这似乎相当奇怪，我不知道如何做到这一点在胡子。是否支持?

这是我悲哀的尝试:

    {{#author}}
      {{#avatar}}
        <img src="{{avatar}}"/>
      {{/avatar}}
      {{#!avatar}}
        <img src="/images/default_avatar.png" height="75" width="75" />
      {{/avatar}}
    {{/author}}

这显然是不对的，但是文档中并没有提到类似的内容。“else”这个词甚至没有被提到:(

还有，为什么胡子是这样设计的?这种事情被认为是坏事吗?它是否试图强迫我在模型本身中设置默认值?那不可能的情况呢?

varchar和varchar2的区别是什么?

我有可变长度的字符数据，想存储在SQL Server(2005)数据库。我想学习一些关于如何选择TEXT SQL类型或选择VARCHAR SQL类型的最佳实践，在性能/占用空间/功能方面的利弊。

我用PHP7在Ubuntu 16.04服务器上运行laravel 5.4。安装cviebrock/eloquent-sluggable包时抛出一些错误:

pish@let:/home/sherk/ftp/www$ sudo composer require cviebrock/eloquent-sluggable
Do not run Composer as root/super user! See https://getcomposer.org/root for details
Using version ^4.2 for cviebrock/eloquent-sluggable
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - phpunit/php-code-coverage 4.0.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/php-code-coverage 4.0.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - Installation request for phpunit/php-code-coverage (installed at 4.0.7) -> satisfiable by phpunit/php-code-coverage[4.0.7].

  To enable extensions, verify that they are enabled in those .ini files:
    - /etc/php/7.0/cli/php.ini
    - /etc/php/7.0/cli/conf.d/10-mysqlnd.ini
    - /etc/php/7.0/cli/conf.d/10-opcache.ini
    - /etc/php/7.0/cli/conf.d/10-pdo.ini
    - /etc/php/7.0/cli/conf.d/20-calendar.ini
    - /etc/php/7.0/cli/conf.d/20-ctype.ini
    - /etc/php/7.0/cli/conf.d/20-exif.ini
    - /etc/php/7.0/cli/conf.d/20-fileinfo.ini
    - /etc/php/7.0/cli/conf.d/20-ftp.ini
    - /etc/php/7.0/cli/conf.d/20-gd.ini
    - /etc/php/7.0/cli/conf.d/20-gettext.ini
    - /etc/php/7.0/cli/conf.d/20-iconv.ini
    - /etc/php/7.0/cli/conf.d/20-json.ini
    - /etc/php/7.0/cli/conf.d/20-mbstring.ini
    - /etc/php/7.0/cli/conf.d/20-mcrypt.ini
    - /etc/php/7.0/cli/conf.d/20-mysqli.ini
    - /etc/php/7.0/cli/conf.d/20-pdo_mysql.ini
    - /etc/php/7.0/cli/conf.d/20-phar.ini
    - /etc/php/7.0/cli/conf.d/20-posix.ini
    - /etc/php/7.0/cli/conf.d/20-readline.ini
    - /etc/php/7.0/cli/conf.d/20-shmop.ini
    - /etc/php/7.0/cli/conf.d/20-sockets.ini
    - /etc/php/7.0/cli/conf.d/20-sysvmsg.ini
    - /etc/php/7.0/cli/conf.d/20-sysvsem.ini
    - /etc/php/7.0/cli/conf.d/20-sysvshm.ini
    - /etc/php/7.0/cli/conf.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, reverting ./composer.json to its original content.

我在本地版本的应用程序上安装这个包没有问题。

当我运行php artisan db:seed时，我得到以下错误:

[ReflectionException] Class SongsTableSeeder does not exist

这是怎么回事?

我的DatabaseSeeder类:

<?php

use Illuminate\Database\Seeder;
use Illuminate\Database\Eloquent\Model;

class DatabaseSeeder extends Seeder {

    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        Model::unguard();

        $this->call('SongsTableSeeder');
    }

}

我的SongsTableSeeder类:

<?php

// Composer: "fzaninotto/faker": "v1.4.0"
use Faker\Factory as Faker;
use Illuminate\Database\Seeder;
use DB;

class SongsTableSeeder extends Seeder {

    public function run()
    {
        $faker = Faker::create();
        $songs = [];
        foreach(range(1, 10) as $index)
        {
            $songs[] = ['title' => $faker->words(rand(1,4))];
        }

        DB::table('songs')->insert($songs);

    }

}

在Oracle数据库中是否存在布尔类型，类似于Ms SQL Server中的BIT数据类型?

Intersect可以用来查找两个集合之间的匹配，如下所示:

// Assign two arrays.
int[] array1 = { 1, 2, 3 };
int[] array2 = { 2, 3, 4 };
// Call Intersect extension method.
var intersect = array1.Intersect(array2);
// Write intersection to screen.
foreach (int value in intersect)
{
    Console.WriteLine(value); // Output: 2, 3
}

然而，我想实现的是相反的，我想从一个集合中列出从另一个集合中缺失的项目:

// Assign two arrays.
int[] array1 = { 1, 2, 3 };
int[] array2 = { 2, 3, 4 };
// Call "NonIntersect" extension method.
var intersect = array1.NonIntersect(array2); // I've made up the NonIntersect method
// Write intersection to screen.
foreach (int value in intersect)
{
    Console.WriteLine(value); // Output: 4
}

您如何确定地检测用户是否在浏览器中按下了后退按钮?

如何使用#URL系统在单页web应用程序中强制使用页面内返回按钮?

为什么浏览器的后退按钮不触发它们自己的事件!?

我想在MySQL数据库中存储许多记录。它们都包含货币价值。但我不知道每个数字要插入多少位。 为此，我必须使用哪种数据类型? VARCHAR或INT(或其他数值数据类型)?

我们有一个大量使用象形文字的项目。 Bootstrap v4完全删除了字形字体。

是否有一个等效的图标与Bootstrap V4?

http://v4-alpha.getbootstrap.com/migration/