Change text item size and maxlength dynamically

I just wrap up solution from this OTN forum post here.

If you need change item size dynamically based on some value e.g. select list, I did find it is good store values, item names and size to own table.

I did create table, sequence and trigger:

CREATE TABLE DEMO_ITEM_DYN_SIZE(
    PK_ID        NUMBER NOT NULL,
    LOV_VALUE    VARCHAR2(2) NOT NULL,
    ITEM_NAME    VARCHAR2(80) NOT NULL,
    ITEM_SIZE    NUMBER NOT NULL,
    CONSTRAINT DEMO_ITEM_DYN_SIZE_PK PRIMARY KEY(PK_ID)
);

CREATE SEQUENCE DEMO_ITEM_DYN_SIZE_SEQ NOCACHE;

CREATE OR REPLACE TRIGGER DEMO_ITEM_DYN_SIZE_TRG
BEFORE INSERT ON DEMO_ITEM_DYN_SIZE FOR EACH ROW 
BEGIN 
  IF inserting THEN
    IF :NEW.PK_ID IS NULL THEN
      SELECT DEMO_ITEM_DYN_SIZE_SEQ.nextval
      INTO :NEW.PK_ID
      FROM DUAL ;
    END IF;
  END IF;
END;
/

Insert some data to table:

INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('IN', 'P214_ATTRIBUTE_1', '15');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('IN', 'P214_ATTRIBUTE_2', '10');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('IN', 'P214_ATTRIBUTE_3', '5');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('IN', 'P214_ATTRIBUTE_4', '8');

INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('US', 'P214_ATTRIBUTE_1', '5');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('US', 'P214_ATTRIBUTE_2', '10');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('US', 'P214_ATTRIBUTE_3', '2');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('US', 'P214_ATTRIBUTE_4', '8');

INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('CN', 'P214_ATTRIBUTE_1', '1');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('CN', 'P214_ATTRIBUTE_2', '5');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('CN', 'P214_ATTRIBUTE_3', '8');
INSERT INTO DEMO_ITEM_DYN_SIZE(LOV_VALUE,ITEM_NAME,ITEM_SIZE)
VALUES ('CN', 'P214_ATTRIBUTE_4', '10');

COMMIT;

Create On Demand Process GET_ITEM_SIZE:

DECLARE
  l_sql VARCHAR2(32700);
BEGIN

  l_sql := '
    SELECT item_name,
      item_size
    FROM demo_item_dyn_size
    WHERE lov_value = :P214_COUNTRY'
    ;
   APEX_UTIL.JSON_FROM_SQL(l_sql);

EXCEPTION WHEN OTHERS THEN 
  HTP.PRN('{"row":[]}');
END ;

Remember change P214_COUNTRY according your select list name.

Insert to page JavaScript Function and Global Variable Declaration:

function getItemSize(pThis){
 var lVal=$v(pThis),
 lId=$x(pThis).id;
 if(lVal!="%"+"null%"&&lVal){
  $.ajax({
   url:"wwv_flow.show",
   dataType:"json",
   traditional:true,
   cache:false,
   type:"POST",
   data:{
    p_flow_id:"&APP_ID.",
    p_flow_step_id:"&APP_PAGE_ID.",
    p_instance:"&APP_SESSION.",
    p_request:"APPLICATION_PROCESS=GET_ITEM_SIZE",
    p_arg_names:lId,
    p_arg_values:lVal
   },
   success:function(jd){
    if(jd.row.length==0){
     $("#R_DYN_SIZE input[type='text']").attr({"size":30,"maxlength":30});
     return;
    }
    $.each(jd.row,function(i,jr){
     $($x(jr.ITEM_NAME)).attr({"size":jr.ITEM_SIZE,"maxlength":jr.ITEM_SIZE});
    });
   }
  });
 }else{
  $("#R_DYN_SIZE input[type='text']").attr({"size":30,"maxlength":30}).val("");
 }
}

Insert to page JavaScript Execute when Page Loads:

$("#P214_COUNTRY").change(function(){
 getItemSize(this);
}).trigger("change");

Remember change P214_COUNTRY according your select list name.

Above JavaScript code should set default length for text items, if select list value is null. In example I set all text items on region at once. For that you need set region static id "R_DYN_SIZE".

I did also create validation for each text item to check length is what specified on control table.

Validation Function Returning Boolean

DECLARE
  l_size NUMBER;
BEGIN
  BEGIN
    SELECT item_size
    INTO l_size
    FROM demo_item_dyn_size
    WHERE item_name = 'P214_ATTRIBUTE_1' -- Text item
      AND lov_value = :P214_COUNTRY      -- Select list
    ;
  EXCEPTION WHEN NO_DATA_FOUND THEN
    /* Default size */
    l_size := 30;
  END;

  IF LENGTH(:P214_ATTRIBUTE_1) > l_size THEN
    RETURN FALSE;
  END IF;
  RETURN TRUE;
END;

Remember change P214_COUNTRY according your select list name and P214_ATTRIBUTE_1 according text item name.