Apex.ajax.clob - retrieving data from a clob field

Question

I have an application that uses a table that stores xml data, and the field in the table that stores the data is a clob. I used Carl Backstrom's example to build what I have so far, (God's blessings on his family). Here is the script I use to store the data from an HTML Editor into the database:
function clob_set(request){
var oEditor = FCKeditorAPI.GetInstance('P59_CONTENT');
var clob_ob = new apex.ajax.clob(
function(){
var rs = p.readyState
if(rs == 1||rs == 2||rs == 3){
$x_Show('AjaxLoading');
}else if(rs == 4){
$x_Hide('AjaxLoading');
$s('P59_CONT', p.responseText);
doSubmit(request)
}else{return false;}
$x('P59_CONT').value = oEditor.GetHTML();
oEditor.SetHTML('');
if(!$v_IsEmpty('P59_CONT')){clob_ob._set($v('P59_CONT'))};
The submit calls a process that inserts the data from the clob001 field in the CLOB_CONTENT collection into my table.
How do I get the data out of the table again to present in the HTML Editor? Each option I use gets me into trouble with the 32k length limitation that is extant in Apex. What would be the best way to address this?

Answer 1

Inserting or retrieving a clob in the database is simple and can be done with a pl/sql process. It gets more more complex when the clob is large; I believe the limit is 32k? Larger than that and the HTTP process cannot manipulate the data stream.
The key to manipulating clobs successfully is through the use of collections, and javascript. In my case, I used the standard html editor item (fckeditor) to retrieve the data and present it on the page through the apex.ajax.clob javascript function. The clob_set method in the apex.ajax.clob function that I mention in the previous sections of this post calls the 'doSubmit(request)' that causes a pl/sql function to be fired that writes the clob to the database from the collection created by the clob_get method. The collection that the clob_get method creates is called 'CLOB_CONTENT', and can be accessed through the 'apex_collections' view through standard sql within APEX. In my case, the pull the 'clob001' field from the 'CLOB_CONTENT' collection after the clob_set method runs, and I insert the value from 'clob001' into the table I have created for storing the clob content. The clob_set pulls the data from the HTML editor (FCKeditorAPI.GetInstance('P59_CONTENT')) through the GetHTML() method that is part of the FCKeditorAPI.
function clob_set(request){
var oEditor = FCKeditorAPI.GetInstance('P59_CONTENT');
var clob_ob = new apex.ajax.clob(
function(){
var rs = p.readyState
if(rs == 1||rs == 2||rs == 3){
$x_Show('AjaxLoading');
}else if(rs == 4){
doSubmit(request);
$x_Hide('AjaxLoading');
}else{return false;}
var p_html = oEditor.GetHTML();
if (p_html){
clob_ob._set(p_html);
else {
p_html = ' '
clob_ob._set(p_html);
The clob_get method pulls the data from the 'CLOB_CONTENT' collection and puts it into the html editor item I have created, performing the process in reverse. The primary difference with reversing the process is that a pl/sql function is created that populates the clob001 field in the 'CLOB_CONTENT' collection prior to the clob_get function firing:
declare
l_clob clob:= empty_clob();
begin
if apex_collection.collection_exists(p_collection_name=>'CLOB_CONTENT') then
apex_collection.delete_collection(p_collection_name=>'CLOB_CONTENT');
end if;
apex_collection.create_or_truncate_collection(p_collection_name=>'CLOB_CONTENT');
dbms_lob.createtemporary( l_clob, false, dbms_lob.SESSION );
if trim(:P123_ID) <> 0 then
select
nvl (ltr,'There is no letter assigned.')
into
l_clob
from grant_tbl
where id = to_number(:P123_ID);
apex_collection.add_member(p_collection_name => 'CLOB_CONTENT'
,p_clob001 => l_clob
ELSE
apex_collection.add_member(p_collection_name => 'CLOB_CONTENT'
,p_clob001 => 'You must select an item to view its letter.');
end if;
end;
The clob_get function is below. Notice that the line "$s('P123_CONTENT',p.responseText);" is taking the output from the clob_get and setting the value of the P123_CONTENT page item (which is my standard html editor item) with the 'responseText'. the 'p' object and the 'responseText' method are built into the clob_get function when a 'new apex.ajax.clob' object is created. Confusing? Tell me about it!
function clob_get(){
var clob_ob = new apex.ajax.clob(
function(){
var rs = p.readyState
if(rs == 1||rs == 2||rs == 3){
null;
}else if(rs == 4){
$s('P123_CONTENT',p.responseText);
null;
}else{return false;}
clob_ob._get();
}