For those of you that are not familiar with GlideAjax. getXMLWait() is a Synchronous GlideAjax call. Meaning your script cannot continue without the GlideAjax response. This stops the session until the response is received.

How to use getXMLWait

Scenario

If we look at a scripting example. Lets say we want to do some checks onSubmit of a Catalog item. In our case, we want to validate the user is part of a company. If the user is not part of the company, we want to abort the Catalog Item request and show an error message. To do this, we can use a Script Include to handle the Server lookup and an onSubmit Catalog Client script that prevents submission. We do not want to continue submission until we get a response from the Server back, stating it is alright.

The script

To do this we can write the following Client Callable script include. If you want to do a different validation, you can change it.

var catItemHelper = Class.create();
catItemHelper.prototype = Object.extendsObject(AbstractAjaxProcessor, {

    checkCompany: function () {
        var answer = false;
        var user = this.getParameter('sysparm_user');
        var gr = new GlideRecord('sys_user');
        gr.addQuery('sys_id', user);
        gr.addQuery('company.name', "ACME North America");
        gr.query();
        if (gr.next()) {
            answer = true;
        }
        return answer;
    },

    type: 'catItemHelper'
});

As an onSubmit client script we have the following script:

function onSubmit() {
    var user = g_user.userID;
    var ga = new GlideAjax('catItemHelper'); //Name of the Script Include 
    ga.addParam('sysparm_name', 'checkCompany'); //name of function in script include 
    ga.addParam('sysparm_user', user);
    ga.getXMLWait();
    var answer = ga.getAnswer();
    if (answer == 'false') {
        g_form.addErrorMessage('Only users from company ACME North America are allowed');
        return false;
    }
}

The result

User has company "ACME North America":

User does not have company "ACME North America":

The issue

getXMLWait() is not supported by the Service Portal:

https://docs.servicenow.com/bundle/orlando-servicenow-platform/page/build/service-portal/reference/c...

When we try the same item in the Service Portal we get the following:

In the console:

To prevent the error from appearing we can set our Client Script as UI Type Desktop. Because that is where the script is working:

We do not get the popup anymore, but the validation is also not happening anymore on the Service Portal.

Asynchronous Ajax call

In the Service Portal Asynchronous Ajax calls are supported.

The issue with these Asynchronous Ajax calls however, is that the script will not wait for the Server response. Meaning the Catalog Item will continue to be submitted, before we have a response back from the Server. So the validation we want will not work.

The solution

When the user clicks the submit button, we can return false, which will stop submission. We also trigger the Ajax call to the server. In the Callback function that handles the response (asynchronous) we can trigger the Submit from script again. But this time, if the response from the Server is not false, we set g_scratchpad.isFormValid to true. Which results in the script returning true and allowing us to submit the item.

To do this we add the following onSubmit Catalog Client Script. UI Type: Mobile/Service Portal:

function onSubmit() {
    if (g_scratchpad.isFormValid)
        return true;
    var user = g_user.userID;
    var ga = new GlideAjax('catItemHelper'); //Name of the Script Include 
    ga.addParam('sysparm_name', 'checkCompany'); //name of function in script include 
    ga.addParam('sysparm_user', user);
    ga.getXMLAnswer(setAnswer);
    return false;


    function setAnswer(answer) {
        if (answer == 'false') {
            g_form.addErrorMessage('Only users from company ACME North America are allowed');
            return false;
        }
        var actionName = g_form.getActionName();
        g_scratchpad.isFormValid = true;
        g_form.submit(actionName);

    }
}

The result

User has company "ACME North America":

User does not have company "ACME North America":