JSON字符串中的格式错误

I have this piece of code

$bom = Foo::getFooFromName($fooName);
            $content = json_decode($foo['content'], true);
            $content[] =  $foo_name . ':'.  $qty  ;

            Foo::where('id', $foo['id'])->update([
                'content' => json_encode($content, JSON_FORCE_OBJECT | JSON_UNESCAPED_SLASHES)
            ]);

that when executed it fives me this JSON STRING:

{"0":{"171":"3"},"1":"396:3"}

This part already exists, so the JSON string is correct: {"0":{"171":"3"} but when I run `$content[] = $foo_name . ':'. $qty ;

            Foo::where('id', $foo['id'])->update([
                'content' => json_encode($content, JSON_FORCE_OBJECT | JSON_UNESCAPED_SLASHES)
            ]);

It seems that I am unable to properly format the JSON String to look like this:

{"0":{"171":"3"},"1":{"396":"3"}}

Any idea would be greatly appreciated.

You're inserting a string to the array, while you should be inserting another array.

Replace

$content[] =  $foo_name . ':'.  $qty  ;

with

$content[] =  [$foo_name =>  $qty];