What is the most elegant way to validate the presence of ONLY one out of two attributes using Rails?

class Followup < ActiveRecord::Base belongs_to :post belongs_to :comment end This model needs to only have either a post or a comment, but only one of the two.

Azure, SLAs and CAP theorem

Azure itself is imo PaaS and not IaaS. Do you agree? MS gurantees an availability of 99% and a strong consistency. You can find MS SLAs here: http://www.microsoft.com/windowsazure/sla

有些人忘了自己是什么歌？

Calling a void async. - Event based pattern, or another method?

I have a class that basically stores files in amazon s3. Here is what it looks like (simplified) public class S3FileStore

一位老手的心声？

蓝天2号_035 2开发者_JAVA百科022-04-23 20:34 顶霸剑横空 开发者_如何学编程 2022-04-23 20:58

Django anonymous user in model

I have a model defined as below: class Example(models.Model): user = models.ForeignKey(User, null=True)

Writing A Good C# Equals Method

Does anyone have a template for writing a decent equals method - I rememb开发者_如何学Cer in Effective Java there was problems around handling equals when dealing with subclasses.

trying to connect mysql with vb.net

I\'ve found this at connection strings.com http://connectionstrings.c开发者_如何转开发om/mysql

how to add column dynamically in datagridview using c#

how to add column dynamical开发者_JAVA百科ly in datagridview using c#For example: DataGridViewColumn col = new DataGridViewTextBoxColumn();

宇舶表多少钱啊？瑞士宇舶表大概多少钱啊？

yrwUITLV 开发者_开发问答2022-05-19 19:54 最便宜四万多！上档次的10万以上！定制版限量版几百万都有，别轻信淘宝上几千快的哦！都是骗子！