Using exception filters with ASP.NET Web Pages / Razor

Question

User-745470448 posted

I'm trying (hoping?) to use exception filtering in a ASP.NET Web Pages / Razor website. I'm using C# 7 with Microsoft.AspNet.Razor 3.27 and Microsoft.AspNet.WebPages 3.2.7, but I'm still getting errors when trying to use the keyword 'when' in a try catch block, like:

try
{
   // do something
}
catch (Exception ex) when (Log("log an error"))
{

}

The error is:

Error Expected a "{" but found a "when". Block statements must be enclosed in "{" and "}". You cannot use single-statement control-flow statements in CSHTML pages. For example, the following is not allowed:

@if(isLoggedIn)
<p>Hello, @user</p>

Instead, wrap the contents of the block in "{}":

@if(isLoggedIn) {
<p>Hello, @user</p>
} 

Does Web Pages Razor 3.2.7 just not support exception filtering? It looks like it was added to the Razor that's part of .NET Core Razor back in 2015.

Answer 1

User1724605321 posted

Hi tsulli,

Do you want to use try..catch in razor ? 

@try
{
    <div>typical Razor view stuff here...</div>
}
catch (Exception ex)
{
   
}

In addition .  i would suggest to learn the tutorial for error handling in razor page :

https://www.mikesdotnetting.com/article/266/error-handling-in-asp-net-razor-web-pages 

Best Regards,

Nan Yu

Answer 2

User-745470448 posted

I'm familiar with how to use try ... catch in Razor and with the topics discussed on the linked page. I'm asking specifically about using C# 6 exception filtering (the when keyword followed by a method call, as shown in my question) in Razor code blocks. 

Answer 3

User1724605321 posted

Hi tsilli ,

That seems a bug in MVC razor page since .net core won't meet this problem .

Best Regards,

Nan Yu

Answer 4

User-1038772411 posted

hii tsulli,

Please refere the below link , I hope it helps you

Try with this 

 https://weblogs.asp.net/dixin/c-6-0-exception-filter-and-when-keyword

Thank you