小编Hen*_*nri的帖子

我需要在提交表单之前预览图像.我使用Rails 3并需要与浏览器兼容的东西.有什么想法我能做到吗？

在更新之前一切正常.使用带有RVM的ruby 1.9.3p392和rails(3.2.12)使用MySQL 5.7.16和Nginx和Unicorn

日志显示

LoadError: libmysqlclient.so.18: cannot open shared object file: No such file or directory - /home/bill/apps/xxx/shared/bundle/ruby/1.9.1/gems/mysql2-0.3.16/lib/mysql2/mysql2.so

我试过了:

1. 卸载/安装mysql2 gem
2. 运行 bundle install

没有任何效果.更新后有人遇到过这个问题吗？

我正在使用 ruby​​ 3.0.1p64 并使用 macOS bigsur 11.04 mysql 安装并运行

捆绑安装要求我安装 mysql2

我正在尝试像这样安装 mysql2 gem：

sudo gem install mysql2 -v '0.5.3' --source 'https://rubygems.org/'

我得到这个：

 Building native extensions. This could take a while...
ERROR:  Error installing mysql2:
    ERROR: Failed to build gem native extension.

    current directory: /Users/henri/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/mysql2-0.5.3/ext/mysql2
/Users/henri/.rbenv/versions/3.0.1/bin/ruby -I /Users/henri/.rbenv/versions/3.0.1/lib/ruby/3.0.0 -r ./siteconf20210617-53969-y4phap.rb extconf.rb
checking for rb_absint_size()... yes
checking for rb_absint_singlebit_p()... yes
checking for rb_wait_for_single_fd()... yes
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries …

我正在使用Rails 3和carrierwave以及Rmagick.我想要将图片精确调整为192 x 135这个开始时很简单,但直到现在我才尝试过.

有人找到了解决方案吗？这是我的上传代码.

class AvatarUploader < CarrierWave::Uploader::Base

   #Include RMagick or MiniMagick support:
  include CarrierWave::RMagick
  include CarrierWave::MiniMagick

  # Choose what kind of storage to use for this uploader:
  storage :file
  # storage :fog

  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end


  # Provide a default URL as a default if there hasn't been a file uploaded:
   def default_url
  #   # For Rails 3.1+ asset pipeline compatibility:
   ActionController::Base.helpers.asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
   end
  process :resize_to_fit => [250, 250]


  # …

希望可以有人帮帮我：

我的服务器上运行着许多站点，并且我正在使用 mariadb。\n当我这样做时：

sudo service mysql restart\n

我得到：

Job for mariadb.service failed because the control process exited with \nerror code. See "systemctl status mariadb.service" and "journalctl -xe" \nfor details.\n

\n

systemctl 状态 mariadb.service

\n

    mariadb.service - MariaDB database server\n\n    Loaded: loaded (/lib/systemd/system/mariadb.service; enabled; vendor preset: enabled)\n\n    Drop-In: /etc/systemd/system/mariadb.service.d\n             \xe2\x94\x94\xe2\x94\x80migrated-from-my.cnf-settings.conf\n    Active: failed (Result: exit-code) since Thu 2017-09-14 03:16:51 UTC; 1min 6s ago\n    Process: 13247 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION (code=\n    Process: 13086 ExecStartPre=/bin/sh -c [ ! …

当我的服务器突然停止工作时,一切都运行得很顺利.我正在使用Linode和Nginx fast-cgi

这是我的日志文件:

上游超时(110:连接超时),同时从上游读取响应头,客户端:76.66.174.147,服务器:iskacanada.com,请求:"GET/HTTP/1.1",上游:"fastcgi://127.0.0.1: 9000",主持人:"www.iskacanada.com"

location ~ \.php$ {
    include        fastcgi_params;
    fastcgi_read_timeout 120;
    fastcgi_pass   localhost:9000;
    fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
}

当我想重启mysql时,它说:

sudo service mysql restart stop:未知实例:start:作业无法启动

怎么知道发生了什么？

我知道变量在 go 中是按值传递的。但是，我想在此函数外的 func 内调用一个变量。让我给你举个例子：

package main

import (

    "fmt"
)

func Smile(){
  A := 5
}

func main() {

   fmt.Println(A)

}

这给了我 undefine A。

通过 A 的最佳方法是什么？我应该使用指针吗？我怎么做？