Injector is returning null using injector.get()

Question

1. I'm facing an issue with the injector.get(ViewContainerRef) to get the instance of ViewContainerRef. It is returning null/undefined
   when try to get the instance of ViewContainerRef.
2. It is available before i reach to the class to get the instance of ViewContainerRef. The injector argument is being passed from child to parent using constructor arguments and trying to get the instance using injector.get(). That is returning null all the time.
3. Please help me to come out of this situation,Thanks.

export abstract class ChildClass extends ParentClass {

    constructor(injector: Injector) {
        super(injector);
    }
}

export abstract class ParentClass{
    public viewContainerRef:ViewContainerRef;
    constructor(injector: Injector) {
        this.viewContainerRef = injector.get(ViewContainerRef) **Here it is returning null.**
    }
}

Answer 1

I'd struggled the same issue, finally identified that injector.get(ViewContainerRef) returns null when Ivy is disabled. (If Ivy is enabled, then injector correctly resolves it).

Seems ViewContainerRef should be specified as a param of the constructor in ViewEngine environment.