Utilizing Application Items and Application processes for base URL'S and constant values

Oracle APEX offers developers the flexibility to use Application Items and Application Processes to manage reusable values and execute logic at an application-wide level. One practical use case is dynamically constructing URLs by storing the base domain as an application item and referencing it in processes. This guide provides an overview and examples to help you understand and implement these features effectively.

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What Are Application Items?

Application Items are global variables in Oracle APEX that are accessible throughout the application. They are ideal for storing values such as:

• Configuration settings (e.g., base URLs, API keys)

• User-specific or session-specific values

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What Are Application Processes?

Application Processes are pieces of PL/SQL code that execute at specific points during the application lifecycle. They are often used for:

• Data preparation

• Shared business logic

• Reusable operations

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Step-by-Step Implementation: Storing and Using Base URLs

1. Creating an Application Item

To store the base URL:

1. Navigate to Shared Components > Application Items.

2. Click Create and define the application item:

   • Name: BASE_DOMAIN

   • Value: https://example.com (default value for your base URL)

2. Creating an Application Process

To define reusable logic:

1. Go to Shared Components > Application Processes.

2. Click Create and configure the process:

   • Name: Send_Notification

   • Point: On Demand Process (for AJAX calls)

   • PL/SQL Code:

DECLARE
    l_full_url VARCHAR2(4000);
    l_recipient_email VARCHAR2(100) := 'user@example.com';
BEGIN
    -- Construct the full URL using the application item
    l_full_url := :BASE_DOMAIN || '/send_notification?email=' || l_recipient_email;

    -- Example: Use UTL_HTTP to send a GET request
    UTL_HTTP.REQUEST(l_full_url, 'GET');

    -- Log the URL for debugging
    APEX_DEBUG.MESSAGE('Notification URL Called: ' || l_full_url);
END;

3. Calling the Application Process

In your APEX page:

• Use a Dynamic Action to call the process via AJAX when a button is clicked.

apex.server.process("Send_Notification", {
    x01: "User Email"
}, {
    success: function(data) {
        apex.message.alert("Notification sent successfully!");
    },
    error: function(error) {
        apex.message.alert("Error sending notification: " + error.responseText);
    }
});

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Example 2: Storing API Keys and Constructing API Calls

1. Storing the API Key

1. Create an application item called API_KEY.

2. Set its value to your API key: 123456789ABCDEFG.

2. Using the API Key in a Process

DECLARE
    l_full_url VARCHAR2(4000);
    l_api_key  VARCHAR2(100);
BEGIN
    -- Fetch the API key from the application item
    l_api_key := :API_KEY;

    -- Construct the API endpoint URL
    l_full_url := :BASE_DOMAIN || '/fetch_user_data?key=' || l_api_key;

    -- Log the constructed URL
    APEX_DEBUG.MESSAGE('API URL: ' || l_full_url);

    -- Example logic: Fetch data from the API (using DBMS_OUTPUT here as a placeholder)
    DBMS_OUTPUT.PUT_LINE('Calling API: ' || l_full_url);
END;

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Example 3: Dynamically Changing the Base URL per Environment

Problem

Your application is deployed across multiple environments (e.g., Development, Testing, Production), and each environment has a different base URL.

Solution

1. Set the Application Item Dynamically:

   • In the Initialization PL/SQL Code under Shared Components > Application Definition > Initialization Code:

BEGIN
    IF :APP_USER = 'DEV_USER' THEN
        :BASE_DOMAIN := 'https://dev.example.com';
    ELSIF :APP_USER = 'TEST_USER' THEN
        :BASE_DOMAIN := 'https://test.example.com';
    ELSE
        :BASE_DOMAIN := 'https://prod.example.com';
    END IF;
END;

2. Reference the Base URL in Processes:

   • Use :BASE_DOMAIN as shown in earlier examples.

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Example 4: Using Application Items in Page Processes

Scenario

You want to use the base URL stored in the application item within a page process to redirect the user to an external URL.

Implementation

BEGIN
    -- Redirect to the external URL
    owa_util.redirect_url(:BASE_DOMAIN || '/welcome_page');
END;

This process could be triggered, for instance, when a user logs in.

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