Error message:

The appearance is as follows:

Inject @inject (‘ apiUrl ‘) as myName parameter:

The following error was encountered:

Dependency injection entry functions:

/ * * *@fileoverview added by tsickle
 * Generated from: packages/core/src/render3/instructions/di.ts
 * @suppress {checkTypes,constantProperty,extraRequire,missingOverride,missingReturn,unusedPrivateMembers,uselessCode} checked by tsc
 */
/ * * *@template T
 * @param {? } token
 * @param {? =} flags
 * @return {? }* /
functionɵ ɵdirectiveInject(token, flags = InjectFlags.Default) {
    / * *@type {? } * /
    const lView = getLView();
    // Fall back to inject() if view hasn't been created. This situation can happen in tests
    // if inject utilities are used before bootstrapping.
    if (lView == null)
        returnɵ ɵ inject (token, flags);/ * *@type {? } * /
    const tNode = getPreviousOrParentTNode();
    return getOrCreateInjectable((/ * *@type {? } * / (tNode)), lView, resolveForwardRef(token), flags);
}
Copy the code

This token is passed in automatically:

The injector records map indicates that the value corresponding to the apiUrl is null:

Error:

core.js:6242 ERROR NullInjectorError: R3InjectorError(AppModule)[apiUrl -> apiUrl -> apiUrl]: NullInjectorError: No provider for apiUrl! at NullInjector.get (http://localhost:4200/vendor.js:62758:27) at R3Injector.get (http://localhost:4200/vendor.js:76765:33) at R3Injector.get (http://localhost:4200/vendor.js:76765:33) at R3Injector.get (http://localhost:4200/vendor.js:76765:33) at NgModuleRef$1.get (http://localhost:4200/vendor.js:94067:33) at Object.get (http://localhost:4200/vendor.js:91801:35) at GetOrCreateInjectable (http://localhost:4200/vendor.js:66560:39) at the Module. ɵ ɵ directiveInject (http://localhost:4200/vendor.js:80581:12) at NodeInjectorFactory.SearchInputComponent_Factory [as factory] (http://localhost:4200/main.js:1432:174) at getNodeInjectable (http://localhost:4200/vendor.js:66705:44)

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