Server Side Validation - Ajax

Let’s take a scenario where server side validation is required to check whether employee is already in a project or not.

Here I'll explain implementation of avove requirement using Ajax in a Struts 2 application but the concept will be same for any other framework.

Step 1: Using JQuery invoke ajax and based on return value display the proper message to user.

$(document).ready(function(){

         $("#associateID").blur(function(){

                var assId =  $("#associateID");

               

   //checkAssociateId function returns true if employee is already available in DB  

        

               if(checkAssociateId(assId.val())){

                          // Display message and set focus on Associate ID field

                          $('#spnassociateID').html('Associate is already On-boarded'); 

                          $('#spnassociateID').css('color', 'red'); 

                          $('#spnassociateID').css( 'font-size', 'small'); 

                          $("#associateID").focus();

                          return false;

                } else{                      

                         

                          $('#spnassociateID').html('ID is accepted and not available in project data base'); 

                          $('#spnassociateID').css('color', 'green'); 

                          $('#spnassociateID').css( 'font-size', 'small'); 

                           return true;                         

                }          

         })

       })

function

checkAssociateId(id){

        //checkAssociateAjaxCall returns "not-available" if associate id is not present in employee_details

       var

result = checkAssociateAjaxCall(id);

       if

(result.indexOf("not-available")>=0){

            return

false;

       }else

{

            return

true;

   }

}

// checkAssociateAjaxCall actually do the Ajax call

function

checkAssociateAjaxCall(id)

{

// Ajax implementation

    var

result;

    var

xmlhttp;

// random parameter is added to make each request unique other wise cache will automatically take previous result without hitting DB

    var

strURL = "validateAssociateId?associateId="+ id + "&random=" + Math.random(); ;

  if

(window.XMLHttpRequest)

   {

// code for IE7+, Firefox, Chrome, Opera, Safari

          xmlhttp=

new XMLHttpRequest();

   }

   else

 {

// code for IE6, IE5

        xmlhttp=

new ActiveXObject("Microsoft.XMLHTTP");

  }

        xmlhttp.onreadystatechange=

function()

{

if (xmlhttp.readyState==4 && xmlhttp.status==200)

{

      result = xmlhttp.responseText;

}

}

   xmlhttp.open(

"GET",strURL,false);

  xmlhttp.send();

  return result;

}

Step 2: In Above code calling "validateAssociateId" action thus add below piece of code in struts configure xml (struts.xml).

<

action name="validateAssociateId"

class="com.assetman.action.OnboardEmployeeAction" method="validateAssociateId" >

           <result type="stream">

             <param name="contentType">text/html</param>

             <param name="inputName">inputStream</param>

          </result></action>
Step 3:  In OnboardEmployeeAction struts action class define followings

private static String BLANK ="";// declare a inputStream and gette setter for in

private InputStream inputStream;

public InputStream getInputStream() {

return inputStream;

}

Step 4: In OnboardEmployeeAction struts action class define validateAssociateId method

@SuppressWarnings("deprecation")

public String validateAssociateId() throws Exception{

   String result=

BLANK;

// ValidateTask calls validateAssociateId method which returns either "success" or "error"

// PLease implement back end code as per your requirement

  ValidateTask validateTask =  new ValidateTask();

  result = validateTask.validateAssociateId( associateId);

if(result.equals(SUCCESS)){

// inputStream = new ByteArrayInputStream("available".getBytes("UTF-8"));

inputStream = new StringBufferInputStream("available");

}

else{

// inputStream =new ByteArrayInputStream("not-available".getBytes("UTF-8"));

inputStream = new StringBufferInputStream("not-available");

}

return SUCCESS;

}