Data Traversal

TECH TIP: Fundamentals of Report Data Traversal

Single Table Listing Report
  1. Assign the Report.DataPipeline property and leave the DetailBand.Pipeline unassigned. The report will traverse the data from start to end (based on the datapipeline range settings and honoring any filters you’ve placed on the datset etc.)

Master/Detail Report:
  1. Assign the Report.DataPipeline property to the master. Create a subreport in the detail band and assign the childreport.DataPipeline to the detail datapipeline.
  2. Use either the visual linking features available from the Report Designer’s Data tab, or Use standard Delphi dataset linking to define the relationships between the datasets. The Report will traverse the master records and for each, the subreport will traverse the detail data related to the master.

Master with 2 Details

Configure as in 2 above. Add an additional subreport to the detailband. Set subreport.ShiftRelativeTo property to the point to the first subreport.¬† Connect the ChildReport’s DataPipeline to the detail data.

Report connected to no datapipelines.

When Report.AutoStop is set to True, the Report will print a single detail band.

When Report.AutoStop is set to False, the Report will print detail bands until instructed to stop. You can control when the report stops by setting the Report.PageLimit property or by calling  Report.DataTraversalCompleted method. Otherwise the report will never stop.

Additional Notes:

  1. SubReports have a Report property that is of type TppChildReport. Thus, programmatically you can code SubReport.Report.DataPipeline := myDataPipeline.
  2. ChildReport’s traverse data following the same rules as above. A ChildReport prints in its entirety each time it gets a turn to print.
  3. For a Child style SubReport use the Title/Summary band rather than the Header/Footer (or use a GroupHeader/GroupFooter combo). A standard Header/Footer will not work because these always print at the very top/bottom of the page.
  4. Do not filter the dataset of modify it any way once the report.Print command is issued. If you need to do master/detail and cannot use linked datasets, then use the master DataPipeline.OnRecordPositionChange
    event to filter the detail dataset.
  5. The reports and datapipelines use dataset bookmarking. Make sure the dataset can support bi-directional navigation.

Check out the RBuilder\Demos\Reports\Demo.dpr project. Reports 0071, 0072, 0073 show examples of master w/mutliple detail style reports. Number 0072 has two detail reports.