AuthenticationSagas.js

export function* signup (action) {
  const { email, password } = action
  try {
    const user = yield call(parseService.signup, email, password)
    yield put({ type: authActionTypes.SIGNUP_SUCCESS, user })
    yield call(loginSuccess, user)
  } catch (err) {
    const error = err.message || err
    yield put({ type: authActionTypes.SIGNUP_FAILURE, error })
  }
}    

parseServer.js

export const signup = async (email, password) => {
  const user = new Parse.User()
  user.set('username', email)
  user.set('email', email)
  user.set('password', password)
  const loggedUser = await user.signUp()
  return loggedUser.toJSON()
}

uiSagas.js

export function* showErrorAlert (action) {
  const { error } = action
  yield call(Alert.alert, i18n.t('ERROR_TITLE'), error)
}