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Django: Get an object form the DB, or 'None' if nothing matches
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In Django 1.6 you can use the first() Queryset method. It returns the first object matched by the queryset, or None if there is no matching object.
Usage:
p = Article.objects.order_by('title', 'pub_date').first()
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Understanding MongoDB BSON Document size limit
From MongoDB The Definitive Guide:
7 Answers
7
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How do I use reflection to invoke a private method?
...s BindingFlags:
MethodInfo dynMethod = this.GetType().GetMethod("Draw_" + itemType,
BindingFlags.NonPublic | BindingFlags.Instance);
dynMethod.Invoke(this, new object[] { methodParams });
Here's the BindingFlags enumeration documentation.
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What is the difference between #import and #include in Objective-C?
...as added to Objective-C as an improved version of #include. Whether or not it's improved, however, is still a matter of debate. #import ensures that a file is only ever included once so that you never have a problem with recursive includes. However, most decent header files protect themselves agains...
What is the best way to solve an Objective-C namespace collision?
Objective-C has no namespaces; it's much like C, everything is within one global namespace. Common practice is to prefix classes with initials, e.g. if you are working at IBM, you could prefix them with "IBM"; if you work for Microsoft, you could use "MS"; and so on. Sometimes the initials refer to ...
How to detect when cancel is clicked on file input?
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While not a direct solution, and also bad in that it only (as far as I've tested) works with onfocus (requiring a pretty limiting event blocking) you can achieve it with the following:
document.body.onfocus = function(){ /*rock it*/ }
What's nice about this, is that you c...
How to analyze a java thread dump?
...ead id and NID is: Native thread ID. This ID is highly platform dependent. It's the NID in jstack thread dumps. On Windows, it's simply the OS-level thread ID within a process. On Linux and Solaris, it's the PID of the thread (which in turn is a light-weight process). On Mac OS X, it is said to b...
java.net.SocketException: Connection reset
...eliberately reset the connection, in a way which I will not document here. It is rare, and generally incorrect, for application software to do this, but it is not unknown for commercial software.
More commonly, it is caused by writing to a connection that the other end has already closed normally. I...
How do SQL EXISTS statements work?
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Think of it this way:
For 'each' row from Suppliers, check if there 'exists' a row in the Order table that meets the condition Suppliers.supplier_id (this comes from Outer query current 'row') = Orders.supplier_id. When you find th...
Why is whitespace sometimes needed around metacharacters?
A few months ago I tattooed a fork bomb on my arm, and I skipped the whitespaces, because I think it looks nicer without them. But to my dismay, sometimes (not always) when I run it in a shell it doesn't start a fork bomb, but it just gives a syntax error.
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