Triggers and Actions

Triggers are mechanisms that allow to perform a flow of actions when a given event occurs. For instance, triggers allow to define a flow of actions that will be executed after a record is updated in the database, or when a user clicks a form button in the user interface.

Topics

Trigger contexts

The context of a trigger is the point in the application where the trigger is activated. There are three types of trigger contexts possible to define in Genio: Table, Form, and Menu. For each type of context, a set of concrete objects and events are available to be observed, as shown in Table 1.

Context Object Event Parameters Base table
Table Record Before update Table The specified table.
Table Record Before update Table The specified table.
Table Record Before insert Table The specified table.
Table Record Before eliminate Table The specified table.
Table Record Before duplicate Table The specified table.
Table Record After update Table The specified table.
Table Record After insert Table The specified table.
Table Record After eliminate Table The specified table.
Table Record After duplicate Table The specified table.
Form Form Periodical Form, Periodicity The base table of the form.
Form Button Click Form, Form button The base table of the form of the specified button.
Menu Button Click Menu continuation -

Table 1. Types of trigger contexts.

Trigger conditions

When these events occur, triggers observing them will evaluate whether the defined flow of actions should be executed or not. There are different mechanisms that can be used to conditionally execute the actions of triggers, as shown in Table 2.

Condition Description Example
Expression An expression that will be evaluated at runtime. The actions of the trigger are executed if the expression evaluates to true. [INCID->ESTADO] == "FE"
Permission A role that the user that triggered the event must have. Administrator

Table 2. Types of trigger conditions.

At runtime, each one of theses conditions will be evaluated. All must evaluated to true in order for the flow of actions of the trigger to be executed. A condition is ignored if it is not defined.

Trigger actions

As discussed, triggers allow to specify a flow of actions. This support this, the order in which the actions are specified is the order in which they will be executed. Table 3 shows a summary of the actions that are currently offered by Genio.

Action Description Necessary context
Update the value of a field Updates the value of a field with the value computed by an expression. Table or Form or Menu
Update formulas Recalculates the computed fields of a record. Table or Form or Menu
Save Saves the form and navigates to the previous page. Form
Save without leaving Saves the form (applies the changes). Form
Internal import Performs an internal import. Table or Form or Menu
Reload the page Reloads the page. Form or Menu
Reload a control Reloads a control of the form. Form

Table 3. Types of trigger actions.

Update the value of a field

The "Update the value of a field" action updates the value of the specified field with the value computed by the provided expression. This action requires four parameters, as shown in Table 4.

Parameter Description
Table The table to be updated.
Table field The target table field.
Formula The expression to be evaluated at runtime to compute the value of the field.
Update formulas Whether or not to update the formulas of the affected rows after this operation.

Table 4. Definition of the "Update the value of a field" action.

To better understand how Genio determines the rows that will be affected by this action, consider the example illustrated by Figure 1 and a trigger based on the "After update" event of the table "District".

figure1

Figure 1. Illustration of the running example.

The execution of the action will change depending on the relation of the trigger's base table to the table of the action's target field, as shown in Table 5.

Target table Target table (example) Affected Rows
Parent COUNTRY 1 row, referenced by the main row.
Self DISTRICT 1 row, the main row.
Child CITY N rows, all the child rows of the main row.

Table 5. Summary of the affected rows of the "Update the value of a field" action.

Update formulas

The "Update formulas" action recalculates the computed fields of a given set of rows. The set of rows to affect is determined in the same manner as previously shown in Table 5. This action requires one parameter, as shown in Table 6.

Parameter Description
Table The table to be updated.

Table 6. Definition of the "Update formulas" action.

Save

The "Save" action is the same action that is executed when users click the "Save" button in forms. Now, available as an action of a trigger, it is possible to chain it with other actions.