1. Triggers
1.1 About Triggers and Processes
Triggers are blocks of PL/SQL code that you write to perform specific tasks. There are pre-defined runtime events for which you can create triggers. Trigger names correspond to these events. For ease of description, the terms events and triggers are synonymous in this chapter. In effect, an Oracle Forms trigger is an event-handler written in PL/SQL to augment (or occasionally replace) the default processing behavior.
A process is a series of individual, related events that occurs during a specific Oracle Forms Runform operation. Oracle Forms includes navigational, validation, and database transaction processes. To see a visual representation of Oracle Forms processes showing where each trigger fires, refer to the flowchart for the process named in the "Fires In" section for each trigger. All the flowcharts are in the Oracle Forms Reference Manual, Vol. 2, Chapter 8, "Processing Flow Charts".
1.2 SQL Statements in Trigger Text
The trigger descriptions in this chapter include a section called "Legal Commands." This section lists the types of statements that are valid in the indicated trigger type, including:
• restricted built-in subprograms
• unrestricted built-in subprograms
• SELECT statements
• Data Manipulation Language (DML) statements
Restricted built-in subprograms initiate navigation. They include built-ins that move the input focus from one item to another, such as NEXT_ITEM , and those that involve database transactions, such as CREATE_RECORD.
Restricted built-ins are illegal in triggers that fire in response to navigation, such as Pre- and Post- navigational triggers. Each built-in description includes a "Built-in Type" section that indicates whether the built-in is restricted or unrestricted. For more information, refer to the Oracle Forms Developers Guide, Chapter 7, "Writing Event Triggers."
While you can write a trigger that uses any DML statement, Oracle Corporation advises that you follow the recommendations that are stated for each trigger type. Using DML statements in certain triggers can desynchronize the state of records in Oracle Forms and rows in the database, and can cause unexpected results.
1.3 Trigger Tables
The following cross references are included to help you locate the triggers you need in each category.
1.3.1 Block Processing Triggers
1.3.1.1 When-Clear-Block
Fires just before Oracle Forms clears the data from the current block. Note that the When-Clear-Block trigger does not fire when Oracle Forms clears the current block during the CLEAR_FORM event.
1.3.1.2 When-Create-Record
Fires whenever Oracle Forms creates a new record. For example, when the operator presses the [Insert] key, or navigates to the last record in a set while scrolling down, Oracle Forms fires this trigger.
1.3.1.3 When-Database-Record
Fires when Oracle Forms first marks a record as an insert or an update. That is, the trigger fires as soon as Oracle Forms determines through validation that the record should be processed by the next post or commit as an insert or update. This generally occurs only when the operator modifies the first item in a record, and after the operator attempts to navigate out of the item.
1.3.1.4 When-Remove-Record
Fires whenever the operator or the application clears or deletes a record.
1.3.2 Interface Event Triggers
1.3.2.1 When-Button-Pressed
Fires when an operator selects a button, either by way of a key, or by clicking with a mouse.
1.3.2.2 When-Checkbox-Changed
Fires whenever an operator changes the state of a check box, either by clicking with the mouse, or through keyboard interaction.
1.3.2.3 When-Custom-Item-Event
Fires whenever a VBX control sends an event to Oracle Forms.
1.3.2.4 When-Image-Activated
Fires when an operator double-clicks on an image item with the mouse.
Note that When_Image_Pressed also fires on a double-click.
1.3.2.5 When-Image-Pressed
Fires when an operator uses the mouse to:
• single-click on an image item
• double-click on an image item (note that When_Image_Activated also fires on a double-click)
1.3.2.6 When-List-Changed
Fires when an operator selects a different element in a list item or de-selects the currently selected element. In addition, if a When-List-Changed trigger is attached to a combo box style list item, it fires each time the operator enters or modifies entered text.
1.3.2.7 When-Mouse-Click
Fires after the operator clicks the mouse if one of the following events occurs:
• if attached to the form, when the mouse is clicked within any canvas-view or item in the form
• if attached to a block, when the mouse is clicked within any item in the block
• if attached to an item, when the mouse is clicked within the item
Three events must occur before a When-Mouse-Click trigger will fire:
• Mouse down
• Mouse up
• Mouse click
Any trigger that is associated with these events will fire before the When-Mouse-Click trigger fires.
1.3.2.8 When-Mouse-DoubleClick
Fires after the operator double-clicks the mouse if one of the following events occurs:
• if attached to the form, when the mouse is double-clicked within any canvas-view or item in the form
• if attached to a block, when the mouse is double-clicked within any item in the block
• if attached to an item, when the mouse is double-clicked within the item
Six events must occur before a When-Mouse-DoubleClick trigger will fire:
• Mouse down
• Mouse up
• Mouse click
• Mouse down
• Mouse up
• Mouse double-click
Any trigger that is associated with these events will fire before the When-Mouse-DoubleClick trigger fires.
1.3.2.9 When-Mouse-Down
Fires after the operator presses down the mouse button if one of the following events occurs:
• if attached to the form, when the mouse is pressed down within any canvas-view or item in the form
• if attached to a block, when the mouse is pressed down within any item in the block
• if attached to an item, when the mouse is pressed within the item
Note: The mouse down event is always followed by a mouse up event.
1.3.2.10 When-Mouse-Enter
Fires when the mouse enters an item or canvas-view if one of the following events occurs:
• if attached to the form, when the mouse enters any canvas-view or item in the form
• if attached to a block, when the mouse enters any item in the block
• if attached to an item, when the mouse enters the item
1.3.2.11 When-Mouse-Leave
Fires after the mouse leaves an item or canvas-view if one of the following events occurs:
• if attached to the form, when the mouse leaves any canvas-view or item in the form
• if attached to a block, when the mouse leaves any item in the block
• if attached to an item, when the mouse leaves the item
1.3.2.12 When-Mouse-Move
Fires each time the mouse moves if one of the following events occurs:
• if attached to the form, when the mouse moves within any canvas-view or item in the form
• if attached to a block, when the mouse moves within any item in the block
• if attached to an item, when the mouse moves within the item When-Mouse-Up
1.3.2.13 When-Mouse-Up
Fires each time the operator presses down and releases the mouse button if one of the following events occurs:
• if attached to the form, when the mouse up event is received within any canvas-view or item in a form
• if attached to a block, when the mouse up event is received within any item in a block
• if attached to an item, when the mouse up event is received within an item
Two events must occur before a When-Mouse-Up trigger will fire:
• Mouse down
• Mouse up
1.3.2.14 When-Radio-Changed
Fires when an operator selects a different radio button in a radio group, or de-selects the currently selected radio button, either by clicking with the mouse, or by way of keyboard selection commands.
1.3.2.15 When-Timer-Expired
Fires when a timer expires.
Note: Timers are created programmatically by calling the CREATE_TIMER built-in procedure.
1.3.2.16 When-Window-Activated
Fires when a window is made the active window. This occurs at form startup and whenever a different window is given focus. Note that on some window managers, a window can be activated by, say, clicking on its title bar. This operation is independent of navigation to an item in the window. Thus, navigating to an item in a different window always activates that window, but window activation can also occur independently of navigation.
1.3.2.17 When-Window-Closed
Fires when an operator closes a window using a window-manager specific Close command.
1.3.2.18 When-Window-Deactivated
Fires when an operator deactivates a window by setting the input focus to another window.
1.3.2.19 When-Window-Resized
Fires when a window is resized, either by the operator or programmatically through a call to RESIZE_WINDOW or SET_WINDOW_PROPERTY. (Even if the window is not currently displayed, resizing the window programmatically fires the When-Window-Resized trigger.) This trigger also fires at form startup, when the root window is first drawn. It does not fire when a window is iconified.
1.3.3 Key Triggers
1.3.3.1 Function Key
Function key triggers are associated with individual Runform function keys. A function key trigger fires only when an operator presses the associated function key. The actions you define in a function key trigger replace the default action that the function key would normally perform.
| The following paragraph shows all function key triggers and the corresponding Runform function keys : Key-CLRBLK [Clear Block], Key-CLRFRM [Clear Form], Key-CLRREC [Clear Record], Key-COMMIT [Accept], Key-CQUERY [Count Query Hits], Key-CREREC [Insert Record], Key-DELREC [Delete Record], Key-DOWN [Down], Key-DUP-ITEM [Duplicate Item], Key-DUPREC [Duplicate Record], Key-EDIT [Edit], Key-ENTQRY [Enter Query], Key-EXEQRY [Execute Query], Key-EXIT [Exit], Key-HELP [Help], Key-LISTVAL [List of Values], Key-MENU [Block Menu], Key-NXTBLK [Next Block], Key-NXT-ITEM [Next Item], Key-NXTKEY [Next Primary Key], Key-NXTREC [Next Record], Key-NXTSET [Next Set of Records], Key-PRINT [Print], Key-PRVBLK [Previous Block], Key-PRV-ITEM [Previous Item], Key-PRVREC [Previous Record], Key-SCRDOWN [Scroll Down], Key-SCRUP [Scroll Up], Key-UP [Up], Key-UPDREC (Equivalent to Record, Lock command on the default menu). |
Note that you cannot redefine all Runform function keys with function key triggers. Specifically, you cannot ever redefine the following static function keys because they are often performed by the terminal or user interface management system and not by Oracle Forms.
[Clear Item], [Copy],
[Cut], [Delete Character],
[Delete Line], [Display Error],
[End of Line], [First Line],
[Insert Line], [Last Line],
[Left], [Paste],
[Refresh], [Right],
[Scroll Left], [Scroll Right],
[Search], [Select],
[Show Keys], [Toggle Insert/Replace],
[Transmit].
The default functionality performed by the following keys is not allowed in Enter Query mode:
[Clear Block], [Clear Form],
[Clear Record], [Accept],
[Insert Record], [Delete Record],
[Down], [Duplicate Item],
[Duplicate Record], [Block Menu],
[Next Block], [Next Primary Key],
[Next Record], [Next Set of Records],
[Previous Block], [Previous Record],
[Up], [Lock Record].
1.3.3.2 Key-Fn
A Key-Fn trigger fires when an operator presses the associated key. You can attach Key-Fn triggers to 10 keys or key sequences that normally do not perform any Oracle Forms operations. These keys are referred to as Key-F0 through Key-F9. Before you can attach key triggers to these keys, you or the DBA must use Oracle Terminal to map the keys to the appropriate functions.
1.3.3.3 Key-Others
A Key-Others trigger fires when an operator presses the associated key.
A Key-Others trigger is associated with all keys that can have key triggers associated with them but are not currently defined by function key triggers (at any level).
A Key-Others trigger overrides the default behavior of a Runform function key (unless one of the restrictions apply). When this occurs, however, Oracle Forms still displays the function key's default entry in the Show Keys screen.
1.3.4 Master-Detail Triggers
1.3.4.1 On-Check-Delete-Master
Oracle Forms creates this trigger automatically when you define a master-detail relation and set the Master Deletes property to Non-Isolated. It fires when there is an attempt to delete a record in the master block of a master-detail relation.
1.3.4.2 On-Clear-Details
Fires when a coordination-causing event occurs in a block that is a master block in a master-detail relation. A coordination-causing event is any event that makes a different record the current record in the master block.
1.3.4.3 On-Populate-Details
Oracle Forms creates this trigger automatically when you define a master-detail relation. It fires when Oracle Forms would normally need to populate the detail block in a master-detail relation.
1.3.5 Message-Handling Triggers
1.3.5.1 On-Error
An On-Error trigger fires whenever Oracle Forms would normally cause an error message to display.
1.3.5.2 On-Message
Fires whenever Oracle Forms would normally cause a message to display.
1.3.6 Navigational Triggers
1.3.6.1 Post-Block
Fires during the Leave the Block process.
1.3.6.2 Post-Form
Fires during the Leave the Form process, when a form is exited.
1.3.6.3 Post-Record
Fires during the Leave the Record process. Specifically, the Post-Record trigger fires whenever the operator or the application moves the input focus from one record to another. The Leave the Record process can occur as a result of numerous operations, including INSERT_RECORD, DELETE_RECORD, NEXT_RECORD, CREATE_RECORD, NEXT_BLOCK, PREVIOUS_BLOCK, etc.
1.3.6.4 Post-Text-Item
Fires during the Leave the Item process for a text item. Specifically, this trigger fires when the input focus moves from a text item to any other item.
1.3.6.5 Pre-Block
Fires during the Enter the Block process, during navigation from one block to another.
1.3.6.6 Pre-Form
Fires during the Enter the Form event, at form startup.
1.3.6.7 Pre-Record
Fires during the Enter the Record process, during navigation to a different record.
1.3.6.8 Pre-Text-Item
Fires during the Enter the Item process, during navigation from an item to a text item.
1.3.6.9 When-Form-Navigate
Fires whenever any peer form navigation takes place.
1.3.6.10 When-New-Block-Instance
Fires when the input focus moves to an item in a block that is different than the block that previously had input focus. Specifically, it fires after navigation to an item, when Oracle Forms is ready to accept input in a block that is different than the block that previously had input focus.
1.3.6.11 When-New-Form-Instance
At form start-up, Oracle Forms navigates to the first navigable item in the first navigable block. A When-New-Form-Instance trigger fires after the successful completion of any navigational triggers that fire during the initial navigation sequence. This trigger does not fire when control returns to a calling form from a called form. In a multiple-form application, this trigger does not fire when focus changes from one form to another.
1.3.6.12 When-New-Item-Instance
Fires when the input focus moves to an item. Specifically, it fires after navigation to an item, when Oracle Forms is ready to accept input in an item that is different than the item that previously had input focus.
1.3.6.13 When-New-Record-Instance
Fires when the input focus moves to an item in a record that is different than the record that previously had input focus. Specifically, it fires after navigation to an item in a record, when Oracle Forms is ready to accept input in a record that is different than the record that previously had input focus.
Fires whenever Oracle Forms instantiates a new record.
1.3.7 Query-Time Triggers
1.3.7.1 Post-Query
When a query is open in the block, the Post-Query trigger fires each time Oracle Forms fetches a record into a block. The trigger fires once for each record placed on the block's list of records.
1.3.7.2 Pre-Query
Fires during Execute Query or Count Query processing, just before Oracle Forms constructs and issues the SELECT statement to identify rows that match the query criteria.
1.3.8 Transactional Triggers
1.3.8.1 On-Check-Unique
During a commit operation, the On-Check-Unique trigger fires when Oracle Forms normally checks that primary key values are unique before inserting or updating a record in a base table. It fires once for each record that has been inserted or updated.
1.3.8.2 On-Close
Fires when an operator or the application causes a query to close. By default, Oracle Forms closes a query when all of the records identified by the query criteria have been fetched, or when the operator or the application aborts the query. The On-Close trigger augments the normal Oracle Forms "close cursor" phase of
1.3.8.3 On-Column-Security
Fires when Oracle Forms would normally enforce column-level security for each block that has the Column Security block property set On.
1.3.8.4 On-Commit
Fires whenever Oracle Forms would normally issue a database commit statement to finalize a transaction. By default, this operation occurs after all records that have been marked as updates, inserts, and deletes have been posted to the database.
1.3.8.5 On-Count
Fires when Oracle Forms would normally perform default Count Query processing to determine the number of rows in the database that match the current query criteria. When the On-Count trigger completes execution, Oracle Forms issues the standard query hits message: FRM-40355: Query will retrieve
1.3.8.6 On-Delete
Fires during the Post and Commit Transactions process. Specifically, it fires after the Pre-Delete trigger fires and before the Post-Delete trigger fires, replacing the actual database delete of a given row. The trigger fires once for each row that is marked for deletion from the database.
1.3.8.7 On-Fetch
When a query is first opened, fires immediately after the On-Select trigger fires, when the first records are fetched into the block. While the query remains open, fires again each time a set of rows must be fetched into the block.
1.3.8.8 On-Insert
Fires during the Post and Commit Transactions process. Specifically, it fires after the Pre-Insert trigger fires and before the Post-Insert trigger fires, when Oracle Forms would normally insert a record in the database. It fires once for each row that is marked for insertion into the database.
1.3.8.9 On-Lock
Fires whenever Oracle Forms would normally attempt to lock a row, such as when an operator presses a key to modify data in an item. The trigger fires between the keypress and the display of the modified data.
1.3.8.10 On-Logon
Fires once per logon when Oracle Forms normally initiates the logon sequence.
1.3.8.11 On-Logout
Fires when Oracle Forms normally initiates a logout procedure.
1.3.8.12 On-Rollback
Fires when Oracle Forms would normally issue a ROLLBACK statement, to roll back a transaction to the last savepoint that was issued.
1.3.8.13 On-Savepoint
Fires when Oracle Forms would normally issue a Savepoint statement. By default, Oracle Forms issues savepoints at form startup, and at the start of each Post and Commit Transaction process.
1.3.8.14 On-Select
Fires when Oracle Forms would normally execute the selection phase of a query, to identify the records in the database that match the current query criteria.
1.3.8.15 On-Sequence-Number
Fires when Oracle Forms would normally perform the default processing for generating sequence numbers for default item values.
1.3.8.16 On-Update
Fires during the Post and Commit Transactions process. Specifically, it fires after the Pre-Update trigger fires and before the Post-Update trigger fires, when Oracle Forms would normally update a record in the database. It fires once for each row that is marked for update in the form.
1.3.8.17 Post-Change
Fires when any of the following conditions exist:
• The Validate the Item process determines that an item is marked as Changed and is not NULL.
• An operator returns a value into an item by making a selection from a list of values, and the item is not NULL.
• Oracle Forms fetches a non-NULL value into an item. In this case, the When-Validate-Item trigger does not fire. If you want to circumvent this situation and effectively get rid of the Post-Change trigger, you must include a Post-Query trigger in addition to your When-Validate-Item trigger. See "Usage Notes" below.
1.3.8.18 Post-Database-Commit
Fires once during the Post and Commit Transactions process, after the database commit occurs. Note that the Post-Forms-Commit trigger fires after inserts, updates, and deletes have been posted to the database, but before the transaction has been finalized by issuing the Commit. The Post-Database-Commit Trigger fires after Oracle Forms issues the Commit to finalize the transaction.
1.3.8.19 Post-Delete
Fires during the Post and Commit Transactions process, after a row is deleted. It fires once for each row that is deleted from the database during the commit process.
1.3.8.20 Post-Forms-Commit
Fires once during the Post and Commit Transactions process. If there are records in the form that have been marked as inserts, updates, or deletes, the Post-Forms-Commit trigger fires after these changes have been written to the database but before Oracle Forms issues the database Commit to finalize the transaction.
If the operator or the application initiates a Commit when there are no records in the form have been marked as inserts, updates, or deletes, Oracle Forms fires the Post-Forms-Commit trigger immediately, without posting changes to the database.
1.3.8.21 Post-Insert
Fires during the Post and Commit Transactions process, just after a record is inserted. It fires once for each record that is inserted into the database during the commit process.
1.3.8.22 Post-Logon
Fires after either of the following events:
• The successful completion of Oracle Forms default logon processing.
• The successful execution of the On-Logon trigger.
1.3.8.23 Post-Logout
Fires after either of the following events:
• Oracle Forms successfully logs out of ORACLE.
• The successful execution of the On-Logout trigger.
1.3.8.24 Post-Select
The Post-Select trigger fires after the default selection phase of query processing, or after the successful execution of the On-Select trigger. It fires before any records are actually retrieved through fetch processing.
1.3.8.25 Post-Update
Fires during the Post and Commit Transactions process, after a row is updated. It fires once for each row that is updated in the database during the commit process.
1.3.8.26 Pre-Commit
Fires once during the Post and Commit Transactions process, before Oracle Forms processes any records to change. Specifically, it fires after Oracle Forms determines that there are inserts, updates, or deletes in the form to post or commit. The trigger does not fire when there is an attempt to commit, but validation determines that there are no changed records in the form.
1.3.8.27 Pre-Delete
Fires during the Post and Commit Transactions process, before a row is deleted. It fires once for each record that is marked for delete. Note: Oracle Forms creates a Pre-Delete trigger automatically for any master-detail relation that has the Master Deletes property set to Cascading.
Pre-Insert Fires during the Post and Commit Transactions process, before a row is inserted. It fires once for each record that is marked for insert.
1.3.8.28 Pre-Logon
Fires just before Oracle Forms initiates a logon procedure to the data source.
1.3.8.29 Pre-Logout
Fires once before Oracle Forms initiates a logout procedure.
1.3.8.30 Pre-Select
Fires during Execute Query and Count Query processing, after Oracle Forms constructs the SELECT statement to be issued, but before the statement is actually issued. Note that the SELECT statement can be examined in a Pre-Select trigger by reading the value of the system variable SYSTEM.LAST_QUERY.
1.3.8.31 Pre-Update
Fires during the Post and Commit Transactions process, before a row is updated. It fires once for each record that is marked for update.
1.3.9 Validation Triggers
1.3.9.1 When-Validate-Item
Fires during the Validate the Item process. Specifically, it fires as the last part of item validation for items with the New or Changed validation status.
1.3.9.2 When-Validate-Record
Fires during the Validate the Record process. Specifically, it fires as the last part of record validation for records with the New or Changed validation status.
1.3.9.3 User-Named Trigger
A user-named trigger is a trigger that you define yourself in a form, and then call explicitly from other triggers or user-named subprograms. Each user-named trigger defined at the same definition level must have a unique name.
To execute a user-named trigger, you must call the EXECUTE_TRIGGER built-in procedure, as shown here:
Execute_Trigger('my_user_named_trigger');
Note: You can write user-named PL/SQL subprograms to perform almost any task for which you might use a user-named trigger.
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