.NET6

#CASBAN6: Function base class (and an update to the DTO models)

#CASBAN6: Function base class (and an update to the DTO models)

After we have been setting up our Azure Function project last time, we are now able to create a base class for our Azure functions. The main goal is to achieve a common configuration for all functions to make our life easier later on.

CRUD defintion

Our API endpoints should provide us a CRUD (Create-Read-Update-Delete) interface. Our implementation will reflect this pattern as follows:

  • A creation endpoint
  • Two read endpoints – one for list results (like a list of posts) and one for receiving details of an entity
  • An update endpoint to change existing entities
  • A delete endpoint

As all of our entities are tied to a single blog’s Id, we will use this base class for all entities besides the Blog entity itself.

The base class

    public abstract class BlogFunctionBase
    {
        internal readonly BlogContext BlogContext;
        internal ILogger? Logger;
        internal JsonSerializerSettings? JsonSerializerSettings;

        protected BlogFunctionBase(BlogContext blogContext)
        {
            BlogContext = blogContext ?? throw new ArgumentNullException(nameof(blogContext));

            CreateNewtonSoftSerializerSettings();
        }

        private void CreateNewtonSoftSerializerSettings()
        {
            JsonSerializerSettings = NewtonsoftJsonObjectSerializer.CreateJsonSerializerSettings();

            JsonSerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();

            JsonSerializerSettings.NullValueHandling = NullValueHandling.Ignore;
            JsonSerializerSettings.Formatting = Formatting.Indented;
            JsonSerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
            JsonSerializerSettings.DateFormatHandling = DateFormatHandling.IsoDateFormat;
            JsonSerializerSettings.DateParseHandling = DateParseHandling.DateTimeOffset;
        }

        public virtual Task<HttpResponseData> Create([HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = null)] HttpRequestData req,
            string blogId) =>
            throw new NotImplementedException();

        public virtual Task<HttpResponseData> GetList([HttpTriggerAttribute(AuthorizationLevel.Anonymous, "get", Route = null)] HttpRequestData req, string blogId) =>
            throw new NotImplementedException();

        public virtual Task<HttpResponseData> GetSingle([HttpTriggerAttribute(AuthorizationLevel.Anonymous, "get", Route = null)] HttpRequestData req, string blogId, string id) =>
            throw new NotImplementedException();

        public virtual Task<HttpResponseData> Update([HttpTriggerAttribute(AuthorizationLevel.Anonymous, "put", Route = null)] HttpRequestData req, string blogId, string id) =>
            throw new NotImplementedException();

        public virtual Task<HttpResponseData> Delete([HttpTriggerAttribute(AuthorizationLevel.Anonymous, "delete", Route = null)] HttpRequestData req, string blogId, string id) =>
            throw new NotImplementedException();

    }

Knowing the definition of our API endpoints, there shouldn’t be any surprises with that implementation. As a base class, the definition is of course abstract.

In the constructor, I am setting up how JSON objects will be handled. I am following common practices in formatting. The only thing that is different from using JSON.NET directly is the fact we need to explicitly use the NewtonsoftJsonObjectSerializer.CreateJsonSerializerSettings method to create an instance of the JsonSerializerSettings property.

We also have an internal ILogger? property, which will be used in the derived class to create a typed instance for logging purposes. Last but not least, I am enforcing passing in a BlogContext instance from our Entity Framework implementation.

If you look at the method declaration, you’ll see the authorization level is set to Anonymous. As I am using Azure Active Directory, I am handling the authorization on a separate layer (there will be a post on that topic as well). Besides that, there is nothing special. All methods need a blogId and those endpoints that interact with a resource need a resource id as well.

The blog entity has a similar structure, with some differences in the parameter definitions. To keep things simple, I decided to let it be different from the base class definition above. We will see this in the next post of this series.

Update to the DTO models

While the blog series is ongoing, it still lags a bit behind on what I am currently working on (you can follow the dev branch on GitHub for an up-to-date view). As I am currently working on the administration client for our blog, I started to implement an SDK that can be used by all clients (the blog’s website will also just be a client). See the original post on DTOs here.

To be able to create a generic implementation of the calls to the API endpoints, I needed to create also a base class for the DTO models. It is a very simple class, as you can see:

public abstract class DtoModelBase
{
    public virtual Guid? BlogId { get; set; }

    public virtual Guid? ResourceId { get; set; }
}

This base class allows me to specify a Type that derives from it in the SDK API calls – which was my main goal. Second, I have now a common ResourceId property instead of the Id being named after the class name of the DTO. Both properties are virtual to allow me to specify the Required attributes in the derived classes as needed. You can see these changes on GitHub.

The reason I am writing about the change already today is that it will have impact on how the functions are implemented, as both the API functions and the Client SDK use the same DTO classes.

Conclusion

In this post, we had a look at the base class for our Azure functions we will use as an API and on the updated DTO models. With this prerequisite post in place, we will have a look at the function implementations in the next post.

Until the next post, happy coding, everyone!

Posted by msicc in Azure, Dev Stories, MAUI, 0 comments
#CASBAN6: Setting up an Azure Functions project for the API

#CASBAN6: Setting up an Azure Functions project for the API

Now that we have our Entity Framework project in place and our DTO mappings ready, it is finally time to create the API for our blogging engine. I am using Azure Functions for this.

Out-of-Process vs. In-Process

Azure Functions can be run in-process or in an isolated process. The isolated project decouples the function app from the underlying process, which enables additional features like custom middleware and Dependency Injection. Besides that, it allows you to run non-LTS versions, which can be helpful sometimes. These were the main reasons for choosing the Out-of-Process model. If you want to learn more about that topic, I recommend reading the docs.

Create the project

As you may have noticed, I recently became kind of a fan of JetBrains’ Rider IDE. Some steps may be different if done in Visual Studio, but you will be able to follow along.

First, make sure you have the Azure plugin installed. Go to the Settings, and select Plugins on the list at the left-hand side. Search for ‘Azure’ and install the Azure Toolkit for Rider. You will need to restart the application.

JetBrains Rider Plugin Settings

Once you have the plugin installed, open your solution and create a new project in it (I made it in a separate folder). Select the Azure Functions template on the left.

JetBrains Rider New Project dialog with Azure Functions selected.

I named the project BlogFunctions. Select the Isolated worker runtime option, and as Framework, we keep it on .NET 6 for the time being.

NuGet packages and project references

To enable all the functionalities we are going to use and add, we need some NuGet packages:

  • Microsoft.Azure.Functions.Worker, Version=1.10.0
  • Microsoft.Azure.Functions.Worker.Sdk, Version=1.7.0
  • Microsoft.Azure.Functions.Worker.Extensions.Http, Version=3.0.13
  • Microsoft.Azure.Functions.Worker.Extensions.ServiceBus, Version=5.7.0
  • Microsoft.Extensions.DependencyInjection, Version=6.0.1
  • Microsoft.Azure.Core.NewtonsoftJson, Version=1.0.0

Please note that I use the latest version that support .NET 6 and not the .NET 7. We also need to reference the projects we already created before, as you can see in this picture:

Project and Package references in the Function app

Program.cs

Now we finally can have a look at our Program.cs file. I am not using top-level statements here, but feel free if you want to, the code doesn’t change, just the surroundings.

To make our application running, we need to create a new HostBuilder object. I still prefer Newtonsoft.Json over System.Text.Json, so let’s add that one first:

IHost? host = new HostBuilder().ConfigureFunctionsWorkerDefaults(worker => worker.UseNewtonsoftJson()).Build();

host.Run();

In order to be able to use our Entity Framework project we created already earlier, we need to add a ConnectionString and also configure the application to instantiate our DBContext. Update the code above as follows:

string? sqlConnectionString = Environment.GetEnvironmentVariable("SqlConnectionString");

IHost? host = 
	new HostBuilder().
		ConfigureFunctionsWorkerDefaults(worker => worker.UseNewtonsoftJson()).              
		ConfigureServices(services =>
		{
			if (!string.IsNullOrWhiteSpace(sqlConnectionString))
				services.AddDbContext<BlogContext>(options =>
					options.UseSqlServer(sqlConnectionString));	              
		}).
		Build();

host.Run();

The connection string will be read from the local.settings.json file locally and from the Function app’s configuration on Azure. For the moment, just add your local ConnectionString:

{
  "IsEncrypted": false,
    "Values": {
        "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
        "AzureWebJobsStorage": "UseDevelopmentStorage=true",
        "SqlConnectionString": "Data Source=localhost;Initial Catalog=localDB;User ID=sa;Password=thisShouldB3Stronger!",
        
    }
}

Side note: If you have a look into the GitHub repo, you will see that there are some entries for OpenAPI in both files. The OpenAPI integration will get its own blog post later in this blog series, but for this post, they are not important.

Conclusion

In this post, we had a look at how to set up an Azure Functions app with Newtonsoft.Json and our Entity.Framework DbContext. In the next post, we will have a look at some Extensions that will be helpful, as well as the base class implementation of most functions within the app. As always, I hope this post was helpful for some of you.

Until the next post, happy coding, everyone!

Posted by msicc in Azure, Dev Stories, 2 comments
#CASBAN6: Implementing the data model using EntityFramework Core (separate libraries)

#CASBAN6: Implementing the data model using EntityFramework Core (separate libraries)

EntityModel library

When I started the project, I started with creating the classes for all the tables that I need for my blog engine. I have put them into their own library to keep things clean.

The classes also use ICollection references for relationships whenever required. Let’s have a look at the Blog class:

public class Blog 
{
    public Guid BlogId { get; set; }

    public string Name { get; set; }

    public string Slogan { get; set; }

    public Uri LogoUrl { get; set; }

    public ICollection<Post> Posts { get; set; }

    public ICollection<Author> Authors { get; set; }

    public ICollection<Tag> Tags { get; set; }

    public ICollection<Medium> Media { get; set; }

}

The other classes are implemented similarly to reflect the data model I showed you in my last post. You can have a look at the other class implementations in the GitHub repo (folder: EntityModel).

EFCore library

The EFCore library has three main components:

  1. BlogContext
  2. Configurations
  3. Seed extension

BlogContext

The BlogContext is straight forward and follows the pattern described here in the documentation for using a factory (spoiler: we will do that later):

public sealed class BlogContext : DbContext
{
    public BlogContext(DbContextOptions<BlogContext> options) : base(options)
    {

    }

    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }
    public DbSet<Author> Authors { get; set; }
    public DbSet<MSiccDev.ServerlessBlog.EntityModel.Medium> Media { get; set; }
    public DbSet<MediumType> MediaTypes { get; set; }
    public DbSet<Tag> Tags { get; set; }
}

The class is declaring a constructor that uses the DBContextOptions<DBContext> parameter that allows our factory to configure the context later on for the migrations. Of course, we need references to all the possible DbSets as well to be able to access them via the BlogContext instance.

Configurations

In Entity Framework, we can configure our tables with configurations. By implementing the IEntityTypeConfiguration interface for all of our models in a separate file for each, we are continuing to keep our code clean and easily maintainable. Here is how the implementation for the Blog table:

public class BlogConfiguration : IEntityTypeConfiguration<Blog>
{
    public void Configure(EntityTypeBuilder<Blog> builder)
    {
        builder.Property(nameof(Blog.BlogId)).
            IsRequired();

        builder.Property(nameof(Blog.BlogId)).
            ValueGeneratedOnAdd();

        builder.HasKey(blog => blog.BlogId).
            HasName($"PK_{nameof(Blog.BlogId)}");

        builder.Property(nameof(Blog.Name)).
            HasMaxLength(255).
            IsRequired();

        builder.Property(nameof(Blog.Slogan)).
            HasMaxLength(255).
            IsRequired();

        builder.Property(nameof(Blog.LogoUrl)).
            IsRequired();
    }
}

Most of the fluent implementations above are self-explaining. The other classes of the project are implemented in a similar way, you can find them here in the Github repository.

I implemented my configurations by following the docs, which I absolutely recommend reading:

To apply the configurations, we need to override the OnModelCreating method:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.ApplyConfiguration(new BlogConfiguration());
    modelBuilder.ApplyConfiguration(new MediumypeConfiguration());
    modelBuilder.ApplyConfiguration(new MediumConfiguration());
    modelBuilder.ApplyConfiguration(new AuthorConfiguration());
    modelBuilder.ApplyConfiguration(new TagConfiguration());
    modelBuilder.ApplyConfiguration(new PostConfiguration());
}

Seed extension

To verify our configurations are working, we need some test data. This is where the seeding feature of EF Core comes in handy, and it helped me to improve my data model a lot. I am using the extension method approach here to implement a blog with three test posts, including all relations, constraints, and property configurations. You can find the full implementation here in the Github repository.

Besides the docs on EF Core data seeding, these links helped me to understand and write my seed implementation:

With this extension method in place, applying the seed is just one line of code at the end of the OnModelCreating override away:

modelBuilder.Seed();

Now we have everything together, we finally can turn to actually migrate our code to database.

EFCore.DesignDummy library

Because I am running this whole thing on a Mac, I need to use the CLI tools for all migrations. To keep also this step in its own library, I created a DesignDummy library which I use for pushing the migrations to my local database.

The library requires a reference to the EFCore library as well as to the EntityModel library. On top of that, we need the Microsoft.EntityFrameworkCore.Design NuGet package.

Now that our dependencies are in place, we just need to create an implementation of the IDesignTimeDbContextFactory interface as described here in the docs:

public class BlogContextFactory : IDesignTimeDbContextFactory<BlogContext>
{
    public BlogContext CreateDbContext(string[] args)
    {
        BlogContext? instance = null;

        var optionsBuilder = new DbContextOptionsBuilder<BlogContext>();

        optionsBuilder.UseSqlServer(dbContextBuilder =>
            dbContextBuilder.MigrationsAssembly("EFCore.DesignDummy")).
            EnableSensitiveDataLogging();

        instance = new BlogContext(optionsBuilder.Options);

        return instance;
    }
}

Now let’s create our first migration and push it to the database (find the docs here). In your terminal window, change to the folder of your dummy project. Once you’re in the correct folder, create a new migration with the add command:

dotnet ef migrations add {MigrationName}

To push the migration you just created to the database, use the update command with the connection parameter:

dotnet ef database update --connection 'Data Source=localhost;Initial Catalog=localDB;User ID=sa;Password=thisShouldB3Stronger!'

If all goes well, you should now be able to view your database with the seeded data:

database seeded

Conclusion

In this post, I showed you how to create the model for the database and their matching IEntityTypeConfiguration implementations. We learned how to create a IDesignTimeDbContextFactory and how to add migrations and push them to the database. The full code is on GitHub for your further exploration.

As always, I hope this post is helpful for some of you.

Until the next post, happy coding, everyone!

Posted by msicc in Azure, Database, Dev Stories, 3 comments
#CASBAN6: the data model explained

#CASBAN6: the data model explained

Preface

Initially, this post should have been about the direct implementation and design of the data model for my serverless blog engine. As the data model became a bit more complex, I decided to split the data model post into two posts. The first aims to explain the data model, while the second post is for the implementation with Entity Framework Core.

The data model

A picture is worth a thousand words, they say. So here is a complete picture of the data model:

CASBAN6 data model

I will go through the model table by table and tell you a sentence or two on each of it for the rest of this post.

The tables

__EFMigrationsHistory

This table just stores all the MigrationIds and is handled by the Entity Framework. I recommend you to not touch this table.

Blogs

In theory, the database could hold more than one blog. By adding a new row to this table, you are creating a new blog in the database. The BlogId is essential for a range of other tables.

Authors

To be able to issue blog posts, our blog needs at least one author. As you may have more than one person to fill your blog, a collection of authors can be saved within this table. One author can only be assigned to one blog (at least for now, this is intentional).

Posts

The content fuelling our blog is in the posts table. One post can only be on one blog. The published date will be set on insert, all subsequent changes will modify the LastModified column. Also, one post can only have one author. The author can be replaced on updating the row in the table.

The slug can be used to create a human-readable URL for the post (instead of the PostId, which is a GUID). The slug must be unique across all blogs.

Tags

In order to group and categorize posts, I decided to go with a tags-only approach (unlike other platforms, which allow both categories and tags). Tags are unique to a blog, but can be used in multiple posts.

Media

Of course, our blog should support also media content like images, videos and other types. I opted in for a URL-based approach, which is making it easier to add content from other platforms (like videos hosted on dedicated platforms). A medium can be used in several posts.

MediaTypes

To make it a bit easier to determine a medium’s type, I added the MediaTypes table. It holds information about the MIME-Type and possibly also the encoding of a file. The uniqueness is based off the MIME-Type.

Mapping tables

As we learned already above, both tags and media can be used in multiple posts. At the same time, posts can have multiple media and also multiple tags. To cover this many-to-many relationships, I use two mapping-tables with a composite primary key to ensure their uniqueness across the blog.

Conclusion

In this post, I outlined the data model of my serverless blog engine. In the next post, I will show you the implementation of this model with Entity Framework Core.

Until the next post, happy coding, everyone!

Posted by msicc in Azure, Database, Dev Stories, 2 comments
#CASBAN6: Creating A Serverless Blog on Azure with .NET 6 (new series)

#CASBAN6: Creating A Serverless Blog on Azure with .NET 6 (new series)

Motivation

I was planning to run my blog without WordPress for quite some time. For one, because WordPress is really blown up as a platform. The second reason is more of a practical nature – this project gives me lots of stuff to improve my programming skills. I already started to move my developer website away from WordPress with ASP.NET CORE and Razor Pages. Eventually I arrived at the point where I needed to implement a blog engine for the news section. So, I have two websites (including this one here) that will take advantage of the outcome of this journey.

High Level Architecture

Now that the ‘why’ is clear, let’s have a look at the ‘how’:

There are several layers in my concept. The data layer consists of a serverless MS SQL instance on Azure, on which I will work with the help of Entity Framework Core and Azure Functions for all the CRUD operations of the blog. I will use the powers of Azure API Management, which will allow me to provide a secure layer for the clients – of course, an ASP.NET CORE Website with RazorPages, flanked by a .NET MAUI admin client (no web administration). Once the former two are done, I will also add a mobile client for this blog. It will be the next major update for my existing blog reader that is already in the app stores.

For comments, I will use Disqus. This way, I have a proven comment system where anyone can use his/her favorite account to participate in discussions. They also have an API, so there is a good chance that I will be able to implement Disqus in the Desktop and Mobile clients.

Last but not least, there are (for now) two open points – performance measuring/logging and notifications. I haven’t decided yet how to implement these – but I guess there will be an Azure based implementation as well (until there are good reasons to use another service).

Open Source

Most of the software I will write and blog about in this series will be available publicly on GitHub. You can find the repository already there, including stuff for the next two upcoming blog posts already in there.

Index

I will update this blog post regularly with a link new entries of the series.

Additional note

Please note that I am working on this in my spare time. This may result in delays between the blog posts and the updates committed into the repository on GitHub.

Until the next post – happy coding, everyone!


Title Image by Roman from Pixabay

Posted by msicc in Android, Azure, Dev Stories, iOS, MAUI, Web, 2 comments