如何在php中读取多级json的值？

Question

I have the following code to read a Json and store some values into an array:

<?php
$json = '[{
        "provider_id":1,
        "nro_chart":1,
        "control": {
            "color": "blue",
            "total_value": 21.5,
            "car_id": 421118
        }
    },
    {
        "control": {
            "color": "green",
            "total_value": 25,
            "car_id": 421119
        }
    },
    {
        "control": {
            "color": "red",
            "total_value": 18,
            "car_id": 421519
        }
    }
]';

$j = json_decode($data);
$result = [];
foreach ($j as $item) {
    array_push($result,[
        'total_value' => $item->control->total_value,
        'car_id' => $item->control->car_id
    ]);
}

Now I need to get the two values that are outside of "control" like "provider_id" and "nro_chart" inside a variable.

Answer 1

The JSON contains an array of one element, so to access provider_id and nro_chart, get the first element and directly access the properties:

$j = json_decode($json);
var_dump($j[0]->provider_id); // /Applications/MAMP/htdocs/trello/up.php:28:int 1
var_dump($j[0]->nro_chart); // /Applications/MAMP/htdocs/trello/up.php:28:int 1

Demo

Or, within that same foreach loop:

foreach ($j as $item) {
    array_push($result,[
        'total_value' => $item->control->total_value,
        'car_id' => $item->control->car_id
    ]);
    if (isset($item->provider_id)) {
        var_dump($item->provider_id);
    }
    if (isset($item->nro_chart)) {
        var_dump($item->nro_chart);
    }
}

Be sure to check if the property is set for that element with isset() first.

Answer 2

json_decode($json, true);

will transform your json string to an associative array. so now you can use : $item['provider_id'].

Answer 3

Here is a way to modify the array and declare the two extra variables with less iterated functions.

Code: (Demo)

$array = json_decode($json,true);  // decode as array because that is what you are generating in the result

$provider_id=$array[0]['provider_id'];
$nro_chart=$array[0]['nro_chart'];

foreach($array as $index=>&$subarray){  // modify $subarray by reference
    $subarray=['total_value'=>$subarray['control']['total_value'],'car_id'=>$subarray['control']['car_id']];  // overwrite each subarray using the first two elements from deeper "control" subarray
}

echo "provider_id = $provider_id
";  // display integer value
echo "nro_chart = $nro_chart
";      // display integer value
var_export($array);                   // display updated array

Output:

provider_id = 1
nro_chart = 1
array (
  0 => 
  array (
    'total_value' => 21.5,
    'car_id' => 421118,
  ),
  1 => 
  array (
    'total_value' => 25,
    'car_id' => 421119,
  ),
  2 => 
  array (
    'total_value' => 18,
    'car_id' => 421519,
  ),
)