Why Am I Getting a \"Trying to Access Array Offset on Value of Type Bool\" Error in PHP?

"Trying to Access Array Offset on Value of Type Bool" Error in PHP

The error "Trying to access array offset on value of type bool" occurs when you attempt to access an element of an array that doesn't exist or that is of an invalid type, specifically a boolean.

In the provided code snippet, you're executing queries to check if a username or email already exists in the database. If the query doesn't return any results, it assigns false to the corresponding variable ($emailRes or $nameRes).

When you then try to access the Username or Email key of $nameRes or $emailRes, you get the error because they're both booleans, not arrays.

Solution:

1. Check for Existence:

Before accessing the array offsets, check if the database returned any results:

$emailRes = $query->fetch(PDO::FETCH_ASSOC);
if ($emailRes) {
    // Proceed to use $emailRes['Email']
}

2. Assign Default Value:

If you don't care whether the database returned anything, you can assign a default value:

$emailRes = $query->fetch(PDO::FETCH_ASSOC);
$email = $emailRes['Email'] ?? ''; // Default to empty string

3. Use PDO's fetchColumn() for Existence Check:

A more efficient way to check for existence in the database is to use fetchColumn():

if ($query->fetchColumn()) {
    // Record exists
}
else {
    // Record does not exist
}

4. One-Query Approach:

You can also check for the existence of both username and email in one query:

$query = $pdo->prepare("SELECT COUNT(*) FROM Users WHERE Username =:Username OR Email =:Email");
$query->execute([':Username' => $name, ':Email' => $email]);
if ($query->fetchColumn()) {
    // Username or email already exist
}
else {
    // Username and email are both available
}

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