ASP.NET Core Tutorial

In .NET Core we have the option to build applications using command line tool called dotnet command.Though we can use visual studio directly but dotnet  CLI command tool is quite useful.

Building a Console App

The dotnet command-line tool can be used for creating different types of applications.It has one option that allows to create a simple console application.

To see all the templates you can use “dotnet new” without any parameters.

Create a new console application from CLI dotnet command

Following will create a console application in the current directory.Note as that this will create project files in the current directory so change to the directory where you want to create the project.

go to windows command prompt.execute the following command:

This will create the required dependencies such as downloading the required nugets. After the above command executes required folders and files are created in the specified folder:

Target framework version

You can check the target framework version of the newly created application by looking at the TargetFramework element of the .csproj file.

Program.cs

This is the main file where program execution starts in .NET Core application.Following is the Program.cs created automatically by the CLI:

using System;

namespace sample_apps
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
}
}
}

Running the console application

You can run the above console application using the following command:

dotnet run

If you open the above application in Visual Studio you can see SDK node under dependencies .SDK stands for .NET Core Software Development Kit and consists of libraries and tools required for developing .NET Core application.

ashish

Here we will see how to create a sample asp.net core 2.0 razor page application in Visual Studio.

In Visual Studio select New Project option .In the new project template select .NET Core –> ASP.NET Core Web Application option.

Enter application name and select OK.

In the next screen select ASP.NET Core 2.0 in the dropdown and Web Application in the template

In the solution explorer you can see the following important items:

• wwwroot Contains static files such as css,js and images.
• Pages Folder for Razor Pages.
• appsettings.json  settings defined using JSON.
• Program.cs  Starts the ASP.NET Core app.
• Startup.cs Configures request pipeline.

If you expand the pages folder you can see the following razor pages:

If you look in the in the Startup class in StartUp.cs file you can see the following methods:

public void ConfigureServices(IServiceCollection services)
{
//Add Razor Pages in pipeline
services.AddMvc();
}

public void Configure(IApplicationBuilder app)
{
app.UseMvc();
}

the UseMvc() method above adds MVC to the request  pipeline.

Now if you look at any razor page you can see @page directive at the top.This directive makes a cshtml file as a action method.So the page handles the request without needing separate controller.

There is no controller but if you execute the application you can see the response:

The urls are mapped to razor pages based on the path of the page.So /Index will match /Pages/Similarly /Pages/Employee/Details.cshtml / will match Employee/Details

ashish

Since its inception in year 2001 , lots of versions of ASP.NET have been released.The current version is 4.6.You can also call it the legacy version.So you can use it for developing new applications or moving existing ASP.NET applications to newer version.ASP.NET legacy applications can run only on Windows OS.

ASP.NET Core applications can run on different operating systems and not just windows.So you can run ASP.NET Core applications on Linux ,Windows or any other OS.

ASP.NET Core is the next generation of ASP.NET framework and is complete rewrite of ASP.NET.It is a modular framework and is distributed as NuGet packages.It can run on .NET Framework as well as the .NET Core.

The main advantage of ASP.NET Core over previous versions of ASP.NET is that ASP.NET Core is modular and lightweight.

It is cross platform and can run on Linux, Unix, or OSX. It can run outside IIS via OWIN. ASP.NET Core is open source and is suitable for building applications for the cloud.You can deploy your ASP.NET Core applications directly to Azure from Visual Studio.

Anybody can contribute to ASP.NET core here https://github.com/aspnet/home

Configuration consists of name value pairs and can be defined using different formats such as JSON,XML,variables.

ASP.NET Core unifies MVC and WebAPI in a single framework.

Create ASP.NET Core application

To create a new ASP.NET Core application in Visual Studio 2017:

1. Select create new project from the files menu.In the dialog that opens select .NET Core project type  on the left

2.In the next dialog select Empty project template

3.Following are the files added in the solution explorer

There are two important files in ASP.NET core application:

• Program.cs
• Startup.cs

Program.cs

It consists of public static void Main() method which is the starting point of the application.We are hosting this ASP.NET Core application in a Console application.But you can host it in different hosts such as IIS or Apache.

 public class Program
    {
        public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .Build();
    }​

It defines the request pipeline of the application.

Following is a sample class

  public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello World!");
            });
        }
    }

the Run() method of the IApplicationBuilder is used to set up the request pipeline.The context parameter allows you to access Request or Response.

Now if you want to use MVC in your application then you can use the following:

app.UseMvc();

ashish