Why Object IDs & Primary Keys Are Implementation Details

Word-Definition.cs

public class Word {
  public int Id { get; set; }
  public string Name { get; set; }
  public IList<Definition> Definitions { get; private set; }
}

public class Definition {
  public int Id { get; set; }
  public int WordId { get; set; }
  public string Text { get; set; }
  public string Example { get; set; }
}

Word-definitions-correct.cs

public class Word {
  private object Id { get; set; }
  public string Name { get; set; }
  public IList<Definition> Definitions { get; private set; }
  public void Add(Definition definition) {
    if (definition == null) throw new ArgumentNullException();
    Definitions.Add(definition);
  }
}

public class Definition {
  public Definition(string text, string example) {
    Text = text;
    Example = example;
  }
  private object Id { get; set; }
  public string Text { get; private set; }
  public string Example { get; private set; }
}

Word-definitions.json

{
  "_id": "09823bcf7de88c",
  "name": "LOL",
  "definitions": [
    {
      "text": "Laugh Out Loud"
      "example": "I can't wait for the wedding. LOL"
    },
    {
      "text": "Lots Of Love",
      "example": "I don't have the heart to let my mom know that LOL doesn't actually mean Lots Of Love"
    }
  ]
}