Adding, Modifying, and Removing DataRowView Objects from a DataView
It's important to understand that DataRowView objects in a DataView provide access to
the underlying DataRow objects in a DataTable. Therefore, when you examine and edit
the contents of a DataRowView, you're actually working with the underlying DataRow.
Similarly, when you remove a DataRowView, you are removing the underlying
DataRow.
Adding a DataRowView to a DataView
To add a new DataRowView to a DataView, you call the AddNew() method of your
DataView. The AddNew() method returns a DataRowView object that you use to set the
column values for the new row.The following example calls the AddNew() method of the
customersDV DataView:
DataRowView customerDRV = customersDV.AddNew();
customerDRV["CustomerID"] = "J7COM";
customerDRV["CompanyName"] = "J7 Company";
customerDRV["Country"] = "UK";
customerDRV.EndEdit();
Notice the use of the EndEdit() method of the customerDRV DataRowView to end the
editing. The EndEdit() method creates a new DataRow in the underlying DataTable. The
DataColumn objects in the new DataRow will contain the column values specified in the
previous code.
N
ote You can undo the addition by calling the CancelEdit() method of a DataRowView.
You can get the underlying DataRow added to the DataTable using the Row property of a
DataRowView. For example:
DataRow customerDR = customerDRV.Row;
Modifying an Existing DataRowView
To begin modifying an existing DataRowView in a DataView, you call the BeginEdit()
method of the DataRowView in your DataView. The following example calls the
BeginEdit() method for the first DataRowView in customersDV:
customersDV[0].BeginEdit();
N
ote Remember that DataRowView objects in a DataView start at index 0, and therefore
customersDV[0] is the first DataRowView in customersDV.
You can then modify a DataColumn in the underlying DataRow through the
DataRowView. The following example sets the CompanyName DataColumn to Widgets
Inc.:
customersDV[0]["CompanyName"] = "Widgets Inc.";
Once you've finished making your modifications, you call the EndEdit() method to make
your modifications permanent in the underlying DataTable. For example:
customersDV[0].EndEdit();
N
ote You can undo the modification by calling the CancelEdit() method of a
D
ataRowView.
Removing an Existing DataRowView
To remove an existing DataRowView from a DataView, you can call the Delete() method
of either the DataView or the DataRowView. When calling the Delete() method of a
DataView, you pass the index of the DataRowView you want to remove. The following
example removes the second DataRowView from customersDV:
customersDV.Delete(1);
When calling the Delete() method of a DataRowView, you simply call that method of the
DataRowView in your DataView. The following example removes the third
DataRowView from customersDV:
customersDV[2].Delete();
With either of these Delete() methods, the deletion isn't committed in the underlying
DataTable until you call the AcceptChanges() method of your DataTable. For example:
customersDT.AcceptChanges();
N
ote You can call the RejectChanges() method of a DataTable to undo the deletions.
This method will also undo any uncommitted additions and modifications of rows.
Listing 13.3 shows a program that adds, modifies, and removes DataRowView objects
from a DataView. This program also displays the IsNew and IsEdit properties of the
DataRowView objects, which indicate whether the DataRowView is new and is being
edited.
Listing 13.3: ADDMODIFYANDREMOVEDATAROWVIEWS.CS
/*
AddModifyAndRemoveDataRowViews.cs illustrates how to
add, modify, and remove DataRowView objects from a DataView
*/
using System;
using System.Data;
using System.Data.SqlClient;
class AddModifyAndRemoveDataRowViews
{
public static void DisplayDataRow(
DataRow myDataRow,
DataTable myDataTable
)
{
Console.WriteLine("\nIn DisplayDataRow()");
foreach (DataColumn myDataColumn in myDataTable.Columns)
{
Console.WriteLine(myDataColumn + "= " +
myDataRow[myDataColumn]);
}
}
public static void Main()
{
SqlConnection mySqlConnection =
new SqlConnection(
"server=localhost;database=Northwind;uid=sa;pwd=sa"
);
SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
mySqlCommand.CommandText =
"SELECT CustomerID, CompanyName, Country " +
"FROM Customers";
SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
mySqlDataAdapter.SelectCommand = mySqlCommand;
DataSet myDataSet = new DataSet();
mySqlConnection.Open();
mySqlDataAdapter.Fill(myDataSet, "Customers");
mySqlConnection.Close();
DataTable customersDT = myDataSet.Tables["Customers"];
// set up the filter expression
string filterExpression = "Country = 'UK'";
// create a DataView object named customersDV
DataView customersDV = new DataView();
customersDV.Table = customersDT;
customersDV.RowFilter = filterExpression;
// add a new DataRowView (adds a DataRow to the DataTable)
Console.WriteLine("\nCalling customersDV.AddNew()");
DataRowView customerDRV = customersDV.AddNew();
customerDRV["CustomerID"] = "J7COM";
customerDRV["CompanyName"] = "J7 Company";
customerDRV["Country"] = "UK";
Console.WriteLine("customerDRV[\" CustomerID\"] = " +
customerDRV["CustomerID"]);
Console.WriteLine("customerDRV[\" CompanyName\"] = " +
customerDRV["CompanyName"]);
Console.WriteLine("customerDRV[\" Country\"] = " +
customerDRV["Country"]);
Console.WriteLine("customerDRV.IsNew = " + customerDRV.IsNew);
Console.WriteLine("customerDRV.IsEdit = " + customerDRV.IsEdit);
customerDRV.EndEdit();
// get and display the underlying DataRow
DataRow customerDR = customerDRV.Row;
DisplayDataRow(customerDR, customersDT);
// modify the CompanyName of customerDRV
Console.WriteLine("\nSetting customersDV[0][\" CompanyName\"] to Widgets Inc.");
customersDV[0].BeginEdit();
customersDV[0]["CompanyName"] = "Widgets Inc.";
Console.WriteLine("customersDV[0][\" CustomerID\"] = " +
customersDV[0]["CustomerID"]);
Console.WriteLine("customersDV[0][\" CompanyName\"] = " +
customersDV[0]["CompanyName"]);
Console.WriteLine("customersDV[0].IsNew = " + customersDV[0].IsNew);
Console.WriteLine("customersDV[0].IsEdit = " + customersDV[0].IsEdit);
customersDV[0].EndEdit();
// display the underlying DataRow
DisplayDataRow(customersDV[0].Row, customersDT);
// remove the second DataRowView from customersDV
Console.WriteLine("\ncustomersDV[1][\" CustomerID\"] = " +
customersDV[1]["CustomerID"]);
Console.WriteLine("\nCalling customersDV.Delete(1)");
customersDV.Delete(1);
Console.WriteLine("customersDV[1].IsNew = " + customersDV[1].IsNew);
Console.WriteLine("customersDV[1].IsEdit = " + customersDV[1].IsEdit);
// remove the third DataRowView from customersDV
Console.WriteLine("\ncustomersDV[2][\" CustomerID\"] = " +
customersDV[2]["CustomerID"]);
Console.WriteLine("\nCalling customersDV[2].Delete()");
customersDV[2].Delete();
// call the AcceptChanges() method of customersDT to
// make the deletes permanent in customersDT
customersDT.AcceptChanges();
// display the rows in the customersDV DataView object
Console.WriteLine("\nDataRowView objects in customersDV:\n");
foreach (DataRowView myDataRowView in customersDV)
{
for (int count = 0; count < customersDV.Table.Columns.Count; count++)
{
Console.WriteLine(myDataRowView[count]);
}
Console.WriteLine("");
}
}
}
The output from this program is as follows:
Calling customersDV.AddNew()
customerDRV["CustomerID"] = J7COM
customerDRV["CompanyName"] = J7 Company
customerDRV["Country"] = UK
customerDRV.IsNew = True
customerDRV.IsEdit = True
In DisplayDataRow()
CustomerID = J7COM
CompanyName = J7 Company
