blank fields in ODATA webservice


i'm testing a page, that is exposed as odata webservice. it does simple insert operation on customer table. However, i noticed, when sending a blank value(fx. blank address) to NAV. the field validate trigger does not trigger? i used testfield and tried to throw an error if the field is empty.the trigger does not fire, it seems like the webservice skips blank fields.

is there a way to measure if a field is blank, when sending from webservice?

it is a must to use ODATA. therefor, SOAP cannot be used.