Tag: Form Validation

“The best preparation for good work tomorrow is to do good work today.”
— Elbert Hubbard

At the end of the last installment in this series, I mentioned two possible options for the next item on which to focus our energies. At the time, I wasn’t really sure which direction would be the preferable choice, but now that it is time to fish or cut bait, a decision needs to be made. Given that the entire purpose of this exercise is to demonstrate the use of Event Management practices on internal ServiceNow processes, I believe it would be good to go ahead and wrap up our example Use Case at this point so that we can devote the remainder of our time exclusively on the Event Management aspects. All that is really left to do in order to to complete our address verification scenario is to add the form validation to the User Profile form. That process will leverage the new Script Include and Outbound REST Message that we have already completed.

There are two different ways that we can go about this: we can use an onSubmit Business Rule on the server side, or we can use an onSubmit Client Script on the client side. The Business Rule route is actually a little easier, as you have access to both the current and previous versions of the GlideRecord, and you can call the Script Include directly, without the need for GlideAjax. My problem with that, though, from a User Experience perspective, is that you have to submit the entire form to the server for processing, which then gets reloaded if you have validation issues. My preference is to validate the form right where it sits on the client side, before the form ever gets submitted to the server. For that, we need to build a Client Script.

In fact, for our purpose, we will need two Client Scripts, one an onLoad script and the other an onSubmit script. The reason that we have to have an onLoad script is because you do not have access to the previous field values on the client side like you do with a server-side Business Rule. We will need to snag those values and stuff them somewhere for safekeeping as soon as the form loads. The ServiceNow platform provides a place for just that sort of thing called the g_scratchpad. You can pretty much throw whatever you want in there and it will be available for use until the form is reloaded. The entire onLoad script is just a few short lines of code.

function onLoad() {
	g_scratchpad.originalStreet = g_form.getValue('street');
	g_scratchpad.originalCity = g_form.getValue('city');
	g_scratchpad.originalState = g_form.getValue('state');
	g_scratchpad.originalZip = g_form.getValue('zip');
}

That’s all there is to that. With those initial values safely tucked away, we can then pull them back out later on and refer to them in our onSubmit script to see if anything has changed. Before we start in on our onSubmit script, however, we need to go back to our Script Include and add just a bit of code. When we first built out Script Include, we did not set it up to be client callable, but we are going to need to do that now so that we can access it via GlideAjax. It’s a simple checkbox on the Script Include form, which triggers a slight change in the prototype for the script. That change is handled automatically for any new script, but since we have been working on ours for a while, checking the box may not actually alter any modified code. In that case, you just need to modify the prototype line yourself to look like this:

AddressValidationUtils.prototype = Object.extendsObject(AbstractAjaxProcessor, {

Also, you will need to go down to the very bottom of the script and insert a closing paren in between the final curly brace and the terminating semi-colon. Once that’s done, we can add a new function that we can call from the client side.

validateAddressViaClient: function() {
	var street = this.getParameter('sysparm_street');
	var city = this.getParameter('sysparm_city');
	var state = this.getParameter('sysparm_state');
	var zip = this.getParameter('sysparm_zip');
	return JSON.stringify(this.validateAddress(street, city, state, zip));
},

This function just grabs all of the parameters passed via GlideAjax and passes them to our existing function, and then turns the response object into a string that can be returned in the XML Ajax response. Now we are all set up to receive calls from the client side.

Being a validation script, our onSubmit script will need to prevent the submission of the form in the event that any validation errors are detected. Without an Ajax call back to the server, that’s easily accomplished by returning false from the onSubmit function. However, making an asynchronous Ajax call means you are leaving your function without the answer in hand, so you don’t know whether or not any issues were detected until the response comes back, which will be in a completely different thread. Although you could utilize the getXMLWait() method to simply wait for the answer, that approach is quite frowned upon in Client Scripts for a variety of reasons, so we do not want to go down that road. Instead, we will use a modified version of this technique.

The approach is to cancel submission of the form before making the Ajax call, and then when the response comes in, submit the form a second time if all is well. Of course, submitting the form again will launch the onSubmit script again, so we need to make it smart enough to know that this is the second submit and to not start the whole process all over again. To accomplish that, we use yet another g_scratchpad property to let the script know that validation has already taken place. Here is the main onSubmit script:

function onSubmit() {
	var submitForm = true;

	var actionName = g_form.getActionName();
	if (!g_scratchpad.isFormValid) {
		submitForm = checkAddress();
	}

	return submitForm;
}

On the first submit, we default the submitForm variable to true, capture the name of the button that was pushed to submit the form so that we can use it when we submit again later, and then check to see if validation has already taken place and passed by testing the isFormValid scratchpad property. In the case of the first submit, isFormValid has not been set to true, so we check the address to see if it needs validated. If it does, then the submitForm variable will be set to false, and the form will not be submitted.

Assuming that it does need to be validated, the checkAddress function will make the Ajax call and cancel the original form submission by returning false. When the Ajax response comes in, if the address is valid, the response function will then submit the form a second time using the saved actionName after setting the isFormValid scratchpad property to true. When the onSubmit function then starts again due to the second submit, it will bypass the address check and simply allow the form to submit due to the isFormValid scratchpad property being set to true.

It’s all a little convoluted, but it works. Here is the checkAddress function:

function checkAddress() {
	var submitForm = true;

	var street = g_form.getValue('street');
	var city = g_form.getValue('city');
	var state = g_form.getValue('state');
	var zip = g_form.getValue('zip');
	if (street || city || state || zip) {
		if (street != g_scratchpad.originalStreet || city != g_scratchpad.originalCity || state != g_scratchpad.originalState || zip != g_scratchpad.originalZip) {
			GlideUI.get().clearOutputMessages();
			var ga = new GlideAjax("AddressValidationUtils");
			ga.addParam('sysparm_name', 'validateAddressViaClient');
			ga.addParam('sysparm_street', street);
			ga.addParam('sysparm_city', city);
			ga.addParam('sysparm_state', state);
			ga.addParam('sysparm_zip', zip);
			ga.getXMLAnswer(processXMLAnswer);
			submitForm = false;
		}
	}

	return submitForm;
}

Just like in the main onSubmit function, we first default the submitForm variable to true, and then we grab all of values for the four address components off of the g_form object. The first thing that we check is if there is even any data in any of the four fields. If they are all empty, then there is nothing to validate. If there is some data there, then the next thing that we check is if it is any different than the values that we squirreled away in our onLoad script. If there are no changes, then again there is no need for validation. But if there is data there and it has changed in any way, now we are going to be making that GlideAjax call. Most of that is pretty standard GlideAjax stuff, but we also clear out any error messages on the screen from previous attempts and set the submitForm variable to false to kill the original form submission.

To process the Ajax response, we have yet another function, processXMLAnswer:

function processXMLAnswer(answer) {
	var response = JSON.parse(answer);
	if (response.result == 'invalid') {
		g_form.addErrorMessage('Unable to verify address entered using the US Address validation service');
		g_form.showFieldMsg('street', 'Unverifiable address', 'error');
		g_form.showFieldMsg('city', 'Unverifiable address', 'error');
		g_form.showFieldMsg('state', 'Unverifiable address', 'error');
		g_form.showFieldMsg('zip', 'Unverifiable address', 'error');
	} else {
		if (response.result == 'valid') {
			g_form.setValue('street', response.street);
			g_form.setValue('city', response.city);
			g_form.setValue('state', response.state);
			g_form.setValue('zip', response.zip);
		}
		g_scratchpad.isFormValid = true;
		g_form.submit(actionName);
	}
}

The response comes back in the form of a string, so the first thing that we have to do is convert it back to an object. If the result property of that object is ‘invalid’, then we leave the form unsubmitted and throw a few error messages up on the screen; otherwise, we are going to submit the form a second time. But before we do that, we check to see if the result property is ‘valid’, in which case we overlay the user’s input with the clean address values returned by the service. After that , we set our isFormValid scratchpad property to true and resubmit the form using the saved actionName.

It’s all a little complicated, having to pass through the onSubmit script twice due to the double submit, but it all makes sense if you really think about it. Of course, we won’t really know if it works until we try it, so let’s pull up a user’s profile and give it a shot.

For our first test, let’s see if we can get a validation error. We can use the test address that we have been using up to this point, but let’s change the state from FL to TX and let’s drop the zip code entirely. Also, let’s put everything in lower case, just for fun. OK, let’s see what happens.

Having both form-level and field-level error messages is probably a little overkill, but everything seems to have worked. Now, let’s change the state back to FL and see if that is enough to consider it a valid address.

Not only did it pass validation, it also corrected our capitalization and added the missing zip code. That’s actually pretty slick. This wasn’t really the point of this series, but I like this address validation feature. I was originally just looking for something that might have a failure to showcase the Event Management stuff, but this turned out to be a pretty handy little addition that could be useful in a number of other places, such as the Building and Location forms.

This now completes the example working feature that has the potential for failure. From this point on, we can focus on what we came here for, which is to log and process Events that originate in ServiceNow. Next time out, we will start in on the logging.