title: Specify object value with vuex v-model
body: <p>I'm coordinating input elements with the keys of an object on Vuex state. Let's say I've got this object:</p>
  
  <pre><code>myObj: { foo: 1, bar: 2 }
  </code></pre>
  
  <p>And a computed property in a component:</p>
  
  <pre><code>myObjVals: {
    get(){ return this.$store.state.myObj },
    set(//?) { //? },
  },
  </code></pre>
  
  <p>In the template, I can get values <em>from</em> the store:</p>
  
  <pre><code>&lt;input type="number" v-model="myObjVals['foo']"/&gt;  // displays "1"
  &lt;input type="number" v-model="myObjVals['bar']"/&gt;  // displays "2"
  </code></pre>
  
  <p>But when I adjust the value on an input, I get the error: "Do not mutate vuex store state outside mutation handlers."</p>
  
  <p>One obvious solution here is to have a different computed property for <em>each</em> key in <code>myObj</code>... but for larger objects, this gets repetitious/cumbersome. I am wondering if there is any way to code this as I am attempting to above, that is, using only one computed property to reference the object for both <code>get</code> and <code>set</code> functions in <code>v-model</code>.</p>