DataView Class

Definition

Namespace:

System.Data

Assembly:

System.Data.Common.dll

Source:

DataView.cs

Represents a databindable, customized view of a DataTable for sorting, filtering, searching, editing, and navigation. The DataView does not store data, but instead represents a connected view of its corresponding DataTable. Changes to the DataView's data will affect the DataTable. Changes to the DataTable's data will affect all DataViews associated with it.

public ref class DataView : System::ComponentModel::MarshalByValueComponent, System::Collections::IList, System::ComponentModel::IBindingListView, System::ComponentModel::ISupportInitialize, System::ComponentModel::ISupportInitializeNotification, System::ComponentModel::ITypedList

public class DataView : System.ComponentModel.MarshalByValueComponent, System.Collections.IList, System.ComponentModel.IBindingListView, System.ComponentModel.ISupportInitialize, System.ComponentModel.ISupportInitializeNotification, System.ComponentModel.ITypedList

type DataView = class
    inherit MarshalByValueComponent
    interface ICollection
    interface IEnumerable
    interface IList
    interface IBindingList
    interface IBindingListView
    interface ISupportInitialize
    interface ISupportInitializeNotification
    interface ITypedList

Public Class DataView
Inherits MarshalByValueComponent
Implements IBindingListView, IList, ISupportInitialize, ISupportInitializeNotification, ITypedList

Inheritance

Object

MarshalByValueComponent

DataView

Implements

ICollection IEnumerable IList IBindingList IBindingListView ISupportInitialize ISupportInitializeNotification ITypedList

Examples

The following example creates a single DataTable with one column and five rows. Two DataView objects are created and the RowStateFilter is set on each to show different views of the table data. The values are then printed.

using System;
using System.Xml;
using System.Data;
using System.Data.Common;
using System.Windows.Forms;

public class Form1: Form
{
    protected DataSet DataSet1;
    protected DataGrid dataGrid1;

    private void DemonstrateDataView()
    {
        // Create one DataTable with one column.
        DataTable table = new DataTable("table");
        DataColumn colItem = new DataColumn("item",
            Type.GetType("System.String"));
        table.Columns.Add(colItem);

        // Add five items.
        DataRow NewRow;
        for(int i = 0; i <5; i++)
        {
            NewRow = table.NewRow();
            NewRow["item"] = "Item " + i;
            table.Rows.Add(NewRow);
        }
        // Change the values in the table.
        table.AcceptChanges();
        table.Rows[0]["item"]="cat";
        table.Rows[1]["item"] = "dog";

        // Create two DataView objects with the same table.
        DataView firstView = new DataView(table);
        DataView secondView = new DataView(table);

        // Print current table values.
        PrintTableOrView(table,"Current Values in Table");

        // Set first DataView to show only modified
        // versions of original rows.
        firstView.RowStateFilter=DataViewRowState.ModifiedOriginal;

        // Print values.
        PrintTableOrView(firstView,"First DataView: ModifiedOriginal");

        // Add one New row to the second view.
        DataRowView rowView;
        rowView=secondView.AddNew();
        rowView["item"] = "fish";

        // Set second DataView to show modified versions of
        // current rows, or New rows.
        secondView.RowStateFilter=DataViewRowState.ModifiedCurrent
            | DataViewRowState.Added;
        // Print modified and Added rows.
        PrintTableOrView(secondView,
            "Second DataView: ModifiedCurrent | Added");
    }

    private void PrintTableOrView(DataTable table, string label)
    {
        // This function prints values in the table or DataView.
        Console.WriteLine("\n" + label);
        for(int i = 0; i<table.Rows.Count;i++)
        {
            Console.WriteLine(table.Rows[i]["item"]);
        }
        Console.WriteLine();
    }

    private void PrintTableOrView(DataView view, string label)
    {

        // This overload prints values in the table or DataView.
        Console.WriteLine("\n" + label);
        for(int i = 0; i<view.Count;i++)
        {
            Console.WriteLine(view[i]["item"]);
        }
        Console.WriteLine();
    }
}

Private Sub DemonstrateDataView()
    ' Create one DataTable with one column.
    Dim table As New DataTable("table")
    Dim colItem As New DataColumn("item", _
        Type.GetType("System.String"))
    table.Columns.Add(colItem)

    ' Add five items.
    Dim NewRow As DataRow
    Dim i As Integer
    For i = 0 To 4
    
    NewRow = table.NewRow()
    NewRow("item") = "Item " & i
    table.Rows.Add(NewRow)
    Next
    table.AcceptChanges()

    ' Create two DataView objects with the same table.
    Dim firstView As New DataView(table)
    Dim secondView As New DataView(table)
    
    ' Change the values in the table.
    table.Rows(0)("item") = "cat"
    table.Rows(1)("item") = "dog"
    
    ' Print current table values.
    PrintTableOrView(table, "Current Values in Table")
        
    ' Set first DataView to show only modified versions of original rows.
    firstView.RowStateFilter = DataViewRowState.ModifiedOriginal

    ' Print values.    
    PrintTableOrView(firstView, "First DataView: ModifiedOriginal")

    ' Add one New row to the second view.
    Dim rowView As DataRowView
    rowView = secondView.AddNew()
    rowView("item") = "fish"
    ' Set second DataView to show modified versions of 
    ' current rows, or New rows.
    secondView.RowStateFilter = DataViewRowState.ModifiedCurrent _
        Or DataViewRowState.Added
    ' Print modified and Added rows.
    PrintTableOrView(secondView, _
        "Second DataView: ModifiedCurrent or Added")
End Sub
    
Overloads Private Sub PrintTableOrView( _
    ByVal view As DataView, ByVal label As String)
    Console.WriteLine(label)
    Dim i As Integer
    For i = 0 To view.count - 1
    
    Console.WriteLine(view(i)("item"))
    Next
    Console.WriteLine()
End Sub
    
Overloads Private Sub PrintTableOrView( _
    ByVal table As DataTable, ByVal label As String)
    Console.WriteLine(label)
    Dim i As Integer
    For i = 0 To table.Rows.Count - 1
    Console.WriteLine(table.Rows(i)("item"))
    Next
    Console.WriteLine()
End Sub

The following example creates a DataView of online orders ordered by total due from a LINQ to DataSet query:

DataTable orders = dataSet.Tables["SalesOrderHeader"];

EnumerableRowCollection<DataRow> query =
    from order in orders.AsEnumerable()
    where order.Field<bool>("OnlineOrderFlag") == true
    orderby order.Field<decimal>("TotalDue")
    select order;

DataView view = query.AsDataView();

bindingSource1.DataSource = view;

Dim orders As DataTable = dataSet.Tables("SalesOrderHeader")

Dim query = _
    From order In orders.AsEnumerable() _
    Where order.Field(Of Boolean)("OnlineOrderFlag") = True _
    Order By order.Field(Of Decimal)("TotalDue") _
    Select order

Dim view As DataView = query.AsDataView()
bindingSource1.DataSource = view

Remarks

A major function of the DataView is to allow for data binding on both Windows Forms and Web Forms.

Additionally, a DataView can be customized to present a subset of data from the DataTable. This capability lets you have two controls bound to the same DataTable, but that show different versions of the data. For example, one control might be bound to a DataView that shows all the rows in the table, and a second might be configured to display only the rows that have been deleted from the DataTable. The DataTable also has a DefaultView property. This returns the default DataView for the table. For example, if you want to create a custom view on the table, set the RowFilter on the DataView returned by the DefaultView.

To create a filtered and sorted view of data, set the RowFilter and Sort properties. Then, use the Item[] property to return a single DataRowView.

You can also add and delete from the set of rows using the AddNew and Delete methods. When you use those methods, the RowStateFilter property can set to specify that only deleted rows or new rows be displayed by the DataView.

Note

If you do not explicitly specify sort criteria for DataView, the DataRowView objects in DataView are sorted based on the index of DataView's corresponding DataRow in the DataTable.Rows DataRowCollection.

LINQ to DataSet allows developers to create complex, powerful queries over a DataSet by using LINQ. A LINQ to DataSet query returns an enumeration of DataRow objects, however, which is not easily used in a binding scenario. DataView can be created from a LINQ to DataSet query and takes on the filtering and sorting characteristics of that query. LINQ to DataSet extends the functionality of the DataView by providing LINQ expression-based filtering and sorting, which allows for much more complex and powerful filtering and sorting operations than string-based filtering and sorting. See Data Binding and LINQ to DataSet for more information.

Constructors

DataView()	Initializes a new instance of the DataView class.
DataView(DataTable, String, String, DataViewRowState)	Initializes a new instance of the DataView class with the specified DataTable, RowFilter, Sort, and DataViewRowState.
DataView(DataTable)	Initializes a new instance of the DataView class with the specified DataTable.

Properties

AllowDelete	Gets or sets a value that indicates whether deletes are allowed.
AllowEdit	Gets or sets a value that indicates whether edits are allowed.
AllowNew	Gets or sets a value that indicates whether the new rows can be added by using the AddNew() method.
ApplyDefaultSort	Gets or sets a value that indicates whether to use the default sort. The default sort is (ascending) by all primary keys as specified by PrimaryKey.
Container	Gets the container for the component. (Inherited from MarshalByValueComponent)
Count	Gets the number of records in the DataView after RowFilter and RowStateFilter have been applied.
DataViewManager	Gets the DataViewManager associated with this view.
DesignMode	Gets a value indicating whether the component is currently in design mode. (Inherited from MarshalByValueComponent)
Events	Gets the list of event handlers that are attached to this component. (Inherited from MarshalByValueComponent)
IsInitialized	Gets a value that indicates whether the component is initialized.
IsOpen	Gets a value that indicates whether the data source is currently open and projecting views of data on the DataTable.
Item[Int32]	Gets a row of data from a specified table.
RowFilter	Gets or sets the expression used to filter which rows are viewed in the DataView.
RowStateFilter	Gets or sets the row state filter used in the DataView.
Site	Gets or sets the site of the component. (Inherited from MarshalByValueComponent)
Sort	Gets or sets the sort column or columns, and sort order for the DataView.
Table	Gets or sets the source DataTable.

Methods

AddNew()	Adds a new row to the DataView.
BeginInit()	Starts the initialization of a DataView that is used on a form or used by another component. The initialization occurs at runtime.
Close()	Closes the DataView.
ColumnCollectionChanged(Object, CollectionChangeEventArgs)	Occurs after a DataColumnCollection has been changed successfully.
CopyTo(Array, Int32)	Copies items into an array. Only for Web Forms Interfaces.
Delete(Int32)	Deletes a row at the specified index.
Dispose()	Releases all resources used by the MarshalByValueComponent. (Inherited from MarshalByValueComponent)
Dispose(Boolean)	Disposes of the resources (other than memory) used by the DataView object.
EndInit()	Ends the initialization of a DataView that is used on a form or used by another component. The initialization occurs at runtime.
Equals(DataView)	Determines whether the specified DataView instances are considered equal.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Find(Object)	Finds a row in the DataView by the specified sort key value.
Find(Object[])	Finds a row in the DataView by the specified sort key values.
FindRows(Object)	Returns an array of DataRowView objects whose columns match the specified sort key value.
FindRows(Object[])	Returns an array of DataRowView objects whose columns match the specified sort key value.
GetEnumerator()	Gets an enumerator for this DataView.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetService(Type)	Gets the implementer of the IServiceProvider. (Inherited from MarshalByValueComponent)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IndexListChanged(Object, ListChangedEventArgs)	Occurs after a DataView has been changed successfully.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnListChanged(ListChangedEventArgs)	Raises the ListChanged event.
Open()	Opens a DataView.
Reset()	Reserved for internal use only.
ToString()	Returns a String containing the name of the Component, if any. This method should not be overridden. (Inherited from MarshalByValueComponent)
ToTable()	Creates and returns a new DataTable based on rows in an existing DataView.
ToTable(Boolean, String[])	Creates and returns a new DataTable based on rows in an existing DataView.
ToTable(String, Boolean, String[])	Creates and returns a new DataTable based on rows in an existing DataView.
ToTable(String)	Creates and returns a new DataTable based on rows in an existing DataView.
UpdateIndex()	Reserved for internal use only.
UpdateIndex(Boolean)	Reserved for internal use only.

Events

Disposed	Adds an event handler to listen to the Disposed event on the component. (Inherited from MarshalByValueComponent)
Initialized	Occurs when initialization of the DataView is completed.
ListChanged	Occurs when the list managed by the DataView changes.

Explicit Interface Implementations

IBindingList.AddIndex(PropertyDescriptor)	For a description of this member, see AddIndex(PropertyDescriptor).
IBindingList.AddNew()	For a description of this member, see AddNew().
IBindingList.AllowEdit	For a description of this member, see AllowEdit.
IBindingList.AllowNew	For a description of this member, see AllowNew.
IBindingList.AllowRemove	For a description of this member, see AllowRemove.
IBindingList.ApplySort(PropertyDescriptor, ListSortDirection)	For a description of this member, see ApplySort(PropertyDescriptor, ListSortDirection).
IBindingList.Find(PropertyDescriptor, Object)	For a description of this member, see Find(PropertyDescriptor, Object).
IBindingList.IsSorted	For a description of this member, see IsSorted.
IBindingList.RemoveIndex(PropertyDescriptor)	For a description of this member, see RemoveIndex(PropertyDescriptor).
IBindingList.RemoveSort()	For a description of this member, see RemoveSort().
IBindingList.SortDirection	For a description of this member, see SortDirection.
IBindingList.SortProperty	For a description of this member, see SortProperty.
IBindingList.SupportsChangeNotification	For a description of this member, see SupportsChangeNotification.
IBindingList.SupportsSearching	For a description of this member, see SupportsSearching.
IBindingList.SupportsSorting	For a description of this member, see SupportsSorting.
IBindingListView.ApplySort(ListSortDescriptionCollection)	For a description of this member, see ApplySort(ListSortDescriptionCollection).
IBindingListView.Filter	For a description of this member, see Filter.
IBindingListView.RemoveFilter()	For a description of this member, see RemoveFilter().
IBindingListView.SortDescriptions	For a description of this member, see SortDescriptions.
IBindingListView.SupportsAdvancedSorting	For a description of this member, see SupportsAdvancedSorting.
IBindingListView.SupportsFiltering	For a description of this member, see SupportsFiltering.
ICollection.IsSynchronized	For a description of this member, see IsSynchronized.
ICollection.SyncRoot	For a description of this member, see SyncRoot.
IList.Add(Object)	For a description of this member, see Add(Object).
IList.Clear()	For a description of this member, see Clear().
IList.Contains(Object)	For a description of this member, see Contains(Object).
IList.IndexOf(Object)	For a description of this member, see IndexOf(Object).
IList.Insert(Int32, Object)	For a description of this member, see Insert(Int32, Object).
IList.IsFixedSize	For a description of this member, see IsFixedSize.
IList.IsReadOnly	For a description of this member, see IsReadOnly.
IList.Item[Int32]	For a description of this member, see Item[Int32].
IList.Remove(Object)	For a description of this member, see Remove(Object).
IList.RemoveAt(Int32)	For a description of this member, see RemoveAt(Int32).
ITypedList.GetItemProperties(PropertyDescriptor[])	For a description of this member, see GetItemProperties(PropertyDescriptor[]).
ITypedList.GetListName(PropertyDescriptor[])	For a description of this member, see GetListName(PropertyDescriptor[]).

Extension Methods

Cast<TResult>(IEnumerable)	Casts the elements of an IEnumerable to the specified type.
OfType<TResult>(IEnumerable)	Filters the elements of an IEnumerable based on a specified type.
AsParallel(IEnumerable)	Enables parallelization of a query.
AsQueryable(IEnumerable)	Converts an IEnumerable to an IQueryable.

Thread Safety

This type is safe for multithreaded read operations. You must synchronize any write operations.

See also

• DataSet
• DataTable
• DataViewManager
• AsDataView
• DataSets, DataTables, and DataViews (ADO.NET)