INFO: Programming in Reports w/ Band Expressions on Entry/Exit (130505)

SUMMARY

In FoxPro version 2.x, programmatic manipulation within a report is accomplished by placing a user-defined function (UDF) within an expression of a field object. The proper execution of the code, in many cases, depends on where the field object resides on the report because report expressions are evaluated from left to right and top to bottom.

Visual FoxPro includes "band expressions" that are called On Entry and On Exit. These expressions can be found for each report band. The expressions are evaluated once per band on each page of the report. Band Expressions eliminate the need for careful placement of field objects to control when the code is executed. By double-clicking a report band, you can access the the On Entry and On Exit expressions. This article shows by example how to use band expressions.

MORE INFORMATION

Step-by-Step Example

The following example demonstrates what happens when you place code in the On Entry expression:

Issue the command SET DEFAULT TO SYS(2004)+"\SAMPLES\DATA"
Use the Customer table.
In the Command window, issue this command:
```
   CREATE REPORT BANDTEST.
					
```
Populate the report by doing a Quick Report.
Double-click the Detail band and enter BandTest() in the On Entry field. In the Expression Builder, do not attempt to verify this expression.
Create a new program containing the following code, and name it BANDTEST.PRG:
```
   Wait Window "Record Number: " + Alltrim(Str(RecNo()))
					
```
Preview the report by right-clicking the report and choosing Preview.

Notice that the code is excuted before entering the Detail band and before any data from the Detail band is displayed. If this code was placed in the On Exit expression, it would have executed on leaving the Detail band.