BindingManagerBase Class

Definition

Namespace:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

Manages all Binding objects that are bound to the same data source and data member. This class is abstract.

public ref class BindingManagerBase abstract

public abstract class BindingManagerBase

type BindingManagerBase = class

Public MustInherit Class BindingManagerBase

Inheritance

Object

BindingManagerBase

Derived

System.Windows.Forms.CurrencyManager

System.Windows.Forms.PropertyManager

Examples

The following code example uses the BindingContext to return a BindingManagerBase for a specific data source. (The example assumes you have declared myBindingManagerBase in the Declarations section of the module.) The example then adds event delegates to the CurrentChanged and PositionChanged events. Lastly, the example contains four methods (MoveNext, MovePrevious, MoveFirst, and MoveLast) that increment or decrement the Position property, and set the Position to the first or last row in the list. The last row in the list is determined by using the Count property.

void GetBindingManagerBase()
{
   
   /* CustomersToOrders is the RelationName of a DataRelation. 
      Therefore, the list maintained by the BindingManagerBase is the
      list of orders that belong to a specific customer in the 
      DataTable named Customers, found in DataSet1. */
   myBindingManagerBase = this->BindingContext[DataSet1, "Customers.CustomersToOrders"];
   
   // Adds delegates to the CurrentChanged and PositionChanged events.
   myBindingManagerBase->PositionChanged += gcnew EventHandler( this, &Form1::BindingManagerBase_PositionChanged );
   myBindingManagerBase->CurrentChanged += gcnew EventHandler( this, &Form1::BindingManagerBase_CurrentChanged );
}

void BindingManagerBase_PositionChanged( Object^ sender, EventArgs^ /*e*/ )
{
   
   // Prints the new Position of the BindingManagerBase.
   Console::Write( "Position Changed: " );
   Console::WriteLine( (dynamic_cast<BindingManagerBase^>(sender))->Position );
}

void BindingManagerBase_CurrentChanged( Object^ sender, EventArgs^ /*e*/ )
{
   
   // Prints the new value of the current object.
   Console::Write( "Current Changed: " );
   Console::WriteLine( (dynamic_cast<BindingManagerBase^>(sender))->Current );
}

void MoveNext()
{
   
   // Increments the Position property value by one.
   myBindingManagerBase->Position = myBindingManagerBase->Position + 1;
}

void MovePrevious()
{
   
   // Decrements the Position property value by one.
   myBindingManagerBase->Position = myBindingManagerBase->Position - 1;
}

void MoveFirst()
{
   
   // Goes to the first row in the list.
   myBindingManagerBase->Position = 0;
}

void MoveLast()
{
   
   // Goes to the last row in the list.
   myBindingManagerBase->Position = myBindingManagerBase->Count - 1;
}

private void GetBindingManagerBase()
{
   /* CustomersToOrders is the RelationName of a DataRelation. 
   Therefore, the list maintained by the BindingManagerBase is the
   list of orders that belong to a specific customer in the 
   DataTable named Customers, found in DataSet1. */
   myBindingManagerBase = 
   this.BindingContext[DataSet1, "Customers.CustomersToOrders"];

   // Adds delegates to the CurrentChanged and PositionChanged events.
   myBindingManagerBase.PositionChanged += 
   new EventHandler(BindingManagerBase_PositionChanged);
   myBindingManagerBase.CurrentChanged +=
   new EventHandler(BindingManagerBase_CurrentChanged);
}

private void BindingManagerBase_PositionChanged
(object sender, EventArgs e)
{
   // Prints the new Position of the BindingManagerBase.
   Console.Write("Position Changed: ");
   Console.WriteLine(((BindingManagerBase)sender).Position);
}

private void BindingManagerBase_CurrentChanged
(object sender, EventArgs e)
{
   // Prints the new value of the current object.
   Console.Write("Current Changed: ");
   Console.WriteLine(((BindingManagerBase)sender).Current);
}

private void MoveNext()
{
   // Increments the Position property value by one.
   myBindingManagerBase.Position += 1;
}

private void MovePrevious()
{
   // Decrements the Position property value by one.
   myBindingManagerBase.Position -= 1;
}

private void MoveFirst()
{
   // Goes to the first row in the list.
   myBindingManagerBase.Position = 0;
}

private void MoveLast()
{
   // Goes to the last row in the list.
   myBindingManagerBase.Position = 
   myBindingManagerBase.Count - 1;
}

Private Sub GetBindingManagerBase
   ' CustomersToOrders is the RelationName of a DataRelation.
   ' Therefore, the list maintained by the BindingManagerBase is the
   ' list of orders that belong to a specific customer in the
   ' DataTable named Customers, found in DataSet.
   myBindingManagerBase = Me.BindingContext(DataSet1, _
   "Customers.CustomersToOrders")

   ' Adds delegates to the CurrentChanged and PositionChanged events.
   AddHandler myBindingManagerBase.PositionChanged, _
   AddressOf BindingManagerBase_PositionChanged
   AddHandler myBindingManagerBase.CurrentChanged, _
   AddressOf BindingManagerBase_CurrentChanged
End Sub

Private Sub BindingManagerBase_PositionChanged _
(sender As Object, e As EventArgs)

   ' Prints the new Position of the BindingManagerBase.
   Console.Write("Position Changed: ")
   Console.WriteLine(CType(sender, BindingManagerBase).Position)
End Sub

Private Sub BindingManagerBase_CurrentChanged _
(sender As Object, e As EventArgs)

   ' Prints the new value of the current object.
   Console.Write("Current Changed: ")
   Console.WriteLine(CType(sender, BindingManagerBase).Current)
End Sub

Private Sub MoveNext
   ' Increments the Position property value by one.
   myBindingManagerBase.Position += 1
End Sub

Private Sub MovePrevious
   ' Decrements the Position property value by one.
   myBindingManagerBase.Position -= 1
End Sub

Private Sub MoveFirst
   ' Goes to the first row in the list.
   myBindingManagerBase.Position = 0
End Sub

Private Sub MoveLast
   ' Goes to the last row in the list.
   myBindingManagerBase.Position = _
   myBindingManagerBase.Count - 1
End Sub

Remarks

The BindingManagerBase enables the synchronization of data-bound controls on a Windows Form that are bound to the same data source. (For more information about simple binding a control to a data source, see the Binding class.) For example, suppose that a form contains two TextBox controls that are bound to the same data source but to different columns. The data source might be a DataTable that contains customer names, while the columns might contain the first and last names. The two controls must be synchronized in order to display the correct first and last names together for the same customer. The CurrencyManager, which inherits from the BindingManagerBase class, accomplishes this synchronization by maintaining a pointer to the current item in the data source. The TextBox controls are bound to the current item so they display the information for the same row. When the current item changes, the CurrencyManager notifies all the bound controls so that they can refresh their data. Furthermore, you can set the Position property to specify the row in the DataTable that the controls point to. To determine how many rows exist in the data source, use the Count property.

The CurrencyManager is necessary because data sources do not necessarily maintain a current-item pointer. For instance, arrays and ArrayList objects can be data sources, but they do not have a property that returns the current item. To get the current item, use the Current property.

The PropertyManager also inherits from the BindingManagerBase, and it is used to maintain the current property of an object, rather than the property of a current object in a data source. For this reason, trying to set the Position or Count property for a PropertyManager has no effect.

To create a BindingManagerBase, use the BindingContext class, which returns either a CurrencyManager or a PropertyManager, depending on the data source being managed.

Solutions programmers are encouraged to bind controls directly to a BindingSource component, which acts as both a data source and data connector to the actual target data source. BindingSource greatly simplifies both simple and complex data binding, including managing currency between the control and its target.

Notes to Implementers

When you inherit from BindingManagerBase, you must override the following abstract members: AddNew(), Count, CancelCurrentEdit(), Current, EndCurrentEdit(), GetItemProperties(), OnCurrentChanged(EventArgs), Position, RemoveAt(Int32), ResumeBinding(), SuspendBinding(), and UpdateIsBinding().

Constructors

BindingManagerBase()

Initializes a new instance of the BindingManagerBase class.

Fields

onCurrentChangedHandler	Specifies the event handler for the CurrentChanged event.
onPositionChangedHandler	Specifies the event handler for the PositionChanged event.

Properties

Bindings	Gets the collection of bindings being managed.
Count	When overridden in a derived class, gets the number of rows managed by the BindingManagerBase.
Current	When overridden in a derived class, gets the current object.
IsBindingSuspended	Gets a value indicating whether binding is suspended.
Position	When overridden in a derived class, gets or sets the position in the underlying list that controls bound to this data source point to.

Methods

AddNew()	When overridden in a derived class, adds a new item to the underlying list.
CancelCurrentEdit()	When overridden in a derived class, cancels the current edit.
EndCurrentEdit()	When overridden in a derived class, ends the current edit.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetItemProperties()	When overridden in a derived class, gets the collection of property descriptors for the binding.
GetItemProperties(ArrayList, ArrayList)	Gets the collection of property descriptors for the binding using the specified ArrayList.
GetItemProperties(Type, Int32, ArrayList, ArrayList)	Gets the list of properties of the items managed by this BindingManagerBase.
GetListName(ArrayList)	When overridden in a derived class, gets the name of the list supplying the data for the binding.
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnBindingComplete(BindingCompleteEventArgs)	Raises the BindingComplete event.
OnCurrentChanged(EventArgs)	Raises the CurrentChanged event.
OnCurrentItemChanged(EventArgs)	Raises the CurrentItemChanged event.
OnDataError(Exception)	Raises the DataError event.
PullData()	Pulls data from the data-bound control into the data source, returning no information.
PushData()	Pushes data from the data source into the data-bound control, returning no information.
RemoveAt(Int32)	When overridden in a derived class, deletes the row at the specified index from the underlying list.
ResumeBinding()	When overridden in a derived class, resumes data binding.
SuspendBinding()	When overridden in a derived class, suspends data binding.
ToString()	Returns a string that represents the current object. (Inherited from Object)
UpdateIsBinding()	When overridden in a derived class, updates the binding.

Events

BindingComplete	Occurs at the completion of a data-binding operation.
CurrentChanged	Occurs when the currently bound item changes.
CurrentItemChanged	Occurs when the state of the currently bound item changes.
DataError	Occurs when an Exception is silently handled by the BindingManagerBase.
PositionChanged	Occurs after the value of the Position property has changed.

See also

• BindingSource
• BindingContext
• CurrencyManager
• PropertyManager