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Fastest way to get the first object from a queryset in django?

Often I find myself wanting to get the first object from a queryset in Django, or return None if there aren't any. There are lots of ways to do this which all work. But I'm wondering which is the most performant. ...
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private[this] vs private

In Scala I see such feature as object-private variable. From my not very rich Java background I learnt to close everything (make it private) and open (provide accessors) if necessary. Scala introduces even more strict access modifier. Should I always use it by default? Or should I use it only in som...
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Convert sqlalchemy row object to python dict

...em. if you want just column data (for example, to take a list of instances from a query and drop them in a pandas dataframe) then {col.name: getattr(self, col.name) for col in self.__table__.columns} as answered by Anurag Uniyal (with important corrections from comments to that answer) seems both mo...
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How to cherry pick only changes for only one file, not the whole commit

... patchfile git apply patchfile EDIT: Since you need to take the changes from a commit, create the patch like this: git show sha1 -- filename > patchfile share | improve this answer ...
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How can I scan barcodes on iOS?

...ation for the iPhone. It can decode QR Codes. The source code is available from the zxing project; specifically, you want to take a look at the iPhone client and the partial C++ port of the core library. The port is a little old, from circa the 0.9 release of the Java code, but should still work rea...
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How to get String Array from arrays.xml file

I am just trying to display a list from an array that I have in my arrays.xml . When I try to run it in the emulator, I get a force close message. ...
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What does the unary plus operator do?

...r than the operator itself. For example, it can be used to force widening from smaller integral types to int, or ensure that an expression's result is treated as an rvalue and therefore not compatible with a non-const reference parameter. I submit, however, that these uses are better suited to cod...
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How is Racket different from Scheme?

... The rationale for the name-change from PLT Scheme to Racket is discussed on the Racket site. share | improve this answer | follow ...
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Clearing purchases from iOS in-app purchase sandbox for a test user

...y, in your tester@gmail.com inbox you will receive two verification emails from Apple to confirm both test accounts. Say that you have a non-consumable with product ID @"Extra_Levels". Instead of writing @"Extra_Levels" in all methods (requestProduct, purchaseProduct, ...), just write PRODUCT_ID1 an...
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Read stream twice

... the contents of the InputStream to a byte array, and then repeatedly read from the byte array using a ByteArrayInputStream. E.g.: ByteArrayOutputStream baos = new ByteArrayOutputStream(); org.apache.commons.io.IOUtils.copy(in, baos); byte[] bytes = baos.toByteArray(); // either while (needToReadA...