PDO update not returning variables - php

Question

I'm trying to use PDO to update a row in my postgres database.
The form is not sending the variables to the handler file.
I'm not sure where the problem lies, I've been battling with this for a few days.
Form
//$maxContent is set and available
//$context_number is set and available
echo"<form method='post' action='updateSpatialPhoto_handler.php'>";
$query3 = $conn->prepare("SELECT * FROM excavation.contexts_spatial_photographs
WHERE contexts_spatial.area_easting = {$_SESSION['area_easting']}
AND contexts_spatial.area_northing = {$_SESSION['area_northing']}
AND contexts_spatial.context_number = {$_SESSION['context_number']}");
//contexts_spatial_photographs
$query3->execute();
while($r = $query3->fetch(PDO::FETCH_OBJ))
{
// for each needed
echo"<input type='hidden' name='photograph_date' value='".$r->photograph_date."'>";
echo"<input type='hidden' name='photograph_number' value='".$r->photograph_number."'>";
echo"<input type='hidden' name='primary_shot' value='".$r->primary_shot."'>";
echo"<input type='hidden' name='maxContext' value='", $maxContext,"'>";
};
echo"<input type='submit' value='Update Spatial Photo'>";
echo "</form>";
handler
<?php
session_start();
//
include 'connect/connect.php';
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
if (!isset($_SESSION['photograph_date'])) {$_SESSION['photograph_date'] = $_POST['photograph_date'];}
if (!isset($_SESSION['photograph_number'])) {$_SESSION['photograph_number'] = $_POST['photograph_number'];}
if (!isset($_SESSION['primary_shot'])) {$_SESSION['primary_shot'] = $_POST['primary_shot'];}
if (!isset($_SESSION['maxContext'])) {$_SESSION['maxContext'] = $_POST['maxContext'];}
if (isset($_SESSION['photograph_date'])) {$_SESSION['photograph_date'] = $_POST['photograph_date'];}
if (isset($_SESSION['photograph_number'])) {$_SESSION['photograph_number'] = $_POST['photograph_number'];}
if (isset($_SESSION['primary_shot'])) {$_SESSION['primary_shot'] = $_POST['primary_shot'];}
if (isset($_SESSION['maxContext'])) {$_SESSION['maxContext'] = $_POST['maxContext'];}
//echo "Photograph Date: "; echo $_SESSION['photograph_date']; echo "<br />";
//echo "Photograph Number: "; echo $_SESSION['photograph_number']; echo "<br />";
//echo "Primary Shot: "; echo $_SESSION['primary_shot']; echo "<br />";
try {
$sql3 = "UPDATE excavation.contexts_spatial_photographs SET
context_number = :context_number
WHERE contexts_spatial_photographs.area_easting = $area_easting
AND contexts_spatial_photographs.area_northing = $area_northing
AND contexts_spatial_photographs.context_number = $context_number";
$stmt2 = $conn->prepare($sql3);
// prepare sql and bind parameters
$stmt2->bindParam(':context_number', $maxContext, PDO::PARAM_INT);
$stmt2->execute();
echo "Record updated successfully in contexts spatial photographs<br />";
}
catch(PDOException $e)
{
echo "Error: " . $e->getMessage();
}
?>

Answer 1

At the top of the handler, your using lines like...
if (isset($_SESSION['maxContext'])) {$_SESSION['maxContext'] = $_POST['maxContext'];}
These are setting the values in the session variables, which is fine.
But in your SQL -
AND contexts_spatial_photographs.context_number = $maxContext";
$maxContext doesn't seem to be set anywhere. This may be the same as the session variables, so you need
$maxContext = $_SESSION['maxContext'];
or
AND contexts_spatial_photographs.context_number = $_SESSION['maxContext']";
Although it would be even better if you use bindParam with them, the same way you use it with :context_number.