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When saving, how can you check if a field has changed?
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Essentially, you want to override the __init__ method of models.Model so that you keep a copy of the original value. This makes it so that you don't have to do another DB lookup (which is always a good thing).
class Person(models.Model):
name = models.CharF...
sqlalchemy: how to join several tables by one query?
...integer primary keys for everything, but whatever):
class User(Base):
__tablename__ = 'users'
email = Column(String, primary_key=True)
name = Column(String)
class Document(Base):
__tablename__ = "documents"
name = Column(String, primary_key=True)
author_email = Column(Strin...
How to avoid having class data shared among instances?
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You want this:
class a:
def __init__(self):
self.list = []
Declaring the variables inside the class declaration makes them "class" members and not instance members. Declaring them inside the __init__ method makes sure that a new instance of th...
Is there a benefit to defining a class inside another class in Python?
... use a metaclass, it's sometimes handy to do
class Foo(object):
class __metaclass__(type):
....
instead of defining a metaclass separately, if you're only using it once.
The only other time I've used nested classes like that, I used the outer class only as a namespace to group a bun...
Django - filtering on foreign key properties
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Asset.objects.filter( project__name__contains="Foo" )
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How to get Linux console window width in Python
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rows, columns = subprocess.check_output(['stty', 'size']).split() is a little shorter, plus subprocess is the future
– cdosborn
Mar 17 '15 at 2:00
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Concatenating two lists - difference between '+=' and extend()
... function call, which is slightly more expensive in Python than the INPLACE_ADD.
It's really nothing you should be worrying about, unless you're performing this operation billions of times. It is likely, however, that the bottleneck would lie some place else.
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How to Execute SQL Server Stored Procedure in SQL Developer?
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You don't need EXEC clause. Simply use
proc_name paramValue1, paramValue2
(and you need commas as Misnomer mentioned)
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How do you get assembler output from C/C++ source in gcc?
.... The output file can be still be set by using the -o option.
gcc -S -o my_asm_output.s helloworld.c
Of course this only works if you have the original source.
An alternative if you only have the resultant object file is to use objdump, by setting the --disassemble option (or -d for the abbreviat...
Removing multiple keys from a dictionary safely
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Why not like this:
entries = ('a', 'b', 'c')
the_dict = {'b': 'foo'}
def entries_to_remove(entries, the_dict):
for key in entries:
if key in the_dict:
del the_dict[key]
A more compact version was provided by mattbornski using dict.pop()
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