Whenever i submit the checkbox when pressing the "Save All" button, it does not update to the database. How do I debug it$?$ save.php is in charge of handling submitting the data.

$1$st image: Checkbox code

$2$nd image: Submitform function

$3$rd image: Save all button

$4$th: Home page

save.php:

session$\_$start$()$;

include$("./$database$/$connection$.$php$")$;

$//$ Check if the request is a POST request with JSON data

if $($$$\_$SERVER$[\text{'}$REQUEST$\_$METHOD'$]===$ 'POST' && strpos$($$$\_$SERVER$[\text{'}$CONTENT$\_$TYPE'$],$ 'application$/$json$\text{'})!==$ false$)\{$

$//$ Get the JSON input

$json $=$ file$\_$get$\_$contents$(\text{'}$php:$//$input$\text{'})$;

$data $=$ json$\_$decode$($$json, true$)$;

$//$ Process the data here

if $($$data$)\{$

$//$ Process the sizes

if $($isset$($$data$[\text{'}$size$\text{'}])$ && $(($$$\_$SESSION$[\text{'}$level$\text{'}]??\text{'}\text{'})==\text{'}1\text{'}))\{$

foreach $($$data$[\text{'}$size$\text{'}]$ as $id $=>$ $sizes$)\{$

$sizesString $=$ implode$(\text{'},\text{'},$ $sizes$)$;

$//$ Use upsert to insert or update sizes

$stmt $=$ $conn$->$prepare$("$INSERT INTO testdatabase$3($id$,$ size$)$ VALUES $(?,?)$ ON DUPLICATE KEY UPDATE size $=$ VALUES$($size$)")$;

if $($$stmt$)\{$

$stmt$->$bind$\_$param$(\text{'}$is$\text{'},$ $id$,$ $sizesString$)$;

if $(!$$stmt$->$execute$())\{$

echo json$\_$encode$([\text{'}$status$\text{'}=>$ 'error', 'message' $=>$ "Error executing statement: $".$ $stmt$->$error$])$;

exit$()$;

$\}$

$stmt$->$close$()$;

$\}$ else $\{$

echo json$\_$encode$([\text{'}$status$\text{'}=>$ 'error', 'message' $=>$ "Error preparing statement: $".$ $conn$->$error$])$;

exit$()$;

$\}$

$\}$

$//$ Process sizes that might have been unticked

$existingSizesQuery $=$ "SELECT id$,$ size FROM testdatabase$3"$;

$result $=$ $conn$->$query$($$existingSizesQuery$)$;