大约有 13,335 项符合查询结果（耗时：0.0222秒） [XML]
How do I import the Django DoesNotExist exception?
...mentation:
self.assertRaises(Answer.DoesNotExist, Answer.objects.get, body__exact='<p>User can reply to discussion.</p>')
or better:
with self.assertRaises(Answer.DoesNotExist):
Answer.objects.get(body__exact='<p>User can reply to discussion.</p>')
...
Good examples of Not a Functor/Functor/Applicative/Monad?
...onoid;
instance Monoid Data.Void where
mempty = undefined
mappend _ _ = undefined
mconcat _ = undefined
Since _|_ is a legal value in Haskell, and in fact the only legal value of Data.Void, this meets the Monoid rules. I am unsure what unsafeCoerce has to do with it, because your pro...
What does new self(); mean in PHP?
...etInstance method is in a class name MyClass, the following line :
self::$_instance = new self();
Will do the same as :
self::$_instance = new MyClass();
Edit : a couple more informations, after the comments.
If you have two classes that extend each other, you have two situations :
get...
Types in MySQL: BigInt(20) vs Int(20)
...264 (22003): Out of range value for column 'id' at row 1
mysql> SET sql_mode = '';
Query OK, 0 rows affected, 1 warning (0,00 sec)
mysql> INSERT INTO `test` (`id`) VALUES (401421228216);
Query OK, 1 row affected, 1 warning (0,06 sec)
mysql> SELECT * FROM `test`;
+------------+
| id ...
Reading a huge .csv file
...tly over getdata() in your code:
for row in getdata(somefilename, sequence_of_criteria):
# process row
You now only hold one row in memory, instead of your thousands of lines per criterion.
yield makes a function a generator function, which means it won't do any work until you start looping ...
Temporarily disable auto_now / auto_now_add
...s:
# my model
class FooBar(models.Model):
title = models.CharField(max_length=255)
updated_at = models.DateTimeField(auto_now=True, auto_now_add=True)
# my tests
foo = FooBar.objects.get(pk=1)
# force a timestamp
lastweek = datetime.datetime.now() - datetime.timedelta(days=7)
FooBar.obj...
Checking for empty queryset in Django
...is the code I refer to is only an example that it contains a line if not my_objects: to demonstrate that this is how they do it in the docs. All else is utterly irrelevant so I do not get your point. They could as well make a thousand queries and it would still be totally irrelevant as this is not t...
Why does Javascript's regex.exec() not always return the same value? [duplicate]
... matches by performing the assignment as the loop condition.
var re = /foo_(\d+)/g,
str = "text foo_123 more text foo_456 foo_789 end text",
match,
results = [];
while (match = re.exec(str))
results.push(+match[1]);
DEMO: http://jsfiddle.net/pPW8Y/
If you don't like the placem...
How to calculate moving average using NumPy?
... an off-by-one wrong indexing spotted by Bean in the code. EDIT
def moving_average(a, n=3) :
ret = np.cumsum(a, dtype=float)
ret[n:] = ret[n:] - ret[:-n]
return ret[n - 1:] / n
>>> a = np.arange(20)
>>> moving_average(a)
array([ 1., 2., 3., 4., 5., 6., 7....
Preferred way to create a Scala list
...
That is, you can now work on that IndexedSeq:
scala> list.foldLeft(0)(_+_)
res0: Int = 55
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