The BeforeMap Event on the dataset has a special purpose. It allows you to skip the processing of records that you do not want to process - this can be set at any level. If set a header level, then no child or lower level records will be processed.

This Event fires once before each record is processed.

If LinkedData is set, then multiple records could be processed and this Event will fire once before each of those records.

However if LinkedData is not set, then this will only fire once.

The BeforeMap Event has one parameter called Value, which determines whether the record is processed or not. This parameter defaults to True but can manually be set to either True or False. Set the parameter to False to skip the record.

If this parameter is set to True then the fields in the record will be processed.

The value of this parameter is passed into the AfterMap event script if there is one set.

Setting The BeforeMap Event

Within the script you can perform some checks as to whether you want to process the record and set the parameter Value appropriately.

If you do not specify a script for the BeforeMap Event then the parameter defaults to True and the record will be processed.

In the following example, the value is being set to False, meaning that the record will be skipped over.

procedure BeforeMapEvent(var Value:Variant); //ORDER_HEADER
begin
Value := False;
end;

During the BeforeMap Event the record in the dataset is not yet open for setting individual field values because the record may be cancelled if the parameter is set to False.

A successful BeforeMap Event will display in the Map as green. A failed BeforeMap Event will display in the Map as red.