TSyringe: How to change a parameter of an injected object?

Question

I have an app with multiple different components, each component having their own dependency and am using TSyringe to manage dependency injection. One of the components is an operator such as this:

// myoperator.ts

@injectable()
export class MyOperator {
    constructor(
        private dependencyA: DependencyA,
        protected dependencyB: DependencyB,
        protected dependencyC: DependencyC,
        protected operationType: string
    ){
         // initialize operator, etc.
    }

    // ...

}

It is a class that does an operation, depends on a bunch of other classes and has a single string parameter that specifies the way it will operate.

In the main application I'm initializing all the different components that the main app uses and I need to initialize MyOperator with several different operation types.

// mainapp.ts

@singleton()
export class MainApp {
    constructor(
        componentA: ComponentA,
        componentB: ComponentB,
        componentC: ComponentC,
        operatorWithOperationTypeFoo: MyOperator // the operationType should be "foo"
        operatorWithOperationTypeBar: MyOperator // the operationType should be "bar"
        operatorWithOperationTypeBaz: MyOperator // the operationType should be "baz"
    ) {
         // initialize main app, etc.        
    }

    public start() {
        // start main app etc.
    
    }
}

// main.ts

const app = container.resolve(MainApp);
app.start();

My question is, how can I change that single operationType parameter in the MyOperator class when defining them in the MainApp constructor parameters?

What do you exactly do you mean when told: "change the operationType parameter in the MyOperator class"? This is a protected parameter and you can not change it in instances outside (only from a method inside the instance). For injecting primitive values use this https://github.com/microsoft/tsyringe#injecting-primitive-values-named-injection — Денищук Павло Миколайович, Jan 10 '22 at 09:31
@ДенищукПавлоМиколайович I meant it as change it at initialization. I have a MyOperator class and I need the operationType to be different for each instance initialized. — hyk, Feb 11 '22 at 08:57

score 0 · Accepted Answer · answered Apr 22 '22 at 08:17

I eventually realized that the solution is really simple: inheritance.

I declare my base operator:

@singleton()
export class MyOperator {
    constructor(
        private dependencyA: DependencyA,
        protected dependencyB: DependencyB,
        protected dependencyC: DependencyC,
        protected operationType: string
    ){
         // initialize operator, etc.
    }

    // ...

}

And then I extend my other operators from this operator, injecting the dependency:

container.register(CustomType.BAZ, { useValue: CustomType.BAZ });


@singleton()
export class MyOperatorWithOperationTypeBaz extends MyOperator {
    constructor(
        private dependencyA: DependencyA,
        protected dependencyB: DependencyB,
        protected dependencyC: DependencyC,
        @inject(CustomType.BAZ) protected operationType: string
    ){
         super()
         // initialize operator, etc.
    }

    // ...

}

TSyringe: How to change a parameter of an injected object?

1 Answers1