大约有 40,000 项符合查询结果（耗时：0.0504秒） [XML]
ModelSerializer using model property
... Meta is optional. If you omit fields, in the above example, you would get all the MyModel fields plus ext_link in the serialized data. And this is really awesome for complex models! EDIT: At least, this is true for djangorestframework==2.3.14.
– e.thompsy
Feb ...
PostgreSQL: insert from another table
...000/svg\"\u003e\u003cpath d=\"M46.1709 9.17788C46.1709 8.26454 46.2665 7.94324 47.1084 7.58816C47.4091 7.46349 47.7169 7.36433 48.0099 7.26993C48.9099 6.97997 49.672 6.73443 49.672 5.93063C49.672 5.22043 48.9832 4.61182 48.1414 4.61182C47.4335 4.61182 46.7256 4.91628 46.0943 5.50789C45.7307 4.9328 4...
What is the copy-and-swap idiom?
...s arguably the most nuanced and difficult. How should it be done? What pitfalls need to be avoided?
The copy-and-swap idiom is the solution, and elegantly assists the assignment operator in achieving two things: avoiding code duplication, and providing a strong exception guarantee.
How does it wor...
Reset auto increment counter in postgres
...ated the table product with an id column, then the sequence is not simply called product, but rather product_id_seq (that is, ${table}_${column}_seq).
This is the ALTER SEQUENCE command you need:
ALTER SEQUENCE product_id_seq RESTART WITH 1453
You can see the sequences in your database using the...
Why dict.get(key) instead of dict[key]?
...
It allows you to provide a default value if the key is missing:
dictionary.get("bogus", default_value)
returns default_value (whatever you choose it to be), whereas
dictionary["bogus"]
would raise a KeyError.
If omitted...
How to JSON serialize sets?
...s.
As shown in the json module docs, this conversion can be done automatically by a JSONEncoder and JSONDecoder, but then you would be giving up some other structure you might need (if you convert sets to a list, then you lose the ability to recover regular lists; if you convert sets to a dictionar...
Creating a blocking Queue in .NET?
...threads reading from the same queue. If the queue reaches a specific size all threads that are filling the queue will be blocked on add until an item is removed from the queue.
...
Add Text on Image using PIL
...rial')
In [30]: draw = ImageDraw.Draw(im)
In [31]: t1 = 'hello world!'
In [32]: t2 = 'hello \nworld!'
In [33]: font.getsize(t1), font.getsize(t2) # the height is the same
Out[33]: ((52, 10), (60, 10))
In [35]: draw.textsize(t1, font), draw.textsize(t2, font) # handles multi-lined text
Out[35]: ((5...
decorators in the python standard lib (@deprecated specifically)
...r('always', DeprecationWarning) # turn off filter
warnings.warn("Call to deprecated function {}.".format(func.__name__),
category=DeprecationWarning,
stacklevel=2)
warnings.simplefilter('default', DeprecationWarning) # reset filter
...
How do you use the ellipsis slicing syntax in Python?
... item):
... if item is Ellipsis:
... return "Returning all items"
... else:
... return "return %r items" % item
...
>>> x = TestEllipsis()
>>> print x[2]
return 2 items
>>> print x[...]
Returning all items
Of course, there is the ...