Array_push gives null in JSON file

Question

I want to adding array's to an existing .json file with with a HTML form.

this is my PHP:

$myFile = "data.json";      
$newArray = array(
    'name'=> $_POST['name'],
    'date'=> $_POST['date']
);

$fileTmp = file_get_contents($myFile);
$tempArray = json_decode($fileTmp);
array_push($tempArray, $newArray);
$jsonData = json_encode($tempArray);
file_put_contents($myFile, $jsonData);

this is my JSON:

[
  {
    "name": "name 1",
    "date": "01.02.2017"
  },
  {
    "name": "name 2",
    "date": "05.02.2017"
  },
  {
    "name": "name 3",
    "date": "05.03.2017"
  }
]

The problem is i got the warning

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

and in the JSON there's is only null. What is my problem with my code?

$tempArray = json_decode($fileTmp,true); array_push($tempArray, $newArray); try it and tell — Death-is-the-real-truth
– Death-is-the-real-truth, Commented Feb 25, 2017 at 14:01
Does the error happen also with the provided json file or only when starting with an empty one? — aghidini
– aghidini, Commented Feb 25, 2017 at 14:05
@Anant oh yes, thank you! didnt seen that... aghidini problem solved but it was with the provided json — Patrick Dully
– Patrick Dully, Commented Feb 25, 2017 at 14:06

Death-is-the-real-truth · Accepted Answer · 2017-02-25 14:14:17Z

2

Add a second parameter to json_decode() and set it to true:-

$tempArray = json_decode($fileTmp,true); 
array_push($tempArray, $newArray);

edited Feb 25, 2017 at 14:14

answered Feb 25, 2017 at 14:03

Death-is-the-real-truth

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Comments

aghidini · Accepted Answer · 2017-02-25 14:29:02Z

1

Apart from using the associative version of json_decode as already stated in the other answer, I think that the problem is your input json file.

You should check for valid content and create your default array if the json is empty:

$fileTmp = file_get_contents($myFile);
$tempArray = json_decode($fileTmp, true);
if (!$tempArray) {
    $tempArray = array();
}
...

edited Feb 25, 2017 at 14:29

answered Feb 25, 2017 at 14:07

aghidini

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4 Comments

Death-is-the-real-truth Over a year ago

Actually his json what he shown is valid, but this code is also useful to prevent from errors. so +1.

aghidini Over a year ago

@Anant I agree that his input json is valid but I suspected that he was receiving the errors only at the beginning, that is when the input json was empty (or does not exist). I thought that json_decode should produce a valid array also with false as the second parameter, it should simply produce an array of objects, but the OP error is about the first parameter (i.e. the array).

Death-is-the-real-truth Over a year ago

when you will try to push an array into an array of objects you will get this error too (i think)

aghidini Over a year ago

@Anant Actually it works (albeit the final array contains objects and the newly added array): codepad.org/ITdcXai5 it even produces a valid output json: codepad.org/V5STYCCB

Blauharley · Accepted Answer · 2017-02-25 14:52:16Z

-1

I complied code, it works. Check permissions for data.json file.

edited Feb 25, 2017 at 14:52

Blauharley

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answered Feb 25, 2017 at 14:10

user3049289

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