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MongoDB atomic “findOrCreate”: findOne, insert if nonexistent, but do not update
...findOrCreate like operations.
This is thanks to the $setOnInsert operator new to 2.4, which allows you to specify updates which should only happen when inserting documents.
This, combined with the upsert option, means you can use findAndModify to achieve an atomic findOrCreate-like operation.
db....
What Makes a Method Thread-safe? What are the rules?
...unction () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f9848067%2fwhat-makes-a-method-thread-safe-what-are-the-rules%23new-answer', 'question_page');
}
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...
bundle install returns “Could not locate Gemfile”
I'm new to Rails and am currently working through a guide.
The guide states:
9 Answers
...
How to send parameters from a notification-click to an activity?
...t when launching the activity, and then in the activity class implement onNewIntent(Intent intent) event handler, that way you can access the new intent that was called for the activity (which is not the same as just calling getIntent(), this will always return the first Intent that launched your a...
Remove folder and its contents from git/GitHub's history
...mp;& git gc --prune=now --aggressive
git push --mirror https://project/new-repository
If you want to delete files then use the delete-files option instead:
java -jar bfg.jar --delete-files *.pyc
share
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Why always ./configure; make; make install; as 3 separate steps?
...target is all, but not always. So you could only make all install if you knew that was the target.
So ...
#!/bin/sh
if ./configure $*; then
if make; then
make install
fi
fi
or:
./configure $* && ./make && ./make install
The $* is included because one often has to pro...
Call UrlHelper in models in ASP.NET MVC
...llowing will work anywhere in an ASP.NET MVC application:
UrlHelper url = new UrlHelper(HttpContext.Current.Request.RequestContext);
url.Action("ContactUs"); // Will output the proper link according to routing info
Example:
public class MyModel
{
public int ID { get; private set; }
publi...
Detect backspace in empty UITextField
...long shot but it could work. Try setting the text field's text to a zero width space character \u200B. When backspace is pressed on a text field that appears empty, it will actually delete your space. Then you can just reinsert the space.
May not work if the user manages to move the caret to the...
How to increase font size in a plot in R?
...
Did you read help(par) about ps? Does not seem text-related as far as I can tell.
– Dirk Eddelbuettel
Nov 22 '10 at 2:51
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PG::ConnectionBad - could not connect to server: Connection refused
...
It could be as simple as a stale PID file. It could be failing silently because your computer didn't complete the shutdown process completely which means postgres didn't delete the PID (process id) file.
The PID file is used by postgres to make sure only on...