Call to Undefined Method

Why This Happens

This error occurs when you call a method that is not defined on the object's class. Unlike undefined function errors which are about standalone functions, this is specifically about class methods. It can happen due to typos, calling a method from a different class, or expecting a method that was never implemented.

The Problem

class User {
    public string $firstName;
    public string $lastName;
}
$user = new User();
$user->firstName = 'Alice';
echo $user->getFullName(); // Method doesn't exist

The Fix

class User {
    public string $firstName;
    public string $lastName;

    public function getFullName(): string {
        return $this->firstName . ' ' . $this->lastName;
    }
}

Step-by-Step Fix

1. 1

   Check the method name

   Verify the method name for typos. Check the class definition to see which methods are available.

2. 2

   Verify the object type

   Use get_class() to confirm you have the expected object type. The method may exist on a different class.

3. 3

   Implement or fix the method

   Either add the missing method to the class, fix the typo in the method call, or use the correct object type.