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How can I rename a database column in a Ruby on Rails migration?
...mething else or do nothing
end
end
For Rails 3.1 use:
While, the up and down methods still apply, Rails 3.1 receives a change method that "knows how to migrate your database and reverse it when the migration is rolled back without the need to write a separate down method".
See "Active Record...
Is there a cross-browser onload event when clicking the back button?
... does nothing. But somehow this seems to trigger a reload in Safari, Opera and Mozilla -- no matter what the event handler contains.
[edit(Nickolay): here's why it works that way: webkit.org, developer.mozilla.org. Please read those articles (or my summary in a separate answer below) and consider w...
Two versions of python on linux. how to make 2.7 the default
...'t actually want to change your default Python.
Your distro installed a standard system Python in /usr/bin, and may have scripts that depend on this being present, and selected by #! /usr/bin/env python. You can usually get away with running Python 2.6 scripts in 2.7, but do you want to risk it?
O...
How can I get the URL of the current tab from a Google Chrome extension?
I'm having fun with Google Chrome extension, and I just want to know how can I store the URL of the current tab in a variable?
...
How do I auto-reload a Chrome extension I'm developing?
... add a browse to
"http://reload.extensions" using Chrome to your script, and you'll
have a refreshed Chrome window.
Update: As of January 14, 2015, the extension is open-sourced and available on GitHub.
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Traverse all the Nodes of a JSON Object Tree with JavaScript
...3],
subo: {
foo2:"bar2"
}
};
//called with every property and its value
function process(key,value) {
console.log(key + " : "+value);
}
function traverse(o,func) {
for (var i in o) {
func.apply(this,[i,o[i]]);
if (o[i] !== null && typeof(o[i])=="ob...
equals vs Arrays.equals in Java
...ntents of the arrays.
Similarly array.toString() may not be very useful and you need to use Arrays.toString(array).
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CSV file written with Python has blank lines between each row
This code reads thefile.csv , makes changes, and writes results to thefile_subset1 .
9 Answers
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What is a non-capturing group in regular expressions?
How are non-capturing groups, i.e. (?:) , used in regular expressions and what are they good for?
15 Answers
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Static nested class in Java, why?
I was looking at the Java code for LinkedList and noticed that it made use of a static nested class, Entry .
14 Answers
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