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How do I clone a Django model instance object and save it to the database?
...imary key of your object and run save().
obj = Foo.objects.get(pk=<some_existing_pk>)
obj.pk = None
obj.save()
If you want auto-generated key, set the new key to None.
More on UPDATE/INSERT here.
Official docs on copying model instances: https://docs.djangoproject.com/en/2.2/topics/db/que...
How to concatenate two MP4 files using FFmpeg?
...puts).
ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv \
-filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a]
concat=n=3:v=1:a=1 [v] [a]" \
-map "[v]" -map "[a]" output.mkv
Note that this method performs a re-encode.
2. concat demuxer
Use this method wh...
Generate JSON string from NSDictionary in iOS
...ke easier to read).
@interface NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint;
@end
.
@implementation NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint {
NSError *error;
NSData *jsonData = [NSJSONSerial...
List comprehension: Returning two (or more) items for each item
...bda x: x + 2
>>> g = lambda x: x ** 2
>>> list(chain.from_iterable((f(x), g(x)) for x in range(3)))
[2, 0, 3, 1, 4, 4]
Timings:
from timeit import timeit
f = lambda x: x + 2
g = lambda x: x ** 2
def fg(x):
yield f(x)
yield g(x)
print timeit(stmt='list(chain.from_itera...
Mathematical functions in Swift
...l math functions and constanst.
A small snippet of the file
...
func pow(_: CDouble, _: CDouble) -> CDouble
func sqrtf(_: CFloat) -> CFloat
func sqrt(_: CDouble) -> CDouble
func erff(_: CFloat) -> CFloat
...
var M_LN10: CDouble { get } /* loge(10) */
var M_PI: CDouble { get } /...
How can I create directory tree in C++/Linux?
...he standard header <filesystem> with
function
std::filesystem::create_directories
which should be used in modern C++ programs.
The C++ standard functions do not have the POSIX-specific explicit
permissions (mode) argument, though.
However, here's a C function that can be compiled with C++ com...
sbt-assembly: deduplication found error
...le
assemblyMergeStrategy in assembly := {
case PathList("META-INF", xs @ _*) => MergeStrategy.discard
case x => MergeStrategy.first
}
This helped me a lot.
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...
How to .gitignore files recursively
... the repo root (parent directory of /Webapp).
– lucid_dreamer
May 6 '18 at 22:33
1
...
jekyll markdown internal links
...ou can now post internal links by using the following:
[Some Link]({% post_url 2010-07-21-name-of-post %})
This is also referenced in the Jekyll Documentation.
https://github.com/mojombo/jekyll/pull/369
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How to get the request parameters in Symfony 2?
...ndation\Request;
public function updateAction(Request $request)
{
// $_GET parameters
$request->query->get('name');
// $_POST parameters
$request->request->get('name');
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