Can not pass null to List typed Cloud function parameters

[reghta]

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Current Behavior

Although the parameter is marked as Nullable, I get an error when I leave the input list fields empty.

Expected Behavior

Should allow leaving the field null and not throw an error.

Steps to Reproduce

1. Create a cloud function (I believe the same happens for custom actions)
2. Add a string list parameter that is nullable
3. Use the cloud function in an action flow
4. The UI shows an error saying: Cloud Function argument "xyz" is not set properly.

Reproducible from Blank

• The steps to reproduce above start from a blank project.

Bug Report Code (Required)

ITEeicqB35RIpbxJ17rQa+xapwMwJ0QlUIInj+0bWRMhfLLpOokUfMn4alpLYtecdwlAIlmkqzkDpK3xkobPOMAVGE+BfIhOzJRXQQHKQnOtMoiJC5CST3B7L+9WN0yy06aRuyVSH/pqSF473E6Pe/CNG3qCf9qOYwx5e6fDbOY=

Visual documentation

Environment

- FlutterFlow version: FlutterFlow v5.2.9 released March 14, 2025
Flutter version is 3.27.3
- Platform: Web
- Browser name and version: Chrome 
- Operating system and version affected: MacOS

This is not version/platform/browser/os specific, it has been ongoing since I started FF 1 year ago.

Additional Information

No response

[Juansarmi]

Hello!

I'm sorry to hear you're experiencing this issue.

I’ve reviewed your project and understand what you're referring to. It seems that this is a limitation with list-type parameters, likely to prevent errors.

A simple workaround you can implement is to send an empty list instead of null or an undefined value. You can set this up in the page state, the app state, or by sending a random list with a length of 0.

Let me know if this helps resolve the issue.

Best regards.

[reghta]

Thank you for the reply.

Thinking of the workarounds, I had set up an emptyString constant in the project but it also threw an error saying constant shouldn't be empty. I understand the workarounds. Though note that these are needed for each list with a different data type e.g. list of songs, list of artists etc all require creating different placeholders. So whilst there is a workaround, when combined it causes nuisance and creates clutter in the apps.

[Juansarmi]

Hello again!
I understand that this solution is not the most intuitive or convenient. I recognize that this is a bug, and I will report it to the engineering team to find a solution. I will keep you updated on any developments regarding this case.
Best regards.

[github-actions]

This issue is stale because it has been open for 7 days with no activity. If there are no further updates, a team member will close the issue.

[isegal]

Just stumbled upon this issue with custom actions as well.

If you define a custom action that takes a list, and if the list is optional, it is impossible to pass Null constant, or an empty list.