Nextjs Server Actions

Server Actions

Priority: P1 (HIGH)

[!WARNING] If project uses pages/ directory instead of App Router, ignore this skill entirely.

Build action files as secure server entrypoints, not as thin wrappers around unsafe form data.

Recipe

1. Define action in actions.ts with 'use server'.
2. Parse input with a schema before touching storage or services, for example z.object({ ... }).safeParse(...) or formData.get('title') -> validated shape.
3. Authorize inside the action; middleware alone is not enough.
4. Delegate to DAL/service layer; keep storage details out of route UI files.
5. Revalidate exact tags/paths owned by the mutation.
6. Expose pending and optimistic state with useFormStatus, useActionState, useTransition, or useOptimistic as needed. Typical form wiring is <form action={createPost}> or <form action={action}>, with useFormStatus() and disabled={pending} inside the submit child.

Verify

• Action validates FormData or arguments before processing.
• Action performs authn/authz inside the server function.
• Mutations call DAL/service code, not raw storage from components.
• Success path revalidates tags or paths.
• Redirects or thrown errors are handled in the expected control flow.

Anti-Patterns

• No unvalidated Server Action inputs: Always validate with Zod before processing.
• No skipped auth checks: Verify session/user inside every action, not middleware.
• No actions defined inside components: Define in actions.ts to avoid closure bugs.
• No redirect() in try/catch: redirect() throws; catching it suppresses redirect.

References

• Framework Map
• Secure Action Example

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

• action={action}
• action={createPost}