In Form Editor, “null” isn’t the same as NULL (huh?)
You don’t really know Marketo forms until you grok the differences between these 3 form field setups:
Setup #1
This first screenshot is what you get simply by adding a field and flipping its type to Hidden.The field is set to have an empty string as the default value, as you can see in the field details:
However, if you don’t pop up the details, Marketo displays the default value as the string “null”. This can be confusing, as the actual value sent is the empty string “”. (Remember that form fields are always sent as strings, regardless of the back end datatype.)
What’s the difference? It’s huge! Sending an empty string does not change the existing value in the Marketo database. Sending the magic string “null” (or capital “NULL” or “Null”, it’s not actually case-sensitive) erases the current value.[1]
So at a glance, you might think the hidden field is going to nullify/empty out the server value.
