Laravel登录验证：如何在比较前转换数据库邮箱值为小写？

Great question! You’ve already nailed converting the user’s input email to lowercase in the credentials method—that’s a solid first step. To make the database-side email match regardless of its stored case, you’ve got two reliable approaches: one for immediate query-time matching, and a better long-term fix that standardizes your data for good:

1. Match by converting stored emails to lowercase during authentication #

If you can’t modify existing database data right now, you can adjust the authentication logic to convert the stored email to lowercase on the fly when checking credentials.

Option A: Override the attemptLogin method #

Update your LoginController to build a custom query that uses the database’s LOWER() function to compare emails:

protected function attemptLogin(Request $request)
{
    $credentials = $this->credentials($request);
    
    // Fetch the user by matching the lowercase version of their stored email
    $user = $this->guard()->getProvider()->retrieveByCredentials([
        \DB::raw('LOWER('.$this->username().')') => $credentials[$this->username()],
    ]);

    if (!$user) {
        $this->fireFailedEvent($request, null);
        return false;
    }

    // Validate password and handle "remember me"
    return $this->guard()->login($user, $request->filled('remember'));
}

Option B: Override the validateCredentials method #

Alternatively, you can directly compare the lowercase stored email to your already-lowercased input:

use Illuminate\Contracts\Auth\Authenticatable as UserContract;

protected function validateCredentials(UserContract $user, array $credentials)
{
    $plainPassword = $credentials['password'];
    
    // Compare lowercase stored email to lowercase input email
    return strtolower($user->getAuthIdentifier()) === $credentials[$this->username()] &&
           $this->hasher->check($plainPassword, $user->getAuthPassword());
}

2. Standardize stored emails to lowercase (Recommended) #

The cleaner, more efficient long-term fix is to ensure all emails are stored in lowercase from the start. This eliminates runtime conversions and prevents duplicate accounts (e.g., MyName@email.com and myname@email.com being treated as separate users).

Step 1: Add an attribute mutator to your User model #

Add a mutator to automatically convert emails to lowercase whenever they’re set (during registration, profile updates, etc.):

// app/Models/User.php
public function setEmailAttribute($value)
{
    $this->attributes['email'] = strtolower(trim($value));
}

Step 2: Update existing database emails to lowercase #

Run a one-time query to convert all existing mixed-case emails to lowercase. You can do this via a migration or Artisan tinker:

// Via a migration file:
public function up()
{
    \DB::statement('UPDATE users SET email = LOWER(email)');
}

// Or via Artisan tinker (run `php artisan tinker` first):
// User::query()->update(['email' => \DB::raw('LOWER(email)')]);

Step 3: Optional: Add database-level constraints (Laravel 9+) #

For extra safety, enforce lowercase storage at the database level using Laravel’s lowercase() column modifier:

Schema::table('users', function (Blueprint $table) {
    $table->string('email')->unique()->lowercase()->change();
});

内容的提问来源于stack exchange，提问作者Jonatan Uran