Introduction
ASP.NET Core is a new framework for building web applications and APIs. It is a cross-platform framework that can be run on Windows, macOS, and Linux. ASP.NET Core is a major update to the ASP.NET framework. It is designed to be more lightweight and modular than its predecessor.
One of the key features of ASP.NET Core is its support for web APIs. A web API is an interface that allows external applications to access your application's data and functionality. ASP.NET Core makes it easy to create web APIs that can be used by any type of client, including web browsers, mobile devices, and desktop applications.
In this article, we will learn how to write a web API in ASP.NET Core. We will start by creating a new project in Visual Studio 2019. Then we will add a controller that will handle requests from clients. Finally, we will test our API using Postman.
Prerequisites
Before you start writing a web API in Asp.net core, there are a few things you need to know.
First, you need to have a basic understanding of the Asp.net core framework. Second, you should have some experience with C# programming. Third, it would be helpful if you have a text editor or IDE installed on your computer.
Once you have the prerequisites out of the way, you can start writing your web API. The first thing you need to do is create a new project in Visual Studio. To do this, go to File > New > Project. In the New Project dialog, select the ASP.NET Core Web Application template. Give your project a name and click OK.
In the next dialog, select the Empty template and click OK. This will create a new empty ASP.NET Core project for you.
Now that you have a new project created, you can start adding code to it. The first thing you need to do is add a reference to the Microsoft.AspNetCore.Mvc namespace. This namespace contains all the classes and methods necessary for writing a web API in Asp.net core.
To add a reference to this
Managing Dependencies
In order to write a web API in Asp.net core, it is necessary to manage dependencies. This can be done using the NuGet Package Manager. The NuGet Package Manager is a tool that allows developers to manage dependencies in their applications. It can be used to add, remove, and update dependencies in an Asp.net core application.
Once the NuGet Package Manager is installed, it can be used to add the necessary dependencies for a web API. These dependencies include the Asp.net core framework, Entity Framework, and Newtonsoft.Json. Once these dependencies have been added, they will be automatically downloaded and installed by the NuGet Package Manager.
After the dependencies have been installed, it is necessary to configure them in the Asp.net core application. This can be done by adding the following lines of code to the Startup class:
using Microsoft.AspNetCore.Builder;
using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json;
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc()
Setup Project from Sample in
1. Setup Project from Sample in
1. Create a new ASP.NET Core web application project using the "Web API" template.
2. Add the following NuGet packages to the project:
- Microsoft.AspNetCore.Mvc
- Microsoft.EntityFrameworkCore
3. Create a folder named "Models" and add a class named "TodoItem" to it:
```
public class TodoItem
{
public long Id { get; set; }
public string Name { get; set; }
public bool IsComplete { get; set; }
}
```
4. In the "Startup.cs" file, add the following code to the "ConfigureServices" method to configure Entity Framework Core:
```
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<TodoContext>(opt => opt.UseInMemoryDatabase("TodoList"));
services.AddMvc()
.SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
MVC Core and Areas:
MVC Core is a framework for building web applications using the Model-View-Controller design pattern. Areas are a way of grouping related functionality in an MVC Core application. For example, you might have an area for admin functions and another area for customer facing functions.
Web API:
A web API is an interface that allows your application to interact with other applications or services over the internet. For example, you might use a web API to allow your application to access data from a database. ASP.NET Core provides support for building web APIs.
3. Security:
When you build a web API, it's important to consider security. You need to make sure that only authorized users can access your API and that data is transmitted securely. ASP.NET Core provides several features that help with security, such as authentication and authorization.
Configure Web API for ASP.NET Core MVC Application
ASP.NET Core MVC applications can use the Microsoft.AspNetCore.Mvc.WebApiCompatShim NuGet package to configure Web API compatibility in the application's Startup class:
public void ConfigureServices(IServiceCollection services)
{
// Add MVC services to the services container.
services.AddMvc();
// Add Web API compatibility services to the services container.
services.AddWebApiCompatiblity();
}
Web API Controllers
Web API controllers are the classes that handle the HTTP requests and responses in a web API. Each controller handles a specific set of URLs. For example, a controller might handle requests for all URLs that start with /products.
When a request comes in, the web API routes the request to the appropriate controller. The controller then processes the request and produces the appropriate response.
Controllers can be created manually or they can be generated automatically from an existing database. In either case, they must be registered with the web API so that they can be found when a request comes in.
2. Routing
Routing is how the web API maps incoming requests to controllers and action methods. By default, the web API uses attribute routing, which means that the routes are defined in the attributes of the controllers and action methods. Attribute routing makes it easy to define routes for a large number of URLs.
3. Actions Methods
Action methods are the methods in a controller that handle requests. Each action method is associated with a specific URL. For example, if you have a controller with an action method named GetProducts, that action method will handle requests for the /
1. Web API Services:
Web API services are a type of web service that allows communication between devices over the internet. They use HTTP requests and responses to communicate with clients. Asp.net core is a framework that allows you to build web API services.
When building a web API service, you will need to define the methods that your service will expose. These methods will be used by clients to interact with your service. You will also need to define the data that your methods will return. This data can be in the form of JSON or XML.
Once you have defined your methods and data, you can start building your service. Asp.net core makes it easy to build web API services. You can use Visual Studio to create your project and add the necessary files. Once you have created your project, you can add your methods and data to it. Visual Studio will also help you to deploy your service to a server.
1. Error Handling and Routing
When writing a web API in Asp.net core, it is important to handle errors correctly. Otherwise, your API will not work as expected and could cause problems for users.
One way to handle errors is to use the built-in error handling middleware. This middleware will catch any errors that occur during the execution of your API and will return a suitable error response.
Another way to handle errors is to use custom error handling middleware. This allows you to define your own error handling logic and return a custom error response.
Routing is also important when writing a web API in Asp.net core. Routing allows you to map incoming requests to the correct controller action. Without routing, your API would not be able to handle requests correctly.
Publishing the Project to Remove Headers and Footers
1. To remove headers and footers from a web page, you need to publish the project.
2. Go to the project properties window and select the 'Build' tab.
3. In the 'Output' section, select 'No Header and Footer Files'.
4. Click 'OK' to save your changes and close the window.
5. Now when you publish your project, the headers and footers will not be included in the output.
Conclusion
Web API is a powerful tool for building web applications. It allows you to easily create RESTful interfaces that can be used by your clients to access data and perform actions on your server. In this article, we've shown you how to write a web API in Asp.net core. We hope you've found this information helpful and that it will help you get started with writing your own web APIs.