title: Updating state of vuex array when one item has some changes
body: <p>I have an array called cases in my vuex store.</p>
  
  <p>I want to update the array with the new content when I update a few fields within an existing item in the array.</p>
  
  <p>I thought I could do something like this in my mutation but doesn't work and get the error <code>typeError: undefined is not an object (evaluating 'state.objects.find')</code> —</p>
  
  <pre><code>EDIT_CASE (state, payload) {
      const item = state.objects.find(item =&gt; item.id === payload.recordId);
  Object.assign(item, payload.case_status);
  </code></pre>
  
  <p>my array is as follows:</p>
  
  <pre><code>[
      {
          "case_name": "Laptop not working",
          "case_status": "live",
          "case_summary": "This is some summary content",
          "createdBy": "zippy",
          "createdDate": "2018-06-21T15:20:22.932Z",
          "id": "-LFXvk9yY5c-O8yIdf8k"
      },
      {
          "case_name": "Something else",
          "case_status": "live",
          "case_summary": "This is some summary content",
          "createdBy": "zippy",
          "createdDate": "2018-06-21T15:20:22.932Z",
          "id": "-STVvk9yY5c-O3yiTy8k"
      }
  ]
  </code></pre>
  
  <p>I also think from what I have read Vue does not observe changes within arrays so it may be I'm going completely the wrong way with this, and need to remove and then re-add the array item? </p>
  
  <p>Basically I have a list, I make a change to my backend, now I want that list to reflect the changes I have made through updating the cases state, can anyone help?</p>