php - PDO bind array index (postgresql JSONB) for reading -

i'm storing array of objects in postgresql jsonb column, i'm tring load property of nth's object fails bind pdo.

test setup

<?php error_reporting(e_all); ini_set('display_errors',1);  $db = new pdo('...');       $db->exec('create table public.test (id serial primary key, jb jsonb not null )');      $insert = $db->prepare('insert public.test(jb) values (?)');      $insert->execute([json_encode([                                      'q' => 'qst1'                                      , 'a' => [['txt' => 'ans1', 'iscorrect' => true], ['txt' => 'ans2', 'iscorrect' => false], ['txt' => 'ans3', 'iscorrect' => false], ['txt' => 'ans4', 'iscorrect' => false]]                                  ], json_numeric_check)]); 

if read whole array can check

$allanswers = $db->prepare("select jb->'a' public.test id=?"); $allanswers->execute([1]); $result  = json_decode($allanswers->fetchcolumn(),true); foreach ([0,1,2,3,17] $answerid) {     if (!array_key_exists($answerid,$result) ) {         echo $answerid,':','null',"\n";     }     else {         $r = $result[$answerid]['iscorrect'];         echo $answerid,':',($r?'true':'false'),"\n";     } } 

but if need nths don't know how bind (i'm not getting error null values)

$answeriscorrect = $db->prepare("select jb->'a'->?->>'iscorrect' public.test id = ?"); foreach ([0,1,2,3,17] $answerid) {     $succ = $answeriscorrect->execute([$answerid, 1]);     if (true !== $succ) {         die('execute failed');     }     $result = $answeriscorrect->fetchcolumn();     echo $answerid,':',is_null($result)?'null':('true'===$result?'true':'false'),"\n"; } 

current output

0:null 1:null 2:null 3:null 17:null

excepted output

0:true 1:false 2:false 3:false 17:null

finnaly found it

$answeriscorrect = $db->prepare("select jsonb_extract_path(jb->'a',?)->>'iscorrect' public.test id = ?"); 

instead of

$answeriscorrect = $db->prepare("select jb->'a'->?->>'iscorrect' public.test id = ?"); 

worked