les20

20Copyright © 2004, Oracle. All rights reserved.

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20-2 Copyright © 2004, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to do the following:

• Distinguish between internal and external navigation

• Control navigation with properties

• Describe and use navigation triggers to control navigation

• Use navigation built-ins in triggers


Navigation Overview

• What is the navigational unit?– Outside the form– Form– Block– Record– Item

• Entering and leaving objects

• What happens if navigation fails?


v

^x

Understanding Internal Navigation

Next Record

Exit item

Exit record

Enter record

Enter item


Using Object Properties to Control Navigation

• Block– Navigation Style– Previous Navigation Data Block– Next Navigation Data Block

• Item– Enabled– Keyboard Navigable– Mouse Navigate – Previous Navigation Item– Next Navigation Item


Using Object Properties to Control Navigation

• Form module– Mouse

Navigation Limit– First Navigation

Data Block


v

^

Mouse Navigate Property

x

MOUSE NAVIGATE = YES

Exit item

Exit record

Exit block

Enter block

Enter record

Enter item


v

^x

Writing Navigation Triggers

Pre- and Post-

When-New-<object>-Instance


Navigation Triggers

When-New-<object>-Instance

Fire after navigation

Fire even when validation unit is higher than the trigger object

Allow restricted and unrestricted built-ins

Are not affected by failure

Pre- and Post-

Fire during navigation

Do not fire if validation unit is higher than trigger object

Allow unrestricted built-ins

Handle failure by returning to initial object


When-New-<object>-Instance Triggers

• When-New-Form-Instance

• When-New-Block-Instance

• When-New-Record-Instance

• When-New-Item-Instance


SET_<object>_PROPERTY Examples

SET_FORM_PROPERTY(FIRST_NAVIGATION_BLOCK,

’ORDER_ITEMS’);

SET_BLOCK_PROPERTY(’ORDERS’, ORDER_BY,

’CUSTOMER_ID’);

SET_RECORD_PROPERTY(3, ’ORDER_ITEMS’, STATUS,

QUERY_STATUS);

SET_ITEM_PROPERTY(’CONTROL.stock_button’,

ICON_NAME, ’stock’);


The Pre- and Post-Triggers

• Pre/Post-Form

• Pre/Post-Block

• Pre/Post-Record

• Pre/Post-Text-Item


Post-Block Trigger Example

Disabling Stock button when leaving the ORDER_ITEMS block:

SET_ITEM_PROPERTY(’CONTROL.stock_button’,

enabled, property_false);


v

^

The Navigation Trap

A Post-Text-Item

Pre-Text-Item

Pre-Text-Item

B


Using Navigation Built-Ins in Triggers

GO_FORM

GO_BLOCK

GO_ITEM

GO_RECORD

NEXT_BLOCK

NEXT_ITEM

NEXT_KEY

NEXT_RECORD

NEXT_SET

UP

DOWN

PREVIOUS_BLOCK

PREVIOUS_ITEM

PREVIOUS_RECORD

SCROLL_UP

SCROLL_DOWN


IF CHECKBOX_CHECKED(’ORDERS.order_mode’) --Online

THEN -- order

ORDERS.order_status := 4; --Credit order

GO_ITEM(‘ORDERS.order_status’);

END IF;

IF CHECKBOX_CHECKED(’ORDERS.order_mode’) --Online

THEN -- order

ORDERS.order_status := 4; --Credit order

GO_ITEM(‘ORDERS.order_status’);

END IF;

Using Navigation Built-Ins in Triggers

• When-New-Item-Instance

• Pre-Text-Item


Summary

In this lesson, you should have learned that:

• External navigation is visible to the user, while internal navigation occurs behind the scenes.

• You can control navigation with properties of the form, block, or item:– Set in Navigation category of the Property Palette

OR– Use SET_[FORM | BLOCK | ITEM]_PROPERTY


Practice 20 Overview

This practice covers the following topics:

• Registering the bean area’s JavaBean at form startup

• Setting properties on a Pluggable Java Component at form startup

• Executing a query at form startup

• Populating product images when cursor arrives on each record of the ORDER_ITEMS block

les20

Technology

previous navigation

navigation data block

form form block record

navigation overview

navigation trap

navigation category

block record item scroll

block record item key