PHP - How to Loop through JSON array with fields starting with "$"

Question

I have been trying to workout how to loop through and output the contents of a json file where field names start with "$" and keep getting an Undefined variable error message

Here is an example of the json file example (taken from https://mixpanel.com/help/reference/webhooks):

[
   {
      "$distinct_id":"13b20239a29335",
      "$properties":{
         "$region":"California",
         "$email":"[email protected]",
         "$last_name":"Bovik",
         "$created":"2012-11-20T15:26:16",
         "$country_code":"US",
         "$first_name":"Harry",
         "Referring Domain":"news.ycombinator.com",
         "$city":"Los Angeles",
         "Last Seen":"2012-11-20T15:26:17",
         "Referring URL":"http://news.ycombinator.com/",
         "$last_seen":"2012-11-20T15:26:19",
      }
   },
   {
      "$distinct_id":"13a00df8730412",
      "$properties":{
         "$region":"California",
         "$email":"[email protected]",
         "$last_name":"Lytics",
         "$created":"2012-11-20T15:25:38",
         "$country_code":"US",
         "$first_name":"Anna",
         "Referring Domain":"www.quora.com",
         "$city":"Mountain View",
         "Last Seen":"2012-11-20T15:25:39",
         "Referring URL":"http://www.quora.com/What-...",
         "$last_seen":"2012-11-20T15:25:42",
      }
   }
]

I am testing with a static string just to try and get things working. Here is my test code...

<?php

    $input = '[{"$distinct_id":"13b20239a29335","$properties":"dddd"}]';
    $jsonObj = json_decode($input, true);

    foreach ($jsonObj as $item) {
        foreach ($item as $rec) {
            echo '<br>';
            $my_id = $rec->$distinct_id;
            echo($my_id);
            $my_id = $rec->$properties;
            echo($my_id);
        }
        echo '<br>';
    }
?>

Any help would be appreciated.

Noob!

UPDATE: Musa gave this example which works for the single level json: foreach ($jsonObj as $item) {

    echo '<br>';
    $my_id = $item->{'$distinct_id'};
    echo($my_id);
    $my_id = $item->{'$properties'};
    echo($my_id);

echo '<br>';

}

How can this then be adapted to read and output all elements of the bigger multi-level json file?

Musa · Accepted Answer · 2014-01-05 20:15:50Z

5

Use Curly bracket notation

$object->{'$property'};

Edit

foreach ($jsonObj as $item) {

        echo '<br>';
        $my_id = $item->{'$distinct_id'};
        echo($my_id);
        foreach ($item->{'$properties'} as $my_prop => $value){
            echo("$my_prop => $value");
        }

    echo '<br>';
}

http://codepad.org/1cudZqlu

With the nested loop you're iterating the properties $distinct_id and $properties so $rec is actually a string and not an object.

Also your json is invalid as it has trailing , in the $properties field.

edited Jan 5, 2014 at 20:15

answered Jan 5, 2014 at 18:35

Musa

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1 Comment

user2525060 Over a year ago

Thanks for that Musa. Much appreciated. How could I then loop through the deeper elements from the main json file?

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