大约有 30,000 项符合查询结果（耗时：0.0517秒） [XML]
List of lists changes reflected across sublists unexpectedly
...s visible via all three references to it:
x = [1] * 4
l = [x] * 3
print(f"id(x): {id(x)}")
# id(x): 140560897920048
print(
f"id(l[0]): {id(l[0])}\n"
f"id(l[1]): {id(l[1])}\n"
f"id(l[2]): {id(l[2])}"
)
# id(l[0]): 140560897920048
# id(l[1]): 140560897920048
# id(l[2]): 140560897920048
x...
Post JSON using Python Requests
...rsion 2.4.2 and onwards, you can alternatively use 'json' parameter in the call which makes it simpler.
>>> import requests
>>> r = requests.post('http://httpbin.org/post', json={"key": "value"})
>>> r.status_code
200
>>> r.json()
{'args': {},
'data': '{"key": "...
Get the latest record from mongodb collection
...oDB are B-Trees. Searching a B-Tree is a O(logN) operation, so even find({_id:...}) will not provide constant time, O(1) responses.
That stated, you can also sort by the _id if you are using ObjectId for you IDs. See here for details. Of course, even that is only good to the last second.
You may t...
How to inspect Javascript Objects
...e properties are not available for inspection, unless you use a "spy"; basically, you override the object and write some code which does a for-in loop inside the object's context.
For in looks like:
for (var property in object) loop();
Some sample code:
function xinspect(o,i){
if(typeof i==...
MySQL Error 1093 - Can't specify target table for update in FROM clause
...n case certain operations are carried out, merging cannot happen. E.g. provide the derived dummy table with a LIMIT (to inifity) and the error will never occur. That's pretty hackish though and there is still the risk that future versions of MySQL will support merging queries with LIMIT after all.
...
Foreign Key to multiple tables
...on your needs.
You could simply create two columns in Ticket, OwnedByUserId and OwnedByGroupId, and have nullable Foreign Keys to each table.
You could create M:M reference tables enabling both ticket:user and ticket:group relationships. Perhaps in future you will want to allow a single ticket to ...
Rails 3: Get Random Record
... on an indexed column (PostgreSQL syntax):
select *
from my_table
where id >= trunc(
random() * (select max(id) from my_table) + 1
)
order by id
limit 1;
share
|
improve this answer
...
Switching the order of block elements with CSS [duplicate]
...ly need to support a single modern browser: Mobile Safari.
See: http://jsfiddle.net/thirtydot/hLUHL/
You can remove the -moz- prefixed properties if you like, I just left them in for future readers.
#blockContainer {
display: -webkit-box;
display: -moz-box;
disp...
Getting root permissions on a file inside of vi? [closed]
... We can't just run :write because it won't process the necessary function call.
! represents the :! command: the only command that :write accepts. Normally, :write accepts a file path to which to write. :! on its own runs a command in a shell (for example, using bash -c). With :write, it will r...
How unique is UUID?
...inding ways to introduce as much entropy ("real randomness", I guess you'd call it) as possible into random number APIs. See en.wikipedia.org/wiki/Entropy_%28computing%29
– broofa
Dec 6 '14 at 13:48
...