How to force Marketo to accept a *blank* field

[Sam_Taylor]

Hi, I have a very simple Marketo form where someone fills out (amongst other things) their address.

We use Address Line 1, 2 & 3 rather than the 'Address' field.

On the form, Add 1 & 2 are compulsory fields and 3 is not.

In the following example, someone fills out the form, who is already on the database and has changed address

PREVIOUS VALUES FILLED IN ON FORM

Address Line 1 1 The High Street 21 Harbour Road

Address Line 2 Botley Portsmouth

Address Line 3 Southampton *this field is left blank*

As Marketo will not overwrite actual data with a blank, how can I make sure that Address Line 3 does not stay "Southampton" and becomes a blank?

[SanfordWhiteman]

An excellent question and one that isn't asked enough IMO (that is, people don't understand how the default behavior affects their data health).

A deep explanation is at Clearing lead fields based on unanswered form questions​.

For the case of a text field, use this custom Forms JS code, listing your fields in the emptyToNull array.

MktoForms2.whenReady(function(form) {
   var userConfig = {
      emptyToNull: ["AddressLine2", "AddressLine3"]
   };
   /* --- No need to edit below this line! --- */
   var formEl = form.getFormElem()[0];
   form.onSubmit(function(form) {
      var currentValues = form.getValues(),
         mktoFieldsObj = {};
      Object.keys(currentValues)
         .filter(function(fieldName) {
            return (
               currentValues[fieldName] == "" &&
               userConfig.emptyToNull.indexOf(fieldName) != -1
            );
         })
         .forEach(function(fieldName) {
            mktoFieldsObj[fieldName] = "NULL";
            formEl.querySelector("[name='" + fieldName + "']").style.color = "transparent";
         });
      form.setValues(mktoFieldsObj);
   });
});