Category: DotNet

.NET: Roslyn Has a Missing Path

This error seems to occur when I am opening an upgraded web project in Visual Studio 2019: 
  

This happens when the current codebase is using older VS2015 templates. 

The simplest approach is to open NuGet’s Package Configuration Console in Visual Studio and enter the following to upgrade the compiler: 

Update-Package Microsoft.CodeDom.Providers.DotNetCompilerPlatform -r 
REFERENCE:  

https://stackoverflow.com/questions/32780315/could-not-find-a-part-of-the-path-bin-roslyn-csc-exe

.NET: How To Use ViewData, ViewBag And TempData in MVC

ViewData 

It is a dictionary which can contain key-value pairs where each key must be string. We can use it in transferring data from Controller to View. We can only transfer data from Controller to view but if we wish to pass data back again to controller then it is not possible. So it is valid only for the current request.

ViewBag

ViewBag is also similar to ViewData. It is used to transfer data from Controller to View. It is a type of Dynamic object, that means you can add new fields to viewbag dynamically and access these fields in the View. You need to initialize the object of viewbag at the time of creating new fields.

TempData

TempData is a dictionary object derived from TempDataDictionary. It is for subsequent HTTP requests; unlike ViewBag and ViewData, those stay only for current request. It can be used to maintain data between controller actions as well as redirects.

REFERENCES:

.NET: What Version Is On the Target Server

I’m upgrading .NET (legacy 4.*) applications on multiple unfamiliar servers.  This includes needing to know if the currently installed framework meets my requirements.  Instead of fumbling through the actual registry, I can pasted this C# snippet into a console app and all is good:

REFERENCE: https://docs.microsoft.com/en-us/dotnet/framework/migration-guide/how-to-determine-which-versions-are-installed

C# Access Modifiers

Access Modifiers are keywords that define the accessibility of a member, class or datatype in a program. These are mainly used to restrict unwanted data manipulation by external programs or classes. There are 4 access modifiers (public, protected, internal, private) which defines the 6 accessibility levels as follows:



  • public
  • protected
  • internal
  • protected internal
  • private
  • private protected



The Accessibility table of these modifiers is given below:
public 
protected 
internal 
protected internal 
private 
private protected 
Entire program 
Yes 
No 
No 
No 
No 
No 
Containing class 
Yes 
Yes 
Yes 
Yes 
Yes 
Yes 
Current assembly 
Yes 
No 
Yes 
Yes 
No 
No 
Derived types 
Yes 
Yes 
No 
Yes 
No 
No 
Derived types within current assembly 
Yes 
Yes 
No 
Yes 
No 
Yes