What's a harvester ? It's a report that runs reports and gathers their output. This article describes a harvester report that runs a standard SAP report for a series of Legel persons. The ALV output is scooped up and the output of the combined report runs is reported or stored in a file. Complete turn-key example available !
So how does a harverster work ?
In short, it runs a report and it picks up the output of that report. It then runs the report again, with slightly different information in the selection screen. Techniques used involve submit into memory and turning list output into something manageable.
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The example report demonstrates a repetative call to report RPLLAEN0 which produces an ALV report for a specific legal person. As the information was required for a list of legal persons, a serial call was created in a harvester.
The harvester calls the report and extracts it's output for the full series of report callls. When an ALV report is called in background mode, the output is transformed to classic report output. The same happens when spool output is retrieved as is done in this example. The ALV output can quite easily be manipulated into a collumn configuration. Header lines are removed, vertical lines are stripped, columns are added at the beginning. The output of a series of report calls is harvested into a single list. Harvesting.
purpose?
With a good topic the actual purpose is clear as glass. This topic can be used for multiple report calls, but also for different reports. Produce a file with the results and run another turn-key tool "mail a file" - to send the results to an email receiver.