Field Validation

This basic example renders a single text input which prompts for a GitHub username; the current username of this input is stored in React component state.

Aperture

Only one source is observed:

• The username prop.

Every time the input's username changes, the new username is passed to the stream. Any blank strings are filtered from the stream, and then the usernames are debounced for one second.

After debouncing, a fetch request is made and resolved. If a user is found, an effect with type USER_FOUND is output; if no user is found, an effect with type USERNAME_AVAILABLE is output.

Handler

The Refract handler toggles the available state appropriately depending on the effect's type.

Result

The end result is an input field with asynchronous validation handled as a side-effect.