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@UniqueConstraint annotation in Java
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@Entity
@Table(uniqueConstraints={@UniqueConstraint(columnNames = {"id_1" , "id_2"})})
public class class_name {
@Id
@GeneratedValue
public Long id;
@NotNull
public Long id_1;
@NotNull
public Long id_2;
}
Hope it helped.
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Auto code completion on Eclipse
I want Eclipse to automatically suggest to me all possible options, while I'm writing some variable/class name or keyword, like in Flash Develop or Visual Studio.
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Division of integers in Java [duplicate]
This is a basic question but I can't find an answer. I've looked into floating point arithmetic and a few other topics but nothing has seemed to address this. I'm sure I just have the wrong terminology.
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Foreign keys in mongo?
...his:
class Student
include Mongoid::Document
field :name
embeds_many :addresses
embeds_many :scores
end
class Address
include Mongoid::Document
field :address
field :city
field :state
field :postalCode
embedded_in :student
end
class Score
include Mongoi...
Add a new item to a dictionary in Python [duplicate]
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default_data['item3'] = 3
Easy as py.
Another possible solution:
default_data.update({'item3': 3})
which is nice if you want to insert multiple items at once.
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Using querySelector with IDs that are numbers
...haracter 1 is U+0031, so you would escape it as \000031 or \31 .
Basically, to escape any numeric character, just prefix it with \3 and append a space character ( ). Yay Unicode!
So your code would end up as (CSS first, JS second):
#\31 {
background: hotpink;
}
document.getElementById(...
Rails: Open link in new tab (with 'link_to')
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The target: :_blank parameter should be a parameter of link_to, whereas you put it in image_tag parameters. Modify your code like this:
<%= link_to image_tag("facebook.png", class: :facebook_icon, alt: "Facebook"), "http://www.facebo...
How can I capitalize the first letter of each word in a string?
...ith an 'that had words right after it and then closed'". With this example all the worlds except for that are capitalized as expected. The results being "There Once Was A String With An 'that Had Words Right After It And Then Closed'"
– devonbleibtrey
Mar 25 '1...
MongoDB with redis
...oDB does not have yet an expiration mechanism. Capped collections cannot really be used to implement a real TTL. Redis has a TTL-based expiration mechanism, making it convenient to store volatile data. For instance, user sessions are commonly stored in Redis, while user data will be stored and index...
The way to check a HDFS directory's size?
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Prior to 0.20.203, and officially deprecated in 2.6.0:
hadoop fs -dus [directory]
Since 0.20.203 (dead link) 1.0.4 and still compatible through 2.6.0:
hdfs dfs -du [-s] [-h] URI [URI …]
You can also run hadoop fs -help for more info and specifics...