Asp Net Core 3.0 web API token based authentication example using JWT in VS2019

In this tutorial, we are going to cover web api token based authentication example using JWT in Asp Net Core 3.0 with Visual Studio 2019 preview. We will build it from scratch. So, First-of-all, we will create a new Asp Net Core 3.0 web API project, and then we will implement Microsoft Identity and then finally we will implement token based authentication using JWT in Asp Net Core 3.0 web API application.

Prerequisites

There are some prerequisites for this web api token based authentication example tutorial. So, before going to next you must need to install these below dependencies.

How to implement token based authentication (JWT) in Asp Net Core 3.0 web api?

Let’s start to implement web api token based authentication example using asp net core 3.0 in step by step.

Step # 1: How to create asp net core 3.0 web api using visual studio 2019?

First-of-all, in this step we will create a new asp net core 3.0 web api using visual studio 2019. So, first-of-all, go to visual studio 2019 preview and then click on Create a new project and then select ASP.NET Core Web Application and click on Next button.

Then enter project name (E.g. AspNetCore3JWT ) in the Project Name field and then Create button

After clicking on the Create button, then you will see a new popup as you see in the below screenshot. So, select ASP.NET Core 3.0 framework from dropdown and then select API and then click on the Create button.

After clicking on the Create button, then you will see a new Asp Net Core 3.0 web api project is created.

Step # 2: How to setup Database and Implement Microsoft Identity in Asp Net Core 3.0 web API Project?

So, in this step, we will setup database in Asp Net Core 3.0 web api project. So, go to project folder structure and then open appsettings.json file and then add connection string as you see in the below file.

Now, go to project folder structure and then enter a new folder with the name of Data. In this folder, we will add all the database database related classes like ApplicationUser, ApplicationDbContext and etc.

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So, right click on the newly created Data folder and then click on Add and then click on Class and then enter the name of class (E.g. ApplicationUser) and then write the code as you see in the below file.

Note: – don’t forget to import libraries.

Now, add another class inside the Data folder with the name of ApplicationDbContext and then write the code as you see in the below file.

Note: – don’t forget to import libraries.

Now, we will add a new seed class which will add a demo data for user account. So, right click on the Data folder and then click on Add and then click on Class and then enter the name of class (E.g. SeedDB) and then write the code as you see in the below file.

This above class will help us to create a new user account. As you see above the username will be Ali and the password will be Ali@123.

Now, we will add services to Startup.cs class. So, go to project folder structure and then open Startup.cs class and then write the code as you see in the below file’s line # 38 to 41 and line # 56..

Let’s understand the above code.

Line # 38: In this line, we are adding the service for sql server db.

Line # 39 to 41: here in this line, we are adding service for Microsoft Identity.

Line # 56: here in this line, we are initializing the SeedDB class to create a new user.

Now, the database and identity implementation part is completed.

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Step # 3: How to implement token based authentication using jwt in asp net core 3.0 web api?

Now, in this step, we will see how to implement token based authentication using JWT in Asp Net Core 3.0 web API. So to do this, first-of-all, we will add a new model class and then add a new controller which will evaluate the token based authentication.

So, go to project folder structure and then add a new folder with the name of Models. Now, right click on newly created Models folder and then Add and then click on Class and then enter the name of class (E.g. LoginModel) and then click on Add button. Now, write the properties as you see in the below screenshot.

Now, go to project folder structure and then right click on the Controllers folder and then Add and then click on Controller… and then select MVC Controller – Empty from the middle pane and then click on Add button and then enter the name of controller (E.g. AuthenticateController) and then click Add button. So, it will create a new controller class with the name of AuthenticateController.cs.

Now, write the code as you see in the below file.

Let’s understand the above code..

Line # 17: here in this line, we are declaring the route path for API.

Line # 20: here in this line, we are injecting the user manager.

Line # 31: here in this line, we are getting the specific user.

Line # 32: here in this line, we are checking the user value and password. If the condition is true, then we will generate the token otherwise it will return Unauthorized response.

Line # 35 to 39: here in these lines, we are creating claims.

Line # 41: here in this line, we are creating signing key.

Line # 43 to 49: here in this block of code, we are generating token using JWT.

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Line # 51 to 55: here in this block, we are returning the ok status with token and expiration time after generating token successfully.

Now, go to controllers folder and then open ValuesController and then just put the Authorize attribute to test the token as you see in the below code.

Now, we need to add Authentication service in the Startup.cs class as you see in the below file’s line # 44 to 62 and line # 81.

Now, token implementation part is completed.

Run Project

Now finally, we will run our project and then will see the output using POSTMAN. So, run your project by pressing f5.

Now, open postman and then enter the API path (E.g. https://localhost:44305/api/values) using get request and then press Send button as you see in the below screenshot.

After clicking on the Send button, then you will see the output with unauthorized status as you see in the below screenshot.

Now, we will generate token using login method by passing username and password as you see in the below screenshot.

Now, if this above login request generated successfully, then you will see the output as you see in the below screenshot.

Now, copy the token value and then paste into the token text area and then request the Values controller with token as you see in the below screenshot.

Now, finally you will see the output with 200 status as you see in the below screenshot.

Congratulation, we have successfully created a web api token based authentication example using JWT and Asp Net Core 3.0 with Visual Studio 2019 preview.