.net – The difference between Html.Action and Html.RenderAction

asp.net-mvc-3html-helpernetrazor

I've been trying to figure out the difference between RenderAction and Action. I don't know if I'm so concerned about the differences at this point, as to why I can't get RenderAction to work. From what I can tell, I'm passing in the correct parameters. The overload I'm using seems to be the same for both:

@Html.RenderAction(Action, Controller, Route)

@Html.Action("Breadcrumb", "Navigation", new {SeoUrl = Model.CarlineBucket.SEOURLName})

@Html.RenderAction("Breadcrumb", "Navigation", new {SeoUrl = Model.CarlineBucket.SEOURLName})

I get a compilation error when I try and use RenderAction:

CS1502: The best overloaded method
match for
'System.Web.WebPages.WebPageExecutingBase.Write(System.Web.WebPages.HelperResult)'
has some invalid arguments.

Any tips or hints? Should I not even be bothering with RenderAction?

Best Answer

Try:

@{Html.RenderAction("Breadcrumb", "Navigation", new {SeoUrl = Model.CarlineBucket.SEOURLName});}

@Html.RenderAction() generates a write call to output something on the page and in your case you are not doing so because RenderAction renders the result directly to the Response.

Instead of

@Html.RenderAction()

Use

@{Html.RenderAction();}

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

.net – What’s the difference between struct and class in .NET

In .NET, there are two categories of types, reference types and value types.

Structs are value types and classes are reference types.

The general difference is that a reference type lives on the heap, and a value type lives inline, that is, wherever it is your variable or field is defined.

A variable containing a value type contains the entire value type value. For a struct, that means that the variable contains the entire struct, with all its fields.

A variable containing a reference type contains a pointer, or a reference to somewhere else in memory where the actual value resides.

This has one benefit, to begin with:

value types always contains a value
reference types can contain a null-reference, meaning that they don't refer to anything at all at the moment

Internally, reference types are implemented as pointers, and knowing that, and knowing how variable assignment works, there are other behavioral patterns:

copying the contents of a value type variable into another variable, copies the entire contents into the new variable, making the two distinct. In other words, after the copy, changes to one won't affect the other
copying the contents of a reference type variable into another variable, copies the reference, which means you now have two references to the same somewhere else storage of the actual data. In other words, after the copy, changing the data in one reference will appear to affect the other as well, but only because you're really just looking at the same data both places

When you declare variables or fields, here's how the two types differ:

variable: value type lives on the stack, reference type lives on the stack as a pointer to somewhere in heap memory where the actual memory lives (though note Eric Lipperts article series: The Stack Is An Implementation Detail.)
class/struct-field: value type lives completely inside the type, reference type lives inside the type as a pointer to somewhere in heap memory where the actual memory lives.

Best Answer

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

.net – What’s the difference between struct and class in .NET

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