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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...
Property getters and setters
...g to backup the computed property. Try this:
class Point {
private var _x: Int = 0 // _x -> backingX
var x: Int {
set { _x = 2 * newValue }
get { return _x / 2 }
}
}
Specifically, in the Swift REPL:
15> var pt = Point()
pt: Point = {
_x = 0
}
16> pt.x = 10...
How to manage client-side JavaScript dependencies? [closed]
...tion may help you
Example:
Client app project hierarchy:
sampleapp
|___ main.js
|___ cs.js
|___ require.js
main.js is where you initialize your client application and configure require.js:
require.config({
baseUrl: "/sampleapp",
paths: {
jquery: "libs/jquery", // Lo...
Is it possible to use argsort in descending order?
... this method is that ids is a view of avgDists:
>>> ids.flags
C_CONTIGUOUS : False
F_CONTIGUOUS : False
OWNDATA : False
WRITEABLE : True
ALIGNED : True
UPDATEIFCOPY : False
(The 'OWNDATA' being False indicates this is a view, not a copy)
Another way to do this is something ...
What are the most common naming conventions in C?
...which can be summarized as follows:
All macros and constants in caps: MAX_BUFFER_SIZE, TRACKING_ID_PREFIX.
Struct names and typedef's in camelcase: GtkWidget, TrackingOrder.
Functions that operate on structs: classic C style: gtk_widget_show(), tracking_order_process().
Pointers: nothing fancy her...
Python: Get relative path from comparing two absolute paths
.... if one of the paths is a common ancestor:
paths = […, …, …]
common_prefix = os.path.commonprefix(list_of_paths)
if common_prefix in paths:
…
You can then find the relative paths:
relative_paths = [os.path.relpath(path, common_prefix) for path in paths]
You can even handle more th...
Double Negation in C++
...ernel). For GCC, they're implemented as follows:
#define likely(cond) (__builtin_expect(!!(cond), 1))
#define unlikely(cond) (__builtin_expect(!!(cond), 0))
Why do they have to do this? GCC's __builtin_expect treats its parameters as long and not bool, so there needs to be some form of conver...
How to initialize an array in one step using Ruby?
...rray = [ '1', '2', '3' ]
You can also use a range:
array = ('1'..'3').to_a # parentheses are required
# or
array = *('1'..'3') # parentheses not required, but included for clarity
For arrays of whitespace-delimited strings, you can use Percent String syntax:
array = %w[ 1 2 3 ]
You can...
javac : command not found
...
yes, i am sure. just look at the java-1.6.0-openjdk.x86_64 package information (scroll to the "Files" section) and see that there is no javac in that package. and then look at the OpenJDK Development Environment package.
– ax.
Mar 23 '11 at ...