json_decode/encode confusion

[TechnoDiver]

I'm having a bit of trouble understanding why json_decode() is returning a null value, hoping someone has the time, will and energy to break it down for me. I've looked it up from various sources and don't get why it's not working. There's the following ->

<?php 
public function hasPermission($key) {
        $group = $this->_db->get("groups", array("id", "=", $this->data()->group));

        if($group->count()) {
            
            $permissions = $group->first()->permissions;
            echo gettype($permissions);
            echo $permissions;
            
        }
    }

This returns $permissions as a string ->

Quote

{'admin': 1, 'moderator': 1}

But when I do this ->

<?php

public function hasPermission($key) {
        $group = $this->_db->get("groups", array("id", "=", $this->data()->group));

        if($group->count()) {
            $permissions = json_decode($group->first()->permissions, true);
           
            echo gettype($permissions);
           
        }
    }

permissions comes back as a null type.

I've been reading about json_decode() and it requires a json string in UTF-8 encoded. Which my data is (or seems to me to be). Could someone point out my error, please?! Thank you

[gw1500se]

From the manual:

"Returns the value encoded in json in appropriate PHP type. Values true, false and null are returned as true, false and null respectively. null is returned if the json cannot be decoded or if the encoded data is deeper than the nesting limit."

The value you are trying to decode is not a JSON encoded string. You need to translate the ' to ".

Edited September 17, 2021 by gw1500se

[TechnoDiver]

9 minutes ago, gw1500se said:

The value you are trying to decode is not a JSON encoded string.

Ok, so I misread that as "a string in JSON format".

Still saying that, then why does

<?php

$permissions = json_decode(json_encode($group->first()->permissions), true);

return a string with the exact same value and type as

$group->first()->permissions)

shouldn't it be returning an array from the json?

[Barand]

This fails

$j = "{'admin': 1, 'moderator': 1}"  ;
$a = json_decode($j, 1);
echo '<pre> a ' . print_r($a, 1) . '</pre>';

This works

$j = '{"admin": 1, "moderator": 1}' ;
$b = json_decode($j, 1);
echo '<pre> b ' . print_r($b, 1) . '</pre>';

Note the quotes in the JSON string.

[gizmola]

You can call json_last_error() to see what the parser said.

[Barand]

My money's on "Syntax error". (Error 4)

[gizmola]

Agree 👍.  Gotta use Double quotes around strings in Json.      ->  Spec Here.  Scroll down to String.  Embedded double quotes have to be escaped with a backslash.  

 

[TechnoDiver]

11 hours ago, Barand said:

Note the quotes in the JSON string.

Interesting, I find that a bit counterintuitive as I've made a habit of keeping singles inside doubles. Thanks for your help