docs-desktop/dotnet-desktop-guide/framework/winforms/interfaces-related-to-data-binding.md

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Interfaces Related to Data Binding	03/30/2017	overview	data [Windows Forms], data-binding interfaces INotifyPropertyChanged interface IBindingListView interface IList interface [Windows Forms], Windows Forms data binding IBindingList interface [Windows Forms], Windows Forms data binding interfaces [Windows Forms], Windows Forms data binding IEditableObject interface [Windows Forms], Windows Forms data binding data binding [Windows Forms], interfaces IDataErrorInfo interface [Windows Forms], Windows Forms data binding	14e49a2e-3e46-47ca-b491-70d546333277

Interfaces Related to Data Binding

With ADO.NET, you can create many different data structures to suit the binding needs of your application and the data you are working with. You may want to create your own classes that provide or consume data in Windows Forms. These objects can offer varying levels of functionality and complexity, from basic data binding, to providing design-time support, error checking, change notification, or even support for a structured rollback of the changes made to the data itself.

Consumers of Data-Binding Interfaces

The following sections describe two groups of interface objects. The first group lists interfaces that are implemented on data sources by data source authors. These interfaces are designed to be consumed by data source consumers, which are in most cases Windows Forms controls or components. The second group lists interfaces designed for use by component authors. Component authors use these interfaces when they are creating a component that supports data binding to be consumed by the Windows Forms data-binding engine. You can implement these interfaces within classes associated with your form to enable data binding; each case presents a class that implements an interface that enables interaction with data. Visual Studio rapid application development (RAD) data design experience tools already take advantage of this functionality.

Interfaces for Implementation by Data Source Authors

The following interfaces are designed to be consumed by Windows Forms controls:

• xref:System.Collections.IList interface

  A class that implements the xref:System.Collections.IList interface could be an xref:System.Array, xref:System.Collections.ArrayList, or xref:System.Collections.CollectionBase. These are indexed lists of items of type xref:System.Object. These lists must contain homogenous types, because the first item of the index determines the type. xref:System.Collections.IList would be available for binding only at run time.

  Note

  If you want to create a list of business objects for binding with Windows Forms, you should consider using the xref:System.ComponentModel.BindingList%601. The xref:System.ComponentModel.BindingList%601 is an extensible class that implements the primary interfaces required for two-way Windows Forms data binding.

• xref:System.ComponentModel.IBindingList interface

  A class that implements the xref:System.ComponentModel.IBindingList interface provides a much higher level of data-binding functionality. This implementation offers you basic sorting capabilities and change notification, both for when the list items change (for example, the third item in a list of customers has a change to the Address field), as well as when the list itself changes (for example, the number of items in the list increases or decreases). Change notification is important if you plan to have multiple controls bound to the same data, and you want data changes made in one of the controls to propagate to the other bound controls.

  Note

  Change notification is enabled for the xref:System.ComponentModel.IBindingList interface through the xref:System.ComponentModel.IBindingList.SupportsChangeNotification%2A property which, when true, raises a xref:System.ComponentModel.IBindingList.ListChanged event, indicating the list changed or an item in the list changed.

  The type of change is described by the xref:System.ComponentModel.ListChangedType property of the xref:System.ComponentModel.ListChangedEventArgs parameter. Hence, whenever the data model is updated, any dependent views, such as other controls bound to the same data source, will also be updated. However, objects contained within the list will have to notify the list when they change so that the list can raise the xref:System.ComponentModel.IBindingList.ListChanged event.

  Note

  The xref:System.ComponentModel.BindingList%601 provides a generic implementation of the xref:System.ComponentModel.IBindingList interface.

• xref:System.ComponentModel.IBindingListView interface

  A class that implements the xref:System.ComponentModel.IBindingListView interface provides all the functionality of an implementation of xref:System.ComponentModel.IBindingList, as well as filtering and advanced sorting functionality. This implementation offers string-based filtering, and multicolumn sorting with property descriptor-direction pairs.

• xref:System.ComponentModel.IEditableObject interface

  A class that implements the xref:System.ComponentModel.IEditableObject interface allows an object to control when changes to that object are made permanent. This implementation affords you the xref:System.ComponentModel.IEditableObject.BeginEdit%2A, xref:System.ComponentModel.IEditableObject.EndEdit%2A, and xref:System.ComponentModel.IEditableObject.CancelEdit%2A methods, which enable you to roll back changes made to the object. Following is a brief explanation of the functioning of the xref:System.ComponentModel.IEditableObject.BeginEdit%2A, xref:System.ComponentModel.IEditableObject.EndEdit%2A, and xref:System.ComponentModel.IEditableObject.CancelEdit%2A methods and how they work in conjunction with one another to enable a possible rollback of changes made to the data:

  • The xref:System.ComponentModel.IEditableObject.BeginEdit%2A method signals the start of an edit on an object. An object that implements this interface will need to store any updates after the xref:System.ComponentModel.IEditableObject.BeginEdit%2A method call in such a way that the updates can be discarded if the xref:System.ComponentModel.IEditableObject.CancelEdit%2A method is called. In data binding Windows Forms, you can call xref:System.ComponentModel.IEditableObject.BeginEdit%2A multiple times within the scope of a single edit transaction (for example, xref:System.ComponentModel.IEditableObject.BeginEdit%2A, xref:System.ComponentModel.IEditableObject.BeginEdit%2A, xref:System.ComponentModel.IEditableObject.EndEdit%2A). Implementations of xref:System.ComponentModel.IEditableObject should keep track of whether xref:System.ComponentModel.IEditableObject.BeginEdit%2A has already been called and ignore subsequent calls to xref:System.ComponentModel.IEditableObject.BeginEdit%2A. Because this method can be called multiple times, it is important that subsequent calls to it are nondestructive; that is, subsequent xref:System.ComponentModel.IEditableObject.BeginEdit%2A calls cannot destroy the updates that have been made or change the data that was saved on the first xref:System.ComponentModel.IEditableObject.BeginEdit%2A call.

  • The xref:System.ComponentModel.IEditableObject.EndEdit%2A method pushes any changes since xref:System.ComponentModel.IEditableObject.BeginEdit%2A was called into the underlying object, if the object is currently in edit mode.

  • The xref:System.ComponentModel.IEditableObject.CancelEdit%2A method discards any changes made to the object.

  For more information about how the xref:System.ComponentModel.IEditableObject.BeginEdit%2A, xref:System.ComponentModel.IEditableObject.EndEdit%2A, and xref:System.ComponentModel.IEditableObject.CancelEdit%2A methods work, see Save data back to the database.

  This transactional notion of data functionality is used by the xref:System.Windows.Forms.DataGridView control.

• xref:System.ComponentModel.ICancelAddNew interface

  A class that implements the xref:System.ComponentModel.ICancelAddNew interface usually implements the xref:System.ComponentModel.IBindingList interface and allows you to roll back an addition made to the data source with the xref:System.ComponentModel.IBindingList.AddNew%2A method. If your data source implements the xref:System.ComponentModel.IBindingList interface, you should also have it implement the xref:System.ComponentModel.ICancelAddNew interface.

• xref:System.ComponentModel.IDataErrorInfo interface

  A class that implements the xref:System.ComponentModel.IDataErrorInfo interface allows objects to offer custom error information to bound controls:

  • The xref:System.ComponentModel.IDataErrorInfo.Error%2A property returns general error message text (for example, "An error has occurred").

  • The xref:System.ComponentModel.IDataErrorInfo.Item%2A property returns a string with the specific error message from the column (for example, "The value in the State column is invalid").

• xref:System.Collections.IEnumerable interface

  A class that implements the xref:System.Collections.IEnumerable interface is typically consumed by ASP.NET. Windows Forms support for this interface is only available through the xref:System.Windows.Forms.BindingSource component.

  Note

  The xref:System.Windows.Forms.BindingSource component copies all xref:System.Collections.IEnumerable items into a separate list for binding purposes.

• xref:System.ComponentModel.ITypedList interface

  A collections class that implements the xref:System.ComponentModel.ITypedList interface provides the ability to control the order and the set of properties exposed to the bound control.

  Note

  When you implement the xref:System.ComponentModel.ITypedList.GetItemProperties%2A method, and the xref:System.ComponentModel.PropertyDescriptor array is not null, the last entry in the array will be the property descriptor that describes the list property that is another list of items.

• xref:System.ComponentModel.ICustomTypeDescriptor interface

  A class that implements the xref:System.ComponentModel.ICustomTypeDescriptor interface provides dynamic information about itself. This interface is similar to xref:System.ComponentModel.ITypedList but is used for objects rather than lists. This interface is used by xref:System.Data.DataRowView to project the schema of the underlying rows. A simple implementation of xref:System.ComponentModel.ICustomTypeDescriptor is provided by the xref:System.ComponentModel.CustomTypeDescriptor class.

  Note

  To support design-time binding to types that implement xref:System.ComponentModel.ICustomTypeDescriptor, the type must also implement xref:System.ComponentModel.IComponent and exist as an instance on the Form.

• xref:System.ComponentModel.IListSource interface

  A class that implements the xref:System.ComponentModel.IListSource interface enables list-based binding on non-list objects. The xref:System.ComponentModel.IListSource.GetList%2A method of xref:System.ComponentModel.IListSource is used to return a bindable list from an object that does not inherit from xref:System.Collections.IList. xref:System.ComponentModel.IListSource is used by the xref:System.Data.DataSet class.

• xref:System.ComponentModel.IRaiseItemChangedEvents interface

  A class that implements the xref:System.ComponentModel.IRaiseItemChangedEvents interface is a bindable list that also implements the xref:System.ComponentModel.IBindingList interface. This interface is used to indicate if your type raises xref:System.ComponentModel.IBindingList.ListChanged events of type xref:System.ComponentModel.ListChangedType.ItemChanged through its xref:System.ComponentModel.IRaiseItemChangedEvents.RaisesItemChangedEvents%2A property.

  Note

  You should implement the xref:System.ComponentModel.IRaiseItemChangedEvents if your data source provides the property to list event conversion described previously and is interacting with the xref:System.Windows.Forms.BindingSource component. Otherwise, the xref:System.Windows.Forms.BindingSource will also perform property to list event conversion resulting in slower performance.

• xref:System.ComponentModel.ISupportInitialize interface

  A component that implements the xref:System.ComponentModel.ISupportInitialize interface takes advantages of batch optimizations for setting properties and initializing co-dependent properties. The xref:System.ComponentModel.ISupportInitialize contains two methods:

  • xref:System.ComponentModel.ISupportInitialize.BeginInit%2A signals that object initialization is starting.

  • xref:System.ComponentModel.ISupportInitialize.EndInit%2A signals that object initialization is finishing.

• xref:System.ComponentModel.ISupportInitializeNotification interface

  A component that implements the xref:System.ComponentModel.ISupportInitializeNotification interface also implements the xref:System.ComponentModel.ISupportInitialize interface. This interface allows you to notify other xref:System.ComponentModel.ISupportInitialize components that initialization is complete. The xref:System.ComponentModel.ISupportInitializeNotification interface contains two members:

  • xref:System.ComponentModel.ISupportInitializeNotification.IsInitialized%2A returns a boolean value indicating whether the component is initialized.

  • xref:System.ComponentModel.ISupportInitializeNotification.Initialized occurs when xref:System.ComponentModel.ISupportInitialize.EndInit%2A is called.

• xref:System.ComponentModel.INotifyPropertyChanged interface

  A class that implements this interface is a type that raises an event when any of its property values change. This interface is designed to replace the pattern of having a change event for each property of a control. When used in a xref:System.ComponentModel.BindingList%601, a business object should implement the xref:System.ComponentModel.INotifyPropertyChanged interface and the BindingList`1 will convert xref:System.ComponentModel.INotifyPropertyChanged.PropertyChanged events to xref:System.ComponentModel.BindingList%601.ListChanged events of type xref:System.ComponentModel.ListChangedType.ItemChanged.

  Note

  For change notification to occur in a binding between a bound client and a data source your bound data-source type should either implement the xref:System.ComponentModel.INotifyPropertyChanged interface (preferred) or you can provide propertyNameChanged events for the bound type, but you shouldn't do both.

Interfaces for Implementation by Component Authors

The following interfaces are designed for consumption by the Windows Forms data-binding engine:

• xref:System.Windows.Forms.IBindableComponent interface

  A class that implements this interface is a non-control component that supports data binding. This class returns the data bindings and binding context of the component through the xref:System.Windows.Forms.IBindableComponent.DataBindings%2A and xref:System.Windows.Forms.IBindableComponent.BindingContext%2A properties of this interface.

  Note

  If your component inherits from xref:System.Windows.Forms.Control, you do not need to implement the xref:System.Windows.Forms.IBindableComponent interface.

• xref:System.Windows.Forms.ICurrencyManagerProvider interface

  A class that implements the xref:System.Windows.Forms.ICurrencyManagerProvider interface is a component that provides its own xref:System.Windows.Forms.CurrencyManager to manage the bindings associated with this particular component. Access to the custom xref:System.Windows.Forms.CurrencyManager is provided by the xref:System.Windows.Forms.ICurrencyManagerProvider.CurrencyManager%2A property.

  Note

  A class that inherits from xref:System.Windows.Forms.Control manages bindings automatically through its xref:System.Windows.Forms.Control.BindingContext%2A property, so cases in which you need to implement the xref:System.Windows.Forms.ICurrencyManagerProvider are fairly rare.

See also

• Data Binding and Windows Forms
• How to: Create a Simple-Bound Control on a Windows Form
• Windows Forms Data Binding