Interacting with other fields

UI extensions can interact with the other fields of the form, and with the form itself.

For these purposes, the form property exposes the following methods:

Method	Signature	Description
`change`	`(fieldName: string, value: any) => Promise<void>`	changes the value of another field
`getState`	`() => Promise<`FormState`>`	returns the current form state
`getFieldState`	`(fieldName: string) => Promise<`FieldState`>`	returns the given field state
`subscribeToFieldState`	`(fieldName: string, callback: (state:` FieldState`, subscription:` FieldSubscription`) => void) => Promise<Unsubscribe>`	opens a subscription to a field's state changes
`subscribeToFormState`	`(callback: (state:` FormState`) => void, subscription:` FormSubscription`) => Promise<Unsubscribe>;`	opens a subscrition to the form's state changes
`setFieldsVisibility`	`(arg:` VisibilityMap`\| ((currentVisibilityMap:`VisibilityMap`) =>` VisibilityMap`)) => void;`	Allows modifying visibility of any field

#Types

Internally, Hygraph uses final-form to manage form and field states.

#FormState

See FormState on final-form.

The FormSubscription param has the same shape as FormState, but using a boolean to describe which state changes you want to subscribe to.

subscribeToFormState((state) => console.log(state.dirty, state.errors), {
  // react only to form `dirty` and `invalid` state changes
  dirty: true,
  invalid: true,
});

#FieldState

See FormState on final-form.

The FieldSubscription param has the same shape as FieldState, but using a boolean to describe which state changes you want to subscribe to.

subscribeToFieldState('title', (state) => console.log(state.value), {
  // react only to field `value` changes
  value: true,
});

#Unsubscribe

Both subscribeToFieldState and subscribeToFormState return a function to be called when needing to unsubscribe from changes. In order to avoid perfomance issues, make sure to unsubscribe any existing subscription before subscribing again.

Example in React:

React.useEffect(() => {
  let unsubscribe;

  subscribeToFieldState('title', (state) => console.log(state.value), {
    value: true,
  }).then((fieldUnsubscribe) => (unsubscribe = fieldUnsubscribe));

  return () => {
    unsubscribe?.();
  };
}, []);

#Set fields visibility

type VisibilityMap = {
  [fieldApiId: string]: 'READ_ONLY' | 'HIDDEN' | 'READ_WRITE';
};

Using object form to set visibility for field with API ID fieldApiId

setFieldsVisibility({
  fieldApiId: 'READ_ONLY',
});

Using callback to calculate next visibility value for field with API ID fieldApiId

setFieldsVisibility((currentVisibilityMap) => {
  const nextVisibilityValue =
    currentVisibilityMap[fieldApiId] === 'READ_ONLY'
      ? 'READ_WRITE'
      : 'READ_ONLY';

  return {
    fieldApiId: nextVisibilityValue,
  };
});