Forms 2.0 API — AddHiddenFields() and Checkboxes

[jtremblay]

I'm working on our implementation of background form submission as described in this Marketo blog post, and suggested to us by their support team.

In doing so, we've run into a challenge (which was noted as "not so easy" in this previous forum answer).  We need to submit a checkbox group through a background form submission.

I've tried adding multiple checked values one at a time using `addHiddenFields()`...

myMktoForm.addHiddenFields( 'My_Field_Name', 'Checked Value 1' );
myMktoForm.addHiddenFields( 'My_Field_Name', 'Checked Value 2' );
myMktoForm.addHiddenFields( 'My_Field_Name', 'Checked Value 3' );

But when I call `getValues()` I only see the last one...

{
  My_Field_Name: 'Checked Value 3'
}

I've also tried adding them as an array...

myMktoForm.addHiddenFields( 'My_Field_Name', [
  'Checked Value 1',
  'Checked Value 2',
  'Checked Value 3'
);

In that case the values in the array get merged into a comma-separated string...

{
  My_Field_Name: 'Checked Value 1,Checked Value 2,Checked Value 3'
}

So next, I tested a checkbox group on a Marketo landing page to see how the values were handled. If I add a checkbox group on a Marketo landing page, check some values, then call `getValues()`, the values appear to be kept as an array, not merged into a string...

{
  My_Field_Name: [
    'Checked Value 1',
    'Checked Value 2',
    'Checked Value 3'
  ]
}

So I'm a bit stuck at how to reproduce the expected behavior before submitting the background form... is there a clever way to add a hidden field containing an array of values using the Forms2 API?

[SanfordWhiteman]

If a field isn’t on the form, then it isn’t actually a Checkboxes group — <input type="hidden"> is equivalent to <input type="text" hidden>.

let serializedMultiString = ['Checked Value 1','Checked Value 2','Checked Value 3'].join("; ");
myMktoForm.addHiddenFields({
  My_Field_Name : serializedMultiString
});

[jtremblay]

Thanks for the tip @SanfordWhiteman, I'll try that approach and report back.