Hidden Metadata Fields can be used to capture metadata about the form submission, such as the URL referrer or supporter’s affiliate ID. These inputs do not display on the supporter-facing form.
You can create Hidden Metadata Fields in Online Actions on the Settings tab. There, you can define the Identifier, Display Name, and Description. Note that the Identifier is an alphanumeric value that always starts with “oa_”, cannot contain any spaces, and is case-insensitive.
Once created, the hidden input is available on every form without the need to republish.
A query string is ideal when the same value should be applied to all supporters coming from the same link, such as from an email or ad. To populate a Hidden Metadata Field using a query string, use the Identifier as the “name” portion of the name-value pair. Example:
oa_visitor_id Hidden Metadata Field.