Master/Detail Reports

To create a master/detail report in Rave, you need two datasets in the corresponding Delphi application, but these datasets don't need to have a master/detail relationship defined in the program—the report can define such a relationship. In the RaveDetails demo program, each of the two datasets is exposed through a Rave connection:

object dsDepartments: TSimpleDataSet
  Connection = SQLConnection1
  DataSet.CommandText = 'select * from DEPARTMENT'
end
object dsEmployee: TSimpleDataSet
  Connection = SQLConnection1
  DataSet.CommandText = 'select * from EMPLOYEE'
end
object RvConnectionDepartments: TRvDataSetConnection
  DataSet = dsDepartments
end
object RvConnectionEmployee: TRvDataSetConnection
  DataSet = dsEmployee
end

The report has two corresponding data views, each connected to a DataBand component (both hosted within a Region). The first DataBand, used for the main dataset, has no special settings. The secondary DataBand defines the master/detail relationship using a few properties. The MasterDataView property refers to the data view of the master dataset, and the MasterKey and DetailKey properties refer to the fields that define the join (in this case, they both refer to the field DEPT_NO). The ControllerBand property refers to the DataBand showing the data of the master dataset.

In case master/details report, the most important settings are managed by the Band Style Editor, where you must set the band as a detail. You can see this editor for the RaveDetails example in Figure 18.6. The master data view's KeepRowTogether property is set to True, to avoid having details end up in a different page than the master.

Figure 18.6:  The master/detail report. The Band Style Editor appears in front of it.

Scripting Reports

At the beginning of this chapter I mentioned the Event Editor window of the Rave Designer, but so far I haven't used it. This tool is used to write code (scripts) within a report, responding to events of the various components as you'd do in Delphi. Writing scripts in the Rave Designer allows you to customize, or fine-tune, the output of a report in sophisticated ways. The language Rave uses for the scripts is Pascal based and a variation of the Delphi language, so you should be able to pick it up easily.

The RaveDetails example shows in bold font salaries that are greater than a specified amount. The obvious way to accomplish this is to write scripting code to be executed for each instance of the detail band—that is, for each record in the employee database. Instead of modifying the Font property directly, I decided to add two different FontManager components to the report page and name them to make their role understandable: fmPlainFont and fmBoldFont. You can open the report to see their properties and layout.

In the report, to highlight values outside a given range, you handle the DataText component's BeforePrint event. To do so, move to the Event Editor page, choose the DataText component connected to the Salary field, and select the event. In the event's code editor window, write the following code:

if DataView2Salary.AsFloat > 100000 then
  self.FontMirror := fmBoldFont;
else
  self.FontMirror := fmPlainFont;
end if;

The script changes the FontMirror property of the current object (self) to refer to one of the two FontManager components on the page, depending on the field value. Notice that DataView2Salary is a reference to one of the fields of the data view—the one connected to the current DataText component. Compile the script and run the report to see its effect, shown in Figure 18.7.

Figure 18.7: The bold text in the report is determined at run time by a script.

Mirroring

Reporting templates can contain one or more components and can be reused via Rave's mirroring technology. The DataMirrorSection component mirrors other Sections based on the contents of a DataField. The use of mirroring sections allows the DataMirrorSection to be very flexible. Remember that Sections can contain any other component including graphics, regions, text, and so on.

For example, you could use a DataMirrorSection component to make a single report produce different envelope formats for international or U.S. addresses. The template for international customers could include a line for the country have the text centered on the envelope, whereas the U.S. format would not include the country line would offset the text to the right of center and lower on the envelope.

Normally, one of the settings will be defined as the default. If a default is not defined and the field value does not match any of the other settings, then the format used will be the normal contents of the DataMirrorSection component.

Calculations to the Max

In addition to the simple CalcText component discussed earlier, the Rave Designer includes three components for handling more complex situations: CalcTotal, CalcController, and CalcOp.