In addition to the visible fields of your campaign forms, BDOW! allows you to create hidden fields. They are a great way to include relevant information about your subscribers beyond what is obtainable via a data form, such as a referral URL or country of origin (see our detailed article on input fields for more information).

You can leverage hidden fields to pass query parameters and cookie values on each form submission. Thus, the first step is opening the designer and adding a hidden field:

Since the exact values are determined dynamically from the state of the subscriber's browser, we'll wrap the values in {}, too.

In order to pass the value of a query parameter, simply create a variable value starting with the word, query, followed by an underscore and the name of the query parameter.

For example, assume you wanted to pass the utm_campaign parameter with a value of "bdow". Your webpage's URL would look like this: http://www.mysite.com?utm_campaign=bdow. To capture this information in the form submission, create a variable with a value of {query_utm_campaign}. Broken down piece by piece:

When the form is submitted, the subscriber data will include a utm_param field with the value pulled from the utm_campaign parameter ("bdow"):

In order to pass the value of a cookie, create a variable value starting with the word, cookie, followed by an underscore then the name of the cookie.

For example, if you wanted to include the value of a cookie named existingSubscriber, you would create the hidden field {cookie_existingSubscriber}, which is composed of:

Suppose the value of the cookie is false. The resulting subscriber data, after submission, would be: