edit-page.js

class EditPage extends React.Component {
  handleUpdate() {
    const form = ...;
    this.props.dispatch(requestUpdate(form));
    this.props.dispatch(change('/posts/update'));
  }
  
  // ...
  
  render() {
    return <div>
      // ...
    
      <button onClick={this.handleUpdate.bind(this)}>Update</button>
    
      // ...
    </div>;
  }
}

routes.js

const routes = {
  '/posts': IndexPage,
  '/posts/edit': EditPage,
  '/posts/update': function* update() {
    yield put(loading(true));
    yield take(SUCCESS_UPDATE);
    yield put(loading(false));
    yield '/posts';
  }
};

saga.js

function* handleUpdate() {
  while (true) {
    const form = yield take(REQUEST_UPDATE);
    const data = yield call(api, form);
    yield put(successUpdate(data));
  }
}