How to populate a field on change of another field's value?

[Linda6]

Hello, 

I'm new to coding and I would very much like to ask you for help.

I need to develop a client script running on change request table, which checks for the value of the field 'cmdb_ci' and when it changes, the CI's GMP Approval Group's value will be populated in the 'u_gmp_approval_group' field.

Some CI's do have this GMP Approval Group filled in, some of them don't.

How do I do this correctly, please?

There's is an existing display BR for this, but the client wants to have it covered with client script instead.

Here's the form:

And here's my sad onChange client script code:

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
    if (isLoading || newValue === '') {
        return;
    }

    if (!g_form.isNewRecord())
        return;

    var businessService = g_form.getValue('business_service');
    var cmdbCi = g_form.getValue('cmdb_ci');
    var serviceOffering = g_form.getValue('service_offering');
    var gmpApprovalGroup = g_form.getValue('u_gmp_approval_group');

//the code needs to compare the fields Business Service, Service Offering and Configuration item
//they have different priority, the highest is Configuration item and if that one has got a value, then that will be used
//if there is no value in Configuration item's GMP Approval Group field, then the value of the Service Offering's GMP Approval Group will be used
//if there is no value in the Service offering's GMP Approval Group field, then the value of the Business Service's GMP Approval will be used

    if (cmdbCi.u_gmp_approval_group !== '') {
        g_form.setValue('u_gmp_approval_group', cmdbCi.u_gmp_approval_group);
    } else if (cmdbCi.u_gmp_approval_group == '' && serviceOffering.u_gmp_approval_group !== '') {
        g_form.setValue('u_gmp_approval_group', serviceOffering.u_gmp_approval_group);
    } else if (cmdbCi.u_gmp_approval_group == '' && businessService.u_gmp_approval_group !== '') {
        g_form.setValue('u_gmp_approval_group', businessService.u_gmp_approval_group);
    }

}

Thank you very much for any help, very appreciaed

[Jaspal Singh · Accepted solution]

Try below

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
    if (isLoading || newValue === '') {
        return;
    }

    if (!g_form.isNewRecord())
        return;

    var businessService = g_form.getValue('business_service');

//changed
    var cmdbCi = g_form.getReference('cmdb_ci',callbackme);


    var serviceOffering = g_form.getValue('service_offering');
    var gmpApprovalGroup = g_form.getValue('u_gmp_approval_group');


function callbackme(cmdbCi)
{
 var grpis=cmdbCi.u_gmp_approval_group; //ensure here the u_gmp_approval_group field is the name of field on the cmdb_ci table

 g_form.setValue('u_gmp_approval_group',grpis); //ensure here the u_gmp_approval_group field is the name of field on change table
}


}

[Linda6]

Thank you very much, Jaspal!