exchange.GetData

The exchange.GetData() function is used to retrieve data loaded by the exchange.SetData() function or data provided by external links.

    
    
    
exchange.GetData(key)

    
    
    
exchange.GetData(key, timeout)

Examples

• Get the calling method for directly writing data.

  • javascript
  • python
  • cpp

  
      javascript
      
      
  /*backtest
  start: 2020-01-21 00:00:00
  end: 2020-02-12 00:00:00
  period: 1d
  basePeriod: 1d
  exchanges: [{"eid":"Bitfinex","currency":"BTC_USD"}]
  */
  function main() {
      exchange.SetData("test", [[1579536000000, _D(1579536000000)], [1579622400000, _D(1579622400000)], [1579708800000, _D(1579708800000)]])
      while(true) {
          Log(exchange.GetData("test"))
          Sleep(1000 * 60 * 60 * 24)
      }
  }
  

  
      python
      
      
  '''backtest
  start: 2020-01-21 00:00:00
  end: 2020-02-12 00:00:00
  period: 1d
  basePeriod: 1d
  exchanges: [{"eid":"Bitfinex","currency":"BTC_USD"}]
  '''
  def main():
      exchange.SetData("test", [[1579536000000, _D(1579536000000/1000)], [1579622400000, _D(1579622400000/1000)], [1579708800000, _D(1579708800000/1000)]])
      while True:
          Log(exchange.GetData("test"))
          Sleep(1000 * 60 * 60 * 24)
  

  
      c++
      
      
  /*backtest
  start: 2020-01-21 00:00:00
  end: 2020-02-12 00:00:00
  period: 1d
  basePeriod: 1d
  exchanges: [{"eid":"Bitfinex","currency":"BTC_USD"}]
  */
  void main() {
      json arr = R"([[1579536000000, ""], [1579622400000, ""], [1579708800000, ""]])"_json;
      arr[0][1] = _D(1579536000000);
      arr[1][1] = _D(1579622400000);
      arr[2][1] = _D(1579708800000);
      exchange.SetData("test", arr);
      while(true) {
          Log(exchange.GetData("test"));
          Sleep(1000 * 60 * 60 * 24);
      }
  }
  

• Supports requesting data through external links. The format of the requested data:

  
              json
              
              
  {
      "schema":["time","data"],
      "data":[
          [1579536000000, "abc"],
          [1579622400000, 123],
          [1579708800000, {"price": 123}],
          [1579795200000, ["abc", 123, {"price": 123}]]
      ]
  }
  

  Where schema is the data format for each record in the loaded data body. This format is fixed as ["time","data"], corresponding to the format of each data item in the data attribute. The data attribute stores the data body, where each data item consists of a millisecond timestamp and data content (the data content can be any JSON-encodable data).

  Test service program written in Go:

  
              golang
              
              
  package main
  
  import (
      "fmt"
      "net/http"
      "encoding/json"
  )
  
  func Handle (w http.ResponseWriter, r *http.Request) {
      defer func() {
          fmt.Println("req:", *r)
          ret := map[string]interface{}{
              "schema": []string{"time","data"},
              "data": []interface{}{
                  []interface{}{1579536000000, "abc"},
                  []interface{}{1579622400000, 123},
                  []interface{}{1579708800000, map[string]interface{}{"price":123}},
                  []interface{}{1579795200000, []interface{}{"abc", 123, map[string]interface{}{"price":123}}},
              },
          }
          b, _ := json.Marshal(ret)
          w.Write(b)
      }()
  }
  
  func main () {
      fmt.Println("listen http://localhost:9090")
      http.HandleFunc("/data", Handle)
      http.ListenAndServe(":9090", nil)
  }
  

  Response data after the program receives a request:

  
              json
              
              
  {
      "schema":["time","data"],
      "data":[
          [1579536000000, "abc"],
          [1579622400000, 123],
          [1579708800000, {"price": 123}],
          [1579795200000, ["abc", 123, {"price": 123}]]
      ]
  }
  

  Test strategy code:

  • javascript
  • python
  • cpp

  
      javascript
      
      
  /*backtest
  start: 2020-01-21 00:00:00
  end: 2020-02-12 00:00:00
  period: 1d
  basePeriod: 1d
  exchanges: [{"eid":"Bitfinex","currency":"BTC_USD"}]
  */
  function main() {
      while(true) {
          Log(exchange.GetData("http://xxx.xx.x.xx:9090/data"))
          Sleep(1000)
      }
  }
  

  
      python
      
      
  '''backtest
  start: 2020-01-21 00:00:00
  end: 2020-02-12 00:00:00
  period: 1d
  basePeriod: 1d
  exchanges: [{"eid":"Bitfinex","currency":"BTC_USD"}]
  '''
  
  def main():
      while True:
          Log(exchange.GetData("http://xxx.xx.x.xx:9090/data"))
          Sleep(1000)
  

  
      c++
      
      
  /*backtest
  start: 2020-01-21 00:00:00
  end: 2020-02-12 00:00:00
  period: 1d
  basePeriod: 1d
  exchanges: [{"eid":"Bitfinex","currency":"BTC_USD"}]
  */
  
  void main() {
      while(true) {
          Log(exchange.GetData("http://xxx.xx.x.xx:9090/data"));
          Sleep(1000);
      }
  }
  

• Method for calling external link data.

  • javascript
  • python
  • cpp

  
      javascript
      
      
  function main() {
      Log(exchange.GetData("http://xxx.xx.x.xx:9090/data"))
      Log(exchange.GetData("https://www.fmz.com/upload/asset/32bf73a69fc12d36e76.json"))
  }
  

  
      python
      
      
  def main():
      Log(exchange.GetData("http://xxx.xx.x.xx:9090/data"))
      Log(exchange.GetData("https://www.fmz.com/upload/asset/32bf73a69fc12d36e76.json"))
  

  
      c++
      
      
  void main() {
      Log(exchange.GetData("http://xxx.xx.x.xx:9090/data"));
      Log(exchange.GetData("https://www.fmz.com/upload/asset/32bf73a69fc12d36e76.json"));
  }
  

• Request query data created on the datadata platform, requiring the response data format to be (must include time and data field descriptions in the schema):

  
              json
              
              
  {
      "data": [],
      "schema": ["time", "data"]
  }
  

  The "data" field contains the required data content, and the data in the "data" field must be consistent with the format agreed upon in the "schema". When calling the exchange.GetData() function, it returns a JSON object, for example: {"Time":1579795200000, "Data":"..."}.

  • javascript
  • python
  • cpp

  
      javascript
      
      
  function main() {
      Log(exchange.GetData("https://www.datadata.com/api/v1/query/xxx/data"))   // The xxx part in the link is the encoding of the queried data, xxx here is an example
  }
  

  
      python
      
      
  def main():
      Log(exchange.GetData("https://www.datadata.com/api/v1/query/xxx/data"))
  

  
      c++
      
      
  void main() {
      Log(exchange.GetData("https://www.datadata.com/api/v1/query/xxx/data"));
  }
  

Returns

Arguments

See Also

Remarks

Data is fetched all at once during backtesting, while data is cached for one minute during live trading. In the backtesting system, when using the API request method to fetch data, the backtesting system will automatically add parameters such as from (timestamp in seconds), to (timestamp in seconds), and period (underlying K-line period, timestamp in milliseconds) to the request to determine the time range of data to be retrieved.