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How to avoid having class data shared among instances?
...
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...
When saving, how can you check if a field has changed?
...
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...
MySQL DROP all tables, ignoring foreign keys
... your database like this:
SELECT concat('DROP TABLE IF EXISTS `', table_name, '`;')
FROM information_schema.tables
WHERE table_schema = 'MyDatabaseName';
Note 1: This does not execute the DROP statements, it just gives you a list of them. You will need to cut and paste the output into your SQL...
Debugging Package Manager Console Update-Database Seed Method
...ext.Database.GetPendingMigrations() instead.
– stevie_c
Apr 27 '18 at 14:11
add a comment
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Casting vs using the 'as' keyword in the CLR
...bject obj) cil managed
{
// Code size 22 (0x16)
.maxstack 8
IL_0000: ldarg.1
IL_0001: isinst MyClass
IL_0006: brfalse.s IL_0015
IL_0008: ldarg.1
IL_0009: castclass MyClass
IL_000e: pop
IL_000f: ldarg.1
IL_0010: call void [mscorlib]System.Console::WriteL...
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 print without newline or space?
...ython 2.6 you can either import the print function from Python 3 using the __future__ module:
from __future__ import print_function
which allows you to use the Python 3 solution above.
However, note that the flush keyword is not available in the version of the print function imported from __futu...
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...
Possibility of duplicate Mongo ObjectId's being generated in two different collections?
...hey are generated on different machines.
Now if you were referring to the _id field in general, we do not require uniqueness across collections so it is safe to reuse the old _id. As a concrete example, if you have two collections, colors and fruits, both could simultaneously have an object like {_...
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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