title: Unmarshaling json into a type
body: <p>I get the following data:</p>
  
  <pre><code>{
    "timestamp": "1526058949",
    "bids": [
      [
        "7215.90",
        "2.31930000"
      ],
      [
        "7215.77",
        "1.00000000"
      ]
    ]
  }
  </code></pre>
  
  <p>via websocket and I would like to unmarshall it into</p>
  
  <pre><code>type OrderBookItem struct {
      Price  string
      Amount string
  }
  
  type OrderBookResult struct {
      Timestamp string            `json:"timestamp"`
      Bids      []OrderBookItem `json:"bids"`
      Asks      []OrderBookItem `json:"asks"`
  }
  </code></pre>
  
  <p>Unmarshal it with: </p>
  
  <pre><code>s := e.Data.(string)
  d := &amp;OrderBookResult{}
  err := json.Unmarshal([]byte(s), d)
  if err == nil {
   ....
  } else {
   fmt.Println(err.Error())
  }
  </code></pre>
  
  <p>But I keep getting the error:</p>
  
  <blockquote>
    <p>json: cannot unmarshal string into Go struct field
    OrderBookResult.bids of type feed.OrderBookItem</p>
  </blockquote>
  
  <p>When I change the struct into</p>
  
  <pre><code>type OrderBookResult struct {
          Timestamp string     `json:"timestamp"`
          Bids      [][]string `json:"bids"`
          Asks      [][]string `json:"asks"`
  } 
  </code></pre>
  
  <p>it works. I would like them to be defined as <code>float64</code> which is what they are. What do I have to change?</p>