A user asked about this mysterious-sounding warning in the Trigger Smart Campaign docs:
![](https://blog.teknkl.com/content/images/2024/06/image.png)
Sounds scarier than it should because something’s omitted. The missing link? It’s that Boolean fields have 3 possible values: true
, false
, and null
.
null
enables more business cases
Nullability lets you distinguish — at least in theory — an unknown or unset value from a value that is known one way or the other.
Among infinite examples:
- opt-in fields: responding “No” (
false
) is different from not having been asked the question (null
) - fields like Is Partner before records are linked with external data: knowing somebody is not a partner (
false
) is different from not yet knowing (null
)
In practice, though, only some Marketo features distinguish false
and null
.
Sometimes true
and false
are the available options and null
doesn’t match either one, which is strict comparison.[1] Other times null
is temporarily treated as false
, a loose comparison.
Overall, we can say Marketo is always null-preserving, because if you can explicitly set null
, the value is stored in the database. But it’s not always null-strict. (Yes, it’s confusing. That’s why your internal Tips ’n’ Tricks doc is so key.😊)
What the warning means
The warning above refers to one specific case: setting a value to null
doesn't trigger Data Value Changes to false
.
Say you use a Flow step to set null
[2] or call the Sync Lead API endpoint like so:
{
"action" : "updateOnly",
"lookupField" : "id",
"input" : [{
"id" : 123456,
"isPartner" : null
}]
}
Regardless of the previous value, this Smart Campaign trigger will not fire:
![](https://blog.teknkl.com/content/images/2024/06/image-14.png)
This trigger also will not fire, despite attempting to compare to null
:
![](https://blog.teknkl.com/content/images/2024/06/image-15.png)
Yet — assuming the previous value was true
, of course — this trigger will fire:
![](https://blog.teknkl.com/content/images/2024/06/image-12.png)
As you can see, nullability adds vital flexibility to the Marketo database, yet can cause surprises[3] if you don’t test thoroughly.
Notes
[1] It’s not usually possible to compare a field value explicitly to null
within Smart List Filters and Flow Choices. But you must prepare for those comparisons in REST API-based apps, which will see the preserved null
values in the language of your choice.
[2] You might not realize Change Data Value can set null
. Though the dropdown just shows true
and false
, you can type it manually:
![](https://blog.teknkl.com/content/images/2024/06/image-8.png)
[3] There’s a whole world of interesting behavior with Custom Objects + null
fields + Velocity, which I’ve written about before.