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Random record from MongoDB
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Do a count of all records, generate a random number between 0 and the count, and then do:
db.yourCollection.find().limit(-1).skip(yourRandomNumber).next()
share
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Rake just one migration
...n a single migration that changed and needed to be re-run independently of all other migrations. Fire up the console and do this:
>> require 'db/migrate/your_migrations.rb'
=> ["YourMigrations"]
>> YourMigrations.up
=> etc... as the migration runs
>> YourMigration.down
Mor...
Why does @foo.setter in Python not work for me?
...operty
def x(self):
print 'called getter'
return self._x
@x.setter
def x(self, value):
print 'called setter'
self._x = value
It works:
>>> k = testDec()
>>> k.x
called getter
Traceback (most recent call last):
File "<stdin>"...
Ruby convert Object to Hash
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instance_values can be used for all ruby objects for the similar output.
– bishal
Jan 22 '19 at 11:37
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libunwind链接时报错：undefined reference to `_Ux86_64_init_local\' - ...
libunwind链接时报错：undefined reference to `_Ux86_64_init_local'编译安装libunwind后，代码编译链接时报错：undefined reference to `_Ux86_64_init_local& 39;，链接选项加了 -lunwind，仍然报错。原因：编译出来的libunwind拆分成了很多个 编译安装libunwi...
How do I return multiple values from a function? [closed]
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Well, the design rationale for namedtuple is having a smaller memory footprint for mass results (long lists of tuples, such as results of DB queries). For individual items (if the function in question is not called often) dictionaries and classes are just fine as well. But namedtu...
How to print struct variables in console?
... @fnr If you have a JSON document, you would need to unmarshall it, before being able to print its field.
– VonC
Jul 1 '14 at 14:16
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What's the difference between comma separated joins and join on syntax in MySQL? [duplicate]
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There is no difference at all.
Second representation makes query more readable and makes it look very clear as to which join corresponds to which condition.
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Programmatically saving image to Django ImageField
...import File # you need this somewhere
import urllib
# The following actually resides in a method of my model
result = urllib.urlretrieve(image_url) # image_url is a URL to an image
# self.photo is the ImageField
self.photo.save(
os.path.basename(self.url),
File(open(result[0], 'rb'))
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How do I set bold and italic on UILabel of iPhone/iPad?
...t {
return with([.traitBold, .traitItalic])
}
func with(_ traits: UIFontDescriptor.SymbolicTraits...) -> UIFont {
guard let descriptor = self.fontDescriptor.withSymbolicTraits(UIFontDescriptor.SymbolicTraits(traits).union(self.fontDescriptor.symbolicTraits)) else {
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