# User Entity ## User Entity Class A User Entity object represents a user in the WebAuthn context. It has the following constraints: * The user ID must be unique and must be a string, * The username must be unique, Here is a minimalist example of user entity: {% code lineNumbers="true" %} ```php users[$userHandle] = $userEntity; return $userEntity; } public function findOneByUsername(string $username): ?PublicKeyCredentialUserEntity { foreach ($this->users as $userEntity) { if ($userEntity->name === $username) { return $userEntity; } } return null; } public function findOneByUserHandle(string $userHandle): ?PublicKeyCredentialUserEntity { return $this->users[$userHandle] ?? null; } } ``` {% endcode %} {% hint style="info" %} For production use, implement your repository with your preferred storage backend. See the [Symfony Bundle section](/symfony-bundle/user-entity-repository.md) for a complete Doctrine example. {% endhint %} ### Important Notes About User ID (userHandle) * **Must be unique**: Each user must have a unique user ID * **Must be persistent**: The user ID must never change for a given user * **Should be random**: Use at least 32 bytes of random data (64 bytes recommended) * **Must not be PII**: Do not use email, username, or any personally identifiable information * **Maximum 64 bytes**: The WebAuthn specification limits user IDs to 64 bytes {% code lineNumbers="true" %} ```php toBinary(); // UUID v4 (16 bytes) // Bad examples - DO NOT USE $userHandle = $email; // Email can change and is PII $userHandle = (string) $autoIncrementId; // Sequential IDs are predictable $userHandle = hash('sha256', $username); // Derived from username, not random ``` {% endcode %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://webauthn-doc.spomky-labs.com/prerequisites/user-entity.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.