title: Redux Form Component -> Value toString() behavior
body: <p>I've a wired problem with toString() behavior of a input value in a (react) redux form. I need a dropdown menu, which contains numbers as values. The json looks like this:</p>
  
  <pre><code>{
   id: 1
   [...]
  }
  </code></pre>
  
  <p>My component looks like this:</p>
  
  <pre><code>export class DropdownField extends React.Component {
    render() {
      var { input, meta: { touched, error } } = this.props
      //The tries of changing input.value to string are placed here
      //e.g. input.value = "2"
      return (
        &lt;div className="field"&gt;
          &lt;select {...input}&gt;
            &lt;option value="1"&gt;1&lt;/option&gt;
            &lt;option value="2"&gt;2&lt;/option&gt;
          &lt;/select&gt;
        &lt;/div&gt;
      )
    }
  };
  </code></pre>
  
  <p>The issue here is, that the input.value isn't a string, so input.value=2 isn't recognized as "2". I thought, I could just change the input.value to a string to solve this. It works well if I do</p>
  
  <pre><code>input.value = "2" //Works
  </code></pre>
  
  <p>But no matter what, if I use the original input.value I can't get it to work, so the following isn't working:</p>
  
  <pre><code>input.value = input.value.toString(); //Doesn't work
  input.value = "" + input.value; //Doesn't work
  input.value = getString(input.value) //Doesn't work
  //Just for completition, this plain stupid method. It runs in case 2, but still doesn't work
  var getString = (input) =&gt;
  {
    switch(input)
    {
      case 1:
      return "1";
      case 2:
      return "2";
      default:
      return "what"
    }
  }
  </code></pre>
  
  <p>Does anyone have a idea what's going on here? I really just need to set up the initial value of the dropdown box, everything else works. As soon as I change the selection via the UI the input.value changes to the corresponding string value and can be saved.</p>