Question

I have come across a situation where the answer should be really straight forward, but it eludes me.

public class Note
{

    #region Properties

    public int Id { get; set; }
    public int ClientId { get; set; }
    public int CandidateId { get; set; }
    public int TypeId { get; set; }
    public DateTime DateCreated { get; set; }
    public string UserId { get; set; }
    public string UserName { get; set; }
    public string Message { get; set; }

    #endregion

    #region Methods

    public void Save()
    {

    }

    #endregion

}

public class History : Note
{
}

As you can see, History inherits Note. They are exactly the same, the only difference between the two is the type Id.

I have this function when getting data from the database

    public static Note Parse(SqlDataReader dr)
    {
        int TypeId = Convert.ToInt32(dr["TypeId"]);
        Note Note;

        if (TypeId == 1)
            Note = new Note();
        else
            Note = new History();

        Note.Id = Convert.ToInt32(dr["Id"]);
        Note.TypeId = TypeId;
        if (dr["ClientId"] != DBNull.Value) Note.ClientId = Convert.ToInt32(dr["ClientId"]);
        if (dr["CandidateId"] != DBNull.Value) Note.CandidateId = Convert.ToInt32(dr["CandidateId"]);
        Note.DateCreated = Convert.ToDateTime(dr["DateCreated"]);

        Note.UserId = Convert.ToString(dr["UserId"]);
        Note.UserName = Convert.ToString(dr["UserName"]);
        Note.Message = Convert.ToString(dr["Message"]);

        return Note;
    }

And then on my MVC page I have this:

<ol id="interview-comments">                                
@foreach (Note Note in Model.Notes().OfType<Note>())
{  
}
</ol>

<ol id="history-comments">                             
@foreach (History Note in Model.Notes().OfType<History>())
{  
}
</ol>

My question is simple. Is this the correct way to do it?

/r3plica

Answer 1

If this is the whole picture I wouldn’t use inheritance here.
You said that Note and History items had different TypeId:s.

Then I would do the following:

@foreach(var item in Model.Notes().Where(x => x.TypeId == Note.NoteTypeId))
{
}

//and

@foreach(var item in Model.Notes().Where(x => x.TypeId == Note.HistoryTypeId))
{
}

public class Note
{
  public static int HistoryTypeId = 1;
  public static int NoteTypeId = 0;
  /* ... the rest of the implementation */
}

You could also change TypeId to an enum and “hide” some of the magic numbers

Edit:
Depending on the usage you could also implement the check for Historic notes as a property on Note.

public class Note
{
  /* ... other properties ... */
  public bool IsHistoric { get { return this.TypeId != 1; } }
}

And then the check would simple be

@foreach(var note in Model.Notes().Where(x => x.IsHistoric))
{
}

// and

@foreach(var note in Model.Notes().Where(x => !x.IsHistoric())
{
}