How to have inherited DataRow class so inherited DataTable can have DataTable.NewRow()

Question

So I would like to extend the DataRow class by adding int to the class Obviously it is simple

public class DataRowWithInt : DataRow
{
    // Properties ///////////////////////////////////////////////////

    public int integer
    {
        get;
        set;
    }

    // Constructor //////////////////////////////////////////////////

    public DataRowWithInt(DataRowBuilder builder)
        : base(builder)
    {
    }
}

Now when you want to create new row you would have to call

DataTable intDataTable = new DataTable();
intDataTable.Columns.Add("temp");
DataRowWithInt row = intDataTable.NewRow();

But this gives you conversion error. How can I avoid this problem and get DataRowWithInt to intDataTable?

Thank you.

-- edit --

I am aware that DataTable class is not going to return me DataRowWithIn. I would like to create an inherited DataTable class but I do not know what to write on NewRow class

Why do you think that `DataTable.NewRow` would return an instance of your class? Apart from that, if the column should be an `int`-column, use the appropriate type in `DataColumnCollection.Add`: `intDataTable.Columns.Add("temp", typeof(int));` — Tim Schmelter, Aug 14 '13 at 20:47
I am aware that it will not return my row. However, even if inherit DataTable class with my own class, I would do not know what DataTable.NewRow() is doing internally so I cannot overwrite it. — Shintaro Takechi, Aug 14 '13 at 20:57
Also I would not like to add this int to the column. I want the row to know about this int but do not wish it to display on table at all. — Shintaro Takechi, Aug 14 '13 at 21:05
How do you want to override `DataTable.NewRow()` if your class inherits from `DataRow`, but even if you inherit from `DataTable` the method is not virtual, so you cannot override it. — Tim Schmelter, Aug 14 '13 at 21:07

score 5 · Accepted Answer · answered Aug 14 '13 at 21:23

If you can't simply use a DataTable with a single DataColumn of type int per @Tim's suggestion in the comments, then consider creating a typed DataTable. With a typed DataTable you can define column names and types as well as a number of other DataTable features and behaviors including how NewRow() works.

A demonstration doing this can be found in this article over at codeproject.com:
How to Manually Create a Typed DataTable

A nice thing about typed DataTable is you don't need to 'indirectly' reference columns by index or by column name, you can reference columns using property notation with Visual Studio's Intellisense helping you out. Here's an example:

var intDataTable = new YourTypedDataTable();
YourTypedDataRow row = intDataTable.NewRow();
row.Temp = 100;
intDataTable.Rows.Add(row);

How to have inherited DataRow class so inherited DataTable can have DataTable.NewRow()

1 Answers1