To view the field triggers, let's look at our 50100 "Radio Show" table. Add the following triggers to the No. field within the curly braces:
Each field has two triggers, the OnValidate() trigger and the OnLookup() trigger, which function as follows:
- OnValidate(): The AL code in this trigger is executed whenever an entry is made by the user. The intended use is to validate that the entry conforms to the design parameters for the field. It can also be executed under program control through use of the VALIDATE function (which we will discuss later).
- OnLookup(): Lookup behavior can be triggered by clicking on the lookup arrow in a field, as shown in the following screenshot:
- If the field's TableRelation property refers to a table, then the default behavior is to display a drop-down list to allow for the selection of a table entry to be stored in this field. The list will be based on Field Groups that have been defined for the table....