Unchecked checkbox on form is setting values to false/no

Hi Megan,

Indeed, a checkbox on a form behaves in a very binary way, so it is true or it is false and nothing in the middle.

I have achieved what you are looking for in different variations using a second "mirror" field for the Opt-in checkbox. A few ways in which you could use this:

• Add the mirror field as hidden field on your form and add a visibility rule to the Opt-in checkbox to only show if the mirror field is set to false. That way, your lead does not even see the checkbox if they already opted in before.
• Simply use the mirror field visibly on the form and let the real Opt-in field update or not depending on what happens with the mirror field.

I'm sure there are other ways to achieve this as well, but these have always delivered reliable results. Hope it helps.

Like Katja says, this is longtime Marketo behavior.

There's good reason (until you're familiar with Marketo's implementation, of course!) to expect that an unchecked <input type="checkbox"> will not be posted to Marketo at all, because pure HTML forms do work this way.

In a vanilla HTML form, an unchecked checkbox is skipped and not sent to the server. There's also no 3rd state: the field is either (1) unchecked = not sent to the server or (2) checked = sent to the server with the current field name and value. The HTML5 standard even remarks about it only having 2 states:

On a Marketo form, the standard Checkbox also only has 2 possible states. But they're not the same 2 states. In Marketo, the field is either (1) unchecked = sent to the server as "no" or (2) checked = sent to the server as "yes".

As you can see, there are 3, let's say "interesting" things that a checkbox can mean in general, but on any given form it can only mean 2 of those 3 things.

There's an interesting solution that avoids the need for the proxy field as Katja mentions (though that would also work). You need to use the Checkboxes field type, not Checkbox, but with only a single checkbox. And set the value of the checkbox to

that's the string "truthy" with no quotes.

Then the value will be updated to true if the checkbox is checked, but otherwise ignored. However, if you do use this method, note that standard Form Pre-Fill will then not work on its own, that is, the checkbox won't be pre-checked — you'd need a line or two of JS to fix that up.

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We want to make it work so this field is not overwritten or modified in any way if the checkbox is unchecked.  

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So for already opted-in persons you want to make the checkbox meaningless. Regardless what they do, they stay opted in. That doesn't make much sense, does it? Why do you show them the checkbox then?

Yes, I know, this is a legal question, and who wants to tread on that territory? But I personally don't like the way these check-boxes are treated. Show them - unchecked - for the unknown person and hide them for the known person. "Known" pretty much equals "opted in" here, because the box can only be hidden if they click through from a Marketo email, so they must be subscribed.

There are some great, creative solutions in these replies!  Thanks all!  

We ended up going another direction - our developer discovered that if we set the field type to "text" instead of "checkbox," blank values won't submit anything to the server.  We're able to keep the checkbox "look" because we style our own customer-facing form and hide the Marketo form behind it (our form passes the data to the Marketo form first, which then submits to Marketo).  

So far it seems to be working: An unchecked checkbox (technically, a blank text field) won't submit anything and therefore won't override any existing data with a no/false value, and a checked checkbox (technically a text field populated with a "true" value) sets the field in Marketo to true.