementation, injectRootLimpMode} from './inject_switch';
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import type {Injector} from './injector';
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import {DecoratorFlags, InjectFlags, InjectOptions, InternalInjectFlags} from './interface/injector';
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import {ProviderToken} from './provider_token';
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import type {HostAttributeToken} from './host_attribute_token';
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const _THROW_IF_NOT_FOUND = {};
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*/
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export function ɵɵinject<T>(token: ProviderToken<T>): T;
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export function ɵɵinject<T>(token: ProviderToken<T>, flags?: InjectFlags): T|null;
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export function ɵɵinject<T>(token: ProviderToken<T>, flags = InjectFlags.Default): T|null {
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return (getInjectImplementation() || injectInjectorOnly)(resolveForwardRef(token), flags);
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export function ɵɵinject(token: HostAttributeToken): string;
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export function ɵɵinject(token: HostAttributeToken, flags?: InjectFlags): string|null;
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export function ɵɵinject<T>(
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token: ProviderToken<T>|HostAttributeToken, flags?: InjectFlags): string|null;
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export function ɵɵinject<T>(
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token: ProviderToken<T>|HostAttributeToken, flags = InjectFlags.Default): T|null {
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return (getInjectImplementation() || injectInjectorOnly)(
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resolveForwardRef(token as Type<T>), flags);
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}
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/**
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* @publicApi
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*/
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export function inject<T>(token: ProviderToken<T>, options: InjectOptions): T|null;
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/**
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* @param token A token that represents a static attribute on the host node that should be injected.
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* @returns Value of the attribute if it exists.
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* @throws If called outside of a supported context or the attribute does not exist.
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*
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* @publicApi
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*/
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export function inject(token: HostAttributeToken): string;
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/**
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* @param token A token that represents a static attribute on the host node that should be injected.
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* @returns Value of the attribute if it exists, otherwise `null`.
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* @throws If called outside of a supported context.
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*
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* @publicApi
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*/
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export function inject(token: HostAttributeToken, options: {optional: true}): string|null;
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/**
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* @param token A token that represents a static attribute on the host node that should be injected.
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* @returns Value of the attribute if it exists.
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* @throws If called outside of a supported context or the attribute does not exist.
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*
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* @publicApi
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*/
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export function inject(token: HostAttributeToken, options: {optional: false}): string;
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/**
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* Injects a token from the currently active injector.
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* `inject` is only supported in an [injection context](/guide/dependency-injection-context). It can
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* @publicApi
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*/
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export function inject<T>(
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token: ProviderToken<T>, flags: InjectFlags|InjectOptions = InjectFlags.Default): T|null {
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return ɵɵinject(token, convertToBitFlags(flags));
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token: ProviderToken<T>|HostAttributeToken,
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flags: InjectFlags|InjectOptions = InjectFlags.Default) {
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// The `as any` here _shouldn't_ be necessary, but without it JSCompiler
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// throws a disambiguation error due to the multiple signatures.
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return ɵɵinject(token as any, convertToBitFlags(flags));
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}
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// Converts object-based DI flags (`InjectOptions`) to bit flags (`InjectFlags`).

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