是否可以在Angular 2+中将服务用于Typescript类

Question

I have a class as follows which is not annotated with @Injectable

export class A extends B {

    calculateTotal(): number {
        //Implementation
    }
} 

The above function calculateTotal needs to use a service which is annotated with @Injectable to be able to get some values to perform some totals. Question is: is it ok to use that service into that class?

Ashley

Answer 1

There are different ways to get one SomeService instance injected into class A . The one I use eg in Ionic 2 is:

• if class A can be a Component, add the @Component decorator to its definition and the providers metadata to it;
• import the service definition in the class A definition file;
• add a constructor method to class A and declare a service instance as argument.

For example, assuming that the service class is named SomeService and is defined in the file some.service.ts in the same directory as the current source file:

import { Component } from '@angular/core';
import { SomeService } from './some.service';

@Component({
    providers: [ SomeService ]
})
export class A extends B {

    constructor( public s:SomeService ){}

    otherMethod(){
        this.s; // SomeService is accessible like this
    }
}

More information is available in the official docs .