Dotnet

First of all, let’s see what are we going to achieve? Let’s say we have an dotnet 9 api application.

Its appsettings.json looks like:

 "Color": "Color from appsettings",
 "Person": {
   "Name": "Name from appsettings"
 }

Let’s try to retrieve these values:

app.MapGet("/", (IConfiguration config) =>
{
    string color = config.GetSection("Color").Value ?? "No color";
    string name = config.GetSection("Person:Name").Value ?? "No name";
    return Results.Ok(new
    {
        color,
        name,
        message = "Hello there..."
    });
});

If you visit this endpoint, you will see this output:

• Azure App Configuration is a fully managed service, which provides you a way to store the configurations in a centralized store. You can store configurations of multiple apps in a single place.
• It is really helpful for cloud native application (eg. Microservices), which runs on multiple virtual machines and use multiple external services.
• It allows us to store Key-value pairs, manage feature flags, and organize configurations using labels and namespaces.
• The main benefit is, it supports dynamic refreshing. Which means, you can change config values without restarting the app.
• You can also add reference of azure key vault secret here.

Let’s see these things in action.

Azure blob storage is a storage solution provided by microsoft. You can store data like images, audio, video, json files, zip files etc etc in the azure.

What are we going to learn?

• How to create a web application that stores and manipulate the images in the cloud.
• We will perform all the CRUD (create, read, update and delete) operations.

Tech used

• .NET Core 9 (MVC app)
• SQL server 2022
• Azure storage account

High level overview

• We will save image url in the database and images in the storage account(blob container)

Let’s create an storage account first

Step 1:

Azure Cosmos DB for NoSQL is a fully managed and serverless NoSQL and vector database for modern app development, including AI applications and agents. With its SLA-backed speed and availability as well as instant dynamic scalability, it is ideal for real-time NoSQL applications that require high performance and distributed computing over massive volumes of NoSQL and vector data.

Soruce: learn.microsoft.com, you can learn more about it from here

• In dotnet, a Middleware is a piece of code that runs in the request pipeline.
• Middlewares are put together in a sequence, and their order matters.
• When a request is made, it goes through each of the middleware.
• Response flow back in reverse order through the middleware.
• Each middleware has capability to modify the request or short circuits the pipeline.
• Each middleware can change the response before it’s sent to the client.

Create a new web api project

Run these commands in a sequence to create a new project.

dotnet new sln -o JwtDotnet9

cd JwtDotnet9

dotnet sln add JwtDotnet9/JwtDotnet9.csproj

Open the project in vs code.

code .

=> Source Code

=> Securing The .NET 9 App: Signup, Login, JWT, Refresh Tokens, and Role Based Access with PostgreSQL

Install the required nuget packages

dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

Jwt configuration in appsettings

Open appsettings.json and add these lines

There has been a discussion around town about the difference between an IEnumerable and an IQueryable, especially in c# interviews. I won’t be diving into the fact that IEnumerable is part of the System.Collections namespace and IQueryable belongs to System.Linq namespace (or did I???). Rather, I’ll focus on the practical usage of both—how they work, and when to use each.

IQueryable

 public IActionResult GetPeople()
 {
  // It will retrieve 2 records from database 
  IQueryable<Person> people = _context.People.Take(2); 
  //  Note: At the above line, no data will be retrieved from the database

  return Ok(people); // Data will be retrieved here
 }

Corresponding sql

Note that, I am using Sqlite, the above code is translated to this query:

There might be instances when you want to insert bulk data. For an instance, you want to create an order, where you need to add multiple items. Let’s see how can we insert bulk data in c# using dapper.

Note: It is only good for adding bunch of rows. But if you are looking for adding hundreds of rows then better to use other approaches. There are many, if you look out.

Let’s say you want to execute a code block when Book table is not empty. In Entity Framework Core, we can achieve this in two ways (there might be others but I am unaware of them):

Option 1:

 if(context.Books.Count()>0)
 {
     // do something
 }

Option 2:

 if (context.Books.Any())
 {
     // do something
 }

Note 📢: I am testing these queries against a table containing 1 million rows.

My Distro

I am using linux mint 22.1 which is based on Ubuntu 24.04.

Straightforeward command

sudo apt-get update

sudo apt-get install -y dotnet-sdk-9.0

But…

I have tried to run this command sudo apt-get install -y dotnet-sdk-9.0 but unfortunately I got no success. I have found that, this command works only with Ubuntu 24.10. For Ubuntu 24.04 I need to use different approach.

Uninstall prior version if exists

sudo apt-get remove dotnet-sdk-8.0

Now, run these commands in a sequence: