Welcome back! In the last lesson, you got a crash course in C# language fundamentals. Now, you'll get to put those skills to use and build a website using ASP.NET Core and Razor Pages!
.NET is pretty magical, because you can build all kinds of apps with it – mobile apps, games, desktop apps, web apps, and more. ASP.NET Core is a .NET toolkit for building web sites, apps, and services with .NET.
There are a few different kinds of web apps out there. Many web apps render content and handle requests from the server - think shopping and commerce websites, web sites for small businesses and portfolios, news sites, etc. Other web apps are highly interactive – like a game or in-browser experiences. Razor Pages is a web UI framework for building web apps that run from the server.
Note: Starting in .NET 8, Blazor is the preferred approach for building web UI with ASP.NET Core. You can use Blazor's rich component model to build both server rendered web apps and interactive client web apps. We'll learn more about Blazor in Week 5.
In Razor Pages applications, you’ll write your logic in a Page Model class, and you’ll write your markup in a Razor file. Razor is a nifty language that blends HTML markup with C# logic, so you can pull in your dynamic information from your Page Model class and display it in Razor. If that sounds complicated, don’t worry, because you’re about to see how easy it is to write a simple Pizza store web app using Razor Pages.
You can utilize your editor of choice for this course. Below we've included instructions for GitHub Codespaces and Visual Studio.
- Open a GitHub Codespace. To do this, simply select the green Code button. Then click the + to create a Codespace on the main branch.
- Navigate to the project files in the 0-start/RazorPagesPizza folder
We'll be using Visual Studio 2022 for whole course. If you don't have Visual Studio 2022 installed, you can follow the directions here.
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Start Visual Studio 2022 and select Create a new project.
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In the Create a new project dialog, select ASP.NET Core Web App, and then select Next.
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In the Configure your new project dialog, enter
RazorPagesPizzafor Project name. It's important to name the project RazorPagesPizza, including matching the capitalization, so the namespaces will match when you copy and paste example code.
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Select Next.
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In the Additional information dialog, select .NET 8.0 (Long-term support) and then select Create.
The following starter project is created:
In the Project menu, select New Folder. Name the folder Models.
With the Models folder still selected in the Solution Explorer, select Project -> Add Class... from the menu. Name the new class Pizza.cs and click the Add button.
In the Pizza.cs file, add the following code:
using System.ComponentModel.DataAnnotations;
namespace RazorPagesPizza.Models;
public class Pizza
{
public int Id { get; set; }
[Required]
public string? Name { get; set; }
public bool IsGlutenFree { get; set; }
[Range(0.01, 9999.99)]
public decimal Price { get; set; }
}Before proceeding to the next step, build the project by selecting Build Solution from the Build menu.
Right-click on the Pages directory in the Solution Explorer, and select Add -> New Scaffolded Item....
NOTE: It is important that you right-click the Pages directory when you add a new scaffolded item. This is because the Pages directory is a special folder in the Solution Explorer that contains all of the Razor Pages files.
In the Add New Scaffold Item dialog, select Razor Pages, Razor Pages using Entity Framework (CRUD) and then select Add.
In the Add Razor Pages using Entity Framework (CRUD) dialog, select Pizza (RazorPagesPizza.Models) for the model class.
Click the + button to the right of the Data context class field. The New data context type field will be pre-filled with RazorPagesPizza.Data.RazorPagesPizzaContext. Click the Add button.
Verify that the dialog looks like this, then click the Add button:
You will receive a warning that you are overriding the existing Index files. Click the Yes button to continue.
Let's take a look at how a sample page in the site works - we'll start with the Index page. As explained earlier, the logic in a Razor Page goes in a Page Model class, and you’ll write your markup in a Razor file. We'll look at how those work, starting with the Index PageModel.
A Razor page's PageModel class file defines any page handlers for HTTP requests sent to the page, and data used to render the page. The PageModel keeps those concerns separate from the Razor page, making your app more modular, and easier to maintain. By convention, the PageModel class is named [PageName]Model and resides in the same namespace as the Razor page.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;
using RazorPagesPizza.Data;
using RazorPagesPizza.Models;
namespace RazorPagesPizza
{
public class IndexModel : PageModel
{
private readonly RazorPagesPizza.Data.RazorPagesPizzaContext _context;
public IndexModel(RazorPagesPizza.Data.RazorPagesPizzaContext context)
{
_context = context;
}
public IList<Pizza> Pizza { get;set; } = default!;
public async Task OnGetAsync()
{
if (_context.Pizza != null)
{
Pizza = await _context.Pizza.ToListAsync();
}
}
}
}A PageModel really has two jobs:
- It assembles all the dynamic content you'll want to show in the page.
- It handles all the page interactions, which normally map to HTTP verbs like GET, POST, DELETE, etc.
The IndexModel uses EF Core to work with the database, allowing the OnGetAsync method to be pretty short. A database context called _context is kind of magically created for us in the class constructor (it's actually using ASP.NET Core's dependency injection system, but it's okay to just treat it as magic for now). EF Core allows us to just work with a C# list of items (our Pizza class in this case), and it does the work to synchronize our changes with a database.
Currently, the IndexModel class handles the HTTP GET request with an OnGetAsync page handler. You can add handlers for any HTTP verb. The most common handlers are:
OnGetAsyncto initialize state needed for the page.OnPostAsyncto handle form submissions. You can see an example inCreate.cshtml.cs, and learn more about how form submissions work in the references in the What's Next section below.
Now that we've got a list of pizzas loaded into a variable (Pizza in this case), we can display it in the page. A Razor page supports Razor syntax, which is HTML and C# combined. The C# code defines the dynamic rendering logic for the page on the server. The default Razor language is HTML. Rendering HTML from Razor markup is no different than rendering HTML from an HTML file. HTML markup in .cshtml Razor page files is rendered by the server unchanged. In Razor Pages, HTML can be used as you're used to. At the same time, you can take advantage of powerful and time-saving Razor features as you learn to use them.
You'll see below that we're transitioning between C# and HTML - starting with some C# to set a few things, then switching over to HTML with our <h1> tag. From then on, it's mostly HTML with some dynamic content sprinkled in.
@page
@model RazorPagesPizza.IndexModel
@{
ViewData["Title"] = "Index";
}
<h1>Index</h1>
<p>
<a asp-page="Create">Create New</a>
</p>
<table class="table">
<thead>
<tr>
<th>
@Html.DisplayNameFor(model => model.Pizza[0].Name)
</th>
<th>
@Html.DisplayNameFor(model => model.Pizza[0].IsGlutenFree)
</th>
<th>
@Html.DisplayNameFor(model => model.Pizza[0].Price)
</th>
<th></th>
</tr>
</thead>
<tbody>
@foreach (var item in Model.Pizza) {
<tr>
<td>
@Html.DisplayFor(modelItem => item.Name)
</td>
<td>
@Html.DisplayFor(modelItem => item.IsGlutenFree)
</td>
<td>
@Html.DisplayFor(modelItem => item.Price)
</td>
<td>
<a asp-page="./Edit" asp-route-id="@item.Id">Edit</a> |
<a asp-page="./Details" asp-route-id="@item.Id">Details</a> |
<a asp-page="./Delete" asp-route-id="@item.Id">Delete</a>
</td>
</tr>
}
</tbody>
</table>Razor has a pretty lightweight syntax, so if you're familiar with HTML you can start with that and add in dynamic content and logic. There's more information about the Razor syntax in the docs, of course, and we cover it in a little more detail in the What's Next tutorial.
From the Tools menu, select NuGet Package Manager > Package Manager Console.
In the Package Manager Console, or PMC, enter the following commands:
Add-Migration InitialCreate
Update-DatabaseFrom the Build menu, select Start Debugging. A console window will open to display debug output, and your browser will open to the web application's URL. It will be something like https://localhost:7242/, where the 7242 is a free port number on your machine.
You've got a running web application that you built! Let's try it out.
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Click the Create New link to navigate to the Create page. Try to break it by leaving all the fields blank and clicking the Create button. You'll see validation errors, which is a good thing!
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Enter a valid pizza name (pineapple is allowed!) and price (between 0.01 and 9999.99 - we've got some expensive pizza here) and click the Create button.
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Play with it a bit by adding a few pizzas and deleting them.
In order to get started quickly, we've kept things as simple as we could, and we've taken advantage of scaffolding to write a lot of code for us. We've got some more advanced tutorials to help you get to the next level, though:
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Create a web UI with ASP.NET Core will walk you through a very similar Pizza application, but in more detail. You'll learn more about how things are working behind the scenes, and write more of the code by hand.
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Create a Razor Pages web app with ASP.NET Core goes even deeper, with more advanced data operations like search and adding new fields to your data model.
We're excited to support you on your learning journey! Check out the .NET Community Page to find links to our blogs, YouTube, Twitter, and more.
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