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@UniqueConstraint annotation in Java
...
@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.
...
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...
What's the fastest way to convert String to Number in JavaScript?
...as I know.
Number(x);
parseInt(x, 10);
parseFloat(x);
+x;
By this quick test I made, it actually depends on browsers.
http://jsperf.com/best-of-string-to-number-conversion/2
Implicit marked the fastest on 3 browsers, but it makes the code hard to read… So choose whatever you feel like it!
...
Browser detection in JavaScript? [duplicate]
...|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [];
if(/trident/i.test(M[1])){
tem= /\brv[ :]+(\d+)/g.exec(ua) || [];
return 'IE '+(tem[1] || '');
}
if(M[1]=== 'Chrome'){
tem= ua.match(/\b(OPR|Edge?)\/(\d+)/);
if(tem!= null) return tem.slice(1).join(...
Java FileReader encoding issue
...to a string, but I found the result is wrongly encoded and not readable at all.
6 Answers
...
In Eclipse, what can cause Package Explorer “red-x” error-icon when all Java sources compile without
I'm using Eclipse for Java development. All my sources compile fine and the resulting application compiles fine. However, I keep getting an "red-x" error notification in the Package Explorer.
...
How to append text to an existing file in Java?
...he file does not already exist. It also does not append a newline automatically (which you often want when appending to a text file). Steve Chambers's answer covers how you could do this with Files class.
However, if you will be writing to the same file many times, the above has to open and close t...
How to test multiple variables against a value?
...wn (False if 0, True otherwise).
You can shorten that using a containment test against a tuple:
if 1 in (x, y, z):
or better still:
if 1 in {x, y, z}:
using a set to take advantage of the constant-cost membership test (in takes a fixed amount of time whatever the left-hand operand is).
When ...
How do I pass command-line arguments to a WinForms application?
...s != null && i > 0)
MessageBox.Show(s + " " + i);
}
To test this, you can open command prompt and go to the location where this exe is placed. Give the file name then parmeter1 parameter2. For example, see below
C:\MyApplication>Yourexename p10 5
From the C# code above, i...
how to check the dtype of a column in python pandas
...ol'). It may be used even for selecting groups of columns based on dtype:
test = pd.DataFrame({'bool' :[False, True], 'int64':[-1,2], 'int32':[-1,2],'float': [-2.5, 3.4],
'compl':np.array([1-1j, 5]),
'dt' :[pd.Timestamp('2013-01-02'), pd.Timestamp('2016-1...