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In a django model custom save() method, how should you identify a new object?
...
Updated: With the clarification that self._state is not a private instance variable, but named that way to avoid conflicts, checking self._state.adding is now the preferable way to check.
self.pk is None:
returns True within a new Model object, unless the object...
What is the difference between '/' and '//' when used for division?
...he 2.x line, there is no difference for integers unless you perform a from __future__ import division, which causes Python 2.x to adopt the 3.x behavior.
Regardless of the future import, 5.0 // 2 will return 2.0 since that's the floor division result of the operation.
You can find a detailed descr...
php stdClass to array
...g functions). "But I already did this" you say. Not exactly - you used json_decode on the array, but you need to encode it with json_encode first.
Requirements
The json_encode and json_decode methods. These are automatically bundled in PHP 5.2.0 and up. If you use any older version there's also a ...
How to create a DataTable in C# and how to add rows?
...e();
dt.Clear();
dt.Columns.Add("Name");
dt.Columns.Add("Marks");
DataRow _ravi = dt.NewRow();
_ravi["Name"] = "ravi";
_ravi["Marks"] = "500";
dt.Rows.Add(_ravi);
To see the structure, or rather I'd rephrase it as schema, you can export it to an XML file by doing the following.
To export only th...
How do I call setattr() on the current module?
...
import sys
thismodule = sys.modules[__name__]
setattr(thismodule, name, value)
or, without using setattr (which breaks the letter of the question but satisfies the same practical purposes;-):
globals()[name] = value
Note: at module scope, the latter is eq...
How to send an email from JavaScript
...= require('node-mandrill')('<your API Key>');
function sendEmail ( _name, _email, _subject, _message) {
mandrill('/messages/send', {
message: {
to: [{email: _email , name: _name}],
from_email: 'noreply@yourdomain.com',
subject: _subject,
...
Is there a way to make mv create the directory to be moved to if it doesn't exist?
... this one-liner (in bash):
mkdir --parents ./some/path/; mv yourfile.txt $_
Breaking that down:
mkdir --parents ./some/path
creates the directory (including all intermediate directories), after which:
mv yourfile.txt $_
moves the file to that directory ($_ expands to the last argument passe...
std::mutex 加锁抛 _DEVICE_OR_RESOURCE_BUSY 异常 - C/C++ - 清泛网 - 专注C/C++及内核技术
std::mutex 加锁抛 _DEVICE_OR_RESOURCE_BUSY 异常device_or_resource_busy最近遇到一个崩溃，在 std::lock_guard<std::mutex> lock(mutex_); 的地方，抛出了_DEVICE_OR_RESOURCE_BUSY 的异常。最终查出原因是：同一个线程对同一个mutex二次加锁导致的 最近遇到...
use of deleted function std::unique_ptr 编译错误剖析，你可能少了一个st...
use of deleted function std::unique_ptr 编译错误剖析，你可能少了一个std::move编译报错日志如下： usr include c++ 4 7 bits stl_construct h:77:7: error: use of deleted function & 39;std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_p 编译报错日志如下：
/usr/...
未能从“const std::string”为“const std::_Tree<_Traits> &”...
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