Right way to update state in redux reducers
<p>I'm a newbie in redux and es6 syntax. I make my app with official redux tutorial, and with this <a href="http://redux.js.org/docs/advanced/ExampleRedditAPI.html" rel="noreferrer">example</a>. </p>

<p>There is JS snippet below. My point - to define REQUEST_POST_BODY and RECEIVE_POST_BODY cases in posts reducer. 
Main difficult - to find and update right object in store.</p>

<p>I try to use code from example:</p>

<pre><code>  return Object.assign({}, state, {
    [action.subreddit]: posts(state[action.subreddit], action)
  })
</code></pre>

<p>But it used simple array of posts. It's not needed to find right post by id.</p>

<p>Here my code:</p>

<pre><code>  const initialState = {
    items: [{id:3, title: '1984', isFetching:false}, {id:6, title: 'Mouse', isFetching:false}]
  }

  // Reducer for posts store
  export default function posts(state = initialState, action) {
    switch (action.type) {
    case REQUEST_POST_BODY:
      // here I need to set post.isFetching =&gt; true
    case RECEIVE_POST_BODY:
      // here I need to set post.isFetching =&gt; false and post.body =&gt; action.body
    default:
      return state;
    }
  }

  function requestPostBody(id) {
    return {
      type: REQUEST_POST_BODY,
      id
    };
  }

  function receivePostBody(id, body_from_server) {
    return {
      type: RECEIVE_POST_BODY,
      id,
      body: body_from_server
    };
  }

  dispatch(requestPostBody(3));
  dispatch(receivePostBody(3, {id:3, body: 'blablabla'}));
</code></pre>