Manually created JSON string is not valid

Question

I created a manual loop to form a json that is used by another API on a project that I am starting, please find below.

The problem is that the API is not recognising my json output. I checked the result of my loop and it looks fine.

If I copy and paste directly my result (echo) it works fine, but through my loop it is not working. Does anyone have any idea?

foreach ($array['hits'] as $key => $value) {

    $message = $message.'{
            "title":"'.$value['Title'].'",
            "image_url":"'.$value['image'].'",
            "subtitle":"'.substr($value['Detail'],0,120).'",
            "buttons":[
                    {
                            "type":"web_url",
                            "url":"'.SITE_ROOT_URL.$value['URL'].'?utm_source=chatbot",
                            "title":"Leia mais"
                    }
            ]
    },';

}

$message = '{"messages": [
             {
                     "attachment":{
                             "type":"template",
                             "payload":{
                                     "template_type":"generic",
                                     "elements":['.rtrim($message,",").']
                             }
                     }
             }
     ]
}';

echo $message;

The output of var_export($array['hits']) looks like:

array ( 0 => array ( 'ID' => '69', 'Title' => 'This is an example', 'URL' => 'example/1', 'Detail' => 'Some description here...', 'image' => 'image1.png', 'objectID' => '75877631') ), 1 => array ....

@JayBlanchard I wouldn't go so far as saying never manually create JSON - there are some genuine cases that do call for it, but this certainly isn't one of them. i.e. json_encode can output the wrong kind of array in certain circumstances. — Luke Briggs
– Luke Briggs, Commented Jan 30, 2017 at 22:06
Can you post the value of $array['hits']? Use var_export() so we can paste it into a script. — Barmar
– Barmar, Commented Jan 30, 2017 at 22:09
FWIW, the original issue is that it adds an extra , at the very end. Everything else validates except when e.g. 'Title' contains illegal characters. (i.e. consider what happens if your title was: "Hello!" - Greetings and you. Those quotes would cause it to generate invalid JSON.) — Luke Briggs
– Luke Briggs, Commented Jan 30, 2017 at 22:27

Barmar · Accepted Answer · 2017-01-30 22:53:13Z

5

Don't generate the JSON by hand. Build the array and then use json_encode().

$messages = array();
foreach ($array['hits'] as $key => $value) {
    $messages[] = array(
        'title' => $value['Title'],
        'image_url' => $value['image'],
        'subtitle' => substr($value['Detail'], 0, 120),
        'buttons' => array(
            array(
                'type' => 'web_url', 
                'url' => SITE_ROOT_URL.$value['URL'].'?utm_source=chatbot', 
                'title' => "Leia mais"
            )
        )
    );
}
$result = array(
    'messages' => array(
        'attachment' => array(
            'type' => 'template',
            'payload' => array(
                'template_type' => 'generic',
                'elements' => $messages
            )
        )
    )
);
echo json_encode($result);

DEMO

Notice how the elements of your hand-constructed JSON arrays and objects map directly to PHP arrays. If the JSON contains:

{ "something": "something else" }

the corresponding PHP is:

array("something" => "something else")

edited Jan 30, 2017 at 22:53

answered Jan 30, 2017 at 22:23

Barmar

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5 Comments

czmarc Over a year ago

thanks, lesson learned! :-) just trying to figure out why the result is not printing with echo json_encode($result);

Barmar Over a year ago

I had one mistake, title instead of Title.

czmarc Over a year ago

My $results['hits] array gives me in this format " Array( [0] => Array ( [ID] => 69 [Title] => This is an example ", which is different from var_export. Inside my loop the values are not being associated with messages[] array. It only works/print if I do, for example, echo $value['Title'];

czmarc Over a year ago

This is the original result that I'm receiving: github.com/algolia/…

Barmar Over a year ago

@czmarc The difference between var_dump() and var_export() is that the latter prints in the format of PHP code, so it can be put into another script like I did in my demo. The structure of the data is the same.

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