How can I construct an array with a specific key using PHP?

Question

I have an array of 4 elements $device_report = []; with these data in it

array:4 [▼
  0 => array:2 [▼
    "up_bytes" => 2818
    "down_bytes" => 948
  ]
  1 => array:2 [▼
    "up_bytes" => 472
    "down_bytes" => 439
  ]
  2 => array:2 [▼
    "up_bytes" => 3364
    "down_bytes" => 1317
  ]
  3 => array:2 [▼
    "up_bytes" => 3102
    "down_bytes" => 1682
  ]
]

Right now, I have this

    $device_report = [];
    foreach ($devices as $device){
        $device_mac = $device->device_mac; //080027E2FC7D
        $data = VSE::device($device_mac);
        array_push($device_report,$data);
    }

I've tried

    $device_report = [];
    foreach ($devices as $device){
        $device_mac = $device->device_mac; //080027E2FC7D
        $data = VSE::device($device_mac);
        array_push($device_report[$device_mac],$data);
    }

It give me error :

array_push() expects parameter 1 to be array, null given

I just want to my key to be a specific device Mac Address rather than 0,1,2,3.

Any hints will be much appreciated !

Just do: $device_report[$device_mac] = $data;

Rizier123
– Rizier123

2015-11-25 14:58:51 +00:00
Commented Nov 25, 2015 at 14:58 — Rizier123
– Rizier123, Commented Nov 25, 2015 at 14:58
Short and elegant. Thanks.

code-8
– code-8

2015-11-25 15:01:16 +00:00
Commented Nov 25, 2015 at 15:01 — code-8
– code-8, Commented Nov 25, 2015 at 15:01
Also see: stackoverflow.com/q/2121548/3933332

Rizier123
– Rizier123

2015-11-25 15:04:51 +00:00
Commented Nov 25, 2015 at 15:04 — Rizier123
– Rizier123, Commented Nov 25, 2015 at 15:04

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

Per the documentation, array_push:

int array_push ( array &$array , mixed $value1 [, mixed $... ] )

array_push() treats array as a stack, and pushes the passed variables onto the end of array. The length of array increases by the number of variables pushed. Has the same effect as:

In your particular case, you're trying to create a new key and assign the array, so you're getting the error that $device_report[$device_mac] is not an array. This is indeed correct since the key doesn't already exist.

To overcome this, assign the array directly as oppose to using array_push.

Try this:

$device_report[$device_mac] = $data;

instead of:

array_push($device_report[$device_mac], $data);

edited Jun 20, 2020 at 9:12

CommunityBot

11 silver badge

answered Nov 25, 2015 at 14:58

War10ck

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Comments

Oberst · Accepted Answer · 2015-11-25 14:59:54Z

1

I wouldnt use array_push for this. No reason to.

$device_report = [];
foreach ($devices as $device){
    $device_mac = $device->device_mac; //080027E2FC7D
    $data = VSE::device($device_mac);
    $device_report[$device_mac]=$data; // <-- This line changed
}

answered Nov 25, 2015 at 14:59

Oberst

47711 silver badges19 bronze badges

Comments

Sebastian Brosch · Accepted Answer · 2015-11-25 14:59:26Z

1

Try the following:

$device_report = [];
foreach ($devices as $device){
    $device_mac = $device->device_mac; //080027E2FC7D
    $data = VSE::device($device_mac);

    //add this to init the array.
    if (is_array($device_report[$device_mac]) === false) {
        $device_report[$device_mac] = [];
    }

    array_push($device_report[$device_mac],$data);
}

The error message appear because $device_report[$device_mac] is null. You have to initialize the value with an array. With the following code you initialize it with a empty array if no array is available:

//add this to init the array.
if (is_array($device_report[$device_mac]) === false) {
    $device_report[$device_mac] = [];
}

answered Nov 25, 2015 at 14:59

Sebastian Brosch

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