title: How the get refs antd componement Select value of antd?
body: <p>I try use last version of antd(3.10.0) and react(16.5.2).</p>
  
  <p>I use the new way of ref according to <a href="https://reactjs.org/docs/refs-and-the-dom.html" rel="nofollow noreferrer">https://reactjs.org/docs/refs-and-the-dom.html</a></p>
  
  <pre><code>this.myRef = React.createRef();
  </code></pre>
  
  <p>when it rend，should like:</p>
  
  <pre><code>rend(){
                      &lt;Select style={{ width: 200 }} ref={this.myRef}&gt;
                      {Object.entries(this.state.catedict)
                          .map(en =&gt; &lt;Option key={en[0]}&gt;{en[1]}&lt;/Option&gt;)}
                  &lt;/Select&gt;
  }
  </code></pre>
  
  <p>But when I want to get the value of Input or Select</p>
  
  <p>I try to:</p>
  
  <pre><code>console.log(this.myRef.current.value);
  </code></pre>
  
  <p>But only get wrong result.</p>
  
  <p>I find even:</p>
  
  <pre><code>console.log(this.myRef.current);
  </code></pre>
  
  <p>the result is:</p>
  
  <pre><code>t {props: {…}, context: {…}, refs: {…}, updater: {…}, saveSelect: ƒ, …}
  context: {}
  props: {style: {…}, children: Array(2), prefixCls: "ant-select", showSearch: false, transitionName: "slide-up", …}
  rcSelect: t {props: {…}, context: {…}, refs: {…}, updater: {…}, onInputChange: ƒ, …}
  refs: {}
  renderSelect: ƒ (n)
  saveSelect: ƒ (n)
  state: null
  updater: {isMounted: ƒ, enqueueSetState: ƒ, enqueueReplaceState: ƒ, enqueueForceUpdate: ƒ}
  _reactInternalFiber: Na {tag: 2, key: null, type: ƒ, stateNode: t, return: Na, …}
  __proto__: v
  </code></pre>
  
  <p>I want give the value of Select. How should I do?</p>