Write JSON into a file with PHP

Question

I have this JSON-File here

{
"id" : "bf75b277-169b-49da-8ab1-b78b8dfg1b43-e25c7f28b3",
"ts" : "1372751172664",
"connected" : {
    "ssid" : "eduroam",
    "bssid" : "00:0f:f9:eb:08:81",
    "rssi" : "-62",
    "speed" : "53"
},
"configured" : [
    {
    "ssid" : "eduroam",
    "bssid" : "null",
    "keyMgmnt" : ["2", "3"],
    "grCiphers" : ["0","1","2","3"]
    },
    {
    "ssid" : "foobar",
    "bssid" : "null",
    "keyMgmnt" : ["0"],
    "grCiphers" : ["0","1","2","3"]
    }
],
"location" : {
    "prov" : "network",
    "lat" : "52.3793203",
    "lon" : "9.7231332",
    "acc" : "22.777"
    }
}

and I'm trying to get the key-value-pairs out into a file (and later into a mysql-database). I am having trouble to go along the nested structure. Maybe I do not understand it correctly?

$LOGPATH = "/var/www/test/";
$out = fopen($LOGPATH."testlog.log", "a");
$result = file_get_contents('php://input');
$data = json_decode($result, true);
$value = $data;

$test = array();

This line beneath causes me headaches, how can I say get the key-value-pairs of "connected"? Trying $test = $data['connected'] did not work, as the output simply is a "{" and nothing more...

$test = $data;

fwrite($out, "test \n");
fwrite($out, $test);
fwrite($out, "\n");

foreach ($test as $entry){
   fwrite($out, $entry);
   fwrite($out, "\n");
}

Any idea how to extract the key-value-pairs and/or help me understand the structure?

Use var_dump to understand the structure of your JSON array ($data). — apartridge
– apartridge, Commented Jul 7, 2013 at 18:37

Andy Gee · Accepted Answer · 2013-07-07 18:37:31Z

2

This should get you on the right track

foreach($data['connected'] as $key => $value){
    echo 'Key: '.$key.' Value:'.$value.'<br>';
}

answered Jul 7, 2013 at 18:37

Andy Gee

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Marcin Orlowski · Accepted Answer · 2013-07-07 18:38:35Z

2

json_decode() will dump JSON into regular array. You can do print_r() or var_dump() on it, to see the structure of the array. So to get your connected leaf you do:

$connected = $data['connected'];

You can then iterate over it:

foreach( $connected as $key=>$val ) {
    echo $key . ": " . $val;
}

answered Jul 7, 2013 at 18:38

Marcin Orlowski

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2 Comments

hamena314 Over a year ago

When I try this, this happens: Invalid argument supplied for foreach()

Marcin Orlowski Over a year ago

use var_dump() to check what is content of vars passed. maybe your input data changed?

hamena314 · Accepted Answer · 2013-07-09 23:07:58Z

Got it, thanks to you guys!

// Get a request from i.e. a webpage (this is a webservice)
$jsonArray = file_get_contents('php://input');
// put the JSON-Data into an array
$jsonData = json_decode($jsonArray, true);
// You can simply choose the entry-points. As they do not change for me, they are hardcoded in here, else you had to use something like a for-loop to extract them
$jsonConnect = $jsonData['connected'];
$jsonLocation = $jsonData['location'];
$jsonConfigured = $jsonData['configured'];

// walk through the JSON-Data and extract the values, although the array has more than 2 levels, you can select your entry-point and walk from there on, which makes this quite easy
for($i = 0; $i < count($jsonConfigured); $i++){
        // keyMgmnt itself is an array and I want to concatenate all of its values and put it into a single field in my MySQL-DB, so implode() is used
        $keyMgmnt = implode(",", $jsonConfigured[$i]['keyMgmnt']);
        $grCiphers = implode(",", $jsonConfigured[$i]['grCiphers']);
        $ssid = $jsonConfigured[$i]['ssid'];
        $bssid = $jsonConfigured[$i]['bssid'];

        // from here on I simply put the variables into my MySQL-DB
        $sql_configured = "INSERT INTO configured (keyMgmnt, grCiphers, ssid, bssid) VALUES ('$keyMgmnt', '$grCiphers', '$ssid', '$bssid')";
        mysql_query($sql_configured) or die ("Failure in configured");
}

$sql_connected = "INSERT INTO connected (rssi, speed, ssid, bssid) VALUES ('$jsonConnect[rssi]', '$jsonConnect[speed]', '$jsonConnect[ssid]', '$jsonConnect[bssid]')";
$enterConnected = mysql_query($sql_connected) or die("Failure in connection!");
$sql_location = "INSERT INTO location (lat, prov, lon, acc) VALUES ('$jsonLocation[lat]', '$jsonLocation[prov]', '$jsonLocation[lon]', '$jsonLocation[acc]')";

$enterLocation = mysql_query($sql_location) or die("Failure in location!");

Thanks again!

Case closed.

PS: The structure of the JSON-Data. You get it by using "print_r()" or "var_dump()".

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