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Django select only rows with duplicate field values
... syntax is also how Django interprets you wanting to do a join. So, essentially when you try to filter on that, Django thinks you're trying to do a join with count which obviously doesn't exist. The fix is to specify a name for your annotation result, i.e. annotate(mycount=Count('id')) and then filt...
How to make a class JSON serializable
...t;>> magic(f)
'{"fname": "/foo/bar"}'
In that case you can merely call json.dumps(f.__dict__).
If you want more customized output then you will have to subclass JSONEncoder and implement your own custom serialization.
For a trivial example, see below.
>>> from json import JSONE...
Can I install Python windows packages into virtualenvs?
Virtualenv is great: it lets me keep a number of distinct Python installations so that different projects' dependencies aren't all thrown together into a common pile.
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Does use of final keyword in Java improve the performance?
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Usually not. For virtual methods, HotSpot keeps track of whether the method has actually been overridden, and is able to perform optimizations such as inlining on the assumption that a method hasn't been overridden - until it lo...
What are some uses of template template parameters?
...alue) {
}
Here, H is a template, but I wanted this function to deal with all specializations of H.
NOTE: I've been programming c++ for many years and have only needed this once. I find that it is a rarely needed feature (of course handy when you need it!).
I've been trying to think of good examp...
How to check BLAS/LAPACK linkage in NumPy and SciPy?
... Given its widespread usefulness, numpy.__config__ should really be a public API. Nonetheless, you win this round, davost.
– Cecil Curry
Feb 5 '16 at 5:51
2
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Find current directory and file's directory [duplicate]
...tive to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os
cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
The os and os.path modules.
The __file__ constant
os.path.rea...
Why does this go into an infinite loop?
...
Note: Originally I posted C# code in this answer for purposes of illustration, since C# allows you to pass int parameters by reference with the ref keyword. I've decided to update it with actual legal Java code using the first MutableInt...
How to select all instances of a variable and edit variable name in Sublime
If I select a variable (not just any string) in my code, all other instances of that variable get a stroke (white outline) around them:
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Can (domain name) subdomains have an underscore “_” in it?
...interior characters only letters, digits, and hyphen." Which part of that allows an underscore?
– claudekennilol
Sep 16 '16 at 19:01
2
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