Exploring Session State in Oracle APEX with JavaScript

Hello APEX developers! Today, we're exploring how to work with session state using JavaScript in Oracle APEX. We'll cover the basics with easy-to-understand examples and show you both the shortcut and long-form ways to do things.

Reading Session State

To get a value from session state, we use the $v() function or its longer form:

// Shortcut
let username = $v('P1_USERNAME');

// Long form
let email = apex.item('P1_EMAIL').getValue();

console.log("Username: " + username);
console.log("Email: " + email);

Writing to Session State

To set a value in session state, we use $s() or the setValue() method:

// Shortcut
$s('P1_FAVORITE_COLOR', 'Blue');

// Long form
apex.item('P1_FAVORITE_ANIMAL').setValue('Dolphin');

Checking if an Item Exists

Before working with an item, it's smart to check if it exists. We use $x() for this:

// Shortcut
if ($x('P1_PHONE')) {
    console.log("Phone field exists");
}

// Long form
if (apex.item('P1_ADDRESS').node) {
    console.log("Address field exists");
}

Working with Select Lists and Radio Groups

For items based on a List of Values (LOV), APEX provides special functions:

// Get the display value
let deptName = apex.item('P1_DEPARTMENT').displayValueFor(10);
console.log("Department 10 is: " + deptName);

// Set both return and display value (useful for Popup LOVs)
apex.item('P1_EMPLOYEE').setValue(7839, 'KING');

Detecting Changes

To check if an item's value has changed:

if (apex.item('P1_SALARY').isChanged()) {
    console.log("Salary has been modified!");
}

Silent Updates

Sometimes, we want to update a value without triggering events. The setValue method accepts three arguments:

1. pValue - The value to set

2. pDisplayValue - The display value

3. pSuppressChangeEvent - defaults to false, true suppresses the change event

// Set value without firing change event
apex.item('P1_DEPARTMENT').setValue(20, null, true);

Wrapping Up

These JavaScript techniques allow you to create more interactive APEX applications. Remember:

1. $v() or getValue() to read

2. $s() or setValue() to write

3. $x() to check for item existence

Remember...these values aren't set into session state until you submit the page in some fashion!

#orclAPEX