验证登录信息

<input id="characters" name="characters" lay-verify="required" placeholder="验证码"  type="text" class="layui-input">
<img id="captcha" src="{{ captcha_src('flat') }}" onclick="this.src='/captcha/flat?'+Math.random()" title="刷新验证码"  alt="刷新验证码"/>

<?php
                // 校验输入格式
        $request->validate(
            [
                'name'          => 'required|max:255',
                'password'      => 'required|max:255',
                'characters'    => 'required|size:4|captcha'    // captcha规则校验验证码是否正确
            ],
              // 自定义校验返回信息提示
              [
                'name.required'         => '用户名不能为空',
                'name.max'              => '用户名最大长度255',
                'password.required'     => '密码不能为空',
                'password.max'          => '密码最大长度255',
                'characters.required'   => '验证码不能为空',
                'characters.size'       => '验证码长度4位',
                'characters.captcha'    => '验证码错误',        
            ]
        );
        // 过滤无用字段
        $input = $request->except('_token');