migrate-frontend-forms

name	migrate-frontend-forms
description	Guide for migrating forms from the legacy JsonForm/FormModel system to the new TanStack-based form system.

Form Migration Guide

This skill helps migrate forms from Sentry's legacy form system (JsonForm, FormModel) to the new TanStack-based system.

Feature Mapping

Old System	New System	Notes
saveOnBlur: true	AutoSaveForm	Default behavior
confirm	confirm prop	string | ((value) => string | undefined)
showHelpInTooltip	variant="compact"	On layout components
disabledReason	disabled="reason"	String shows tooltip
extraHelp	JSX in layout	Render <Text> below field
getData	mutationFn	Transform data in mutation function
mapFormErrors	setFieldErrors	Transform API errors in catch block
saveMessage	onSuccess	Show toast in mutation onSuccess callback
formatMessageValue	onSuccess	Control toast content in onSuccess callback
resetOnError	onError	Call form.reset() in mutation onError
saveOnBlur: false	useScrapsForm	Use regular form with explicit Save button
(automatic)	form.reset()	Call after successful mutation if form stays on page
help	hintText	On layout components
label	label	On layout components
required	required	On layout + Zod schema

Feature Details

confirm → confirm prop

Old:

{
  name: 'require2FA',
  type: 'boolean',
  confirm: {
    true: 'Enable 2FA for all members?',
    false: 'Allow members without 2FA?',
  },
  isDangerous: true,
}

New:

<AutoSaveForm
  name="require2FA"
  confirm={value =>
    value
      ? 'Enable 2FA for all members?'
      : 'Allow members without 2FA?'
  }
  {...}
>

showHelpInTooltip → variant="compact"

Old:

{
  name: 'field',
  help: 'This is help text',
  showHelpInTooltip: true,
}

New:

<field.Layout.Row
  label="Field"
  hintText="This is help text"
  variant="compact"
>

disabledReason → disabled="reason"

Old:

{
  name: 'field',
  disabled: true,
  disabledReason: 'Requires Business plan',
}

New:

<field.Input
  disabled="Requires Business plan"
  {...}
/>

extraHelp → JSX

Old:

{
  name: 'sensitiveFields',
  help: 'Main help text',
  extraHelp: 'Note: These fields apply org-wide',
}

New:

<field.Layout.Stack label="Sensitive Fields" hintText="Main help text">
  <field.TextArea {...} />
  <Text size="sm" variant="muted">
    Note: These fields apply org-wide
  </Text>
</field.Layout.Stack>

getData → mutationFn

The getData function transformed field data before sending to the API. In the new system, handle this in the mutationFn.

Old:

// Wrap field value in 'options' key
{
  name: 'sentry:csp_ignored_sources_defaults',
  type: 'boolean',
  getData: data => ({options: data}),
}

// Or extract/transform specific fields
{
  name: 'slug',
  getData: (data: {slug?: string}) => ({slug: data.slug}),
}

New:

<AutoSaveForm
  name="sentry:csp_ignored_sources_defaults"
  schema={schema}
  initialValue={project.options['sentry:csp_ignored_sources_defaults']}
  mutationOptions={{
    mutationFn: data => {
      // Transform data before API call (equivalent to getData)
      const transformed = {options: data};
      return fetchMutation({
        url: `/projects/${organization.slug}/${project.slug}/`,
        method: 'PUT',
        data: transformed,
      });
    },
  }}
>
  {field => (
    <field.Layout.Row label="Use default ignored sources">
      <field.Switch checked={field.state.value} onChange={field.handleChange} />
    </field.Layout.Row>
  )}
</AutoSaveForm>

Simpler pattern - If you just need to wrap the value:

mutationOptions={{
  mutationFn: fieldData => {
    return fetchMutation({
      url: `/projects/${org}/${project}/`,
      method: 'PUT',
      data: {options: fieldData}, // getData equivalent
    });
  },
}}

Important: Typing mutations correctly

The mutationFn should be typed with the API's data type (e.g., Partial<Organization>, Partial<Project>), not the schema-inferred type. The schema is for client-side field validation only — the mutation receives whatever the API endpoint accepts. Tying the mutation to the schema couples two unrelated concerns and can cause type errors when the schema types don't exactly match the API types.

// ❌ Don't use generic types - breaks field type narrowing
mutationOptions={{
  mutationFn: (data: Record<string, unknown>) => {
    return fetchMutation({url: '/user/', method: 'PUT', data: {options: data}});
  },
}}

// ❌ Don't tie mutation type to the zod schema
mutationOptions={{
  mutationFn: (data: Partial<z.infer<typeof preferencesSchema>>) => {
    return fetchMutation({url: '/user/', method: 'PUT', data: {options: data}});
  },
}}

// ✅ Use the API's data type
mutationOptions={{
  mutationFn: (data: Partial<UserDetails>) => {
    return fetchMutation({url: '/user/', method: 'PUT', data: {options: data}});
  },
}}

Make sure the zod schema's types are compatible with (i.e., assignable to) the API type. For example, if the API expects a string union like 'off' | 'low' | 'high', use z.enum(['off', 'low', 'high']) instead of z.string().

Don't pass generics to useMutation either. Type the mutationFn payload, and let fetchMutation<TReturn> carry the return type. useMutation<TData, TError, TVariables> is not the codebase style.

// ❌ Generics on useMutation
const mutation = useMutation<CodeOwner, RequestError, [Payload]>({
  mutationFn: ([payload]) => fetchMutation({url, method: 'POST', data: payload}),
});

// ✅ Type the payload; fetchMutation<T> carries the return type
const mutation = useMutation({
  mutationFn: (payload: {codeMappingId: string; raw: string}) =>
    fetchMutation<CodeOwner>({
      url: `/projects/${org}/${project}/codeowners/`,
      method: 'POST',
      data: payload,
    }),
});

mapFormErrors → setFieldErrors

The mapFormErrors function transformed API error responses into field-specific errors. In the new system, handle this in the catch block using setFieldErrors.

Old:

// Form-level error transformer
function mapMonitorFormErrors(responseJson?: any) {
  if (responseJson.config === undefined) {
    return responseJson;
  }
  // Flatten nested config errors to dot notation
  const {config, ...rest} = responseJson;
  const configErrors = Object.fromEntries(
    Object.entries(config).map(([key, value]) => [`config.${key}`, value])
  );
  return {...rest, ...configErrors};
}

<Form mapFormErrors={mapMonitorFormErrors} {...}>

New:

import {setFieldErrors} from '@sentry/scraps/form';

const form = useScrapsForm({
  ...defaultFormOptions,
  defaultValues: {...},
  validators: {onDynamic: schema},
  onSubmit: async ({value, formApi}) => {
    try {
      await mutation.mutateAsync(value);
    } catch (error) {
      // Transform API errors and set on fields (equivalent to mapFormErrors)
      const responseJson = error.responseJSON;
      if (responseJson?.config) {
        // Flatten nested errors to dot notation
        const {config, ...rest} = responseJson;
        const errors: Record<string, {message: string}> = {};

        for (const [key, value] of Object.entries(rest)) {
          errors[key] = {message: Array.isArray(value) ? value[0] : String(value)};
        }
        for (const [key, value] of Object.entries(config)) {
          errors[`config.${key}`] = {message: Array.isArray(value) ? value[0] : String(value)};
        }

        setFieldErrors(formApi, errors);
      }
    }
  },
});

Simpler pattern - For flat error responses:

onSubmit: async ({value, formApi}) => {
  try {
    await mutation.mutateAsync(value);
  } catch (error) {
    // API returns {email: ['Already taken'], username: ['Invalid']}
    const errors = error.responseJSON;
    if (errors) {
      setFieldErrors(formApi, {
        email: {message: errors.email?.[0]},
        username: {message: errors.username?.[0]},
      });
    }
  }
},

Note: setFieldErrors supports nested paths with dot notation: 'config.schedule': {message: 'Invalid schedule'}

saveMessage → onSuccess

The saveMessage showed a custom toast/alert after successful save. In the new system, handle this in the mutation's onSuccess callback.

Old:

{
  name: 'fingerprintingRules',
  saveOnBlur: false,
  saveMessageAlertVariant: 'info',
  saveMessage: t('Changing fingerprint rules will apply to future events only.'),
}

New:

import {addSuccessMessage} from 'sentry/actionCreators/indicator';

<AutoSaveForm
  name="fingerprintingRules"
  schema={schema}
  initialValue={project.fingerprintingRules}
  mutationOptions={{
    mutationFn: data => fetchMutation({...}),
    onSuccess: () => {
      // Custom success message (equivalent to saveMessage)
      addSuccessMessage(t('Changing fingerprint rules will apply to future events only.'));
    },
  }}
>

formatMessageValue → onSuccess

The formatMessageValue controlled how the changed value appeared in success toasts. Setting it to false disabled showing the value entirely (useful for large text fields). In the new system, you control this directly in onSuccess.

Old:

{
  name: 'fingerprintingRules',
  saveMessage: t('Rules updated'),
  formatMessageValue: false, // Don't show the (potentially huge) value in toast
}

New:

mutationOptions={{
  mutationFn: data => fetchMutation({...}),
  onSuccess: () => {
    // Just show the message, no value (equivalent to formatMessageValue: false)
    addSuccessMessage(t('Rules updated'));
  },
}}

// Or if you want to show a formatted value:
onSuccess: (data) => {
  addSuccessMessage(t('Slug changed to %s', data.slug));
},

resetOnError → onError

The resetOnError option reverted fields to their previous value when a save failed. In the new system, call form.reset() in the mutation's onError callback.

Old:

// Form-level reset on error
<Form resetOnError apiEndpoint="/auth/" {...}>

// Or field-level (BooleanField always resets on error)
<FormField resetOnError name="enabled" {...}>

New (with useScrapsForm):

const form = useScrapsForm({
  ...defaultFormOptions,
  defaultValues: {password: ''},
  validators: {onDynamic: schema},
  onSubmit: async ({value}) => {
    try {
      await mutation.mutateAsync(value);
    } catch (error) {
      // Reset form to previous values on error (equivalent to resetOnError)
      form.reset();
      throw error; // Re-throw if you want error handling to continue
    }
  },
});

New (with AutoSaveForm):

<AutoSaveForm
  name="enabled"
  schema={schema}
  initialValue={settings.enabled}
  mutationOptions={{
    mutationFn: data => fetchMutation({...}),
    onError: () => {
      // The field automatically shows error state via TanStack Query
      // If you need to reset the value, you can pass a reset callback
    },
  }}
>

Note: AutoSaveForm with TanStack Query already handles error states gracefully - the mutation's isError state is reflected in the UI. Manual reset is typically only needed for specific UX requirements like password fields.

Resetting After Save

When using useScrapsForm for a form that stays on the page after save, call form.reset() after a successful mutation. This re-syncs the form with updated defaultValues so it becomes pristine again — any UI that depends on the form being dirty (like conditionally shown Save/Cancel buttons) will update correctly.

onSubmit: ({value}) =>
  mutation
    .mutateAsync(value)
    .then(() => form.reset())
    .catch(() => {}),

Note: AutoSaveForm handles this automatically. You only need to add this when using useScrapsForm.

saveOnBlur: false → useScrapsForm

Fields with saveOnBlur: false showed an inline alert with Save/Cancel buttons instead of auto-saving. This was used for dangerous operations (slug changes) or large text edits (fingerprint rules).

In the new system, use a regular form with useScrapsForm and an explicit Save button. This preserves the UX of showing warnings before committing.

Old:

{
  name: 'slug',
  type: 'string',
  saveOnBlur: false,
  saveMessageAlertVariant: 'warning',
  saveMessage: t("Changing a project's slug can break your build scripts!"),
}

New:

import {Alert} from '@sentry/scraps/alert';
import {Button} from '@sentry/scraps/button';
import {defaultFormOptions, useScrapsForm} from '@sentry/scraps/form';

const slugSchema = z.object({
  slug: z.string().min(1, 'Slug is required'),
});

function SlugForm({project}: {project: Project}) {
  const mutation = useMutation({
    mutationFn: (data: {slug: string}) =>
      fetchMutation({url: `/projects/${org}/${project.slug}/`, method: 'PUT', data}),
  });

  const form = useScrapsForm({
    ...defaultFormOptions,
    defaultValues: {slug: project.slug},
    validators: {onDynamic: slugSchema},
    onSubmit: ({value}) => mutation.mutateAsync(value).catch(() => {}),
  });

  return (
    <form.AppForm form={form}>
      <form.AppField name="slug">
        {field => (
          <field.Layout.Stack label="Project Slug">
            <field.Input value={field.state.value} onChange={field.handleChange} />
          </field.Layout.Stack>
        )}
      </form.AppField>

      {/* Warning shown before saving (equivalent to saveMessage) */}
      <Alert variant="warning">
        {t("Changing a project's slug can break your build scripts!")}
      </Alert>

      <Flex gap="sm" justify="end">
        <form.ResetButton>Reset</form.ResetButton>
        <form.SubmitButton>Save</form.SubmitButton>
      </Flex>
    </form.AppForm>
  );
}

When to use this pattern:

• Dangerous operations where users should see a warning before committing (slug changes, security tokens)
• Large multiline text fields where you want to finish editing before saving (fingerprint rules, filters)
• Any field where auto-save doesn't make sense

Submit through the form, not around it. Follow the SlugForm pattern above — the mutation runs in onSubmit and the Save button is <form.SubmitButton>. Don't render <form.AppForm> without an onSubmit and trigger the mutation from a standalone <Button onClick>:

// ❌ Form is never submitted; mutation fires from a separate button
const form = useScrapsForm({
  ...defaultFormOptions,
  defaultValues,
  validators: {onDynamic: schema},
  // no onSubmit
});

return (
  <form.AppForm form={form}>
    <form.AppField name="codeMappingId">{...}</form.AppField>
    <Button onClick={() => mutation.mutate(...)}>Save</Button>
  </form.AppForm>
);

A form that's never actually submitted bypasses validation, pending/disabled state, and field-error wiring.

Preserving Form Search Functionality

Sentry's SettingsSearch allows users to search for individual settings fields. When migrating forms, you must preserve this searchability by wrapping migrated forms with FormSearch.

The FormSearch Component

FormSearch is a build-time marker component — it has zero runtime behavior and simply renders its children unchanged. Its route prop is read by a static extraction script to associate form fields with their navigation route, enabling them to appear in SettingsSearch results.

import {FormSearch} from 'sentry/components/core/form';

<FormSearch route="/settings/account/details/">
  <FieldGroup title={t('Account Details')}>
    <AutoSaveForm name="name" schema={schema} initialValue={user.name} mutationOptions={...}>
      {field => (
        <field.Layout.Row label={t('Name')} hintText={t('Your full name')} required>
          <field.Input />
        </field.Layout.Row>
      )}
    </AutoSaveForm>
  </FieldGroup>
</FormSearch>

Props:

Prop	Type	Description
route	string	The settings route for this form (e.g., '/settings/account/details/'). Used for search navigation.
children	ReactNode	The form content — rendered unchanged at runtime.

Rules:

• The route must match the settings page URL exactly (including trailing slash).
• Wrap the entire form section with a single FormSearch, not individual fields.
• Every <AutoSaveForm> or <form.AppField> inside a FormSearch will be indexed. Make sure label and hintText are plain string literals or t() calls — computed/dynamic strings will be skipped by the extractor.

The Form Field Registry

After adding or updating FormSearch wrappers, regenerate the field registry so that search results stay up to date:

pnpm run extract-form-fields

This script (scripts/extractFormFields.ts) scans all TSX files, finds <FormSearch> components, extracts field metadata (name, label, hintText, route), and writes the generated registry to static/app/components/core/form/generatedFieldRegistry.ts. Commit this generated file alongside your migration PR — it is part of the source tree.

Run the command after any change to forms inside a FormSearch wrapper (adds, removals, label changes). The generated file is checked in and should not be edited manually.

Migration: Old Forms Already Searchable

If the legacy JsonForm being migrated was already indexed by SettingsSearch (i.e., it had entries in sentry/data/forms), you must add a FormSearch wrapper to the new form so search functionality is preserved. The old and new sources coexist — new registry entries take precedence over old ones for the same route + field combination — but once you remove the legacy form the old entries will disappear.

Handling Nullable Initial Values

Legacy select fields often started with an empty/undefined value and required a selection. In the new system, use .nullable().refine() in the schema, type defaultValues with z.input<typeof schema>, and call schema.parse(value) in onSubmit.

Old:

{
  name: 'provider',
  type: 'select',
  required: true,
  choices: [['github', 'GitHub'], ['launchdarkly', 'LaunchDarkly']],
}

New:

const schema = z.object({
  provider: z
    .enum(['github', 'launchdarkly'])
    .nullable()
    .refine(v => v !== null, 'Provider is required'),
});

// z.input accepts null; z.output (after refine) does not
const defaultValues: z.input<typeof schema> = {
  provider: null,
};

const form = useScrapsForm({
  ...defaultFormOptions,
  defaultValues,
  validators: {onDynamic: schema},
  onSubmit: ({value}) => {
    // schema.parse narrows null away — mutation receives z.output
    return mutation.mutateAsync(schema.parse(value)).catch(() => {});
  },
});

This pattern is necessary whenever a required field has no meaningful initial value. The z.input / z.output distinction ensures the form accepts null as default while the mutation receives the validated, non-null type.

Intentionally Not Migrated

Feature	Usage	Reason
allowUndo	3 forms	Undo in toasts adds complexity with minimal benefit. Use simple error toasts instead.

Migration Checklist

• Replace JsonForm/FormModel with useScrapsForm or AutoSaveForm
• No generics on useMutation — type the mutationFn payload and use fetchMutation<T> for the return type
• When using useScrapsForm with a Save button: mutation runs in onSubmit, triggered by <form.SubmitButton> (no form that's never submitted)
• Convert field config objects to JSX AppField components
• Replace help → hintText on layouts
• Replace showHelpInTooltip → variant="compact"
• Replace disabledReason → disabled="reason string"
• Replace extraHelp → additional JSX in layout
• Convert confirm object to function: (value) => message | undefined
• Handle getData in mutationFn
• Handle mapFormErrors with setFieldErrors in catch
• Handle saveMessage in onSuccess callback
• Convert saveOnBlur: false fields to regular forms with Save button
• Call form.reset() after successful mutation (for forms that stay on page)
• Verify onSuccess cache updates merge with existing data (use updater function) — some API endpoints may return partial objects
• Wrap the migrated form with <FormSearch route="..."> if the old form was searchable in SettingsSearch
• Run pnpm run extract-form-fields and commit the updated generatedFieldRegistry.ts