emailをログインIDとかメールアドレスとか画面によって言い方を変えたい場合、ログイン画面の場合つまづいたのでメモ。

postLoginメソッドをオーバーライドして$this->validateの第３引数にmessagesを追加

AuthController.php


    /**
     * Handle a login request to the application.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function postLogin(Request $request)
    {

        $messages = [
            'email.required' => 'ログインIDは必須です。'
        ];

        $this->validate(
            $request,
            [$this->loginUsername() => 'required', 'password' => 'required'],
            $messages
        );

        // If the class is using the ThrottlesLogins trait, we can automatically throttle
        // the login attempts for this application. We'll key this by the username and
        // the IP address of the client making these requests into this application.
        $throttles = $this->isUsingThrottlesLoginsTrait();

        if ($throttles && $this->hasTooManyLoginAttempts($request)) {
            return $this->sendLockoutResponse($request);
        }

        $credentials = $this->getCredentials($request);

        if (Auth::attempt($credentials, $request->has('remember'))) {
            return $this->handleUserWasAuthenticated($request, $throttles);
        }

        // If the login attempt was unsuccessful we will increment the number of attempts
        // to login and redirect the user back to the login form. Of course, when this
        // user surpasses their maximum number of attempts they will get locked out.
        if ($throttles) {
            $this->incrementLoginAttempts($request);
        }

        return redirect($this->loginPath())
            ->withInput($request->only($this->loginUsername(), 'remember'))
            ->withErrors([
                $this->loginUsername() => $this->getFailedLoginMessage(),
            ]);
    }