在没有键/值对的情况下在PHP中更改JSON的顺序

Question

I have a situation where i need to sort a JSON object by date. I've searched for solutions online and everything points in the direction of PHP's usort function, but all examples have a key/value pair to sort on.

This is how i load the feed:

$ret = file_get_contents($url);
$res = json_encode($ret);

Wich results in the following JSON

{  
   "2015-12-14":{  
      "direction":"S",
      "snowfall":0.0,
      [..]
  },
   "2015-12-15":{  
      "direction":"S",
      "snowfall":3.0,
      [..]
   },
   "2015-12-12":{  
      "direction":"SE",
      "snowfall":0.0,
      [..]
   },
   "2015-12-13":{  
      "direction":"S",
      "snowfall":0.0,
      [..]
   },
   "2015-12-10":{  
      "direction":"E",
      "snowfall":0.0,
      [..]
   },
   "2015-12-11":{  
      "direction":"S",
      "snowfall":0.0,
      [..]
   }
}

As you can see, the data is not properly ordered by date, but the date value is the key so how can i sort the object by date (2015-12-10, 2015-12-11, 2015-12-12, 2015-12-13, 2015-12-14, 2015-12-15)?

Answer 1

$json = '{  
   "2015-12-14":{  

      "direction":"S",

      "snowfall":0.0

  },

   "2015-12-15":{  

      "direction":"S",

      "snowfall":3.0

   },

   "2015-12-12":{  

      "direction":"SE",

      "snowfall":0.0

   },

   "2015-12-13":{  

      "direction":"S",

      "snowfall":0.0

   },

   "2015-12-10":{  

      "direction":"E",

      "snowfall":0.0

   },

   "2015-12-11":{  

      "direction":"S",

      "snowfall":0.0

   }

}';

$array = get_object_vars(json_decode($json));

ksort($array);

echo json_encode((object)$array);