How to generate zod validation schemas for next.js server actions
- Step 1Construct the expected action input as JSON — Build a JSON object representing the Server Action's expected input: { "title": "My Post", "content": "...", "categoryId": "uuid-here", "published": false }.
- Step 2Generate the Zod schema — Paste the JSON and convert. The generated schema includes z.string(), z.boolean(), and other types matching the input fields.
- Step 3Add constraints specific to your domain — Add: title →’ .string().min(3).max(200), categoryId →’ .string().uuid(), content →’ .string().min(10). These constraints prevent invalid mutations from reaching the database.
- Step 4Use in the Server Action — 'use server'; export async function createPost(input: unknown) { const parsed = PostSchema.safeParse(input); if (!parsed.success) { return { errors: parsed.error.flatten().fieldErrors }; } await db.posts.create({ data: parsed.data }); revalidatePath('/posts'); }.
Frequently asked questions
How do I validate FormData in a Server Action before converting to a Zod schema?+
Convert FormData to a plain object first: const data = Object.fromEntries(formData.entries()). Then parse with Zod: const parsed = Schema.safeParse(data). Note that FormData string values may need coercion — use z.coerce.number() for numeric fields that arrive as strings from form inputs.
What is the difference between using Zod in a Server Action vs a Route Handler?+
The validation logic is identical. The difference is how errors are returned: Server Actions typically return an error state object that is consumed by useFormState, while Route Handlers return a Response.json() with a 400 status code. Generate the same Zod schema for both — only the error response format differs.
Is the action input data transmitted to JAD Apps?+
No. Schema generation runs entirely in your browser. Form data and Server Action inputs are never transmitted to JAD Apps servers.
Privacy first
Conversion runs locally in your browser. No file is uploaded — only metadata counters are saved for signed-in dashboard stats.