title: Using no tracking navigation property EF core
body: <p>Let's say I have 2 tables: Books and Authors. They are represented as following EF models:</p>
  
  <pre><code>class Book {
     Guid Id { get; set; }
     string BookName { get; set; }
     Author Author { get; set; }
  }
  
  class Author {
     Guid Id { get; set; }
     string Name { get; set; }
  }
  </code></pre>
  
  <p>Both entities have autogenerated Guid Id, i.e. before being inserted into database, Ids are generated on client site(that's default behaviour of npgsql)
  Book table has a foreign key to Author table.
  So, lets say I have a several authors already. I would like to add new book by some author. It's a web app, so I have repositories injected into controller. Before inserting new book I load (readonly, i.e AsNoTracking for performance benefits) available authors, find required author and assign that author to newly created book's Author property. On DbContext.SaveChanges I got an error, saying the given Id already exist. I suspect EF is trying to add new Author with a given ID(even though it already exist in a database) because Author entity was loaded as NoTracking.</p>
  
  <p>Is there a way to load foreign key as no tracking to create new entities? </p>
  
  <p>Thanks</p>