How to save value in foreach cycle? - php

Question

I have foreach cycle in PHP. It is going trough json items, and for every item I have value that changes. I set my cycle to run every 20min.
I need my value to be saved and next time foreach runs for that item I need to assign at the beginning old value to variable so I can compare old and new value in foreach cycle.
here is the code:
// Parse results and extract data to display
foreach($json as $quote)
{
//add before value
$state1 = $state2;
// assign object elements to vars
$q_change = $quote->c;
$q_price = $quote->l;
$q_name = $quote->t;
$q_changep = $quote->cp;
$q_symbol = $quote->t;
$q_ltrade = $quote->lt;
$q_exch = $quote->e;
$state2 = $q_change;
$parametar = $q_change - $state1;
// Define class based on change
if ( $parametar < -0.3 ) { $chclass = "minus"; }
else if ( $parametar > 0.3 ) { $chclass = "plus"; }
else if ( $q_change < 0 ) { $chclass = "minus"; }
else if ( $q_change > 0 ) { $chclass = "plus"; }
else { $chclass = "zero"; $q_change = "0.00"; }
}
Any idea how that might work?

Answer 1

You will have to save the JSON on the file system to retrieve the values on subsequent runs:
$oldJsonFile = '/path/to/data.json';
if (is_file($file)) {
$oldJson = file_get_contents($oldJsonFile);
}
// Do the work, and then store it back to the file system
file_put_contents($cacheFile, $newJson);

Answer 2

I'd imagine you are looking to do something like the following. Sessions will store your data for the next foreach execution.
session_start();
$previousData = $_SESSION['PreviousData'];
foreach($array as $key => $value){
//... all your foreach calculations
//end of foreach
}
$_SESSION['PreviousData'] = $thisData;
Alternatively you could store the data into a database, that's what they are for. Then you'll be free to do all kinds of interesting queries on past records etc.