About ASP.NET Web Pages Global - asp.net

Question

I am new learner to asp.net. I saw “_appstart.cshtml”, “_pagestart.cshtml” and “_viewstart.cshtml” which act like global headers or footer.
(1)If I want to trigger something right before the page is output, should I put the code in _viewstart.cshtml of others?
(2)Let C be the html code just before output, beside appending code to C can I replace code from C? Such as making all text uppercase or replace some text?
(3)Will asp.net cache this process so that I won't run each time?

Answer 1

benone
Answer to Point 1
The _ViewStart file can be used to define common view code that you want to execute at the start of each View’s rendering. For example, we could write code within our _ViewStart.cshtml file to programmatically set the Layout property for each View to be the SiteLayout.cshtml file by default
Actually it's like a BasePage in ASP.Net where we can keep the common code.
Or you can write the logic directly in the View like below.
#{
Layout = "~/Views/Shared/_Layout.cshtml";
if (Some Consition) {
Layout = "~/Views/Shared/_AdminLayout.cshtml";
}
}
Alternatively
You can override the Action Executing method, which executes before executing the Action Method. You can set it for a particular Action method or for the Complete Controller
Below is the code for setting it for Complete Controller.
protected override void OnActionExecuting(ActionExecutingContext ctx) {
base.OnActionExecuting(ctx);
}
Below is the Code for Setting it for Particular Action method
[MyAttribute(SomeProperty = "")]
public ActionResult Index()
{
return View("Index");
}
public class MyAttribute : ActionFilterAttribute
{
public string SomeProperty { get; set; }
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
base.OnActionExecuting(filterContext);
}
}
Answer to Point 2
You can use
var str = Html.Partial("_Partial_View_Name");
Partial returns an MvcHtmlString. You can intercept the output by setting it to a variable and make the necessary change.
Answer to Point 3
Yes. Below is the sample code
namespace MvcApplication1.Controllers
{
[HandleError]
public class HomeController : Controller
{
[OutputCache(Duration=10, VaryByParam="none")]
public ActionResult Index()
{
return View();
}
}
}
The output of the Index() action is cached for 10 seconds