在前一个方法完成之前运行的方法，Future Async Dart

Question

我的方法 processData() 在 pullAllData() 完成之前执行，但我需要 processData() 等到 pullAllData () 在运行之前完全完成。当运行 processData() 时，这导致我的 isDownloadSuccessful bool 为 Null。

Future getCoinData() async {
    calculateNumberOfDataPoints();
    pullTimesAndPrices();
    return timesAndPrices;
  }

Future pullTimesAndPrices() async {
    for (String cryptoCurrency in cryptoAbbreviation) {
      pullAllData(cryptoCurrency);
      processData(cryptoCurrency);
    }
  }

Future pullAllData(cryptoCurrency) async {
    String historicalRequestURL =
        '$cryptoAPIURL$cryptoCurrency$currency/ohlc?periods=$periodValue&apikey=$apiKey';
    http.Response historicalResponse = await http.get(historicalRequestURL);
    isPullSuccessful = (historicalResponse.statusCode == 200);
  }

void processData(cryptoCurrency) {
    if (isPullSuccessful) {
      ...
    } else {
      throw 'Problem pulling data';
    }
  }

Answer 1

您将函数pullTimesAndPrices 标记为async，但未使用await。在调用pullAllData 函数之前使用await 关键字。