Typescript: Assign only existing properties of model in constructor using Object.assign [duplicate]

I've assigning to a partial in the constructor works really well, however it can write extra properties (if the object we pass into the data has a property which class T does not, it still gets copied)

    id: number
    username: string
    ....

    constructor(data: Partial<T>)
    {
        Object.assign(this, data)
    }

How can I avoid this? Object.keys(this) is empty when called in the constructor, so I cannot properly compare keys.