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Rails: How do I create a default value for attributes in Rails activerecord's model? [duplicate]
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You can set a default option for the column in the migration
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add_column :status, :string, :default => "P"
....
OR
You can use a callback, before_save
class Task < ActiveRecord::Base
before_save :default_values
def default_values...
Oracle 11.2.0.4 RAC FOR redhat 6.4 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...局热备盘。
选择 配置 然后GO
全局热备 MAKE GLOBAL HSP
最后就是酱紫的， 退出 重启系统。
第四次安装REDHAT 6.4
分区配置
一路选择下来，安装完毕 重启 终于进来了， 我XXXX IBM 的阵列卡居然有这个问题， 必...
What is the fastest way to create a checksum for large files in C#
I have to sync large files across some machines. The files can be up to 6GB in size. The sync will be done manually every few weeks. I cant take the filename into consideration because they can change anytime.
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How do I browse an old revision of a Subversion repository through the web view?
I know how to browse my project's Subversion repository through its web front-end, but it seems that I can only browse the latest revision of the trunk. Is there a way to browse an older revision of the trunk through the web UI?
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A command-line HTML pretty-printer: Making messy HTML readable [closed]
I'm looking for recommendations for HTML pretty printers which fulfill the following requirements:
5 Answers
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How to show all shared libraries used by executables in Linux?
...d like to know which libraries are used by executables on my system. More specifically, I'd like to rank which libraries are used the most, along with the binaries that use them. How can I do this?
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Can you use if/else conditions in CSS?
... use classes for this, if you have access to the HTML. Consider this:
<p class="normal">Text</p>
<p class="active">Text</p>
and in your CSS file:
p.normal {
background-position : 150px 8px;
}
p.active {
background-position : 4px 8px;
}
That's the CSS way to do it.
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Solving “The ObjectContext instance has been disposed and can no longer be used for operations that
I am trying to populate a GridView using Entity Frameworkm but every time I am getting the following error:
7 Answers
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Unit testing that events are raised in C# (in order)
I have some code that raises PropertyChanged events and I would like to be able to unit test that the events are being raised correctly.
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How to get the first non-null value in Java?
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No, there isn't.
The closest you can get is:
public static <T> T coalesce(T ...items) {
for(T i : items) if(i != null) return i;
return null;
}
For efficient reasons, you can handle the common cases as follows:
public static <T> T coalesce(T a, T ...