The handle to the ProDataSet query that contains the currently selected row in the ProBindingSource. This method enables access to the correct child query when a bound .NET grid edits, creates, or deletes a row from a child table.
Use this method when the .NET control is bound to a ProDataSet object that contains child buffers.
Data type: HANDLE
Access: Read-only
Applies to: Data-relation object handle
When a .NET control binds to a ProBindingSource that uses a ProDataSet as its data source object, multiple relations for the same parent-child relationship might be presented to the user simultaneously. When the user first expands a parent row in the bound .NET control, the ProBindingSource creates a new child query and displays all child rows for that parent row. The ProBindingSource uses the ProDataSet object's data-relation query to create and maintain this unique query for all child rows related to the expanded parent row.
The following code fragment shows an event handler. The event handler accepts information from a bound UltraWinGrid displaying Order and Orderline data through the grid's extended version of the .NET System.EventArgs class. From that information, the event handler can find the correct query for the currently selected record.
DEFINE VARIABLE hDataSet AS HANDLE NO-UNDO. ... PROCEDURE BeforeRowUpdate: DEFINE INPUT PARAMETER sender AS System.Object NO-UNDO. DEFINE INPUT PARAMETER args AS Infragistics.Win.UltraWinGrid.CancelableRowEventArgs NO-UNDO. DEFINE VARIABLE cBufferName AS CHARACTER NO-UNDO. DEFINE VARIABLE hRelation AS HANDLE NO-UNDO. DEFINE VARIABLE hQuery AS HANDLE NO-UNDO. cBufferName = args:Row:Band:Key. IF cBufferName EQ "ttOrder" THEN ASSIGN hRelation = hDataSet:GET-RELATION(1) hQuery = hRelation:CURRENT-QUERY. END. ELSE IF cBufferName EQ "ttOrderLine" THEN ASSIGN hRelation = hDataSet:GET-RELATION(2) hQuery = hRelation:CURRENT-QUERY. END. END PROCEDURE. |
When a ProBindingSource is attached to a ProDataSet with a recursive data-relation, the code above does not work because a single buffer is associated with multiple BandIndexes in a hierarchical grid. The event handler must specify the BandIndex of the current row to determine the correct query.
The following example shows a similar event handler using the optional parameter. Because an employee might also be a manager and have employees of his own, dsRecursive has a recursive data-relation between EmpName and Manager. For the top band of the hierarchy, the event handler can use the TOP-NAV-QUERY. For lower bands, it needs the optional parameter to determine the correct query.
DEFINE TEMP-TABLE ttEmp NO-UNDO
BEFORE-TABLE ttEmpB
FIELD EmpName AS CHARACTER
FIELD Manager AS CHARACTER
FIELD HireDate AS INTEGER
INDEX idxEmpName AS UNIQUE EmpName.
DEFINE DATASET dsRecursive FOR ttEmp
DATA-RELATION r1 FOR ttemp, ttemp
RELATION-FIELDS(EmpName,Manager) RECURSIVE.
DEFINE VARIABLE hRelation AS HANDLE NO-UNDO.
DEFINE VARIABLE hTopQuery AS HANDLE NO-UNDO.
...
PROCEDURE BeforeRowUpdate:
DEFINE INPUT PARAMETER sender AS System.Object NO-UNDO.
DEFINE INPUT PARAMETER args AS
Infragistics.Win.UltraWinGrid.CancelableRowEventArgs NO-UNDO.
DEFINE VARIABLE bandIndex AS INTEGER NO-UNDO.
DEFINE VARIABLE hQuery AS HANDLE NO-UNDO.
ASSIGN
bandIndex = args:Row:Band:Index
hRelation = DATASET dsRecursive:GET-RELATION(1).
IF bandIndex EQ 0 THEN
hQuery = hTopQuery.
ELSE IF bandIndex > 0 THEN
hQuery = hRelation:CURRENT-QUERY(bandIndex).
END PROCEDURE.
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