DevelopersGuide/Forms/KeyGenerator.java

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import com.sun.star.uno.*;
import com.sun.star.beans.*;
import com.sun.star.form.*;
import com.sun.star.lang.*;
import com.sun.star.sdb.*;
import com.sun.star.sdbc.*;
import com.sun.star.sdbcx.*;
import com.sun.star.container.*;
import com.sun.star.awt.*;

/**************************************************************************/
/** base class for helpers dealing with unique column values
*/
class UniqueColumnValue
{
	/* ------------------------------------------------------------------ */
	/** extracts the name of the table a form is based on.

		<p>This method works for forms based directly on tables, and for forms based on statements, which
		themself are based on one table.<br/>
		Everything else (especially forms based on queries) is not yet implemented.</p>
	*/
	protected String extractTableName( XPropertySet xForm ) throws com.sun.star.uno.Exception
	{
		String sReturn;

		Integer aCommandType = (Integer)xForm.getPropertyValue( "CommandType" );
		String sCommand = (String)xForm.getPropertyValue( "Command" );

		if ( CommandType.COMMAND == aCommandType.intValue() )
		{
			// get the connection from the form
            XConnection xFormConn = (XConnection)UnoRuntime.queryInterface( XConnection.class,
                xForm.getPropertyValue( "ActiveConnection" ) );
			// and let it create a composer for us
			XSQLQueryComposerFactory xComposerFac =
				(XSQLQueryComposerFactory)UnoRuntime.queryInterface(
					XSQLQueryComposerFactory.class, xFormConn );
			XSQLQueryComposer xComposer = xComposerFac.createQueryComposer( );

			// let this composer analyze the command
			xComposer.setQuery( sCommand );

			// and ask it for the table(s)
			XTablesSupplier xSuppTables = (XTablesSupplier)UnoRuntime.queryInterface(
				XTablesSupplier.class, xComposer );
			XNameAccess xTables = xSuppTables.getTables();

			// simply take the first table name
			String[] aNames = xTables.getElementNames( );
			sCommand = aNames[0];
		}

		return sCommand;
	}

	/* ------------------------------------------------------------------ */
	/** generates a statement which can be used to create a unique (in all conscience) value
		for the column given.
		<p>Currently, the implementation uses a very simple approach - it just determines the maximum of currently
		existing values in the column. If your concrete data source supports a more sophisticated approach of generating
		unique values, you probably want to adjust the <code>SELECT</code> statement below accordingly.</p>

		@returns
			a String which can be used as statement to retrieve a unique value for the given column.
			The result set resulting from such a execution contains the value in it's first column.
	*/
	protected String composeUniqueyKeyStatement( XPropertySet xForm, String sFieldName ) throws com.sun.star.uno.Exception
	{
		String sStatement = new String( "SELECT MAX( " );
		sStatement += sFieldName;
		sStatement += new String( ") + 1 FROM " );
		// the table name is a property of the form
		sStatement += extractTableName( xForm );

		// note that the implementation is imperfect (besides the problem that MAX is not a really good solution
		// for a database with more that one client):
		// It does not quote the field and the table name. This needs to be done if the database is intolerant
		// against such things - the XDatabaseMetaData, obtained from the connection, would be needed then
		// Unfortunately, there is no UNO service doing this - it would need to be implemented manually.

		return sStatement;
	}

	/* ------------------------------------------------------------------ */
	/** generates a unique (in all conscience) key into the column given
		@param xForm
			the form which contains the column in question
		@param sFieldName
			the name of the column
	*/
	protected int generatePrimaryKey( XPropertySet xForm, String sFieldName ) throws com.sun.star.uno.Exception
	{
		// get the current connection of the form
		XConnection xConn = (XConnection)UnoRuntime.queryInterface(
			XConnection.class, xForm.getPropertyValue( "ActiveConnection" ) );
		// let it create a new statement
		XStatement xStatement = xConn.createStatement();

		// build the query string to determine a free value
		String sStatement = composeUniqueyKeyStatement( xForm, sFieldName );

		// execute the query
		XResultSet xResults = xStatement.executeQuery( sStatement );

		// move the result set to the first record
		xResults.next( );

		// get the value
		XRow xRow = (XRow)UnoRuntime.queryInterface( XRow.class, xResults );
		int nFreeValue = xRow.getInt( 1 );

		// dispose the temporary objects
		FLTools.disposeComponent( xStatement );
			// this should get rid of the result set, too

		return nFreeValue;
	}

	/* ------------------------------------------------------------------ */
	/** inserts a unique (in all conscience) key into the column given
		@param xForm
			the form which contains the column in question
		@param sFieldName
			the name of the column
	*/
	public void insertPrimaryKey( XPropertySet xForm, String sFieldName ) throws com.sun.star.uno.Exception
	{
		// check the privileges
		Integer aConcurrency = (Integer)xForm.getPropertyValue( "ResultSetConcurrency" );
		if ( ResultSetConcurrency.READ_ONLY != aConcurrency.intValue() )
		{
			// get the column object
			XColumnsSupplier xSuppCols = (XColumnsSupplier)UnoRuntime.queryInterface(
				XColumnsSupplier.class, xForm );
			XNameAccess xCols = xSuppCols.getColumns();
			XColumnUpdate xCol = (XColumnUpdate)UnoRuntime.queryInterface(
				XColumnUpdate.class, xCols.getByName( sFieldName ) );

			xCol.updateInt( generatePrimaryKey( xForm, sFieldName ) );
		}
	}
};

/**************************************************************************/
/** base class for helpers dealing with unique column values
*/
class KeyGeneratorForReset extends UniqueColumnValue implements XResetListener
{
	/* ------------------------------------------------------------------ */
	private DocumentViewHelper	m_aView;
	private	String				m_sFieldName;

	/* ------------------------------------------------------------------ */
	/** ctor
		@param aView
			the view which shall be used to focus controls
		@param sFieldName
			the name of the field for which keys should be generated
	*/
	public KeyGeneratorForReset( String sFieldName, DocumentViewHelper aView )
	{
		m_sFieldName = sFieldName;
		m_aView = aView;
	}

	/* ------------------------------------------------------------------ */
	/** sets the focus to the first control which is no fixed text, and not the
		one we're defaulting
	*/
	public void defaultNewRecordFocus( XPropertySet xForm ) throws com.sun.star.uno.Exception
	{
		XIndexAccess xFormAsContainer = (XIndexAccess)UnoRuntime.queryInterface(
			XIndexAccess.class, xForm );
		for ( int i = 0; i<xFormAsContainer.getCount(); ++i )
		{
			// the model
			XPropertySet xModel = UNO.queryPropertySet( xFormAsContainer.getByIndex( i ) );

			// check if it's a valid leaf (no sub form or such)
			XPropertySetInfo xPSI = xModel.getPropertySetInfo( );
			if ( ( null == xPSI ) || !xPSI.hasPropertyByName( "ClassId" ) )
				continue;

			// check if it's a fixed text
			Short nClassId = (Short)xModel.getPropertyValue( "ClassId" );
			if ( FormComponentType.FIXEDTEXT == nClassId.shortValue() )
				continue;

			// check if it is bound to the field we are responsible for
			if ( !xPSI.hasPropertyByName( "DataField" ) )
				continue;

			String sFieldDataSource = (String)xModel.getPropertyValue( "DataField" );
			if ( sFieldDataSource.equals( m_sFieldName ) )
				continue;

			// both conditions do not apply
			// -> set the focus into the respective control
			XControlModel xCM = UNO.queryControlModel( xModel );
			m_aView.grabControlFocus( xCM);
			break;
		}
	}

	/* ------------------------------------------------------------------ */
	// XResetListener overridables
	/* ------------------------------------------------------------------ */
    public boolean approveReset( com.sun.star.lang.EventObject rEvent ) throws com.sun.star.uno.RuntimeException
	{
		// not interested in vetoing this
		return true;
	}

	/* ------------------------------------------------------------------ */
    public void resetted( com.sun.star.lang.EventObject aEvent ) throws com.sun.star.uno.RuntimeException
	{
		// check if this reset occured becase we're on a new record
		XPropertySet xFormProps = UNO.queryPropertySet( aEvent.Source );
		try
		{
			Boolean aIsNew = (Boolean)xFormProps.getPropertyValue( "IsNew" );
			if ( aIsNew.booleanValue() )
			{	// yepp

				// we're going to modify the record, though after that, to the user, it should look
				// like it has not been modified
				// So we need to ensure that we do not change the IsModified property with whatever we do
				Object aModifiedFlag = xFormProps.getPropertyValue( "IsModified" );

				// now set the value
				insertPrimaryKey( xFormProps, m_sFieldName );

				// then restore the flag
				xFormProps.setPropertyValue( "IsModified", aModifiedFlag );

				// still one thing ... would be nice to have the focus in a control which is
				// the one which's value we just defaulted
				defaultNewRecordFocus( xFormProps );
			}
		}
		catch( com.sun.star.uno.Exception e )
		{
			System.out.println(e);
			e.printStackTrace();
		}
	}
	/* ------------------------------------------------------------------ */
	// XEventListener overridables
	/* ------------------------------------------------------------------ */
	public void disposing( EventObject aEvent )
	{
		// not interested in
	}
};


/**************************************************************************/
/** base class for helpers dealing with unique column values
*/
class KeyGeneratorForUpdate extends UniqueColumnValue implements XRowSetApproveListener
{
	/* ------------------------------------------------------------------ */
	private	String	m_sFieldName;

	/* ------------------------------------------------------------------ */
	public KeyGeneratorForUpdate( String sFieldName )
	{
		m_sFieldName = sFieldName;
	}

	/* ------------------------------------------------------------------ */
	// XRowSetApproveListener overridables
	/* ------------------------------------------------------------------ */
    public boolean approveCursorMove( com.sun.star.lang.EventObject aEvent ) throws com.sun.star.uno.RuntimeException
	{
		// not interested in vetoing moves
		return true;
	}

	/* ------------------------------------------------------------------ */
    public boolean approveRowChange( RowChangeEvent aEvent ) throws com.sun.star.uno.RuntimeException
	{
		if ( RowChangeAction.INSERT == aEvent.Action )
		{
			try
			{
				// the affected form
				XPropertySet xFormProps = UNO.queryPropertySet( aEvent.Source );
				// insert a new unique value
				insertPrimaryKey( xFormProps, m_sFieldName );
			}
			catch( com.sun.star.uno.Exception e )
			{
				System.out.println(e);
				e.printStackTrace();
			}
		}
		return true;
	}

	/* ------------------------------------------------------------------ */
    public boolean approveRowSetChange( com.sun.star.lang.EventObject aEvent ) throws com.sun.star.uno.RuntimeException
	{
		// not interested in vetoing executions of the row set
		return true;
	}
	/* ------------------------------------------------------------------ */
	// XEventListener overridables
	/* ------------------------------------------------------------------ */
	public void disposing( EventObject aEvent )
	{
		// not interested in
	}
};

/**************************************************************************/
/** allows to generate unique keys for a field of a Form
*/
public class KeyGenerator
{
	/* ------------------------------------------------------------------ */
	private	KeyGeneratorForReset	m_aResetKeyGenerator;
	private KeyGeneratorForUpdate	m_aUpdateKeyGenerator;
	private boolean					m_bResetListening;
	private boolean					m_bUpdateListening;

	private DocumentHelper			m_aDocument;
	private	XPropertySet			m_xForm;

	/* ------------------------------------------------------------------ */
	/** ctor
		@param xForm
			specified the form to operate on
		@param sFieldName
			specifies the field which's value should be manipulated
	*/
	public KeyGenerator( XPropertySet xForm, String sFieldName,
                         XComponentContext xCtx )
	{
		m_xForm = xForm;

		DocumentHelper aDocument = DocumentHelper.getDocumentForComponent( xForm, xCtx );

		m_aResetKeyGenerator = new KeyGeneratorForReset( sFieldName, aDocument.getCurrentView() );
		m_aUpdateKeyGenerator = new KeyGeneratorForUpdate( sFieldName );

		m_bResetListening = m_bUpdateListening = false;
	}

	/* ------------------------------------------------------------------ */
	/** stops any actions on the form
	*/
	public void stopGenerator( )
	{
		XReset xFormReset = UNO.queryReset( m_xForm );
		xFormReset.removeResetListener( m_aResetKeyGenerator );

		XRowSetApproveBroadcaster xFormBroadcaster = (XRowSetApproveBroadcaster)UnoRuntime.queryInterface(
			XRowSetApproveBroadcaster.class, m_xForm );
		xFormBroadcaster.removeRowSetApproveListener( m_aUpdateKeyGenerator );

		m_bUpdateListening = m_bResetListening = false;
	}

	/* ------------------------------------------------------------------ */
	/** activates one of our two key generators
	*/
	public void activateKeyGenerator( boolean bGenerateOnReset )
	{
		// for resets
		XReset xFormReset = UNO.queryReset( m_xForm );
		// for approving actions
		XRowSetApproveBroadcaster xFormBroadcaster = (XRowSetApproveBroadcaster)UnoRuntime.queryInterface(
			XRowSetApproveBroadcaster.class, m_xForm );

		if ( bGenerateOnReset )
		{
			if ( !m_bResetListening )
				xFormReset.addResetListener( m_aResetKeyGenerator );
			if ( m_bUpdateListening )
				xFormBroadcaster.removeRowSetApproveListener( m_aUpdateKeyGenerator );

			m_bUpdateListening = false;
			m_bResetListening = true;
		}
		else
		{
			if ( m_bResetListening )
				xFormReset.removeResetListener( m_aResetKeyGenerator );
			if ( !m_bUpdateListening )
				xFormBroadcaster.addRowSetApproveListener( m_aUpdateKeyGenerator );

			m_bResetListening = false;
			m_bUpdateListening = true;
		}
	}
};