So, currently at work I’ve been rewriting all our Payment Gateways for Your Members. Making them more better Class based an abstracting out the common functions to a base class, to save memory footprint and code etc.
And came across a problem when rewriting the Facebook Credits handler.
The order ID that gets passed around, as well as the Application ID is too long for a 32 Bit PHP installation to handle when treating it as an Integer.
So a number like “239724439419867″ was ending up as “1.7592246582797E+14″ when stored/processed, or converted to a string.
Now the obvious way to process this is to convert it to a string another way, which is somewhat difficult since before you even start it is in a format that you can’t handle.
The saving grace here is the fact that data is passed to you as a JSON packet (aside from the fact the Order ID is in the $_POST variable and thus a string, so I could of used it from there).
This led to me to look at the JSON packet, which starts as a string but when decoded the large integers are still a larger integer than can be processed (whether you json_decode to a Array or to an Object, the problem persists). So I thought about how to process the raw JSON packet and make sure the order ID, and other large integers are treated as strings.
If you look at a Raw JSON packet you can easily spot whats a string, integer, object or array.
Take this example Facebook Credits JSON Packet, (wrapped for readability):
“receiver”:197803678,”amount”:5,”update_time”:1320075413,
“time_placed”:1320075408,”data”:”",”items”:[{"item_id":"
"description":"A New Purchasable Post",
"image_url":"
"price":5,"data":""}],”status”:”
- order_id is an integer as it has no ” around it
- status is a string as its surrounded by “
- Items is an array as its surrounded by [, in this case containing a single object, entries/items are comma separated.
So after thinking about this I decided the best way to sort this out was to convert the integers in the raw JSON packet to strings before decoding.
In pseudo code.
Explode around ,
array walk each item
split on :
check if there are no " in the second bit
if none wrap in "
glue back together
Something alone the lines of:
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function largeint($rawjson) {
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$rawjson = '{', . $rawjson . '}';
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return $json;
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}
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function strfun(&$entry, $key) {
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$data[1] = '"' . $data[1] . '"';
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}
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}
I'm not sure in terms of memory footprint if its cheaper to do a substr of $data[1] and check if its a ” or not.
I suppose it could test the string length of the detected integer to see if its invalid/unable to process, but then you would be performing a string function on an integer and again the problem would arise.
But as a block of code is does the job, its obviously not ideal for all situations, since in this case I want the integer as a string, I’m not using it for math, but if I did, we probably need to do some bizarre unpack-ing or something.
Any opinions or improvements give us a comment below 
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