TS2409 states that the return type of the constructor signature must be compatible with the instance type of the class

Question

TS2409 states that the return type of the constructor signature must be compatible with the instance type of the class

I'm encountering an issue with TypeScript and Angular. In this case, the foo class is a service that utilizes another service called fooService, which has a method getUser() that returns a promise of a specific type.

Although the compilation seems fine, I'm facing this particular error: TS2409: Return type of constructor signature must be assignable to the instance type of the class

Please provide assistance in resolving this problem.

module fooModule {

    export class foo {

        static $inject = ['fooService'];

        constructor(public fooService:services.fooService) {

            return fooService.getUser();
        }
    }
}

angularjs typescript

Answer 1

Answer №1

When compiling, it is important to address the type error TS2409: Return type of constructor signature must be assignable to the instance type of the class.

The issue stems from the return statement in the constructor return fooService.getUser();, which should ideally return an instance of the class foo.

declare class FooService{
    getfoo():foo;
}

class foo {

    constructor(public fooService:FooService) {
        return fooService.getfoo();
    }
}

Without this correction, assigning var f = new foo would not result in a variable of type foo.

Update

If you're unsure about the intended outcome, consider the following guidance:

module fooModule {

    export class Foo {

        static $inject = ['fooService'];

        constructor(public fooService:services.FooService) {
        }
        
        getUser():ng.IPromise<User>{
            return this.fooService.getUser();
        }
    }
    
    var foo = new Foo(); 
    foo.getUser().then(()=>{
        // complete this code here 
    });
}

Answer 2

When compiling, it is important to address the type error TS2409: Return type of constructor signature must be assignable to the instance type of the class.

The issue stems from the return statement in the constructor return fooService.getUser();, which should ideally return an instance of the class foo.

declare class FooService{
    getfoo():foo;
}

class foo {

    constructor(public fooService:FooService) {
        return fooService.getfoo();
    }
}

Without this correction, assigning var f = new foo would not result in a variable of type foo.

Update

If you're unsure about the intended outcome, consider the following guidance:

module fooModule {

    export class Foo {

        static $inject = ['fooService'];

        constructor(public fooService:services.FooService) {
        }
        
        getUser():ng.IPromise<User>{
            return this.fooService.getUser();
        }
    }
    
    var foo = new Foo(); 
    foo.getUser().then(()=>{
        // complete this code here 
    });
}

TS2409 states that the return type of the constructor signature must be compatible with the instance type of the class

Answer №1

Update

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