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Data extension configuration: ExtWriteAction

Description:
Data extension configuration ExtWriteAction - An extension for invoking an event when writing a value
Configuration items:
Data extension identifierSystem text (without spaces and diacritics). It is used for unambiguous identification of data extension in data item (e.g. for Extension property).

The preset value is "wact".

Event "onItemBeforeWrite"Option when to fire the onItemBeforeWrite event.

It is recommended to use this event only for special cases. When this event is enabled, the values are written asynchronously, i.e. this event does not execute the write command instantly, but later, after the active script is finished.

NEVER call for this item
call before EVERY CHANGE of this item value
call before EVERY WRITE to this item
Event "onItemAfterWrite"Option when to fire the onItemAfterWrite event.
NEVER call for this item
call after EVERY CHANGE of this item value
call after EVERY WRITE to this item
Note:
This configuration window can be opened from Data extensions configurator in the data item of the PmData object.
 
If calling the onItemBeforeWrite event is enabled, then the event fires for this variable always closely before writing or before the change of the variable value. Unconsidered enabling for all variables can cause unnecessary utilization of the processor. For example if the object includes 1000 variables and each one has calling enabled then by writing new values into all variables of the object can cause calling the onItemBeforeWrite event 1000 times (each time with another pEvent.Item parameter value). It is also better (if it is required to react to writing or the change of the variable) to enable the onItemAfterWrite event instead of onItemBeforeWrite. Enabling onItemBeforeWrite is useful only if, for example, you need to test the written value and in a necessity to change it (to filter it). The pEvent.NewVal parameter is in the onItemBeforeWrite event defined for reading and writing and thus it is possible in the event to enforce another value than the one that is really written.

If calling the onItemAfterWrite event is enabled, then the event fires for this variable always after writing or the change of the variable value. For enabling this event similar remarks are valid for the onItemBeforeWrite event. Enabling the onItemAfterWrite is useful for variables that change their value not too ofter and then is it suitable to enable calling 'after the change'.

Caution: The onItemBeforeWrite/onItemAfterWrite not fires if it isn't written into the variable directly, i.e. if the variable is bind to another value.

PROMOTIC 8.3.21 SCADA system documentation - MICROSYS, spol. s r.o.

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