Function createTopic

app/actions/topics.js:95–138

(text)

// This function does not need to be pure, and thus allowed
// to have side effects, including executing asynchronous API calls.
export function createTopic(text) {
  return (dispatch, getState) => {
    // If the text box is empty
    if (text.trim().length <= 0) return;

    const id = md5.hash(text);
    // Redux thunk's middleware receives the store methods `dispatch`
    // and `getState` as parameters
    const { topic } = getState();
    const data = {
      id,
      count: 1,
      text
    };

    // Conditional dispatch
    // If the topic already exists, make sure we emit a dispatch event
    if (topic.topics.filter(topic => topic.id === id).length > 0) {
      // Currently there is no reducer that changes state for this
      // For production you would ideally have a message reducer that
      // notifies the user of a duplicate topic
      return dispatch(createTopicDuplicate());
    }
    
    // First dispatch an optimistic update
    dispatch(createTopicRequest(data));

    return makeTopicRequest('post', data)
      .then(res => {
        if (res.ok) {
          // We can actually dispatch a CREATE_TOPIC_SUCCESS
          // on success, but I've opted to leave that out
          // since we already did an optimistic update
          // We could return res.json();
          return dispatch(createTopicSuccess());
        } else {
          throw new Error("Oops! Something went wrong and we couldn't create your topic");
        }
      })
      .catch(ex => {
        return dispatch(createTopicFailure({ id, ex: ex.message }));
      });
  };
}

export function incrementCount(id, index) {
  return dispatch => {