How to use AngularJS ng.resource.IResource with TypeScript.

app.ts

/// <reference path="angular.d.ts" />
/// <reference path="angular-resource.d.ts" />

/*
    The intent of this fork is to show you how to separate your IResource from your Interfaces.
    We had a need in our project to keep the resource separate from the business entity, so this
    updated example reflects those changes.

    Furthermore, I've added TSDoc (comments starting with /**) comments, which your IDE should be
    able to pick up and present while you work.
*/

/*
    Consumers of this module can use the IEmployee or IEmployeeResource types, depending on their needs
*/
/**
 * Intent-free interface representing an IEmployee.  If you are working with the EmployeeResource, 
 * you probably need IEmployeeResource
 */
interface IEmployee {
    /**
     * The ID of the Employee
     */
	id: number;

    /**
     * The First Name of the employee, optional
     */
	firstName ?: string;

    /**
     * The Last Name of the employee, optional
     */
	lastName ?: string;
}

/**
 * This union type provides all of the properties of IEmployee and all of the mutators of IResource.
 * Includes methods like $save, $update
 */
type IEmployeeResource = IEmployee & ng.resource.IResource<IEmployee>;

/*
    You can selectively overload signatures on the IEmployeeResource here.  This is optional.
*/
/**
 * IEmployeeResourceClass provides methods to create or retrieve IEmployeeResource objects.
 * Notice that the update method is overloaded.
 */
interface IEmployeeResourceClass extends ng.resource.IResourceClass<IEmployeeResource>
{
    update(employee: IEmployee) : IEmployeeResource;
}

angular
    .module('myapp', ['ngResource'])
    /*
        This is the factory method that generates and returns the IEmployeeResourceClass, which is the type used
        when you inject the EmployeeResource
    */
    .factory('EmployeeResource', ['$resource', ($resource : ng.resource.IResourceService) : IEmployeeResourceClass => {

        // Define your custom actions here as IActionDescriptor
        var updateAction : ng.resource.IActionDescriptor = {
            method: 'PUT',
            isArray: false
        };

        // Return the resource, include your custom actions
        return <IEmployeeResourceClass> $resource('/api/employee/:id', { id: '@id' }, {
            // This is the attachment of the overloaded signature
            update: updateAction
        });

    }])
    /*
        Note that the Employee parameter's type is `IEmployeeResourceClass`
    */
    .controller('TestCtrl', ['EmployeeResource', (Employee : IEmployeeResourceClass) =>
    {
        // Get all employees
        var employees : Array<IEmployeeResource> = Employee.query();
        // Do something with the result
        employees.forEach( employee => console.log(`Hello, ${employee.firstName}`) )

        // Get specific employee
        var employee : IEmployeeResource = Employee.get({ id: 123 });
        // Change their last name
        employee.lastName = 'Smith';
        
        // Most of these methods are chainable
        employee
            // Save the change... This returns an angular.IPromise
            .$save()
            // Do something with the result of the save (optional)
            .then(success => console.log(`Employee ${success.id} saved`) );

        // Custom action
        var updatedEmployee : IEmployeeResource = Employee.update({ id: 100, firstName: "John" });
    }]);