Logic and workflows - Serval Documentation

A form re-renders every time an answer changes, so it can ask different questions, fetch real data, and validate across fields before anything is submitted. Two kinds of workflow connect to a form, and the workspace shows both:

Workspace card	When it runs	What it’s for
Runs inside the form	While the form is being filled in	Fetching live data to show or shape the questions
Runs on submit	Once, on submit	Doing the work the request asked for

Conditional questions

A field’s current answer is an ordinary value, so logic is ordinary code. No rule builder, no separate condition language.

const [forSomeoneElse, ForSomeoneElse] = field.boolean("for_someone_else", {
  label: "Is this for someone else?",
});
const [recipient, Recipient] = field.user("recipient", { label: "Who's this for?" });

return (
  <Form>
    <ForSomeoneElse />
    {forSomeoneElse && <Recipient required />}
  </Form>
);

Goal	How
Show a field only when relevant	Render it inside a condition
Require a field only sometimes	`<Field required={isContractor} />`
Narrow one field’s options by another	Filter the entity or user picker on the other field’s answer
Warn about a combination	Render a `<Notice tone="warning">` when it occurs
Reject a combination	Set `error` on the field. A non-empty error blocks submit

Ask Catalyst for the behavior, not the code: “only ask for a manager when the request is for someone else.” Then check it in the preview.

Live data inside the form

A form can call one of your workflows while it’s open and render the result: stock levels, license counts, an employee’s current device, a price.

import { runWorkflowMemoized } from "serval/forms";
import checkLaptopStock from "@serval/workflows/check-laptop-stock";

const stock = runWorkflowMemoized(checkLaptopStock, { model });

return (
  <Form>
    <Model required />
    {stock?.outOfStock && (
      <Notice tone="warning">That model is back-ordered until {stock.eta}.</Notice>
    )}
  </Form>
);

Results are cached per set of arguments. The call runs once for each distinct set. Change the selected model and it runs again. Change an unrelated field and it doesn’t run at all. Calling it from the render is cheap, not a request per keystroke.
The form stays usable while it’s in flight, then re-renders with the result.

Query workflows should be read-only. They run whenever their arguments change, including in previews, so anything that creates or modifies belongs in the submit workflow instead.

Every run a form starts, query runs included, appears under Run history.

The submit workflow

<Form submit={{ workflow: orderLaptop, args: { model, justification, neededBy } }}>

On submit, Serval validates every field, starts the workflow with your arguments, and moves the form to its submitted state. You pass an explicit args object rather than the whole form, so the workflow’s inputs are a contract you control: rename a field without breaking the workflow, or pass derived values instead of raw answers. A form doesn’t need a submit workflow. One without it collects and validates answers and stops there, which suits an acknowledgment or informational form.

Safety

Form code runs on Serval’s servers in an isolated sandbox with no network access, no filesystem, and no ambient credentials. The only way a form causes anything to happen is by naming one of your team’s workflows, and every call is re-resolved and re-authorized on the server. A form can never reach further than the workflows the team already has.

Finding the forms attached to a workflow

Open a workflow and look for the forms panel. It lists each form that calls the workflow and whether it does so while the form is open or on submit, so you can see the blast radius before changing it.

Share and fill

Catalog, tickets, Slack, and audience control.

Manage forms

Versions, run history, folders, and copies across teams.

​Conditional questions

​Live data inside the form

​The submit workflow

​Safety

​Finding the forms attached to a workflow

Share and fill

Manage forms

Conditional questions

Live data inside the form

The submit workflow

Safety

Finding the forms attached to a workflow