This post is about configuring Mongo DB and creating ASP.NET Core Web API to work with Mongo DB using MongoDB.EntityFrameworkCore nuget package. Recently MongoDB team announced a EF Core provider for MongoDB. Earlier this year I blogged about MongoDB and ASP.NET Core using MongoFramework nuget package. In this blog post we are using MongoDB.EntityFrameworkCore nuget package which is from MongoDB.

Setting up MongoDB

For configuring MongoDB we can use Docker. First we can run the command - docker run --name mongo-db --publish 27017:27017 -v mongovolume:/data/db -d mongo:latest - the --name parameter helps us to identify the name of the container. The --publish parameter helps us to expose the 27017 port, and --volume parameter helps us to persist the data - it is optional. Once the Mongo DB running, we can use the connection string like this in ASP.NET Core - mongodb://localhost:27017

Setting up the Web API

First we need to create a Web API, we can do this by running the command dotnet new webapi --name BooksApi --output BooksApi --use-minimal-apis. Next we need to add reference of the MongoDB.EntityFrameworkCore nuget package - we can do this with the command - dotnet add .\BooksApi\ package MongoDB.EntityFrameworkCore --prerelease - since it is preview we need the --prerelease parameter. Now we have completed the Web API setup. Next open the project using VS Code. We can create a BookEntity class - which represents the MongoDB collection, Book class which is a view model class. And we need to create and configure DbContext class.

using MongoDB.Bson;

namespace BooksApi.Models;

public class BookEntity
{
    public ObjectId Id { get; set; }
    public string Title { get; set; } = string.Empty;
    public string Author { get; set; } = string.Empty;
    public string? Description { get; set; }
    public string? Genre { get; set; }
    public DateTime PublishDate { get; set; }
    public string? Publisher { get; set; }
    public decimal Price { get; set; }
    public string? Isbn { get; set; }
}

In the BookEntity class for the Id property ObjectId is the type. Here is code for Book view model class.

namespace BooksApi.ViewModels;

public class Book
{
    public string Title { get; set; } = string.Empty;
    public string Author { get; set; } = string.Empty;
    public string? Description { get; set; }
    public string? Genre { get; set; }
    public DateTime PublishDate { get; set; }
    public string? Publisher { get; set; }
    public decimal Price { get; set; }
    public string? Isbn { get; set; }
}

The Book view model class is similar to the BookEntity class except the Id is not part of the Book class. Next we can create the DbContext class.

using BooksApi.Models;
using Microsoft.EntityFrameworkCore;

namespace BooksApi.Data;

public class BooksApiDbContext(DbContextOptions<BooksApiDbContext> options) 
    : DbContext(options)
{
    public DbSet<BookEntity> Books { get; set; }
}

I am using the primary constructor feature of .NET 8.0 / C# 12 for the database context. And finally we can configure DbContext as part of dependency injection.

var connectionString = builder.Configuration.GetConnectionString("MongoDbConnection")
    ?? throw new InvalidOperationException("Connection string is null");

var databaseName = builder.Configuration.GetConnectionString("MongoDbDatabaseName") ?? "BooksStoreDb";
builder.Services.AddDbContext<BooksApiDbContext>(options => options.UseMongoDB(connectionString, databaseName));

I am using the simple overload - there are other overloads are available as well - which accepts the MongoClient instance and all.

Now we are ready to implement the CRUD methods.

Web API implementation

Like any other dependency we will be able to get the instance of DbContext in the minimal API methods like this.

app.MapGet("/books", async Task<Results<Ok<IEnumerable<Book>>, NotFound>> (BooksApiDbContext booksApiDbContext,
    CancellationToken cancellationToken = default) =>
{
    var books = (await booksApiDbContext.Books.ToListAsync(cancellationToken))
        .Select(book => new Book
        {
            Title = book.Title,
            Author = book.Author,
            Description = book.Description,
            Genre = book.Genre,
            PublishDate = book.PublishDate,
            Publisher = book.Publisher,
            Price = book.Price,
            Isbn = book.Isbn
        });

    return TypedResults.Ok(books!);
})
.WithName("GetBooks")
.WithOpenApi();

Like this we will be able to implement all the CRUD methods. Full code implementation is available on GitHub. This nuget package is still in preview. If you encounter any issues / bugs report them. Here is the Youtube video which explains about the NuGet package and how to use it.

Happy Programming.