title: What Go tag should be used while defining struct of a JSON data if "field/key" for some values is varying or not known?
body: <p>While trying to parse a time-series data I found a key field in the JSON data is the timestamp(obviously in string format). But creating a struct for the same beforehand is not possible as I cannot know the timestamp string anyway.</p>
  
  <p>This is how the JSON looks like: </p>
  
  <pre><code>"Time Series (5min)": {
          "2020-01-17 16:00:00": {
              "1. open": "167.2000",
              "2. high": "167.3400",
              "3. low": "167.0100",
              "4. close": "167.0500",
              "5. volume": "1646699"
          },
          "2020-01-17 15:55:00": {
              "1. open": "166.9000",
              "2. high": "167.1600",
              "3. low": "166.8500",
              "4. close": "167.1500",
              "5. volume": "622999"
          },
          "2020-01-17 15:50:00": {
              "1. open": "166.7241",
              "2. high": "166.9200",
              "3. low": "166.7200",
              "4. close": "166.8999",
              "5. volume": "271723"
          }
      }
  </code></pre>
  
  <p>The struct for the some may look like :</p>
  
  <pre><code>
  type TIMESTAMP struct {
      Open   string `json:"1. open"`
      High   string `json:"2. high"`
      Low    string `json:"3. low"`
      Close  string `json:"4. close"`
      Volumn string `json:"5. volumn"`
  }
  
  type TIMESERIES struct {
      TimeStamp TIMESTAMP `json:""`  //DON'T KNOW HOW TO IMPLEMENT THIS
  }
  </code></pre>
  
  <p>How to handle such a situation? Is there any Go struct tag for the same?</p>