Forem: Rajasekar

Cancellation Token in C# - Explained

Rajasekar — Sun, 17 Dec 2023 14:57:58 +0000

Have you come across any scenario where you started long-running asynchronous tasks in C# but want to cancel in the middle of the execution?

Either the user wants to cancel or the application itself is required to cancel the operation, it is a good idea to cancel the resource-heavy long-running operations (logic built using a database, report generation, etc.) gracefully.

Let's discuss about cancellation token in c# which is responsible for canceling tasks.

What is the Cancellation token in C#?

A cancellation token in C# is represented by the CancellationToken struct is a way to notify an operation or task that should be cancelled cooperatively.

A CancellationToken enables cooperative cancellation between threads, thread pool work items, or Task objects.

Why do you need a Cancellation token?

To enable cooperative cancellation of tasks/operations that might be no longer needed or take a long time to complete.

Cooperative cancellation means that the operation can check the cancellation token periodically and gracefully stop if it has been canceled, rather than being aborted abruptly.

This allows the operation to release any resources, close any files, or perform any other cleanup before exiting.

How to create a cancellation token in C#?

You can create a cancellation token by using a CancellationTokenSource object, which manages the cancellation tokens retrieved from its CancellationTokenSource.Token property.

CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
CancellationToken cancellationToken = cancellationTokenSource.Token;

You can then pass the cancellation token to any threads, tasks, or operations that should receive the cancellation notification.

How to cancel the asynchronous operation?

You can either use the Cancel() or CancelAfter() method from CancellationTokenSource to cancel the token.

cancellationTokenSource.Cancel(); //Cancel immediately
cancellationTokenSource.CancelAfter(1000); //Cancel after given time

If you want to cancel the asynchronous APIs, the route endpoint should use the CancellationToken delegate handler as mentioned below. Your code should check for a token.IsCancellationRequested status periodically and acts based on the true/false value.

app.MapGet("/ApiTest", async (CancellationToken token)

How do you know the operation is cancelled?

CancellationToken has a property called IsCancellationRequested returns true if the token has been cancelled.

You can also use the ThrowIfCancellationRequested method to throw an OperationCanceledException if the token has been cancelled.

How to use cancellationtoken in C#?

The asynchronous operations must periodically check for cancellationToken.IsCancellationRequested is true. If true, you should write your logic to gracefully exit all the long-running processes.

while (!cancellationToken.IsCancellationRequested)
{
    //Long running operations here. 
}

Sometimes the OperationCanceledException will be thrown, hence introduce the try-catch block to handle the exceptions.

try
{
    //Operations that might throw OperationCanceledException on cancel
}
catch (OperationCanceledException)
{
    //Handle the cancellation
}

Do the cleanup activities when cancellationToken.IsCancellationRequested true or inside catch block of OperationCanceledException. You may also use CancellationToken.Register() to register your custom cleanup logic as below, which will be executed once the token is cancelled.

WebClient webClient= new WebClient();
cancellationToken.Register(() =>
{
   webClient.CancelAsync();
});

Cancellationtoken example in c# (using WebAPI)

app.MapGet("/ApiTest", async (CancellationToken token) =>
{
    var result = await DoWorkAsync(token);
    return Results.Ok(result);
})
.WithName("ApiTest")
.WithOpenApi();

static async Task<string> DoWorkAsync(CancellationToken cancellationToken)
{
    try
    {
        // A long-running operation like database, business logics
        await Task.Delay(5000, cancellationToken);
        return "Operation completed.";
    }
    catch (OperationCanceledException ex)
    {
        return "Operation canceled. (No output to client)";
    }
}

If the above API is executed without cancellation, it will return the "Operation completed." message.
If the above API is cancelled, it will cancel the operation from DoWorkAsync method as well. Please note that no output will be returned to the client upon cancellation.

Cancellationtoken example using console app

using System;
using System.Threading;

class Program
{
    static void Main(string[] args)
    {
        // Create a cancellation token source
        CancellationTokenSource cts = new CancellationTokenSource();

        // Pass the cancellation token to an asynchronous method
        DoWorkAsync(cts.Token);

        // Wait for user input to cancel the operation
        Console.WriteLine("Press any key to cancel...");
        Console.ReadKey();

        // Cancel the operation by calling Cancel() on the cancellation token source
        cts.Cancel();

        Console.WriteLine("Operation canceled.");
        Console.ReadKey();
    }

    static async void DoWorkAsync(CancellationToken cancellationToken)
    {
        try
        {
            // Simulate some long-running operation
            await Task.Delay(5000, cancellationToken);

            // Check if cancellation has been requested
            if (cancellationToken.IsCancellationRequested)
            {
                Console.WriteLine("Operation canceled.");
            }
            else
            {
                Console.WriteLine("Operation completed.");
            }
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine("Operation canceled.");
        }
    }
}

Please note that the above code is auto-generated using AI.

General recommendations

Check the cancellation token periodically inside the long-running process. If cancelled, exit the process after handling necessary activities like closing database connections, releasing external resources, etc.
Wherever necessary, pass the cancellation token to all the asynchronous methods which can be cancelled at a later time.
Know when you’ve passed the point of no cancellation. Sometimes you may start changing the state of an object in the database and cancellation might lead to data inconsistency or other serious issues.
Don’t throw OperationCanceledException after you’ve completed the work, just because the token was signalled.

Summary

You should now understand how to use CancellationToken in C# to cancel the long-running operations when the request is cancelled. This will help us to save server resources and improve the application performance.

If you enjoyed this post and want to get more valuable tips and insights on .NET/C#, don’t forget to subscribe to my newsletter https://rajasekar.dev/newsletter and get notified whenever I publish a new article.

References

How to Cancel a Task in C# using Cancellation Token - Dot Net Tutorials

Using a CancellationToken in .NET Core Web API | by Danielle | Medium

Why Do You Need a Cancellation Token in C# for Tasks? | HackerNoon

JWT authentication in ASP.NET Core Web API

Rajasekar — Mon, 27 Nov 2023 10:50:00 +0000

What is JSON Web Token(JWT)?

JSON Web Token (JWT) is a secure and compact way of transmitting information between parties as a JSON object. It consists of three parts: header, payload, and signature. The header contains the algorithm used to sign the token, the payload contains the claims, and the signature is used to verify the authenticity of the token. JWTs are commonly used for authentication and authorization purposes in web applications.

Compared to other token formats, JWT has several benefits:

Compactness: JWT is a compact format that can be easily transmitted over the network.
Self-contained: JWT contains all the necessary information within itself, which means that it does not require any additional lookup to validate the token.
Security: JWT can be signed using a secret (with the HMAC algorithm) or a public/private key pair using RSA or ECDSA. This makes JWTs secure and tamper-proof.
Ease of use: JWT is easy to use and can be integrated with various programming languages and frameworks.

Create a minimal API project in Visual Studio Code

Please follow the instructions here if you do not already have VS Code and the C# Dev kit is installed.

Open Visual Studio Code -> Explorer -> Create .NET Project -> select ASP.NET Core Web API project as shown in the below image and select the project folder location.

This will create a new API project with the weather data endpoint.

Test it using Swagger

Click the F5 key, select the C# from the debugger list and default Launch configuration (it will be asked the first time). The Swagger API page will open with endpoints.

Select the "weatherforecast" endpoint, click "Try it out" and click the "Execute" button. Congratulations, now you can see the result as like below. The URL http://localhost:5231/weatherforecast can be tested using Postman or similar tools.

Implement the JWT authentication step-by-step

Follow the below steps one by one to implement the JWT authentication and implement the authorization with the "admin" role.

Add the JWT nuget package

Execute the below command in the terminal to install the JwtBearer package. Make sure you are running the below command in the project folder.

dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

Add JWT secrets in appsettings.json

Before proceeding, you should first add JWT secure key and other necessary details in the appsettings.json.

"Jwt": {
    "Issuer": "https://rajasekar.dev/",
    "Audience": "https://rajasekar.dev/",
    "Key": "This is a secure key, requires a key size of at least '128' bits"
  }

Configure JWT authentication and authorization

Add the below namespaces as we are going to use the same in the project

using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Authorization;
using Microsoft.IdentityModel.Tokens;
using Microsoft.OpenApi.Models;

Add authentication and authorization services as below.

builder.Services.AddAuthentication(options =>
{
    options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    options.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
}).AddJwtBearer(o =>
{
    o.TokenValidationParameters = new TokenValidationParameters
    {
        ValidIssuer = builder.Configuration["Jwt:Issuer"],
        ValidAudience = builder.Configuration["Jwt:Audience"],
        IssuerSigningKey = new SymmetricSecurityKey
(Encoding.UTF8.GetBytes(builder.Configuration["Jwt:Key"] ?? string.Empty)),
        ValidateIssuer = true,
        ValidateAudience = true,
        ValidateLifetime = true,
        ValidateIssuerSigningKey = true,
        ClockSkew = TimeSpan.Zero //required if the expire time is <5 minutes
    };
});
//Adding authorization
// builder.Services.AddAuthorization(); //Used if no authorization policy required
builder.Services.AddAuthorizationBuilder()
  .AddPolicy("admin_policy", policy => policy.RequireRole("admin"));

Here we are adding JWT-bearer authentication using the default scheme and configuring TokenValidationParameters with a secure key along with other necessary values.

Using AddAuthorizationBuilder, we are adding a new policy admin_policy to authorize the admin role.

These settings will be used to validate the JWT token when a request comes to API.

Now you should enable the authentication and authorization with the below code.

app.UseAuthentication();
app.UseAuthorization();

Create login endpoint to authenticate users and return JWT token generation

First, create a new login model to use in the login endpoint

record Login(string Email, string Password);

Now we can create a new login endpoint with the below code.

//Login endpoint that returns Jwt token on successful authentication
app.MapPost("/login", [AllowAnonymous] (Login user) =>
{
    var normalUser = AuthenticateNormalUser(user);
    var adminUser = AuthenticateAdminUser(user);
    if (!(normalUser || adminUser))
        return Results.Unauthorized();

    var issuer = builder.Configuration["Jwt:Issuer"];
    var audience = builder.Configuration["Jwt:Audience"];
    var key = Encoding.ASCII.GetBytes(builder.Configuration["Jwt:Key"] ?? string.Empty);
    var claims = new List<Claim>()
        {
            new Claim("Id", Guid.NewGuid().ToString()),
            new Claim(JwtRegisteredClaimNames.Sub, user.Email),
            new Claim(JwtRegisteredClaimNames.Email, user.Email),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())
        };
    if (adminUser)
    {
        claims.Add(new Claim(ClaimTypes.Role, "admin"));
    }
    var tokenDescriptor = new SecurityTokenDescriptor
    {
        Subject = new ClaimsIdentity(claims),
        Expires = DateTime.UtcNow.AddMinutes(5), //should be at least 5 minutes - https://github.com/IdentityServer/IdentityServer3/issues/1251
        Issuer = issuer,
        Audience = audience,
        SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha512Signature)
    };
    var tokenHandler = new JwtSecurityTokenHandler();
    var token = tokenHandler.CreateToken(tokenDescriptor);
    var stringToken = tokenHandler.WriteToken(token);
    return Results.Ok(stringToken);
});
static bool AuthenticateNormalUser(Login user)
{
    //Check the given user credential is valid - Usually this should be checked from database
    return user.Email == "hello@example.com" && user.Password == "pass123";
}
static bool AuthenticateAdminUser(Login user)
{
    //Check the given user credential is valid - Usually this should be checked from database
    return user.Email == "admin@example.com" && user.Password == "admin123";
}

We have created two methods AuthenticateNormalUser and AuthenticateAdminUser to validate the user's credentials and decide whether the user is a normal or an admin user.

For the sake of simplicity, we are not using the database logic to check the user's credentials.

At least any one of the above methods should return True to authenticate users but for admin access the method AuthenticateAdminUser must return True. If both are not true, the unauthorized error will be thrown.

The issuer, audience, and secure key details are used from the appsettings.json file to create tokens. We are adding user details to tokens like UserId and email via Claims. Additionally, an "admin" role will be added to the claims if the user is an admin.

Finally new SecurityTokenDescriptor object will be created with all the above values and the token will be created using JwtSecurityTokenHandler.

Add the endpoints with authorization

Add the below secure endpoints, one for a regular authenticated user and another one for an admin user. Admin endpoint added with admin_policy which will be validated before accessing the admin page.

//Secure endpoint - All users
app.MapGet("/secure-page", () =>
{
    return "secure page - for all authenticated users 🔐";
})
.RequireAuthorization();

//Secure endpoint - admin user
app.MapGet("/admin-page", () =>
{
    return "Admin page - only for admin users 🔐";
})
.RequireAuthorization("admin_policy");

Adding authorization bearer token support in Swagger UI (optional)

To test the above endpoints using Postman or similar tools, this step is not required.

Since we are using SwaggerUI, you should add the following code for JWT token support just below the builder.Services.AddEndpointsApiExplorer().

builder.Services.AddSwaggerGen(option =>
{
    option.SwaggerDoc("v1", new OpenApiInfo { Title = "Web API with Jwt Authentication", Version = "v1" });
    option.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
    {
        In = ParameterLocation.Header,
        Description = "Please enter a valid token",
        Name = "Authorization",
        Type = SecuritySchemeType.Http,
        BearerFormat = "JWT",
        Scheme = "Bearer"
    });
    option.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type=ReferenceType.SecurityScheme,
                    Id="Bearer"
                }
            },
            new string[]{}
        }
    });
});

Testing the JWT authentication

You can either run dotnet run in the terminal or press the F5 key to run the application.

The application will be running in the localhost with any port that is mentioned in the terminal. Open the localhost link (ex. http://localhost:5033/swagger/index.html) in the browser and it will look like below.

Click login endpoint -> "Try it out", use the below values in the request body and click execute.

{
  "email": "hello@example.com",
  "password": "pass123"
}

The result will look like below.

Copy the token, click the "Authorize" button, past it, click the Authorize button and close the popup. Now the page is saved with a valid JWT token.

Now test the secure-page and the successful output will look like below.

If the user is not authorized or the authorization token is expired, the below 401 error will be shown.

Test the admin-page and it will show the 403 error because the above user is authenticated successfully but not authorized to view the admin page.

Again, go to the login endpoint and use the below admin user to log in. Save the generated token in the "Authorize" section.

{
  "email": "admin@example.com",
  "password": "admin123"
}

Now test the endpoint admin-page and it will show the below successful result. Even secure-page endpoint will work with the above admin credentials.

Complete source code

Find the complete source code of the Program.cs below.

using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Authorization;
using Microsoft.IdentityModel.Tokens;
using Microsoft.OpenApi.Models;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddEndpointsApiExplorer();

//Adding authorization bearer token support in Swagger UI
builder.Services.AddSwaggerGen(option =>
{
    option.SwaggerDoc("v1", new OpenApiInfo { Title = "Web API with Jwt Authentication", Version = "v1" });
    option.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
    {
        In = ParameterLocation.Header,
        Description = "Please enter a valid token",
        Name = "Authorization",
        Type = SecuritySchemeType.Http,
        BearerFormat = "JWT",
        Scheme = "Bearer"
    });
    option.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type=ReferenceType.SecurityScheme,
                    Id="Bearer"
                }
            },
            new string[]{}
        }
    });
});

//Configure Jwt authentication 
builder.Services.AddAuthentication(options =>
{
    options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    options.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
}).AddJwtBearer(o =>
{
    o.TokenValidationParameters = new TokenValidationParameters
    {
        ValidIssuer = builder.Configuration["Jwt:Issuer"],
        ValidAudience = builder.Configuration["Jwt:Audience"],
        IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(builder.Configuration["Jwt:Key"] ?? string.Empty)),
        ValidateIssuer = true,
        ValidateAudience = true,
        ValidateLifetime = true,
        ValidateIssuerSigningKey = true,
        ClockSkew = TimeSpan.Zero //required if the expire time is <5 minutes
    };
});
//Adding authorization
// builder.Services.AddAuthorization(); //Used when no authorization policy is required, otherwise use below AddAuthorizationBuilder
builder.Services.AddAuthorizationBuilder()
  .AddPolicy("admin_policy", policy => policy.RequireRole("admin"));

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

//Enable Authentication and Authorization
app.UseAuthentication();
app.UseAuthorization();

//Login endpoint that returns Jwt token on successful authentication
app.MapPost("/login", [AllowAnonymous] (Login user) =>
{
    var normalUser = AuthenticateNormalUser(user);
    var adminUser = AuthenticateAdminUser(user);
    if (!(normalUser || adminUser))
        return Results.Unauthorized();

    var issuer = builder.Configuration["Jwt:Issuer"];
    var audience = builder.Configuration["Jwt:Audience"];
    var key = Encoding.ASCII.GetBytes(builder.Configuration["Jwt:Key"] ?? string.Empty);
    var claims = new List<Claim>()
        {
            new Claim("Id", Guid.NewGuid().ToString()),
            new Claim(JwtRegisteredClaimNames.Sub, user.Email),
            new Claim(JwtRegisteredClaimNames.Email, user.Email),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())
        };
    if (adminUser)
    {
        claims.Add(new Claim(ClaimTypes.Role, "admin"));
    }
    var tokenDescriptor = new SecurityTokenDescriptor
    {
        Subject = new ClaimsIdentity(claims),
        Expires = DateTime.UtcNow.AddMinutes(5), //should be at least 5 minutes - https://github.com/IdentityServer/IdentityServer3/issues/1251
        Issuer = issuer,
        Audience = audience,
        SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha512Signature)
    };
    var tokenHandler = new JwtSecurityTokenHandler();
    var token = tokenHandler.CreateToken(tokenDescriptor);
    var stringToken = tokenHandler.WriteToken(token);
    return Results.Ok(stringToken);
});
static bool AuthenticateNormalUser(Login user)
{
    //Check the given user credential is valid - Usually this should be checked from database
    return user.Email == "hello@example.com" && user.Password == "pass123";
}
static bool AuthenticateAdminUser(Login user)
{
    //Check the given user credential is valid - Usually this should be checked from database
    return user.Email == "admin@example.com" && user.Password == "admin123";
}

//Secure endpoint - All users
app.MapGet("/secure-page", () =>
{
    return "secure page - for all authenticated users 🔐";
})
.RequireAuthorization();

//Secure endpoint - admin user
app.MapGet("/admin-page", () =>
{
    return "Admin page - only for admin users 🔐";
})
.RequireAuthorization("admin_policy");

app.Run();

//Login user model
record Login(string Email, string Password);

Some key points

No logout option is possible because of no cookie option. You should manually remove the stored JWT token from the client-side application but still, the token is valid until it expires.

Generally the token Expires setting should be a minimum of 5 minutes (refer https://github.com/IdentityServer/IdentityServer3/issues/1251).

Conclusion

You should now understand how to implement the JWT authentication in ASP.NET Core Web API with role-based authorization.

Visit my blog at rajasekar.dev for more articles

References:

JSON Web Token Introduction - jwt.io

How to implement JWT authentication in ASP.NET Core 6

Authentication and authorization in minimal APIs

Role based JWT Tokens in ASP.NET Core APIs - Rick Strahl's Web Log

Getting started with Entity Framework Core: Building a Sample Project

Rajasekar — Tue, 11 Jul 2023 06:46:12 +0000

Introduction:

Entity Framework Core (EF Core) is a powerful Object-Relational Mapping (ORM) framework for .NET developers. With its rich features and versatility, EF Core simplifies database interactions, allowing developers to focus on application logic rather than complex data access operations. In this blog post, we will explore EF Core by building a sample project, and delve into its benefits and other essential details.

What is Entity Framework Core (EF Core)?

Entity Framework Core is a modern, lightweight, and cross-platform ORM framework developed by Microsoft. It enables developers to work with databases using .NET objects, eliminating the need for writing raw SQL queries. EF Core provides a higher-level abstraction, allowing seamless interaction with various database providers, such as SQL Server, PostgreSQL, MySQL, SQLite, and more.

Setting up the sample project:

To get started with EF Core, let's build a simple project that manages a list of books. Follow these steps:

Create a new .NET Core Console project in your preferred IDE. Here I have used Visual Studio with .NET 6 framework.
Install the Entity Framework Core packages via NuGet (using the package manager console in Visual Studio).

2.1. EF Core database provider (I have used SQLite for its simplicity)

2.2. EF Core Tools
```
Install-Package Microsoft.EntityFrameworkCore.Sqlite
Install-Package Microsoft.EntityFrameworkCore.Tools
```

Define your data model

public class Blog
{
    public int BlogId { get; set; }
    public string Url { get; set; }

    public List<Post> Posts { get; } = new();
}

public class Post
{
    public int PostId { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }

    public int BlogId { get; set; }
    public Blog Blog { get; set; }
}

Create a DbContext class that represents your database context:

public class BloggingContext : DbContext
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    public string DbPath { get; }

    public BloggingContext()
    {
        var folder = Environment.SpecialFolder.LocalApplicationData;
        var path = Environment.GetFolderPath(folder);
        DbPath = System.IO.Path.Join(path, "blogging.db");
    }

    // The following configures EF to create a Sqlite database file in the
    // special "local" folder for your platform.
    protected override void OnConfiguring(DbContextOptionsBuilder options)
    {
        if (!options.IsConfigured)
        {
            options
                .LogTo(message => Debug.WriteLine(message))
                .EnableSensitiveDataLogging();

            options.UseSqlite($"Data Source={DbPath}");
        }
    }
}

Add Migrations:

Run the below commands in the package manager console.

Add-Migration InitialCreate //Creating migration(SQL) scripts
Update-Database //Run the above SQL scripts in database

Perform database operations:
```
using var db = new BloggingContext();

// Note: This sample requires the database to be created before running.
Console.WriteLine($"Database path: {db.DbPath}.");

// Create
Console.WriteLine("Inserting a new blog");
db.Add(new Blog { Url = "http://blogs.msdn.com/adonet" });
db.SaveChanges();

// Read
Console.WriteLine("Querying for a blog");
var blog = db.Blogs
    .OrderBy(b => b.BlogId)
    .First();

// Update
Console.WriteLine("Updating the blog and adding a post");
blog.Url = "https://devblogs.microsoft.com/dotnet";
blog.Posts.Add(
    new Post { Title = "Hello World", Content = "I wrote an app using EF Core!" });
db.SaveChanges();

// Delete
Console.WriteLine("Delete the blog");
db.Remove(blog);
db.SaveChanges();
```
From the above examples, you can see that we are using EF Core to read, write and update the data in the database without writing any SQL scripts.

Benefits of Entity Framework Core:
1. Productivity: EF Core enables rapid application development by providing a high-level abstraction and eliminating the need to write repetitive SQL queries. Its intuitive APIs, such as LINQ, allow developers to express complex queries and database operations in a more readable and maintainable manner.
2. Database Independence: With EF Core, you can easily switch between different database providers without modifying your application code significantly. This flexibility allows developers to choose the most suitable database solution for their project requirements.
3. Automatic Schema Migrations: EF Core's migration feature simplifies the process of evolving the database schema over time. It automatically generates SQL scripts to create, update, or delete database objects based on changes made to the data model, eliminating the manual effort of managing database scripts.
4. Performance Optimization: EF Core provides various performance optimization techniques, such as query caching, lazy loading, and eager loading, to enhance the performance of database operations. These optimizations help minimize roundtrips to the database and improve the overall response time of your application.
5. Testability: EF Core facilitates unit testing by allowing developers to mock the database context and perform tests against an in-memory database. This capability ensures that your data access logic can be thoroughly tested without requiring a real database connection.

Conclusion:

Entity Framework Core empowers developers to build efficient and scalable database applications with ease. In this blog post, we explored EF Core by creating a sample project and discussed its numerous benefits, including increased productivity, database independence, automatic schema migrations, performance optimization, and testability. EF Core continues to evolve, offering a robust set of tools and features to streamline data access in the .NET ecosystem.

Embrace the power of Entity Framework Core and unlock the full potential of your database-driven applications!

Happy coding with EF Core!

Angular material Datetime picker

Rajasekar — Wed, 17 Aug 2022 05:39:10 +0000

Who is this for?

This tutorial is for Angular developers who wants to integrate datetime picker in their application. Angular Material Datetime picker can be used in Angular versions 7 - 14.

We have few datetime pickers available for angular and one of them is Angular Material Datetime picker which is easy to use and having good UI/UX. So we will see how to integrate them in angular.

npm package - https://www.npmjs.com/package/@angular-material-components/datetime-picker

The above package extends the functionality of Angular material Datepicker by adding time picker to it.

Step 1: Add required npm packages

Follow the below steps to install the necessary packages.

//Angular material & datetime picker
npm install --save @angular/material
npm install --save  @angular-material-components/datetime-picker

//Add moment related packages since we are using to parse the date
npm install moment
npm install --save @angular/material-moment-adapter
npm install @angular-material-components/moment-adapter
//Others
npm install @angular/platform-browser

Install Angular material then datetime picker package. Since moment supports various parsing formats and different locales, we are installing the same with related packages.

Note: We are installing Angular Material Datetime Picker version 8.x+ for our Angular application based on version 14. If you have different Angular version, please refer the above npm page and install corresponding version.

Step 2: NgModule changes with date format

Update NgModule import & providers section as below.

imports: [
    ...
    FormsModule,  //Required for form controls
    MatDatepickerModule, //Material datepicker module
    NgxMatDatetimePickerModule, //Datetime picker module
    MatInputModule, //Required for material input 
    BrowserAnimationsModule //Required for animation
  ],
  providers: [
...
{
    provide: NgxMatDateAdapter,
    useClass: NgxMatMomentAdapter, //Moment adapter
    deps: [MAT_DATE_LOCALE, MAT_MOMENT_DATE_ADAPTER_OPTIONS]
  },
{ provide: NGX_MAT_DATE_FORMATS, useValue: MY_NGX_DATE_FORMATS }]

We are customizing the datetime picker format by providing custom NGX_MAT_DATE_FORMATS. You can either declare below custom format value in NgModule file or any other place in angular.

const MY_NGX_DATE_FORMATS: NgxMatDateFormats = {
  parse: {
    dateInput: "l, LTS"
  },
  display: {
    dateInput: "DD.MM.yyyy HH:mm",
    monthYearLabel: "MMM YYYY",
    dateA11yLabel: "LL",
    monthYearA11yLabel: "MMMM YYYY"
  }
};

Step 3: Theming & other customization

Import material theme or your custom theme in syles.css file.

@import '~@angular/material/prebuilt-themes/deeppurple-amber.css';

To get font and icon support, add below material design icon font to your index.html

<link href="https://fonts.googleapis.com/icon?family=Material+Icons&display=block" rel="stylesheet">

Step 4: Using in Angular Component

We are done with importing all the necessary packages and configured the same in NgModule. Now we can use the below code to add the datetime picker to our Angular component html.

<mat-form-field>
  <input matInput [ngxMatDatetimePicker]="picker" placeholder="Choose a date" [(ngModel)]="selectedDate">
  <mat-datepicker-toggle matSuffix [for]="$any(picker)">
  </mat-datepicker-toggle>
  <ngx-mat-datetime-picker #picker [showSpinners]="true">
  </ngx-mat-datetime-picker>
</mat-form-field>
<br>
Moment Date - {{selectedDate}} <br>
Javascript Date - {{selectedDate?.toDate()}}

Declare datetime picker model with default value in typescript file as below

selectedDate?: moment.Moment = moment(new Date());

That's it, we are successfully integrated Angular material Datetime picker. Now you may run the application with ng serve and check whether everything is working fine.

Checkout the complete code in the github

Step 5: Customization and additional options

Here I have demonstrated how to integrate the datetime picker in angular application with basic functionalities. The same steps are applicable for Timepicker too.

You can refer the above npm page for additional options and further customization.

Visit my blog at rajasekar.dev for more articles

Happy coding 😊