1. Chapter 6: Creating Custom Forms
Guide to Oracle 10g

2. Lesson A Objectives
After completing this lesson, you should be able to:
Create and use custom forms
Create command buttons that use form triggers to manipulate data
Use the Forms Debugger to find form logic and runtime errors
Work with form triggers
Create form navigation triggers
Guide to Oracle 10g

3. Introduction to Custom Forms
Displays data fields from variety of database tables
Contains programs that support organizational processes
Use lists of values (LOVs) to retrieve data values
Manipulate data using form triggers
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4. Identifying the Business Processes and Database Operations
Identify processes that form supports
Identify associated database tables
Describe process
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5. Designing the Interface
Visualize how form will look
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6. Creating a Custom Form Manually create form canvas in Object Navigator
Create form items by “painting” items on canvas
Using tools on Layout Editor tool palette
Write code that controls form functions
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7. Creating the Form Canvas
Manually create form canvas in Object Navigator
Start Forms Builder
Create and rename form canvas
Rename form module and form window
Change Title property of form window
Perform in Visual View in Object Navigator
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8. Creating a Control Block
Control data block
Also called control block
Data block not associated with particular database table
Create new data block in Object Navigator
Specify data block created manually
Use Ownership View
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9. Creating the Form Items
Create
Boilerplate logo image and text
Form text items
Command button items
Display form in Layout Editor
Draw items on form canvas using tools in tool palette
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10. Creating the LOVs LOV Use LOV Wizard Run form
Retrieve data from database table
Use LOV Wizard
Run form
To test LOV
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11. Displaying System Date and Time Values in Form Text Items
System variable
Variable representing value always available to any form
Display value in text item automatically
Set text item’s Initial Value property
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12. Forms Builder Date and Time System Variables
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13. Creating Command Buttons
Create and configure buttons
Create form triggers associated with buttons
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14. Creating and Configuring Command Buttons
Draw button on canvas using Button tool
Button tool on tool palette
Button group
Buttons should all be same size
Wide enough to accommodate longest button’s label
Draw button with longest label first
Guide to Oracle 10g

15. Creating the Button Triggers
Select Triggers node under button in Object Navigator
Click Create button to create trigger
Select trigger event
Specify trigger code
WHEN-BUTTON-PRESSED button event
Trigger code executes when user clicks button
Guide to Oracle 10g

16. Creating the Button Triggers (continued)
Reference form items:
:block_name.item_name
Clear form text items in form trigger:
Use CLEAR_FORM built-in procedure
Create program unit to set value of text items to blank text string
Procedure
Code block that executes commands to change one or more values
Guide to Oracle 10g

17. Creating the Button Triggers (continued)
Function
Code block
Returns single value
Create program unit:
Open Object Navigator
Select Program Units node
Click Create button
Program unit does not use DECLARE keyword
Guide to Oracle 10g

18. Using the Forms Debugger to Find Runtime Errors
Error that does not keep program from compiling
Generates error while program running
Often result of user error
Retrieve error messages associated with errors
Forms Debugger
Step through triggers and other PL/SQL programs one line at a time
Examine variable values during program execution
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19. Retrieving FRM- Error Messages
Investigate nature of error by looking up error code explanation
Oracle Technology Network (OTN) Web site
FRM- prefix
Forms Builder error codes
ORA- prefix
Generated by the DBMS
Guide to Oracle 10g

20. Using the Forms Debugger
Click Run Form Debug button
Set breakpoint
Pauses execution on specific program command
Examine current values of all program variables
Step through program commands to observe execution path
Examine variable values to see how values change
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21. Using the Forms Debugger (continued)
Breakpoint
Pauses execution on specific command
Set on:
Program lines that contain executable program commands
SQL queries
To set:
Double-click mouse pointer in gray shaded area on left side of PL/SQL Editor window
Guide to Oracle 10g

22. Using the Forms Debug Console
Control form execution and examine form values
Buttons: Go
Step Into
Step Over
Step Out
Execution arrow
Shows program line to execute next
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23. Forms Debug Console
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24. Debug Console Windows
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25. Form Trigger Properties
Trigger activated
In response to event such as clicking button
Trigger name defines event that activates it
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26. Trigger Categories
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27. Trigger Timing Specifies when trigger fires PRE- POST-
Fire just before event successfully completes
POST-
Fire just after event successfully completes
ON-,WHEN-, and KEY-
Fire in response to actions
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28. Trigger Scope
Defines where event must occur in order for associated trigger to fire
Includes object to which trigger attached
And objects within trigger object
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29. Trigger Execution Hierarchy
Defines which trigger fires
When object within form object contains same trigger that form object contains
By default trigger in higher-level object overrides trigger in lower-level object
Can specify custom execution hierarchy
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30. Directing Form External Navigation
User causes form focus to change by making different form item active
Form focus
Item currently selected on form
Internal navigation
Result of internal form code that responds to external navigation operations or trigger commands
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31. Setting the Form Tab Order
Set tab order
Place items in correct order under Items node
In Object Navigator window
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32. Directing External Navigation Using Built-in Subprograms
Called built-ins
Use to direct external form navigation
Cannot use in navigational triggers
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33. Built-in Subprograms to Control External Navigation
Guide to Oracle 10g

34. Lesson A Summary Custom form Runtime errors Forms Debugger
Displays data fields from variety of database tables
Processes data using triggers that contain SQL commands
Runtime errors
Errors that occur while form running
Forms Debugger
Create breakpoints that pause execution
Guide to Oracle 10g

35. Lesson A Summary Form triggers support: Block processing
Interface events
Master-detail processing
Message handling
Navigational events
Query processing
Transaction processing
Validation
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36. Lesson B Objectives
After completing this lesson, you should be able to:
Suppress default system messages
Create alerts and messages to provide system feedback to users
Create applications that avoid user errors
Trap common runtime errors
Guide to Oracle 10g

37. Controlling System Messages
Forms Services message line
Displays FRM- and ORA- messages
Classified according to
Severity
Whether or not they require user intervention
Suppress default system messages
Replace with custom messages
Set :SYSTEM.MESSAGE_LEVEL variable
In PRE-FORM trigger
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38. Providing System Feedback
Important application design principle
Provide users with feedback about what is happening in application
Make applications forgiving
Allow users to undo unintended operations
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39. Custom Messages Short text string that displayed on form message line
Up to 200 characters
Syntax:
MESSAGE('message_string');
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40. Alerts Dialog box Top-level form object
Display text message longer than 200 characters
Displays one or more buttons
Allow user to select between alternatives that execute associated program statements
Top-level form object
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41. Alerts (continued) Styles: Button Label property determines: Note
Caution
Stop
Button Label property determines:
How many buttons appear on alert
Labels on buttons
Maximum 3 buttons
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42. Alerts (continued) To declare/display alert: DECLARE
alert_button NUMBER;
BEGIN
alert_button:=
SHOW_ALERT('alert_name');
END;
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43. Example Alert
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44. Syntax to Display an Alert and Execute Alternate Commands Depending on the Button the User Clicked
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45. Avoiding User Errors Help users avoid errors
Configure forms that validate input values
Programmatically disable form command buttons
Disable navigation for form text items containing values that users should not change
Guide to Oracle 10g

46. Validating Form Input Values
Validate input values
Ensure that values meet specific preset requirements
Use
Text item validation properties
Form validation triggers
Validation unit
Represents largest chunk of data that user can enter before form validates all input values
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47. Text Item Validation Properties
Guide to Oracle 10g

48. Validating Form Input Values (continued)
Item validation trigger
Item-level trigger
Associate with item’s WHEN-VALIDATE-ITEM event
Fires when item validated
As determined by form validation unit
If not valid
Raises built-in exception named FORM_TRIGGER_FAILURE
Guide to Oracle 10g

49. Disabling Form Command Buttons to Avoid User Errors
Enable or disable button while form running:
SET_ITEM_PROPERTY('item_name', property_name, property_value);
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50. Disabling Text Item Navigation
Nonnavigable
User cannot press Tab key to place insertion point in text item
Set item’s Keyboard Navigable property to No
User can still click mouse pointer in text item to enter value
Create trigger that moves insertion point to another form item
WHEN-MOUSE-UP event
Guide to Oracle 10g

51. Generating Runtime Errors
Deliberately generate errors while updating and deleting records
View error messages
Guide to Oracle 10g

52. Trapping Form Runtime Errors
ON-ERROR event occurs
Whenever ORA- or FRM- error occurs while form running
Create form-level trigger that corresponds to ON-ERROR event
Use decision control structure to handle different errors
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53. Forms Builder Built-in Procedures for Handling Errors
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54. General Syntax for an ON-ERROR Trigger
Guide to Oracle 10g

55. Lesson B Summary Create custom messages and alerts
Provide feedback to users
Validate user inputs using
Text item validation properties
Form validation trigger
Guide to Oracle 10g

56. Lesson C Objectives
After completing this lesson, you should be able to:
Convert data blocks to control blocks
Link data blocks to control blocks
Create a form that has multiple canvases
Create tab canvases
Create stacked canvases
Guide to Oracle 10g

57. Converting a Data Block to a Control Block
Use Data Block and Layout Wizards to create data block form and form layout
Convert data block to control block
Add command buttons to control form processing
Simplify creation of control blocks
Guide to Oracle 10g

58. Converting a Data Block to a Control Block (continued)
To convert data block to control block:
Change data block’s Database Data Block property value to No
Change Required property value of text item that represents data block table’s primary key to No
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59. Linking a Data Block to a Control Block
Create forms that link data blocks and control blocks to work together
Usually represent master-detail relationship
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60. Creating the Data Block
Use Data Block Wizard and Layout Wizards
To create and configure data block
Must contain field that links it to control block
Create data block without master-detail relationship
Link two blocks later
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61. Linking the Control Block and the Data Block
Open detail data block’s Property Palette
Modify data block’s WHERE Clause property
General syntax:
fieldname := control_block.text_item_name
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62. Refreshing the Data Block Values
Add commands to:
Initially populate data block display
Periodically refresh data block records
Use the GO_BLOCK built-in:
To move form focus to data block
Then execute EXECUTE_QUERY built-in
Flushes block
Makes information consistent with corresponding database data
Guide to Oracle 10g

63. Creating Forms with Multiple Canvases
Good practice not to show too much information on user’s screen display
Single-form approach
Create one form with multiple canvases
Enables form to share data among different canvases
Impossible for multiple programmers to work simultaneously on different canvases of same application
Guide to Oracle 10g

64. Creating Forms with Multiple Canvases (continued)
Multiple-form approach
Create multiple forms with different .fmb file for each application canvas
Works well when multiple programmers collaborate to create complex application
Enables programmers to use form in many different applications
More difficult for related forms to share data
Guide to Oracle 10g

65. The Northwoods University Student Services Process
Identify sequence of actions that user will employ to interact with canvases
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66. Interface Design Student Log On canvas Menu canvas
Student Information canvas
Course Grades canvas
Enrollment canvas
Guide to Oracle 10g

67. Working with Multiple Canvases and Data Blocks
Create form that contains multiple canvases
Create individual canvases
Specify to display specific block items on specific canvas
Create new data block
Select canvas name on which block items appear
On Layout Wizard Canvas page
Guide to Oracle 10g

68. Working with Multiple Canvases and Data Blocks (continued)
Often forms that have multiple canvases also have multiple data blocks
Group items that appear on same canvas in single data block
To keep blocks small and manageable
Cannot create two items that have same name in same data block
Ensure that Forms Builder places new items in correct block
Guide to Oracle 10g

69. Specifying the Block Navigation Order
Specify which canvas initially appears when user runs form
Canvas whose block items appear first under Data Blocks node in Object Navigator window
Order of canvases in Object Navigator Canvases list does not matter
Only order of data blocks
Guide to Oracle 10g

70. Object Navigator
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71. Referencing Different Canvases, Form Blocks, and Block Items
All form items have Canvas property
Specifies name of canvas on which item appears
Form always displays canvas on which item with focus appears
Execute GO_ITEM built-in
Move form focus to item on target canvas
Good practice to include block name
Guide to Oracle 10g

72. Creating and Configuring Tab Canvases in Forms
Multiple-page canvases
Allow users to move between multiple canvas surfaces
By selecting tabs at top of canvas
Display large number of related items in modular way
Direct user through sequence of steps for performing task
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73. Creating a Tab Canvas Contains two or more tab pages Tab page
Object representing surface
Displays form items
Has tab label identifier at top
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74. Creating a Tab Canvas (continued)
Create form that contains tab canvas
Create form
Create new content canvas in form
Create tab canvas on content canvas
Configure tab pages
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75. Creating Form Items on a Tab Canvas
Use tab pages as any content canvas
Create items on tab pages
Using Data Block Wizard
By creating control block and drawing text items directly on tab canvases
Must be sure to specify placement of items on tab canvas
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76. Lesson C Summary Convert data block to control block
Create relationship between control block and data block
Display information on multiple canvases:
Single-form approach
Multiple-form approach
Tab canvas
Multiple-page canvas
Guide to Oracle 10g

77. Summary Custom form Runtime errors Forms Debugger Form triggers
Create custom messages and alerts
Validate user inputs
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78. Summary (continued) Convert a data block to a control block
Create relationship between control block and data block
Display information on multiple canvases
Tab canvas
Guide to Oracle 10g