using since_id and max_id in Twitter API

问题

I hope I'm overthinking this and there's an obvious solution.

From the API (GET statuses/user_timeline)

max_id - Returns results with an ID less than (that is, older than) or equal to the specified ID.

"or equal to" means it will include the tweet with ID that I sent as my max_id parameter.

My question is this: if I store the id of my oldest tweet (from a previous request), how can I subtract 1 from this id to exclude it from being returned in my next request?

The obvious solution would be to do something like this '&max_id='+lastID-1, but twitter IDs are way to large for such math operations and javascript rounds off the results.

Details about the snowflake update: https://dev.twitter.com/docs/twitter-ids-json-and-snowflake

Posible solutions:

It has been mentioned that I can use the BigInteger Javascript Library: http://silentmatt.com/biginteger/, but in my opinion this is redundant for such as small task.

Do I have to use recursion on the string (id_str) and increment or decrement it by one? I hate to use a hack for such as small detail that should just work.

If you've had this problem please share your solution.

thanks!

回答1:

I ran into this same problem, and ended up solving it by subtracting 1 from the last digit, and then accounting for the scenario when we're subtracting 1 from 0 via recursion.

function decrementHugeNumberBy1(n) {
    // make sure s is a string, as we can't do math on numbers over a certain size
    n = n.toString();
    var allButLast = n.substr(0, n.length - 1);
    var lastNumber = n.substr(n.length - 1);

    if (lastNumber === "0") {
        return decrementHugeNumberBy1(allButLast) + "9";
    }
    else {      
        var finalResult = allButLast + (parseInt(lastNumber, 10) - 1).toString();
        return trimLeft(finalResult, "0");
    }
}

function trimLeft(s, c) {
    var i = 0;
    while (i < s.length && s[i] === c) {
        i++;
    }

    return s.substring(i);
}

回答2:

Indeed, Twitter API will respond with a duplicate tweets unless we decrease max_id parameter.

Here is a nice Twitter API article on max_id: https://dev.twitter.com/docs/working-with-timelines On general concept of working with a large (more than 53-bit) numbers in JavaScritp: http://www.2ality.com/2012/07/large-integers.html

Back to the question: using a library seems like an overkill unless you use it for something else. @bob-lauer has a good lightweight solution but I've written my own function without the recursion:

function decStrNum (n) {
    n = n.toString();
    var result=n;
    var i=n.length-1;
    while (i>-1) {
      if (n[i]==="0") {
        result=result.substring(0,i)+"9"+result.substring(i+1);
        i --;
      }
      else {
        result=result.substring(0,i)+(parseInt(n[i],10)-1).toString()+result.substring(i+1);
        return result;
      }
    }
    return result;
}

To test it run with the following numbers/strings:

console.log("290904187124985850");
console.log(decStrNum("290904187124985850"));
console.log("290904187124985851");
console.log(decStrNum("290904187124985851"));
console.log("290904187124985800");
console.log(decStrNum("290904187124985800"));
console.log("000000000000000001");
console.log(decStrNum("0000000000000000001"));

回答3:

Here is a quick'n'dirty PHP version of @Azat's answer of a non-recursive function to decrement a long string-format (non-negative) integer.

<?php
function decStrNum($n)
{
  $n = (string)$n;
  if ((int)$n == 0 || 0 === strpos($n, '-'))
    return false;
  $result = $n;
  $len = strlen($n);
  $i = $len - 1;
  while ($i > -1) {
    if ($n[$i] === "0") {
      $end = substr($result, $i + 1);
      if ($end === false) $end = '';
      $result = substr($result, 0, -($len - $i)) . "9" . $end;
      $i--;
    } else {
      $end = substr($result, $i + 1);
      if ($end === false) $end = '';
      return substr($result, 0, -($len - $i)) . ((int)$n[$i] - 1) . $end;
    }
  }
  return $result;
}

来源：https://stackoverflow.com/questions/9717488/using-since-id-and-max-id-in-twitter-api

标签

javascript

twitter

increment

biginteger