1 Chapter 12: Form Builder Objects and Flexible Code

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Enhanced Guide to Enhanced Guide to Oracle8iOracle8i

Chapter 12:Form Builder Objects and Flexible Code

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Object-Oriented Principles Object

Abstract representation of something in the real world

Class Group of objects with the same structure and

properties Class instance

Object that belongs to a specific class Inheritance

Specifies that when you create a new object, it inherits its structure and properties from its class

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Subclasses Classes that have similar

properties and structure of their parent class

Subclasses have specializations, which are properties that make them different than their parent class

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Form Builder Approaches For Creating Reusable Objects Property Classes Object Groups Object Libraries PL/SQL Libraries

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Property Classes Top-level Form

Builder objects that specify a collection of properties with specific values

Property classes can be associated with Form Builder objects to define object properties

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Creating a Property Class Approaches:

Create the property class based on an existing object

Explicitly create the property class object, and then define its properties and associated values

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Creating a Property Class Based on an Existing Object Create the object

and configure its properties as desired

In the object’s Property Palette, select the desired properties and then click the Property Class button on the toolbar to create the property class

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Creating a Property Class Explicitly Create the property class object in

the Object Navigator and open its Property Palette

To add a property, click the Add Property button

To remove a property, select the property and then click the Remove Property button

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Using Property Classes to Subclass Form Objects When you apply a property class to

a form object, the form object is subclassed to the property class

To subclass a form object, open the object’s Property Palette, and the the property class name in the Subclass Information dialog box

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Using the Subclass Information Dialog box Select whether

you are subclassing from an object or a property class

Select the property class name

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Object Groups Top-level form objects that contain groups of

objects that can be reused in different forms Examples of object types in object groups:

LOVs Data blocks Alerts

Object groups are created in a source from, and then subclassed into target forms

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Creating an Object Group Create a new

object group object in the form template

Rename the object group

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Adding Objects to an Object Group Create the

objects Drag and drop

the objects on the object group Object Group Children node

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Subclassing Object Groups in Target Forms Select the object group in the

source form Drag the object group to the

Object Groups node in the target form, drop the object group, and click the Subclass button

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Subclassing vs.Copying Objects When you subclass an object,

changes to original object are propagated to subclassed objects

When you copy an object, changes to original object do not affect subclassed objects

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Form With Objects Subclassed From Object Group

Subclassedobject groupSubclassed

objects

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Object Libraries Top-level Form

Builder objects that are independent of specific forms

Contain form objects that can be referenced in specific forms

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Creating an Object Library Create a new object library object

in Form Builder Save the object library file

File has an .olb extension Filename specifies object library

name

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Object Library Structure Consists of multiple library tabs

Tab pages that contain one or more similar object instances

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Creating and Configuring Tab Pages To create a new tab

page, select the Library Tabs node, and then click the Create button

Right-click the new tab page, and then click Property Palette to open the tab page Property Palette

Change the tab page Name and Label values

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Opening the Object Library Double-click the object library icon

to open the Object Library window

Library tabs

Object on tab page

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Adding Form Objects to Library Tab Pages

Create and configure the object in a source form

Open the source form Object Navigator and the Object Library window side-by-side Maximize the Object Navigator window Open the Object Library window, and then click

the Restore button so the Object Library appears in a window

Reposition the windows as necessary Drag and drop the object onto the Library

Tab page

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Window Configuration For Adding Objects

Object Navigator window

ObjectLibrary window

Objectto bestored inlibrary

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Using Object Library Objects in Forms Open the target form Object

Navigator and the Object Library window side-by-side

Drag and drop the object library object into the target form

Subclass the object into the target form

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SmartClasses Object library objects that are defined

as standard object types for an application

SmartClassed objects appear as selections on a pop-up menu when you create a new object and then right-click the object

Speeds up the process of using object libraries

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Creating a SmartClass Select the object in the object

library Click Object on the menu bar, and

then click SmartClass

Green checkindicates objectis a SmartClass

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Selecting a SmartClass

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PL/SQL Libraries Library of PL/SQL named program units

that can be used in forms Top-level Form Builder object that is not

associated with a specific form Specific program units can be attached

to forms Code is not part of form .fmb file Code is only loaded when program unit is

called

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Creating a PL/SQL Library in Form Builder Select the PL/SQL

Libraries node, and then click the Create button

Save the library in the file system Library name is

the same as the filename

File has a .pll extension

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Saving PL/SQL Library Files In general, PL/SQL library files

should be saved in the default PL/SQL library folder Path: Developer_Home\TOOLS\OPEN60

If you save a library file in a different location, that path and file must always be available when you open forms that reference the library

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Adding Program Units to PL/SQL Libraries Select the library Program Units

node, and then click the Create button

Select the named program unit type (procedure, function, package)

Type the program unit code in the PL/SQL Editor window

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Using PL/SQL Libraries in Forms Attach the library to the form Call the library program units from

form triggers

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Attaching a PL/SQL Library to a Form Select the form’s Attached Libraries

node, and then click the Create button Navigate to the library file and attach

the file If the library is saved in the default library

folder, click Yes to discard path information

If the library is not saved in the default library folder, click No to save path information

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Calling a Library Program Unit From a Form Trigger Reference the program unit and

pass the required parameters as specified in the attached library specification in the Object Navigator

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Calendar Windows Associated with a

form text item that displays date values

Allows the user to select a date

The selected date value is returned to the form text item

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Creating a Calendar Window Open the STNDRD20.OLB object

library and copy or subclass the Calendar object group into the form

Attach the CALENDAR.PLL PL/SQL library to the form

Create a trigger associated with the form text item that calls a procedure in the CALENDAR.PLL PL/SQL library

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Subclassing the Calendar Object Group Into the Form Open the target form Open the STNDRD20.OLB object

library Subclass the CALENDAR object

group into the target form

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Subclassing the Calendar Object Group Into the Form

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Attaching the CALENDAR.PLL PL/SQL Library to the Form

Create a new attached library object in the target form

Click Browser, select CALENDAR.PLL, click Open, and then click Attach to attach the library

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Creating a Trigger to Open the Calendar Window Create a Show Calendar button

next to the date text item Create the trigger to call the

GET_DATE procedure in the DATE_LOV package

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Creating a Trigger to Open the Calendar Window

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Flexible Code Allows you to create objects that

can be configured at runtime Approaches

Use system variables to retrieve and set system values

Use built-in subprograms that dynamically retrieve and set form object properties

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Using Built-in Subprograms to Create Flexible Code GET_ built-ins

Allow you to retrieve current object properties

SET_ built-ins Allow you to dynamically set object

properties

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GET_APPLICATION_PROPERTY Built-in

Returns information about the current Form Builder application

Syntax:GET_APPLICATION_PROPERTY(property_name);

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Retrieving Specific Object Properties Syntax:return_value := GET_object_PROPERTY (object_id | ‘object_name’, property_name);

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Retrieving Object ID ValuesUsing the FIND_ Built-ins Syntax:return_value := FIND_object(‘object_name’);

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Dynamically Setting Object Properties Syntax:SET_object_PROPERTY(object_id | ‘object_name’, property_name, property_value);

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Using Indirect Referencing to Write Flexible Code Direct referencing

Directly referencing a form object using the format :block_name.object_name

Indirect referencing Specifying block and item names in

single quotation marks Allows you to reference objects that

are not in the current form

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Commands For Indirect Referencing COPY

Indirectly sets the value of a form item

Syntax:COPY(value, ‘destination’);

Value: desired value Destination: form item

Format: block_name.item_name

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Commands For Indirect Referencing NAME_IN

Indirectly retrieves the value of a form item

Syntax:return_value := NAME_IN(source);

Return_value: retrieved value Is always a character string

Source: form item Format: block_name.item_name