Iterate through JSON String in PHP?

Question

it seems to be a really easy question, but I am a little bit struggling: I am receiving a JSON String via JavaScript. Now I would like to iterate through the element. The resulting string has this form: {"title":value,"title2":value}

How can I iterate through this JSON string without knowing the key and value? I would like to get this output:

title -> value

title2 -> value2

I tried it this way:

$json = file_get_contents('php://input');
$array = json_decode($json,true);
$response = "Test";
foreach($array as $key=>$val) {
    $response = $response. "$key : $val";
}

echo json_encode($response);

It only returns "Test". If I change it to echo json_encode($array), it returns the mentioned JSON String.

wait, are you using php or javascript? You mention both in your question. I answered in php, but it is simple to do in js also — Chris Strickland
– Chris Strickland, Commented Aug 11, 2021 at 7:28
What have you tried to resolve the problem? Where are you stuck? Have you tried to dump $array, just to see what it contains? — Nico Haase
– Nico Haase, Commented Aug 11, 2021 at 8:14

Chris Strickland · Accepted Answer · 2021-08-11 07:33:17Z

2

You mention javascript and php in your question, so I'm going to answer for both. Here is JS, two different ways. I believe that foreach is being deemphasized in favor of the (of) construct now, but I don't work primarily in JS:

var json = '{"title": 12, "title2": "text"}';
var data = JSON.parse(json);

Object.keys(data).forEach(function(key) {
  console.log(key + ' -> ' + data[key])
})

for(key of Object.keys(data)) {
  console.log(key + ' -> ' + data[key]);
}

And for PHP:

You can parse the json string into an array using json_decode:

$json = '{"title": 12, "title2": "text"}';
$arr = json_decode($json, true);
foreach($arr as $key=>$val) {
    echo "$key : $val";
}

true parses it into an array instead of a std object.

https://www.php.net/manual/en/function.json-decode.php

edited Aug 11, 2021 at 7:33

answered Aug 11, 2021 at 7:22

Chris Strickland

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13 Comments

JavaForAndroid Over a year ago

I added the code I used. Unfortanetly it does not enter the loop. Do you have any idea what might be wrong? Might it be an error because of the type? JSON_decode returns a string.

Chris Strickland Over a year ago

json_decode is bad in one way because it will fail silently. You can call json_last_error() to get the last error and troubleshoot. I would start by checking the value of $json, to make sure that it is valid json. php.net/manual/en/function.json-last-error.php

JavaForAndroid Over a year ago

json_decode returns a string, so it seems to fail.

Chris Strickland Over a year ago

You can also check the value of array with something like echo "<pre>"; print_r($array); echo "</pre>"; echo "<pre>"; var_dump($json); echo "</pre>"; exit;

Chris Strickland Over a year ago

What does json_decode return? Does json_last_error show an error? What does $array contain?

|

Karl · Accepted Answer · 2021-08-11 08:43:10Z

0

Because of response's format you must decode the decoded format in order to take the object as you want

$json = '{"title": 12, "title2": "text"}';
$encoded=json_encode($json);
$decoded=json_decode($encoded);
$ddecode=json_decode($decoded);
foreach($ddecode as $key=>$val) {
    echo "$key -> $val";
}

Output :

title -> 12 title2 -> text

answered Aug 11, 2021 at 8:43

Karl

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