Class CustomField

// Logs the label for all the address fields associated with contact
// 'John Doe'. This method can be similarly called for any field that has
// a label.
constcontacts=ContactsApp.getContactsByName('John Doe');
constaddressFields=contacts[0].getAddresses();
for(leti=0;i < addressFields.length;i++){
Logger.log(addressFields[i].getLabel());
}

// Sets the label to 'Apartment' for the first address field associated
// with contact 'John Doe'. This method can be similarly called for any
// field that has a label.
constcontacts=ContactsApp.getContactsByName('John Doe');
constaddressFields=contacts[0].getAddresses();
addressFields[0].setLabel('Apartment');

constcontacts=ContactsApp.getContactsByName('John Doe');
constfields=contacts[0].getCustomFields();
for(leti=0;i < fields.length;i++){
if(fields[i].getLabel()==='foo'){
fields[i].deleteCustomField();
}
}

// Logs the value of all the custom fields for contact 'John Doe'
constcontacts=ContactsApp.getContactsByName('John Doe');
constfields=contacts[0].getCustomFields();
for(constiinfields){
Logger.log(fields[i].getValue());
}

// Sets the first custom field associated with contact 'John Doe' to use 'Mail
// application' as a label, with 'Gmail' as the value.
constcontacts=ContactsApp.getContactsByName('John Doe');
constfield=contacts[0].getCustomFields()[0];
field.setLabel('Mail application');
field.setValue('Gmail');

// Sets the first custom field associated with contact 'John Doe' to use 'Mail
// application' as a label, with 'Gmail' as the value.
constcontacts=ContactsApp.getContactsByName('John Doe');
constfield=contacts[0].getCustomFields()[0];
field.setLabel('Mail application');
field.setValue('Gmail');