Querying the DataRowView Collection in a DataView
The DataView exposes an enumerable collection of DataRowView objects. DataRowView represents a customized view of a DataRow and displays a specific version of that DataRow in a control. Only one version of a DataRow can be displayed through a control, such as a DataGridView. You can access the DataRow that is exposed by the DataRowView through the Row property of the DataRowView. When you view values by using a DataRowView, the RowStateFilter property determines which row version of the underlying DataRow is exposed. For information about accessing different row versions using a DataRow, see Row States and Row Versions. Because the collection of DataRowView objects exposed by the DataView is enumerable, you can use LINQ to DataSet to query over it.
The following example queries the Product table for red-colored products and creates a table from that query. A DataView is created from the table and the RowStateFilter property is set to filter on deleted and modified rows. The DataView is then used as a source in a LINQ query, and the DataRowView objects that have been modified and deleted are bound to a DataGridView control.
Dim products As DataTable = dataSet.Tables("Product")
' Query for red colored products.
Dim redProductsQuery = _
From product In products.AsEnumerable() _
Where product.Field(Of String)("Color") = "Red" _
Order By product.Field(Of Decimal)("ListPrice") _
Select product
' Create a table and view from the query.
Dim redProducts As DataTable = redProductsQuery.CopyToDataTable()
Dim view As DataView = New DataView(redProducts)
' Mark a row as deleted.
redProducts.Rows(0).Delete()
' Modify product price.
redProducts.Rows(1)("ListPrice") = 20.0
redProducts.Rows(2)("ListPrice") = 30.0
view.RowStateFilter = DataViewRowState.ModifiedCurrent Or DataViewRowState.Deleted
' Query for the modified and deleted rows.
Dim modifiedDeletedQuery = From rowView As DataRowView In view _
Select rowView
dataGridView2.DataSource = modifiedDeletedQuery.ToList()
DataTable products = dataSet.Tables["Product"];
// Query for red colored products.
EnumerableRowCollection<DataRow> redProductsQuery =
from product in products.AsEnumerable()
where product.Field<string>("Color") == "Red"
orderby product.Field<decimal>("ListPrice")
select product;
// Create a table and view from the query.
DataTable redProducts = redProductsQuery.CopyToDataTable<DataRow>();
DataView view = new DataView(redProducts);
// Mark a row as deleted.
redProducts.Rows[0].Delete();
// Modify product price.
redProducts.Rows[1]["ListPrice"] = 20.00;
redProducts.Rows[2]["ListPrice"] = 30.00;
view.RowStateFilter = DataViewRowState.ModifiedCurrent | DataViewRowState.Deleted;
// Query for the modified and deleted rows.
IEnumerable<DataRowView> modifiedDeletedQuery = from DataRowView rowView in view
select rowView;
dataGridView2.DataSource = modifiedDeletedQuery.ToList();
The following example creates a table of products from a view that is bound to a DataGridView control. The DataView is queried for red-colored products and the ordered results are bound to a DataGridView control.
' Create a table from the bound view representing a query of
' available products.
Dim view As DataView = CType(bindingSource1.DataSource, DataView)
Dim productsTable As DataTable = CType(view.Table, DataTable)
' Set RowStateFilter to display the current rows.
view.RowStateFilter = DataViewRowState.CurrentRows
' Query the DataView for red colored products ordered by list price.
Dim productQuery = From rowView As DataRowView In view _
Where rowView.Row.Field(Of String)("Color") = "Red" _
Order By rowView.Row.Field(Of Decimal)("ListPrice") _
Select New With {.Name = rowView.Row.Field(Of String)("Name"), _
.Color = rowView.Row.Field(Of String)("Color"), _
.Price = rowView.Row.Field(Of Decimal)("ListPrice")}
' Bind the query results to another DataGridView.
dataGridView2.DataSource = productQuery.ToList()
// Create a table from the bound view representing a query of
// available products.
DataView view = (DataView)bindingSource1.DataSource;
DataTable productsTable = (DataTable)view.Table;
// Set RowStateFilter to display the current rows.
view.RowStateFilter = DataViewRowState.CurrentRows ;
// Query the DataView for red colored products ordered by list price.
var productQuery = from DataRowView rowView in view
where rowView.Row.Field<string>("Color") == "Red"
orderby rowView.Row.Field<decimal>("ListPrice")
select new { Name = rowView.Row.Field<string>("Name"),
Color = rowView.Row.Field<string>("Color"),
Price = rowView.Row.Field<decimal>("ListPrice")};
// Bind the query results to another DataGridView.
dataGridView2.DataSource = productQuery.ToList();