Select value out of array in PHP

Question

Ok, so I have this in a JSON array (the output of retrievedData())

{
    "device": {
        "01AA02AB141208VV": {
            "$version": -148598935,
            "$timestamp": 1344382016000,
            "serial_number": "01AA02AB141208VV"
        }
    }
}

However, I can't seem to select the serial number. I have tried what usually works, but I can't select it. This is assuming we don't already know the "01AA02AB141208VV".

$retrieved_data = retrieveData($array['userid'], $array['urls']['transport_url'], $array['access_token']);
$retrieved_data_array = json_decode($retrieved_data, true);
$serial_number = $retrieved_data_array['device'][0]['serial_number'];

Am I doing something wrong? I bet it's really simple, but I just cannot figure it out!

Thanks!

where is the code for retrieveData function? Show us the result of var_dump($retrieved_data_array). — Jocelyn
– Jocelyn, Commented Aug 8, 2012 at 0:05
If you don't already know the serial number, then you have no way of accessing the data without looping through each device using a foreach and examining the contents. — drew010
– drew010, Commented Aug 8, 2012 at 0:07
retrieveData is a huge script that just outputs the JSON array. Really not needed, since I gave you its output. $array is also sperate from this and has no effect on it. — Devin
– Devin, Commented Aug 8, 2012 at 0:07
@jprofitt: actually it is an array since true was passed as the 2nd argument. — cOle2
– cOle2, Commented Aug 8, 2012 at 0:08

SomeKittens · Accepted Answer · 2012-08-08 00:08:08Z

4

Unfortunately, it's not really simple. You're trying to find 42 Main St. when you don't know the city Main St. is located in. The only way to find the serial_number would be to loop over $retrieved_data_array with foreach until you find the value you want.

answered Aug 8, 2012 at 0:08

SomeKittens

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Comments

Software Guy · Accepted Answer · 2012-08-08 00:31:03Z

3

you can use key() function to access the keys of the associative array (in this case the '$retrieved_data_array['device']' array:

<?php

$data = '{"device": {"01AA02AB141208VV": {"$version": -148598935,"$timestamp": 1344382016000,"serial_number": "01AA02AB141208VV"}}}';

$retrieved_data_array = json_decode($data, true);
$serial_number = key($retrieved_data_array['device']);
reset($retrieved_data_array['device']);

print_r($serial_number);
print_r($retrieved_data_array['device'][$serial_number]);

?>

answered Aug 8, 2012 at 0:31

Software Guy

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Matthew Blancarte · Accepted Answer · 2012-08-08 00:37:07Z

1

This will grab the serial numbers, assuming you have multiple items in the devices array:

$keys = array();

foreach( $retrieved_data_array['device'] as $key => $val ){
  $keys[] = $key;
}

$serial = $keys[0];

This can be reduced if you know you only have one item in the array...

edited Aug 8, 2012 at 0:37

answered Aug 8, 2012 at 0:22

Matthew Blancarte

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1 Comment

Devin Over a year ago

Now, if there were two, would $keys[1] grab the next?

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