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Django select only rows with duplicate field values
...values('name')
.annotate(Count('id'))
.order_by()
.filter(id__count__gt=1)
This is as close as you can get with Django. The problem is that this will return a ValuesQuerySet with only name and count. However, you can then use this to construct a regula...
Is there an expression for an infinite generator?
...te itertools.count: count = lambda start=0, step=1: (start + i*step for i, _ in enumerate(iter(int, 1)))
– Coffee_Table
Aug 13 '18 at 23:43
2
...
When to use Comparable and Comparator
... | Comparable | Comparator
._______________________________________________________________________________
Is used to allow Collections.sort to work | yes | yes
Can compare multiple fields | yes ...
How do I implement interfaces in python?
...the trick.
from abc import ABCMeta, abstractmethod
class IInterface:
__metaclass__ = ABCMeta
@classmethod
def version(self): return "1.0"
@abstractmethod
def show(self): raise NotImplementedError
class MyServer(IInterface):
def show(self):
print 'Hello, World 2!'
...
Filtering for empty or NULL names in a queryset
I have first_name , last_name & alias (optional) which I need to search for. So, I need a query to give me all the names that have an alias set.
...
Ruby: require vs require_relative - best practice to workaround running in both Ruby =1.
... this post.
https://github.com/appoxy/aws/blob/master/lib/awsbase/require_relative.rb
unless Kernel.respond_to?(:require_relative)
module Kernel
def require_relative(path)
require File.join(File.dirname(caller[0]), path.to_str)
end
end
end
This allows you to use require_relati...
Append an object to a list in R in amortized constant time, O(1)?
... 2-element vector named c as is clearly intended!
– j_random_hacker
Dec 5 '11 at 16:45
7
So is th...
Repeat string to certain length
...
def repeat_to_length(string_to_expand, length):
return (string_to_expand * ((length/len(string_to_expand))+1))[:length]
For python3:
def repeat_to_length(string_to_expand, length):
return (string_to_expand * (int(length/len(s...
How to step through Python code to help debug issues?
...rSummoner, pudb is great for that. Also pydev
– alpha_989
Jun 11 '18 at 19:45
pdb is not a command line tool. To use i...
What is the instanceof operator in JavaScript?
...there.
Every object in JavaScript has a prototype, accessible through the __proto__ property. Functions also have a prototype property, which is the initial __proto__ for any objects created by them. When a function is created, it is given a unique object for prototype. The instanceof operator uses...