laravel-admin php artisan admin:install报错问题解决办法

问题描述：根据laravel-admin官方文档安装步骤，执行：php artisan admin:install 安装时报错。

其实是数据库创建特殊字符过长问题，laravel 5.4 改变了默认的数据库字符集，现在utf8mb4包括存储emojis支持。如果你运行MySQL v5.7.7或者更高版本，则不需要做任何事情。

当你试着在一些MariaDB或者一些老版本的的MySQL上运行 migrations 命令时，你可能会碰到下面这个错误：

D:\wwwroot\www.test.com>php artisan admin:install
Migration table created successfully.

In Connection.php line 664:

  SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 1000 bytes (S
  QL: alter table `users` add unique `users_email_unique`(`email`))

In Connection.php line 458:

  SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 1000 bytes

解决方案在app\Providers\AppServiceProvider.php添加默认值，需要删除数据库migrations、users表。重新执行：php artisan admin:install

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Facades\Schema; //add fixed sql

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        Schema::defaultStringLength(191); //add fixed sql
    }

    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}

参考这个issue:https://github.com/z-song/laravel-admin/issues/1541