Cast Entity to Implemented Interface in a Generic Method Using LINQ for Entity Framework

Question

I have a generic method to query objects of type TEntity in EF. I Want to add a condition as a where clause if TEntity implements a specific interface. The method I have is:

Answer 1

If all DbSets has the 'UserID' property then create another interface named 'IUserID' and then try this code:

    protected TEntity GetByUserID(Guid userID) where TEntity : class
    {
        var user = this.Set()
            .ToList()
            .Cast()
            .Where(u => (!u.IsDeleted))
            .Cast()
            .Where(u => (u.UserID == userID))
            .FirstOrDefault();
        return user;
    }