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MongoDB: How to query for records where field is null or not set?
...not set then:
db.emails.count({sent_at: {$exists: false}})
If its there and null, or not there at all:
db.emails.count({sent_at: null})
Refer here for querying and null
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How to convert a DOM node list to an array in Javascript?
...es, but it expects a Javascript array (it runs some Array methods on that) and I want to feed it the output of Document.getElementsByTagName that returns a DOM node list.
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Architecture of a single-page JavaScript web application?
...application in terms of its model objects, UI components, any controllers, and objects handling server persistence.
14 Answ...
What Makes a Method Thread-safe? What are the rules?
...ere overall rules/guidelines for what makes a method thread-safe? I understand that there are probably a million one-off situations, but what about in general? Is it this simple?
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How to calculate time elapsed in bash script?
I print the start and end time using date +"%T" , which results in something like:
20 Answers
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How does the new automatic reference counting mechanism work?
...es to Objective-C has to learn the rigid rules of when to retain, release, and autorelease objects. These rules even specify naming conventions that imply the retain count of objects returned from methods. Memory management in Objective-C becomes second nature once you take these rules to heart an...
What is the advantage of using heredoc in PHP? [closed]
What is the advantage of using heredoc in PHP, and can you show an example?
5 Answers
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What are dictionary view objects?
...sentially what their name says: views are simply like a window on the keys and values (or items) of a dictionary. Here is an excerpt from the official documentation for Python 3:
>>> dishes = {'eggs': 2, 'sausage': 1, 'bacon': 1, 'spam': 500}
>>> keys = dishes.keys()
>>>...
How to convert comma-separated String to List?
...al comma, zero or more whitespace which will place the words into the list and collapse any whitespace between the words and commas.
Please note that this returns simply a wrapper on an array: you CANNOT for example .remove() from the resulting List. For an actual ArrayList you must further use ...
What is a tracking branch?
...a direct relationship to a remote branch. If you’re on a tracking branch and type git push, Git automatically knows which server and branch to push to. Also, running git pull while on one of these branches fetches all the remote references and then automatically merges in the corresponding remote ...