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Creating a dynamic choice field
I'm having some trouble trying to understand how to create a dynamic choice field in django. I have a model set up something like:
...
What is the difference between char * const and const char *?
... changed).
Note:
The following two forms are equivalent:
const char *
and
char const *
The exact reason for this is described in the C++ standard, but it's important to note and avoid the confusion. I know several coding standards that prefer:
char const
over
const char
(with or withou...
What is the attribute property=“og:title” inside meta tag?
...ects in a social graph. They are used for example by Facebook.
og:title stands for the title of your object as it should appear within the graph (see here for more http://ogp.me/ )
share
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improve ...
SQL Server IIF vs CASE
...SE in my queries. I want to know the exact purpose of the IIF statement and when should we prefer using IIF over CASE Statement in the query.
I mostly use nested CASE in my queries.
...
C# generic type constraint for everything nullable
...time check, you can check if the type is not a reference or nullable type, and throw an exception if that's the case.
I realise that only having a runtime check may be unacceptable, but just in case:
public class Foo<T>
{
private T item;
public Foo()
{
var type = typeof(...
What is the fastest factorial function in JavaScript? [closed]
...torial function that uses big numbers to get exact result with memoization and cache as comparison
var f = [new BigNumber("1"), new BigNumber("1")];
var i = 2;
function factorial(n)
{
if (typeof f[n] != 'undefined')
return f[n];
var result = f[i-1];
for (; i <= n; i++)
f[i] = resu...
How to override !important?
...ing the !important modifier
Simply add another CSS rule with !important, and give the selector a higher specificity (adding an additional tag, id or class to the selector)
add a CSS rule with the same selector at a later point than the existing one (in a tie, the last one defined wins).
Some exa...
App Inventor 2 SQLite 拓展：超流行兼容主流SQL语法的迷你本地数据库引擎...
...sql中如果有多个变量则需要多个值，比如：... where age > ? and id < ? bindParams 就是2个元素组成的列表，对应上面的2个占位符。
带 where age > 23的条件查询结果如下：
注册登录案例
.aia 案例源码下载：
login_si...
Can you have multiple $(document).ready(function(){ … }); sections?
...rtup concerns - i.e. some code which is always run when loading completes, and some which is only required on some content nodes? In such a situation, the context should be silo'd, and order of execution should be immaterial - being able to assign to the 'DOM ready' event without overwriting the pre...
Are members of a C++ struct initialized to 0 by default?
...(0),y(0) { }
// other ctors / functions...
};
Will initialize both x and y to 0. Note that you can use x(), y() to initialize them disregarding of their type: That's then value initialization, and usually yields a proper initial value (0 for int, 0.0 for double, calling the default constructor...