oracle apex ajax process + dy check

At present, the back-end verification of apex, that is, after the user enters, click submit to trigger the verification with the back-end server. In order to improve the user experience, this step can be pre-empted, and the js event can be used to trigger the back-end verification to monitor the user name. Is it repeated as an example.
The demo environment is apex 20.2

Create an Ajax process

DECLARE
   l_count NUMBER := 0;
BEGIN
   --名称重复校验
   IF :P5_1 IS NOT NULL THEN
      SELECT COUNT(1)
        INTO l_count
        FROM 666 v
       WHERE v.1 = :P5_1
             AND ROWNUM = 1;
      IF l_count > 0  THEN
         htp.p('客户:' || :P5_1 || '已存在');
      ELSE
         htp.p('success');
      END IF;
   END IF;

   --号重复校验
   IF :P5_2 IS NOT NULL THEN
      SELECT COUNT(1)
        INTO l_count
        FROM 666 v
       WHERE v.2 = :P5_2
             AND ROWNUM = 1;
      IF l_count > 0  THEN
         htp.p('已存号为:' || :P5_2|| '的客户!');
      ELSE
         htp.p('success');
      END IF;
   END IF;

END;

First create a process directly in the process, and then select ajax as the location. Note that the pl/sql must have a return value, and the subsequent js needs to be judged according to the return value.
Note: There will be a space or a tab after the print of htp.p, js needs to consider the string de-space operation when judging. Or you can print json directly in this place (attend the errata at the end of the article)

Create a dynamic action on the corresponding form page item

js event selection change (onchange) or loss of focus (onblur), the real operation is to execute js code

apex.server.process('ajax_validate_customer_repeat',//这儿的名称为process的名称
    {
    
    
        pageItems: '#P5_PARTY_NAME'//注意带#号
    }
    ,
    {
    
    
        dataType: 'text', success: function (data) {
    
    
            
            if (  /*data*/ data.trim() != 'success') {
    
    //用htp.p打印的后面带一个空格，不知道为啥，此处要注意，也可以用apex封装的api直接打印json
                apex.message.clearErrors();
                apex.message.showErrors([
                    {
    
    
                        type: "error",
                        location: ["page", "inline"],
                        pageItem: "P5_PARTY_NAME",
                        message: data,
                        unsafe: false
                    }/*,
                    {
                        type: "error",
                        location: "page",
                        message: data,
                        unsafe: false
                    }*/
                ]);
            }
            else 
            {
    
    
                apex.message.clearErrors();
            }
        }
    }
)

The effect is as follows

Subsequent improvement

The repeated verification can be packaged separately into a js function

function repeat_validate(page_item_name) {
    
    
   apex.server.process('ajax_validate_customer_repeat',
      {
    
    
         pageItems: "#" + page_item_name
      }
      ,
      {
    
    
         dataType: 'text', success: function (data) {
    
    

            if (  /*data*/ data.trim() != 'success') {
    
    
               apex.message.clearErrors();
               apex.message.showErrors([
                  {
    
    
                     type: "error",
                     location: ["page", "inline"],
                     pageItem: page_item_name,
                     message: data,
                     unsafe: false
                  }
               ]);
            }
            else {
    
    
               apex.message.clearErrors();
            }
         }
      }
   )
}

Put the above js into the page "JavaScript" function and global variable declaration.

Then on the form item to be validated "Advanced" customization: οnchange="repeat_validate('P5_XXX');"

In this way, common use is realized, and no dynamic operations need to be defined on this page item.

Reference documents:

https://apex.oracle.com/pls/apex/germancommunities/apexcommunity/tipp/3341/index-en.html

https://www.foxinfotech.in/2020/04/oracle-apex-validation-without-submit-using-javascript-and-ajax-callback.html

json

Implemented without dynamic operations

Errata

There are differences between htp.p, htp.print, and htp.prn:

HTP.p is a shortcut (undocumented) to htp.print. HTP. Print adds a new line to the output.
HTP. PRN does not add a line break.

htp.p and htp.print will automatically have one more /n in the back,
hpt.prn will not have more /n

https://docs.oracle.com/database/121/ARPLS/w_htp.htm#ARPLS70586