In this tutorial, you will learn how to display CLOB contents in Oracle Apex. The Character large object (CLOB) is a collection of character data in the database. Usually stores the large data like HTML, XML, CSV, Plain Text, Word and Excel file, etc. Here I am giving an example to display the CLOB contents into a region in Oracle Apex. Follow these steps:
Steps to Display CLOB Contents in Oracle Apex Page Region
To demonstrate the following example, I am using the SUPPLIERS table. To test this example in your Oracle environment, create the table as shown below:
1. Create the following table with CLOB column
Create TABLE SUPPLIERS ( SUPPLIER_ID INTEGER, SUPPLIER_NAME VARCHAR2(100), ADDRESS VARCHAR2(100), PHONE VARCHAR2(40), AGREEMENT_DOC CLOB, MIMETYPE VARCHAR2(1000) ) /
Insert some data in the above table with some CLOB data also and provide the correct MIME TYPE for each type of CLOB content. For example:
- For HTML Data provide mime type
text/html. - For CSV Data >
text/csv - For Plain Text >
text/plain - Word file >
msword - Excel file >
ms-excel
Below is the screenshot of the data:
2. Create an Interactive Report in Oracle Apex
Create an interactive report in Oracle Apex based on the above table. Use the following query to display all the data except the CLOB column:
select
SUPPLIER_ID,
SUPPLIER_NAME,
ADDRESS,
PHONE,
'Preview' Preview
from SUPPLIERSBelow is the screenshot for the report settings:
3. Create a Page Item
Do the right-click on the interactive report region and from the shortcut menu select Create Page Item. Set the name as SUPPLIER_ID, my page number is 2 so the page item name is P2_SUPPLIER_ID.
4. Create a Static Content Region
Do the right-click on the content region and from the shortcut menu select Create Region and set the following properties:
- Title: Preview
- Type: Static Content
- Start New Row: No
- Advanced > Static ID: preview1
- Source > Text: Add the following code:
<p align="center"> <iframe id="myFrame1" src="" width="99%" height="750"> </iframe> </p>
Below is the screenshot for the above settings:
Save the changes for the page.
5. Create an Application Process
Now create an application process in Oracle Apex. To do this, click on the Shared Components > Application Process and then click on the Create button. The following window will appear:
Specify the name as preview_clob_data and select the Ajax Callback for the Point drop-down.
Then click on the Next button. And in the next screen paste the following PL/SQL code, as shown below:
DECLARE
vClob CLOB;
vblob blob;
vmimetype varchar2(1000);
L_DEST_OFFSET INTEGER := 1;
L_SRC_OFFSET INTEGER := 1;
L_LANG_CONTEXT INTEGER := DBMS_LOB.DEFAULT_LANG_CTX;
L_WARNING INTEGER;
L_LENGTH INTEGER;
BEGIN
Dbms_Lob.Createtemporary(Lob_Loc => vclob,
Cache => TRUE,
Dur => Dbms_Lob.Call);
Dbms_Lob.Createtemporary(Lob_Loc => vblob,
Cache => TRUE,
Dur => Dbms_Lob.Call);
SELECT agreement_doc, mimetype INTO vClob, vmimetype
FROM suppliers
WHERE supplier_id = :P2_SUPPLIER_ID;
-- tranform the input CLOB into a BLOB of the desired charset
begin
DBMS_LOB.CONVERTTOBLOB( DEST_LOB => vblob,
SRC_CLOB => vclob,
AMOUNT => DBMS_LOB.LOBMAXSIZE,
DEST_OFFSET => L_DEST_OFFSET,
SRC_OFFSET => L_SRC_OFFSET,
BLOB_CSID => NLS_CHARSET_ID('WE8MSWIN1252'),
LANG_CONTEXT => L_LANG_CONTEXT,
WARNING => L_WARNING
);
end;
owa_util.mime_header(vmimetype,false);
htp.p('Content-Length: ' || dbms_lob.getlength(vblob));
owa_util.http_header_close;
wpg_docload.download_file(vblob);
exception
when no_data_found then
null;
when others then
null;
END;Below is the screenshot for the above setting:
After that click on the Next button and on the next step click on the Create Process button.
Now come back to your page where you created the report and follow the remaining steps:
6. Create a JavaScript Function
Click on the page and in the Properties, palette add the following JavaScript code in the Function and Global Variable Declaration section:
function getClob(p_supplier_id)
{
apex.item( "P2_SUPPLIER_ID" ).setValue (p_supplier_id);
document.getElementById("myFrame1").src = "f?p=&APP_ID.:0:&SESSION.:APPLICATION_PROCESS=preview_clob_data:NO:RP:P2_SUPPLIER_ID:" + p_supplier_id;
apex.jQuery('#preview1').trigger('apexrefresh');
}7. Add JavaScript Code to Make the Preview Region Sticky
The Preview region, we created in the 4th step, should be sticky when the user will scroll the report. So add the following JavaScript code in the Execute when Page Loads section as shown below:
$("#preview1").stickyWidget({toggleWidth:true});Below is the screenshot for the above JavaScript code reference:
8. Create a Link for Preview in the Interactive Report
Click on the Preview column of the report and set the type as Link and paste the following JavaScript code for the Link Target as URL type: (Also shown in the below image)
javascript:getClob(#SUPPLIER_ID#);
Save the changes and run the page to test. Now when you will click on the Preview link it will display the CLOB contents in the Static Region without refreshing the whole page.
Do you think it is complicated? Don't worry you can download this Oracle Apex application from the GitHub with the link below:
Hello,
I have tried a little modified code but unfortunately I always get Oracle get data services
400 Bad Request{timeStamp} | {requestId}
I think you are missing something because the above code is tested.
I have given the link above to download this app from GitHub, you should download it and install it in your workspace to test.
Then you can import that specific page from this app to your application.
Thanks for fast response.
I have installed the app and it worked well until I set longer supplier_id := 12345678901234567890. In that case strange behaviour started. Somethimes I have got error (400 Bad Request{timeStamp} | {requestId}), sometimes nothing, sometimes worked well.....
Is this supplier id really exists? if not then you should not have to worry about it.
You can do one more thing, in the Ajax process, modify the Exception area as below:
Exception when no_data_found then htp.p('Supplier id not found.'); when others then htp.p('An error occurred.'); End;After making the above changes, it will not show any other error messages. Please try.
Hello,
in case supplier_id = 1 - OK
in case supplier_id = 123456789012345678 'Supplier id not found.'
Then it means it is not found. You should check in your database.
I won't bother anymore.
I doubt it is Database (Suppliers), It is only one row with supplier_id edited and tested with different values (lengths) using SQL Workshop, Tables, Data Edit. It seems that a length of the supplier_id is the reason because the problem occurs only if lenght > certain lenght.
If I replace in prew_clob_data in select, WHERE, P2_SUPPLIER_ID with value '12345678901234567890' (suppliers_id in the table) works well, so I suppose that the problem is 'transfer' P2_SUPPLIER_ID to prew_clob_data if the length is too long.
Anyway, best regards
Another one result in Preview window after Preview button clicked:
xjnr4bcss0cbo6c-dbparbih.adb.eu-frankfurt-1.oraclecloudapps.com refused to connect.
It seems like connection issue. I have no idea about it. I have just tested this app here and it is working fine.
Did you turn off friendly URLs? I had the same problem with friendly URLs turned on
Hi Vinish,
Is this possible with a blob instead of a clob?
I need the user to be able to preview a pdf using your method here, or the user will download the pdf.
Please let me know, thank you.
Yes, please check the following link:
Display BLOB contents (images/PDF) on page in Oracle Apex
Awesome, thank you.
This is great, thank you for this! But it only seems to work if friendly URLs is turned off in Application Definition Attributes I assume because of this which use the old non friendly URL
document.getElementById("myFrame1").src = "f?p=&APP_ID.:0:&SESSION.:APPLICATION_PROCESS=preview_clob_data:NO:RP:P2_SUPPLIER_ID:" + p_supplier_id;I tried to change it to:
document.getElementById("myFrame1").src = apex.util.makeApplicationUrl({pageId:0,session: $v( "pInstance" ), request: 'APPLICATION_PROCESS=preview_clob_data',itemNames:['P2_SUPPLIER_ID'], itemValues:[p_supplier_id]});
But that also only work with Friendly URLs turned off. Do you have a solution for friendly URLs?
If using friendly URL then me also facing some issues in passing parameter. But so far I found the following approach:
Change the static region content as follows:
Change the getClob function as follows:
function getClob(p_supplier_id) { apex.item( "P2_SUPPLIER_ID" ).setValue (p_supplier_id); apex.submit('P2_SUPPLIER_ID'); document.getElementById("myFrame1").src = "f?p=&APP_ID.:0:&SESSION.:APPLICATION_PROCESS=preview_clob_data"; }In this case, I am not passing the supplier id as parameter, instead setting the item value and submitting it using the apex.submit() method.
Thanks Vinish! Works like a charm!
Thanks but I just realized that with this method, the page is submitted every time you click on preview. That obviously takes longer but more importantly it means you lose your place in the report.
Oh well, no big deal I will just use the old URL "unfriendly" URL construct for this app.
Yes, that is the problem. I am looking for the solution to how to pass the parameters to application process URL in friendly URL format. Yesterday I tried everything but it didn't work.
When I will resolve this I will comment again here to let you know.
Finally, the following approach is working with friendly URL without submitting the whole page.
Revert the static region changes:
function getClob(p_supplier_id) { apex.item( "P2_SUPPLIER_ID" ).setValue (p_supplier_id); // below code will set the p2_supplier_id value apex.server.process ( "SAVE_HIDDEN_VALUE_IN_SESSION_STATE", { x01: "set_session_state", pageItems: "#P2_SUPPLIER_ID" }, {dataType: 'text'} ); document.getElementById("myFrame1").src = "f?p=&APP_ID.:0:&SESSION.:APPLICATION_PROCESS=preview_clob_data"; }The above JavaScript code will set the page item value p2_supplier_id including its session state so that the Ajax process can see it.
Very good looks great! Thank you sir!
Hi
I have a question: how can I make a modal window or a form from the region "Preview" so that it opens when the link is clicked.
That is, I want to display the preview only when clicked and in front of the main region and close it after viewing.
I have a slightly different use case where I am generating html content on the fly using PL/SQL code. For some reason, the provided JS code to set the iframe source didn't work. Searched the internet and found it. But this works now: document.getElementById("myFrame1").src = "javascript:'"+html_content+"'";
This is a clever approach, thanks for sharing.
But I'm having an issue, the files keeps getting downloaded in stead of it's contents showing in the preview region.