PHP: Adding a new key-value pair to a JSON object

Question

I am having trouble trying to add a new key-value pair to an existing JSON object. I have tried using array_merge, array_push, array_replace... all without success.

Desired format (blog entry case study)

{  
   "1":{  
      "id":"1",
      "name":"lew",
      "email":"[email protected]",
      "title":"lew",
      "description":"lew",
      "categories":[  
         "science"
      ],
      "image":"no_image"
   },
   "2":{  
      "2",
      "name":"lew",
      "email":"[email protected]",
      "title":"lew",
      "description":"lew",
      "categories":[  
         "science"
      ],
      "image":"no_image"
   }
}

Here is my current code (not that if the JSON file is empty, I will simply add the first element, without the need of a merge etc.)

if ($data == null) {
        $post_array = array('id' => "1",'name' => $_POST['name'], 'email' => $_POST['email'], 'title' => $_POST['title'], 'description' => $_POST['description'], 'categories' => $_POST['categories'], 'image' => $imageFilePath);
        echo json_encode($post_array) . "<br>";
        $blog_entry = array("1" => $post_array);
        echo json_encode($blog_entry) . "<br>";
        file_put_contents('blogPosts.json', json_encode($blog_entry));
} else {
        $length_of_data = count($data);
        $new_id = (string)($length_of_data + 1);

        $post_array = array('id' => $new_id, 'name' => $_POST['name'], 'email' => $_POST['email'], 'title' => $_POST['title'], 'description' => $_POST['description'], 'categories' => $_POST['categories'], 'image' => $imageFilePath);
        $merged = array_push($data, array($new_id => $post_array));
        file_put_contents('blogPosts.json', json_encode($merged));
}

Any suggestions are welcomed, thank you

Can we please get a var_dump( $data ); without any additional mods (in your comment you say json_encode - leave that out, and use var_dump or var_export) — random_user_name
– random_user_name, Commented Nov 30, 2017 at 20:43
'var_dump($data)' before merged line: array(1) { [1]=> array(7) { ["id"]=> string(1) "1" ["name"]=> string(3) "lew" ["email"]=> string(28) "[email protected]" ["title"]=> string(3) "lew" ["description"]=> string(3) "lew" ["categories"]=> array(1) { [0]=> string(7) "science" } ["image"]=> string(8) "no_image" } } — LewisW44
– LewisW44, Commented Nov 30, 2017 at 20:44
after merged line: array(2) { [1]=> array(7) { ["id"]=> string(1) "1" ["name"]=> string(3) "lew" ["email"]=> string(28) "[email protected]" ["title"]=> string(3) "lew" ["description"]=> string(3) "lew" ["categories"]=> array(1) { [0]=> string(7) "science" } ["image"]=> string(8) "no_image" } [2]=> array(1) { [2]=> array(7) { ["id"]=> string(1) "2" ["name"]=> string(4) "test" ["email"]=> string(15) "[email protected]" ["title"]=> string(4) "test" ["description"]=> string(5) "tedst" ["categories"]=> array(1) { [0]=> string(6) "health" } ["image"]=> string(8) "no_image" } } } — LewisW44
– LewisW44, Commented Nov 30, 2017 at 20:45
Seems like you just want array_push($data, $post_array);. The id will be assigned automatically. I'm surprised you had no success with array merge, but I can't tell what went wrong there. — jh1711
– jh1711, Commented Nov 30, 2017 at 20:46

random_user_name · Accepted Answer · 2017-11-30 23:22:09Z

2

So - you don't really need a "key => value" pair, you just want to append the array to your main array.

The simplest way to do this, given your code, is this (NOTE: replace your entire if / else statement with this):

$new_id = count( (array)$data ) + 1;
$data[ $new_id ] = array('id' => $new_id, 'name' => $_POST['name'], 'email' => $_POST['email'], 'title' => $_POST['title'], 'description' => $_POST['description'], 'categories' => $_POST['categories'], 'image' => $imageFilePath);
file_put_contents( 'blogPosts.json', json_encode( $data ) );

edited Nov 30, 2017 at 23:22

answered Nov 30, 2017 at 20:52

random_user_name

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2 Comments

LewisW44 Over a year ago

Just noticed. If the JSON file is empty before trying to add, this looses the key. (outputting

[{"id":"1","name":"lew","email":"[email protected]","title":"lew","description":"lew","categories":["sport"],"image":"no_image"}]

instead of

{"id":"1","name":"lew","email":"test@hotmail.‌co.uk","title":"lew"‌,"description":"lew"‌,"categories":["scie‌nce"],"image":"no_im‌age"}}

LewisW44 Over a year ago

Sorry, I incorrectly copied the second example. It was: {"1":{"id":"1","name":"lew","email":"test@hotmail.‌co.uk","title‌":"lew"‌,"descripti‌on":"lew"‌,"categor‌ies":["scie‌nce"],"‌image":"no_im‌age"}‌}

blueweb · Accepted Answer · 2017-11-30 20:54:14Z

1

This code will work and do want you seem to want !

(This is just a solution, not a elegant or even something i would do...)

<?php
$data = file_get_contents('blogPosts.json');
$data = (empty($data)) ? null : json_decode($data, true);

if ($data == null) {
    $post_array = array('id' => "1", 'name' => $_POST['name'], 'email' => $_POST['email'], 'title' => $_POST['title'], 'description' => $_POST['description'], 'categories' => $_POST['categories'], 'image' => $imageFilePath);
    $blog_entry = array("1" => $post_array);
    file_put_contents('blogPosts.json', json_encode($blog_entry));
}
else {
    $post_array = array('id' => $new_id, 'name' => $_POST['name'], 'email' => $_POST['email'], 'title' => $_POST['title'], 'description' => $_POST['description'], 'categories' => $_POST['categories'], 'image' => $imageFilePath);
    $data[] = $post_array;
    file_put_contents('blogPosts.json', json_encode($data));
}

var_dump($data);

this would work exactly the same and with less code ...

<?php
$data = file_get_contents('blogPosts.json');
$data = (empty($data)) ? array() : json_decode($data, true);

$new_id = count($data) + 1;

$post_array = array('id' => $new_id, 'name' => $_POST['name'], 'email' => $_POST['email'], 'title' => $_POST['title'], 'description' => $_POST['description'], 'categories' => $_POST['categories'], 'image' => $imageFilePath);

$data[] = $post_array;
file_put_contents('blogPosts.json', json_encode($data));

var_dump($data);

(edited, had a mistake...)

edited Nov 30, 2017 at 20:54

answered Nov 30, 2017 at 20:48

blueweb

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2 Comments

LewisW44 Over a year ago

Thanks for taking the time to reply, this solution worked well - and was presented more elegantly by @cale_b

random_user_name Over a year ago

Just a code-style observation: data == NULL is probably better represented as simply ! data, as data == NULL is really the same as "data is falsey", due to the loose equal operator. If it is truly checking for null, it should be data === NULL

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