Multidimensional array "join" in PHP based on a key value

Question

I have two JSON objects which I am converting to arrays. I need to join the two arrays based on a shared key ("locationCode"), and add the "address" array data from one array to the other.

After I successfully pull the JSON from a remote server using CURL, I convert them to arrays:

$json1 = json_decode($jsonresult, true);
$json2 = json_decode($jsonresult2, true);

The resulting arrays look like this:

$json1:

"maxResults":500,
"events":[
  {
     "eventCode":"20140001",
     "eventId":"72",
     "contact":{
        "contactName":"John Doe",
        "organization":"John Doe Inc.",
        "notes":""
     },
     "location":{
        "locationName":"Company Factory",
        "locationCode":"factory",
        "email":"",
        "phone":"866-123-4567",
        "tollfree":"",
        "fax":"",
        "url":"",
        "notes":""
     },
     "timezone":"(GMT-08:00) Pacific Time (US & Canada)",
     "primaryFormURL":"path/to/form"
  },
  {
     "eventCode":"20140002",
     "eventId":"73",
     "contact":{
        "contactName":"John Doe",
        "organization":"John Doe Inc.",
        "notes":""
     },
     "location":{
        "locationName":"Company HQ",
        "locationCode":"hq",
        "email":"",
        "phone":"866-123-4567",
        "tollfree":"",
        "fax":"",
        "url":"",
        "notes":""
     },
     "timezone":"(GMT-08:00) Pacific Time (US & Canada)",
     "primaryFormURL":"path/to/form"
  },
  {
     "eventCode":"20140003",
     "eventId":"74",
     "contact":{
        "contactName":"John Doe",
        "organization":"John Doe Inc.",
        "notes":""
     },
     "location":{
        "locationName":"Company HQ",
        "locationCode":"factory",
        "email":"",
        "phone":"866-123-4567",
        "tollfree":"",
        "fax":"",
        "url":"",
        "notes":""
     },
     "timezone":"(GMT-08:00) Pacific Time (US & Canada)",
     "primaryFormURL":"path/to/form"
  }
]

$json2:

"maxResults":500,
"locations":[
  {
     "numberOfRooms":null,
     "totalSpace":null,
     "address":{
        "line1":"1245 Anystreet, Building 600",
        "line2":"",
        "line3":"",
        "line4":"",
        "city":"Anycity",
        "state":"CA",
        "postalCode":"98765",
        "country":"United States",
        "intlState":""
     },
     "locationCode":"factory",
     "desc":"",
     "url":""
  },
  {
     "numberOfRooms":null,
     "totalSpace":null,
     "address":{
        "line1":"3421 Anystreet, Building 200",
        "line2":"",
        "line3":"",
        "line4":"",
        "city":"Anycity",
        "state":"CA",
        "postalCode":"97654",
        "country":"United States",
        "intlState":""
     },
     "locationCode":"hq",
     "desc":"",
     "url":""
  }
]

Now I need to join the two arrays based on the "locationCode" key matching. The join will consist of adding the "address" array data from $json2 into $json1 in the appropriate matched array position. I have been trying a variety of multidimensional array iterators, but I'm having a hard time figuring out how to actually selectively move the values I need from one array to the other. I have an iterator that finds the matches, like so:

$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($json1));
$iterator2 = new RecursiveIteratorIterator(new RecursiveArrayIterator($json2));
    foreach($iterator as $key1=>$value1) {
        if($key1=="locationCode") {
            foreach($iterator2 as $key2=>$value2) {
                if($key2=="locationCode" && $value1==$value2){
                    echo $key1.' -- '.$value1.':::'.$key2.' -- '.$value2.'<br />';
                }
            }

        }
    }

This successfully outputs the matched values. How do I now grab the "address" array data, and add it to the position within $json1 where the match was identified?

what is your criteria for matching location and address?

user2936213
– user2936213

2014-01-17 06:43:57 +00:00
Commented Jan 17, 2014 at 6:43 — user2936213
– user2936213, Commented Jan 17, 2014 at 6:43
the "locationCode" value will be the same.

Maxwell Donnelly
– Maxwell Donnelly

2014-01-18 01:35:35 +00:00
Commented Jan 18, 2014 at 1:35 — Maxwell Donnelly
– Maxwell Donnelly, Commented Jan 18, 2014 at 1:35

Mike Brant · Accepted Answer · 2014-01-18 01:40:31Z

1

I would first process json2 into a new array with locationCode values as keys and address objects as values. Then I would walk through the events array and add the address to it if you can find a match for the location code in this array.

$json1 = json_decode($jsonresult);
$json2 = json_decode($jsonresult2);
// map locations to associative array
$addresses = array();
foreach($json2['locations'] as $location) {
    $addresses[$location->locationCode] = $location->address;
}
// add addresses to events
$events = $json1['events'];
array_walk($events, function (&$event, $key_not_used, $addresses) {
    if(array_key_exists($event->locationCode, $addresses)) {
        $event->address = $addresses[$event->locationCode];
    }
});

OP Update: Here is the final, working code...

$json1 = json_decode($jsonresult);
$json2 = json_decode($jsonresult2);

// map locations to associative array
$addresses = array();
foreach($json2->locations as $currlocation) {
    $addresses[$currlocation->locationCode] = $currlocation->address;
}

// add addresses to events
$events = $json1->events;

function add_address(&$event, $key_not_used, $searcharray) {
    if(array_key_exists($event->location->locationCode, $searcharray)) {
        $event->address = $searcharray[$event->location->locationCode];
    }
}

array_walk($events, 'add_address', $addresses);

$merged_events = json_encode($events);
print_r($merged_events);

edited Jan 18, 2014 at 1:40

answered Jan 17, 2014 at 6:57

Mike Brant

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3 Comments

Maxwell Donnelly Over a year ago

Do I need to add ",true" to the json_decode function? I've never understood precisely the difference in the return object with/without "true".

Mike Brant Over a year ago

@MaxwellDonnelly The true option will force objects into associative arrays. I personally would recommend working with objects, as when you are "copying" address objects to events you are actually only copying a pointer to the object's memory location, so it is better from a memory management perspective. In this case I also think object are more representative of what you are working with in a real world sense. You are working with addresses with discrete properties (address lines, city, state, etc.) and events with their own properties.

Maxwell Donnelly Over a year ago

Your code got me VERY close. There were a couple of syntax errors I had to clean up (missing a couple of close-parenthesis) and had to access the objects a little differently. I ended up coding the array_walk function outside the array_walk itself, and had to rename a few variable. My finished, working code is added to your answer.

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