asked on

Avoid Updating to Existing Data

While updating a particular user, I don't want user to update Username to an existing one so I assigned a Unique Key to a field (Username) in Users table to prevent duplicates, so, I like to output the Error message to the user on modal.

How can I trap that error and where to put it in the following script?

<?php

if ( ! empty($_POST) ):

    include('../includes/connection.php');

// Let's see if we have values
    if(!isset($_POST['newSubject'])) { $_POST['newSubject'] = array(); }
    if(!isset($_POST['newClass'])) { $_POST['newClass'] = array(); }
    
    $missingSubjects = count( array_filter($_POST['subject_taught'], function($i) { return $i == ''; }) );
    $missingClasses = count( array_filter($_POST['class_taught'], function($i) { return $i == ''; }) );
    $missingNewSubjects = count( array_filter($_POST['newSubject'], function($i) { return $i == ''; }) );
    $missingNewClasses = count( array_filter($_POST['newClass'], function($i) { return $i == ''; }) );

    if ( empty( $_POST["initial"] ) || empty( $_POST["username"] ) || empty( $_POST["password"] ) || empty( $_POST["role"] ) || $missingSubjects || $missingClasses || $missingNewSubjects || $missingNewClasses ):

        $update_err = "<div class='alert alert-danger'><button type='button' class='close' data-dismiss='alert' aria-label='Close'><span aria-hidden='true'>&times;</span></button>
        <span class='badge badge-danger'>Required</span> You must fill in all fields.
        </div>";
        $response = array( 'success' => false, 'message' => $update_err );
        die( json_encode($response) );
        
    endif;

    $newSubClass = $conn->prepare( "INSERT INTO UserClass (UserId, SubjectTaught, ClassTaught) VALUES (?, ?, ?)" );
    $newSubClass->bind_param( "iss", $userId, $newSubject, $newClass );


    $userSubClass = "UPDATE UserClass SET SubjectTaught = ?, ClassTaught = ? WHERE UserClassId = ?";
    $result = $conn->prepare($userSubClass);
    $result->bind_param("ssi", $subject, $class, $userClassId);
        
    $sqlStr = "UPDATE Users SET Initials = ?, Username = ?, Password = ?, Role = ?, ClassAssigned = ? WHERE UserId = ?";
            $stmt = $conn->prepare($sqlStr);
            $stmt->bind_param("sssssi", $initial, $username, $password, $role, $class_assigned, $id);

            $initial = $_POST["initial"];
            $username = $_POST["username"];
            $password = $_POST["password"];
            $role = $_POST["role"];
            $class_assigned = $_POST['class_assigned'];
            $id = $_POST["user_id"];

        if ( $stmt->execute() ):

            foreach ($_POST['subject_taught'] as $userClassId => $subject):
                $class = $_POST['class_taught'][$userClassId];
                $result->execute();
            endforeach;

            if ( $result->execute() ):

                $userId = $_POST["user_id"];

                foreach ($_POST['newSubject'] as $key => $newSubject):
                    $newClass = $_POST['newClass'][$key];
                    $newSubClass->execute();
                endforeach;           

                $update_success = "<div class='alert alert-success'><button type='button' class='close' data-dismiss='alert' aria-label='Close'><span aria-hidden='true'>&times;</span></button>
                  <span class='badge badge-success'>".$_POST["initial"]."</span> was successfully updated.
                  </div>";
                $response = array( 'success' => true, 'message' => $update_success );
                die( json_encode($response) );
        
            endif;

        endif;

endif;

?>

Open in new window

Thanks you

ASKER CERTIFIED SOLUTION

Chris Stanyon

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Opeyemi AbdulRasheed

ASKER

PS - You have an extra $result->execute() on line 52 (and a matching endif on line 67) of your code that doesn't look like it should be there

I thought I needed to put that there for the INSERT part.

Chris Stanyon

Nope. If you look through your code, you have this:

$userSubClass = "UPDATE UserClass SET SubjectTaught = ?, ClassTaught = ? WHERE UserClassId = ?";
$result = $conn->prepare($userSubClass);

and then this:

foreach ($_POST['subject_taught'] as $userClassId => $subject):
$class = $_POST['class_taught'][$userClassId];
$result->execute();
endforeach;

So that will loop through all the subject_taught inputs and execute the UPDATE query for each.

If you then call $result->execute() again, all you're doing is running the last UPDATE query a second time. No need!

Opeyemi AbdulRasheed

ASKER

Quick as usual. Thank you sir