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What exactly is Arel in Rails 3.0?
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What exactly is Arel in Rails 3.0?
It's an object model for an algebra of relational query operators.
I understand that it is a replacement for ActiveRecord
No, it isn't. It's a replacement for hand-crafting SQL queries in strings. It is a common query...
How do you manually execute SQL commands in Ruby On Rails using NuoDB
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edited Jan 23 '19 at 10:24
Jan Klimo
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Update MongoDB field using value of another field
..."name": { "$concat": ["$firstName", " ", "$lastName"]}}}
]
)
MongoDB 3.4+
In 3.4+ you can use $addFields and the $out aggregation pipeline operators.
db.collection.aggregate(
[
{ "$addFields": {
"name": { "$concat": [ "$firstName", " ", "$lastName" ] }
}},
...
PyCharm shows unresolved references error for valid code
...Dmitry Trofimov
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3
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Replace tabs with spaces in vim
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393
IIRC, something like:
set tabstop=2 shiftwidth=2 expandtab
should do the trick. If you alre...
jQuery Tips and Tricks
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share
edited Mar 23 '11 at 18:51
community wiki
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Fastest way to replace NAs in a large data.table
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system.time(a_gdata = f_gdata(dt1))
user system elapsed
18.805 12.301 134.985
system.time(a_andrie = f_andrie(dt1))
Error: cannot allocate vector of size 305.2 Mb
Timing stopped at: 14.541 7.764 68.285
system.time(f_dowle(dt1))
user system elapsed
7.452 4.144 19.590 # EDIT h...
How to change Android Studio's editor font?
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32
Thanks, that worked. Not very intuitive UX, generally you save something after you have edited it, not before! I'll accept once it lets m...
Invalid syntax when using “print”? [duplicate]
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232
That is because in Python 3, they have replaced the print statement with the print function.
T...
How to split (chunk) a Ruby array into parts of X elements? [duplicate]
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341
Take a look at Enumerable#each_slice:
foo.each_slice(3).to_a
#=> [["1", "2", "3"], ["4", "...