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Why does the default parameterless constructor go away when you create one with parameters
...ass, I most likely want to be able to instantiate that class. In order to allow that, the compiler must add a parameterless constructor, which will have no effect but to allow instantiation. This means that I don't have to include an empty constructor in my code just to make it work.
If I've defin...
@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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Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it
...se a dispatcher as descibed in the MSDN article:
How to: Make Thread-Safe Calls to Windows Forms Controls
So instead of setting the text property directly in the serialport1_DataReceived method, use this pattern:
delegate void SetTextCallback(string text);
private void SetText(string text)
{
// I...
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 do I get a list of all the duplicate items using pandas in python?
...rt issues. I would like to get a list of the duplicate items so I can manually compare them. When I try to use pandas duplicated method , it only returns the first duplicate. Is there a a way to get all of the duplicates and not just the first one?
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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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How are POST and GET variables handled in Python?
... self.response.write(name) # this will write on the document
So you really will have to choose one of those frameworks.
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In Python how should I test if a variable is None, True or False
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a = 'foo' if a: print 'its true' a is not actually TRUE, it's just not none
– wesm
Apr 3 '15 at 21:06
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pandas GroupBy columns with NaN (missing) values
...n the Missing Data section of the docs:
NA groups in GroupBy are automatically excluded. This behavior is consistent with R, for example.
One workaround is to use a placeholder before doing the groupby (e.g. -1):
In [11]: df.fillna(-1)
Out[11]:
a b
0 1 4
1 2 -1
2 3 6
In [12]: df.fil...
MVC (Laravel) where to add logic
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I think all patterns / architectures that you present are very useful as long as you follow the SOLID principles.
For the where to add logic I think that it's important to refer to the Single Responsibility Principle. Also, my answe...