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How does Rails keep track of which migrations have run for a database?
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Rails creates a table in your database called schema_migrations to keep track of which migrations have run.
The table contains a single column, version. When Rails runs a migration, it takes the leading digits in the migration's file name and inserts a row for that "version",...
LINQ: Select an object and change some properties without creating a new object
...erties of a LINQ query result object without creating a new object and manually setting every property. Is this possible?
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Java: parse int value from a char
...So e.g. '0' in ascii is 48, '1' is 49, etc. So if you take '2' - '0' you really just get 50 - 48 = 2. Have a look at an ASCII table in order to understand this principle better. Also, 'x' means get the ascii value of the character in Java.
– Kevin Van Ryckegem
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How to implement has_many :through relationships with Mongoid and mongodb?
...uire multiple queries.
https://github.com/mongoid/mongoid/issues/544
Normally if you have a many-many relationship in a RDBMS you would model that differently in MongoDB using a field containing an array of 'foreign' keys on either side. For example:
class Physician
include Mongoid::Document
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What does the smiley face “:)” mean in CSS?
...wsers.
Also there's a hack for <= IE 8:
div {
color: blue; /* All browsers */
color: purple\9; /* IE8 and earlier */
*color: pink; /* IE7 and earlier */
}
However that's not a good idea, they don't validate. You always feel free to work with Conditional comments for targeting...
Process all arguments except the first one (in a bash script)
...a simple script where the first argument is reserved for the filename, and all other optional arguments should be passed to other parts of the script.
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Turning off some legends in a ggplot
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You can use guide=FALSE in scale_..._...() to suppress legend.
For your example you should use scale_colour_continuous() because length is continuous variable (not discrete).
(p3 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
sca...
ipython: print complete history (not just current session)
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First use %hist -o -g -f ipython_history.md to output the history (input and output) to a text file. (http://ipython.readthedocs.io/en/stable/interactive/magics.html#magic-history)
Then you can use the the get_session_info function to retreive the date and...
Get names of all keys in the collection
I'd like to get the names of all the keys in a MongoDB collection.
21 Answers
21
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What is the correct way of using C++11's range-based for?
...x << ' ';
}
the output is something like:
[... copy constructor calls for vector<X> initialization ...]
Elements:
X copy ctor.
1 X copy ctor.
3 X copy ctor.
5 X copy ctor.
7 X copy ctor.
9
As it can be read from the output, copy constructor calls are made during range-based for l...