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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...
What are some uses of decltype(auto)?
...p;&
auto x6a = { 1, 2 }; // decltype(x6a) is std::initializer_list<int>
decltype(auto) x6d = { 1, 2 }; // error, { 1, 2 } is not an expression
auto *x7a = &i; // decltype(x7a) is int*
decltype(auto)*x7d = &i; // error, declared type is not plain declt...
What’s the best way to check if a file exists in C++? (cross platform)
...turns "true" on non-existent files on network shares: "\\machine\share\this_file_doesnt_exist" => true. Last time I checked was on boost 1.33, use caution...
– rlerallut
Nov 6 '08 at 12:54
...
What can you do in MSIL that you cannot do in C# or VB.NET? [closed]
...etty much all over the place. Examine the IL for this: "let print x = print_any x".
– MichaelGG
Feb 24 '09 at 23:22
1
...
Data binding to SelectedItem in a WPF Treeview
...SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(___ICH);
}
void ___ICH(object sender, RoutedPropertyChangedEventArgs<object> e)
{
if (SelectedItem != null)
{
SetValue(SelectedItem_Property, SelectedItem);
}
}
...
Is there a performance difference between i++ and ++i in C++?
... this->data += 1;
return *this;
}
Foo Foo::operator++(int ignored_dummy_value) // called for i++
{
Foo tmp(*this); // variable "tmp" cannot be optimized away by the compiler
++(*this);
return tmp;
}
Since the compiler isn't generating code, but just calling an operator++ ...
Adding external library into Qt Creator project
...your lib files in the project directory, you can reference them with the $$_PRO_FILE_PWD_ variable, e.g.:
LIBS += -L"$$_PRO_FILE_PWD_/3rdparty/libs/" -lpsapi
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How to set -source 1.7 in Android Studio and Gradle
... }
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_7
targetCompatibility JavaVersion.VERSION_1_7
}
}
Gradle 1.7+, Android gradle plugin 0.6.+ are required.
Note, that only try with resources require minSdkVersion 19. Other features works on previous platform...
Do I need dependency injection in NodeJS, or how to deal with …?
...nnection.js: (be sure to choose a better name)
var db = require('whichever_db_vendor_i_use');
module.exports.fetchConnection() = function() {
//logic to test connection
//do I want to connection pool?
//do I need only one connection throughout the lifecyle of my application?
ret...
What is the difference between attribute and property? [closed]
...
In Python...
class X( object ):
def __init__( self ):
self.attribute
def getAttr( self ):
return self.attribute
def setAttr( self, value ):
self.attribute= value
property_name= property( getAttr, setAttr )
A property is a s...