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<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-6A2160F0-6062-4E77-ABA3-B829AF9689FA" xml:lang="en"><title>Contacts

database events</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>A client application of the Contacts Server can be set to observe changes

in the contacts database. When a change in the database occurs, the application

gets an event. The event carries information about the type of the event,

the contact ID, and the connection ID.</p>

<codeblock id="GUID-F552F563-6AA7-4E55-9E0E-F131E2B2C91B" xml:space="preserve">struct TContactDbObserverEvent

    {

    TContactDbObserverEventType iType;

    TContactItemId iContactId;

    TUint iConnectionId;

    };

</codeblock>

<p>The following event types are defined in the <parmname>cntdbobs.h</parmname>:</p>

<codeblock id="GUID-9022E0A5-8CF3-469E-B1D4-2B2CC607F852" xml:space="preserve">enum TContactDbObserverEventType

    {

    EContactDbObserverEventNull,

    EContactDbObserverEventUnused,

    EContactDbObserverEventContactChanged,

    EContactDbObserverEventContactDeleted,

    EContactDbObserverEventContactAdded,

    EContactDbObserverEventUnknownChanges,

    EContactDbObserverEventRecover,

    EContactDbObserverEventRollback,

    EContactDbObserverEventTablesClosed,

    EContactDbObserverEventTablesOpened,

    EContactDbObserverEventTemplateChanged,

    EContactDbObserverEventTemplateDeleted,

    EContactDbObserverEventTemplateAdded,

    EContactDbObserverEventCurrentItemDeleted,

    EContactDbObserverEventCurrentItemChanged,

    EContactDbObserverEventOwnCardChanged,

    EContactDbObserverEventPreferredTemplateChanged,

    EContactDbObserverEventOwnCardDeleted,

    EContactDbObserverEventGroupAdded,

    EContactDbObserverEventGroupChanged,

    EContactDbObserverEventGroupDeleted,

    EContactDbObserverEventCurrentDatabaseChanged,

    EContactDbObserverEventSpeedDialsChanged

    EContactDbObserverEventSortOrderChanged,

    EContactDbObserverEventBackupBeginning,

    EContactDbObserverEventRestoreBeginning,

    EContactDbObserverEventBackupRestoreCompleted,

    EContactDbObserverEventRestoreBadDatabase,

    };

</codeblock>

<p>To receive events on contact database changes, the application must

derive <xref href="GUID-4928B1DE-9800-3887-B456-2DDFE810AFD9.dita"><apiname>MContactDbObserver</apiname></xref> base class and implement <xref href="GUID-4928B1DE-9800-3887-B456-2DDFE810AFD9.dita#GUID-4928B1DE-9800-3887-B456-2DDFE810AFD9/GUID-DECA9730-0504-3D4F-85D4-AFAC70B46580"><apiname>MContactDbObserver::HandleDatabaseEventL()</apiname></xref> virtual

function. The function is called by the system when a contact database event

occurs.</p>

<codeblock id="GUID-EEB33DFB-0009-4CE5-BC96-41B65519F8D1" xml:space="preserve">class CMyContactObserver : public CBase, public MContactDbObserver

    {

     public:

         // any public data and functions

         CMyContactObserver ();

         // override the virtual function from the base class

         virtual void HandleDatabaseEventL( TContactDbObserverEvent aEvent );

         };

     // handling contact database events

     void CMyContactObserver::HandleDatabaseEventL( TContactDbObserverEvent aEvent )

         {

         // Event handling code

         }

</codeblock>

<p>In addition, the application must create the <xref href="GUID-140725B3-8D52-3D2B-9E72-CAF76962B95A.dita"><apiname>CContactChangeNotifier</apiname></xref> object

to register itself to receive events.</p>

<codeblock id="GUID-95A974D8-3D88-4E64-8A33-AF2366C34791" xml:space="preserve">CContactDatabase* contactDb = CContactDatabase::OpenL();

//iContactDbObserver is a CMyContactObserver pointer

CContactChangeNotifier* notifier = CContactChangeNotifier::NewL( *contactDb, iContactDbObserver );

</codeblock>