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Retrieve only the queried element in an object array in MongoDB collection
....color": "red"}, {_id: 0, 'shapes.$': 1});
MongoDB 3.2 Update
Starting with the 3.2 release, you can use the new $filter aggregation operator to filter an array during projection, which has the benefit of including all matches, instead of just the first one.
db.test.aggregate([
// Get just t...
Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why?
I've been wrestling with this for a while and can't quite figure out what's happening. I have a Card entity which contains Sides (usually 2) - and both Cards and Sides have a Stage. I'm using EF Codefirst migrations and the migrations are failing with this error:
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Generating a drop down list of timezones with PHP
Most sites need some way to show the dates on the site in the users preferred timezone. Below are two lists that I found and then one method using the built in PHP DateTime class in PHP 5.
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Global and local variables in R
I am a newbie for R, and I am quite confused with the usage of local and global variables in R.
3 Answers
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How do I copy a version of a single file from one git branch to another?
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Run this from the branch where you want the file to end up:
git checkout otherbranch myfile.txt
General formulas:
git checkout <commit_hash> <relative_path_to_file_or_dir>
git checkout <remote_name>/<branch_name> <file_or_dir>
Some notes (from comment...
How to enable MySQL Query Log?
... statement received from clients and the time that query statement has submitted?
Can I do that in phpmyadmin or NaviCat?
How do I analyse the log?
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What is the difference between printf() and puts() in C?
I know you can print with printf() and puts() . I can also see that printf() allows you to interpolate variables and do formatting.
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Using port number in Windows host file
...cannot put port numbers in there, and there is no way to do what you want with generic OS-level configuration - the browser is what selects the port to choose.
So use bookmarks or something like that.
(Some firewall/routing software might allow outbound port redirection, but that doesn't really sou...
How to fix Error: listen EADDRINUSE while using nodejs?
If I run a server with the port 80, and I try to use xmlHTTPrequest i get this error: Error: listen EADDRINUSE
39 Answer...
sed command with -i option (in-place editing) works fine on Ubuntu but not Mac [duplicate]
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Ubuntu ships with GNU sed, where the suffix for the -i option is optional. OS X ships with BSD sed, where the suffix is mandatory. Try sed -i ''
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