fetch_ohlcv should be useable without endTime for this usecase

Recent changes made to fetch_ohlcv on binance.php prevent us from using fetch_ohlcv to grab the oldest OHLCVs for a pair, due to an enforced use of endTime parameter. I used to be able to call fetch_ohlcv with 0 startTime in previous versions to grab the oldest OHLCV from Binance, because endTime was not used.

I propose the following change to this code block in binance.php to allow use of startTime without endTime in fetch_ohlcv requests, if called with $since => null.

if ($since !== null) {
      $request['startTime'] = $since;
      $endTime = $this->sum($since, $limit * $duration * 1000 - 1);
      $now = $this->milliseconds();
      $request['endTime'] = min ($now, $endTime);
} 

to:

if ($since !== null) {
      $request['startTime'] = $since;
      $endTime = $this->sum($since, $limit * $duration * 1000 - 1);
      $now = $this->milliseconds();
      $request['endTime'] = min ($now, $endTime);
} elseif($since === null) {
      $request['startTime'] = 0;
}

This way, if you call the function with null, it defaults to 0 startTime and no endTime, which brings the oldest candles for that pair from Binance. Then if you’d want to use startTime with endTime, I can always provide 0 to $since parameter.

Eitherway, if you see a better way to do this, please propose it here. I don’t think endTime should be enforced for this specific usecase.

If approved, I’ll submit a PR.

• OS: Ubuntu 20.04
• Programming Language version: PHP 7.4
• CCXT version: 1.4.61

[kroitor]

@yazeed thx for your feedback!

[yazeed]

Thank you, my bad, it works now. Apologies. Have a great day or evening wherever you are!