\"Fatal error: Call to a member function query() on null\": Why is my $db object null in my user_exists() function?

Troubleshooting "Fatal error: Call to a member function query() on null"

When you encounter a "Call to a member function query() on null" error, it typically indicates that a function is attempting to access a property or method of an object that is null, meaning it has not been initialized or created properly.

In the provided code snippet, you've encountered this error within the user_exists() function. To address this issue, pay attention to the usage of $db within the function.

• In your initial declaration, $db is defined outside the function. While this allows you to access it globally, it prevents you from using $db within the function.

• To resolve this, declare $db as a parameter within the function definition:

  <code class="php">function user_exists($db, $username) {
    // ...
  }</code>

• When calling the function, pass the $db connection as a parameter:

  <code class="php">user_exists($db, $username);</code>

This modification ensures that the function can access the database connection object and execute the query successfully.

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