从php访问json中的对象

Question

It's been a while since I've done this, and I'm clearly missing some critical piece. I hope one you all can set me straight.

I have a json file that I'm decoding and I was hoping it was a simple task to access the data for a specific date. Here's what I've done so far.

$solardata = file_get_contents('solar.json');
$solarjson = json_decode("$solardata");
$production = $solarjson->{'2019-01-24 11:00:00'};
echo "$production";

The $production variable is always empty. For reference the solar.json file starts out like this:

{"powerDetails":{"timeUnit":"QUARTER_OF_AN_HOUR","unit":"W","meters":[{"type":"Production","values":[{"date":"2019-01-24 11:00:00","value":273.5632},{"date":"2019-01-24 11:15:00","value":405.8625},{"date":"2019-01-24 11:30:00","value":558.6771},

A var_dump($solarjson) starts out like this:

object(stdClass)#321 (1) { ["powerDetails"]=> object(stdClass)#3 (3) { ["timeUnit"]=> string(18) "QUARTER_OF_AN_HOUR" ["unit"]=> string(1) "W" ["meters"]=> array(1) { [0]=> object(stdClass)#4 (2) { ["type"]=> string(10) "Production" ["values"]=> array(316) { [0]=> object(stdClass)#5 (2) { ["date"]=> string(19) "2019-01-24 11:00:00" ["value"]=> float(273.5632) } [1]=> object(stdClass)#6 (2) { ["date"]=> string(19) "2019-01-24 11:15:00" ["value"]=> float(405.8625) } [2]=> object(stdClass)#7 (2) { ["date"]=> string(19) "2019-01-24 11:30:00" ["value"]=> float(558.6771) }

The server error log says:

Undefined property: stdClass::$2019-01-24 11:00:00 in /home/......

Are the ojects I'm trying to access inside an array that I still need to loop through? I was dreaming that I could avoid all that with a simple object request, as I look for specific data, but as I said, I'm pretty rusty. Thanks for your help.

Answer 1

$solardata = file_get_contents('solar.json');
$solarjson = json_decode("$solardata");
$production = $solarjson['powerDetails']['meters'][0]['values']['date'];
echo "$production";`

this OUTPUT '2019-01-24 11:00:00';

You may also modify the content by :

$solardata = file_get_contents('solar.json');
$solarjson = json_decode("$solardata");
$solarjson['powerDetails']['meters'][0]['values']['date'] = date(y-m-d);
echo $solarjson['powerDetails']['meters'][0]['values']['date'];`