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Ajax Call Back Process in Oracle Apex Method=2

In the world of web development, Ajax (Asynchronous JavaScript and XML) has become an indispensable tool for creating dynamic and interactive web applications. Oracle Application Express (Apex), a low-code development platform, offers a convenient way to implement Ajax functionality in your Oracle databases. One of the methods available in Oracle Apex is Method=2, which allows you to perform Ajax callbacks effortlessly. In this article, we will delve into the Ajax call back process in Oracle Apex Method=2, exploring its benefits, implementation, and best practices.

Ajax Call Back Process in Oracle Apex Method=2: Explained

Ajax callbacks in Oracle Apex Method=2 enable developers to enhance the user experience by providing real-time updates to the web application without requiring a page reload. This method is particularly useful when you need to retrieve and display data from the database dynamically. Let's dive into the process of implementing Ajax call backs in Oracle Apex using Method = 2.

The Process

Step 1: Setting Up the Ajax Callback

To begin with, you need to define the Ajax callback function in Oracle Apex. This function will be triggered when a specific event occurs on the web page. It can be a button click, a value change in a form field, or any other event that you choose to listen to. The Ajax callback function will be responsible for executing the desired logic and updating the relevant parts of the page.

Step 2: Creating the Ajax Callback Process

After setting up the callback function, you need to create an Ajax callback process in Oracle Apex. This process defines the server-side logic that will be executed when the callback is triggered. It can include SQL queries, PL/SQL code, or any other server-side operations required to retrieve or manipulate data.

Step 3: Implementing the Ajax Callback Event

With the callback function and process in place, you can now associate the callback event with the desired page element. In Oracle Apex, you can easily specify the event and the associated callback function using the provided interface. This step ensures that the callback is triggered when the specified event occurs.

Step 4: Handling the Ajax Callback Response

Once the Ajax callback process is executed on the server-side, the response is sent back to the client-side. In the callback function, you can handle this response and update the relevant parts of the page dynamically. This can be achieved by manipulating the DOM (Document Object Model) using JavaScript or jQuery, based on the received data.

Best Practices for Ajax Call Back Process in Oracle Apex Method=2

To make the most out of Ajax call backs in Oracle Apex using Method=2, it's essential to follow some best practices. Here are a few tips to consider:

• Optimize Server-Side Logic: Ensure that your server-side logic in the Ajax callback process is efficient and optimized. This includes using appropriate SQL queries, minimizing database round trips, and handling exceptions gracefully.

• Use Caching: If the data being retrieved through the Ajax callback is relatively static and doesn't change frequently, consider implementing caching mechanisms. Caching can significantly improve the performance of your web application by reducing the load on the database.

• Error Handling: Implement proper error handling in your Ajax callback process. This includes handling exceptions, validating input parameters, and providing meaningful error messages to the user.

• Security: When working with Ajax callbacks, it's crucial to implement appropriate security measures. Ensure that your server-side code is protected against SQL injection attacks and other security vulnerabilities.

1. Create a Region 

1. Name- Call Back Process Method=2

If you haven't seen my Ajax Call Back Process Method = 1 video, please click on the video link to watch it, then it will be easy to get ideas about this video.

 

Method=1 Video Url- https: //youtu.be/PUV9PF97l0I

 

I will work with the data in a table of my choice. You can work with any table. I am currently    working on my PRODUCT_PRICE table. 

2. Since I will be working with the product table, I will create the items in the table that will bring the data. 

3. Create items according to your needs

4. I will rename the items for the convenience of work

1.   PRODUCT_ID, PRICE, SIZE

5. I will the first Item  Select  List

select distinct a.PRODUCT_CODE||', ' ||a.PRODUCT_NAME d,
a.PRODUCT_ID r from PRODUCT a,
PURCHASE_DETALIS b where a.PRODUCT_ID=b.PRODUCT_ID order by a.PRODUCT_ID

6. Create a Ajax Call Back Process

1. Name- price

PL/SQL Code 

DECLARE v_proid1 number;
v_price VARCHAR2 (50);
v_size VARCHAR2 (50);

CURSOR cur_c IS SELECT b.ORIGINAL_PRICE,
c.SIZE_NAME from ITEM_SIZE c,
PRODUCT_PRICE b,
PURCHASE_DETALIS a where a.PROOUCT_SIZE=c.OID and a.PRODUCT_ID=b.PRODUCT_ID and a.PRODUCT_ID=APEX_APPLICATION.g_x01;

BEGIN FOR c IN cur_c LOOP v_price :=c.ORIGINAL_PRICE;
v_size :=c.SIZE_NAME;
END LOOP;

OWA_UTIL.mime_header ('text/xml', FALSE);
HTP.p ('Cache-Control: no-cache');
HTP.p ('Pragma: no-cache');
OWA_UTIL.http_header_close;
HTP.prn ('<body>');
HTP.prn ('<desc>this xml genericly sets multiple items</desc>');
HTP.prn ('<item id="' ||APEX_APPLICATION.g_x02||'">' || v_price || '</item>');
HTP.prn ('<item id="' ||APEX_APPLICATION.g_x03||'">' || v_size || '</item>');
HTP.prn ('</body>');
EXCEPTION WHEN OTHERS THEN OWA_UTIL.mime_header ('text/xml', FALSE);
HTP.p ('Cache-Control: no-cache');
HTP.p ('Pragma: no-cache');
OWA_UTIL.http_header_close;
HTP.prn ('<body>');
HTP.prn ('<desc>this xml genericly sets multiple items</desc>');
HTP.prn ('<item id="' ||APEX_APPLICATION.g_x02||'">' || SQLERRM || '</item>');
HTP.prn ('</body>');
END;

7. Item Properties

1. Advanced
2. Custom Attributes-  onchange="pricetotal();"

8.  Goto Page Properties

1. Function and Global Variable Declaration
2. Paste the following code-

function pricetotal() {
    apex.server.process ("price",

        {
        x01: $v('P11_PRODUCT_ID1'),
        x02: 'P11_PRICE',
        x03: 'P11_SIZE',
    }

    ,
    {

    dataType: 'xml',
    loadingIndicator: '#P11_PRICE,#P11_SIZE',
    success: function(gReturn) {
        var l_Count=gReturn.getElementsByTagName("item").length;

        for(var i=0; i< l_Count; i++) {
            var l_Opt_Xml=gReturn.getElementsByTagName("item")[i]; var l_ID=l_Opt_Xml.getAttribute('id'); var l_El=apex.item(l_ID); if(l_Opt_Xml.firstChild) {
                var l_Value=l_Opt_Xml.firstChild.nodeValue;
            }

            else {
                var l_Value='';
            }

            if(l_El) {
                if(l_El.tagName=='INPUT') {
                    $s(l_ID, l_Value);
                }

                else if(l_El.tagName=='SPAN' & & l_El.className=='grabber') {
                    l_El.parentNode.innerHTML=l_Value; l_El.parentNode.id=l_ID;
                }

                else {
                    $s(l_ID, l_Value);
                }
            }
        }
    }
});
}

FAQs (Frequently Asked Questions)

Q: What are the benefits of using Ajax call backs in Oracle Apex Method=2?

A: Ajax call backs in Oracle Apex Method=2 offer several benefits, including enhanced user experience, real-time updates, reduced page reloads, and improved performance.

Q: Can I use Ajax call backs to update multiple regions on a page simultaneously?

A: Yes, you can use Ajax call backs to update multiple regions on a page simultaneously. By associating multiple callback events and processes, you can achieve dynamic updates in various sections of your web application.

Q: Is Method=2 the only way to implement Ajax call backs in Oracle Apex?

A: No, Oracle Apex provides multiple methods to implement Ajax call backs. Method=2 is one of the options available and is widely used due to its simplicity and ease of implementation.

Q: Can I pass parameters to the Ajax callback process?

A: Yes, you can pass parameters to the Ajax callback process. These parameters can be used in SQL queries or to perform specific actions based on the user's input.

Q: Are there any performance considerations when using Ajax call backs in Oracle Apex?

A: While Ajax call backs can significantly enhance the user experience, it's essential to consider performance aspects. Optimize your server-side logic, minimize database round trips, and leverage caching mechanisms to ensure optimal performance.

Q: Can I use Ajax call backs in Oracle Apex with other JavaScript frameworks, such as jQuery?

A: Yes, you can combine Ajax call backs in Oracle Apex with other JavaScript frameworks, such as jQuery, to leverage their advanced functionalities and simplify your development process.

Conclusion

Ajax call backs in Oracle Apex Method=2 provide a powerful mechanism to create dynamic and responsive web applications. By implementing the Ajax call back process, you can enhance the user experience, reduce page reloads, and improve the performance of your Oracle Apex applications. Remember to follow the best practices and leverage the flexibility offered by Oracle Apex to build robust and efficient web applications.