Why is data in onSuccess of useAction optional?

[maltesa]

Hi,

I was wondering why data is optional in the following example:

useServerAction(createInstituteAction, {
  onSuccess: ({ data }) => {
    // Expecting data to have the type of `createInstituteAction`s return value
    // but value is: <createInstituteAction return value> | undefined
  }
})

Since the actions succeed, the value must be set, right?

[TheEdoRan]

See:

• SafeActionResult returns undefined #175

The reason is that the action runs onSuccess callback even when you use redirect, which internally throws an error caught by Next.js to perform the redirect. In this case, data is undefined.

[maltesa]

Ah great. I searched for this in issues and discussions but didn't find it. Sorry 👍🏻