null and default values in page template
Very often i write code like:
<img c开发者_如何学编程lass="hasMenu" src="<%= (Model.Image==null)?Url.Content("~/Content/NoImage.jpg"):Model.Image.standard %>"
alt="Main image" />
Is there any predefined function which could beauty this code?
Something like: ValueOrDefault(Model.Image.standard,Url.Content("~/Content/NoImage.jpg"))
If what you meant was:
(Model.Image.standard==null)?Url.Content("~/Content/NoImage.jpg"):Model.Image.standard
then you simplify that using the null-coalescing operator:
Model.Image.standard ?? Url.Content("~/Content/NoImage.jpg")
If you meant what you said, you could write a method like this:
static class Obj
{
public static T OrDefault<T>(Func<T> func, T def)
{
T result;
try
{
result = func();
}
catch (NullReferenceException)
{
result = def;
}
return result;
}
}
and use it like this:
Obj.OrDefault(() => Model.Image.standard, Url.Content("~/Content/NoImage.jpg"))
No, there is no way to check if a field is null
and use its property in the same statement with basic operators part from the way you have already done it. There have been discussions about a "property null-coalescing operator", but I am unable to find it when searching the forum.
The way you coded it is the most efficient way and probably the way to go in terms of readability.
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