Hello Mouhamadou,
This is actually a difficult thing to achieve. The newValue as passed into a client script for a reference field will be either the string of the sys_id of the referenced record, or it will be a blank string. The only way to tell whether the user has blanked out the value or entered an invalid value would be to get the actual display control and check. An additional problem is that the onChange script will be called twice when the value is invalid.
These are not insurmountable problems You could use some DOM scripting to work around this, but you must be careful to test thoroughly. Since you will need to do direct DOM manipulation, you should be aware that a customization like this can stop working when the ServiceNow UI is updated. It will be up to you to maintain the functionality if ServiceNow changes the way forms are rendered.
That said, here is an example client script which implements some of the functionality.
function onChange(control, oldValue, newValue, isLoading, isTemplate) {
if (isLoading) {
return;
}
//The new value could be blank because the actual value is blank, or because the user entered an invalid value
if (newValue == '') {
var id = control.id;
id = id.split('.').join('\\.');
id = '#sys_display\\.' + id;
var elem = ($j(id));
var val = elem.val();
//don't run if it's not invalid
if (!elem.hasClass("ref_invalid"))
return;
//it's a legit empty value (should be caught by above check, but just to be safe)
if (!val)
return;
//we might be in the second call
if (window.invalidReferenceValue == val)
return;
//store the value so we can compare on the second time through
window.invalidReferenceValue = val;
setTimeout(function () {
g_form.setValue("cmdb_ci", "");
g_form.showFieldMsg("cmdb_ci", "The Configuration Item you entered does not exist. Please use the magnifying glass to choose from a list of acceptable values", "error");
});
}
}
Again, maintaining a script like this will be your responsibility, since it steps well outside the bounds of the standard g_form API.
Thanks
Cory
