如何实现多HTTP GET请求获取数据后执行指定回调方法？

Hey there! Let's fix this code to properly collect all player data from the HTTP requests and run your callback only once everything's done. Here are the key issues in your current snippet and how to address them:

Key Problems to Fix #

• Partial Response Handling: The res.on('data') event emits chunks of the response, not the full JSON. You need to collect all chunks first before parsing.
• Async Coordination: Since each HTTP request is asynchronous, you can't assume returnData is ready right after looping through players. We need to track when all requests complete.

Corrected Code #

Here's the full working implementation with explanations:

function fetchPlayerStats(players, callbackMethod) {
  var returnData = [];
  var completedRequests = 0;
  var totalRequests = players.length;

  // Edge case: if no players, call callback immediately with empty data
  if (totalRequests === 0) {
    callbackMethod(null, returnData);
    return;
  }

  players.forEach(function(item) {
    var playerRequestUrl = baseUrl + '/' + platform + '/members/' + item.blazeId + '/stats';
    
    https.get(playerRequestUrl, function(res) {
      var chunks = [];

      // Collect all response chunks as they arrive
      res.on('data', function(chunk) {
        chunks.push(chunk);
      });

      // When full response is received
      res.on('end', function() {
        try {
          // Combine chunks into a single buffer, convert to string, then parse JSON
          var playerData = JSON.parse(Buffer.concat(chunks).toString());
          returnData.push(playerData);
        } catch (error) {
          // Handle JSON parsing errors or invalid data
          console.error('Error processing data for player:', item.blazeId, error);
          return callbackMethod(error, null);
        }

        completedRequests++;

        // Trigger callback only when all requests are done
        if (completedRequests === totalRequests) {
          callbackMethod(null, returnData);
        }
      });

      // Handle request-level errors
      res.on('error', function(error) {
        console.error('Request failed for player:', item.blazeId, error);
        callbackMethod(error, null);
      });
    });
  });
}

What's Changed? #

1. Full Response Collection: We now accumulate all response chunks and parse the complete data only when the end event fires, avoiding partial JSON parsing errors.
2. Completion Tracking: Added counters to track how many requests have finished. When the completed count matches the total number of players, we call the callback with all aggregated data.
3. Error Handling: Added listeners for both response parsing errors and request failures, so you can gracefully handle issues and pass errors to your callback.
4. Edge Case Handling: If the input players array is empty, we immediately trigger the callback with an empty dataset to avoid hanging.

How to Use It #

Call the function like this to get your aggregated player stats:

fetchPlayerStats(yourPlayersArray, function(error, statsData) {
  if (error) {
    // Handle any errors that occurred during requests
    console.error('Failed to fetch player stats:', error);
    return;
  }
  // Do something with the fully collected stats data
  console.log('All player stats:', statsData);
});

This ensures your callbackMethod runs only after all HTTP requests have completed successfully (or an error is encountered).

内容的提问来源于stack exchange，提问作者ravibhagw