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Create a web API with ASP.NET Core and MongoDB

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  • قراءة خلال 21 دقائق

By Pratik Khandelwal and Scott Addie

This tutorial creates a web API that runs Create, Read, Update, and Delete (CRUD) operations on a MongoDB NoSQL database.

In this tutorial, you learn how to:

  • Configure MongoDB
  • Create a MongoDB database
  • Define a MongoDB collection and schema
  • Perform MongoDB CRUD operations from a web API
  • Customize JSON serialization

Prerequisites

Configure MongoDB

On Windows, MongoDB is installed at C:\Program Files\MongoDB by default. Add C:\Program Files\MongoDB\Server\<version_number>\bin to the Path environment variable. This change enables MongoDB access from anywhere on your development machine.

Use the previously installed MongoDB Shell in the following steps to create a database, make collections, and store documents. For more information on MongoDB Shell commands, see mongosh.

  1. Choose a directory on your development machine for storing the data. For example, C:\BooksData on Windows. Create the directory if it doesn't exist. The mongo Shell doesn't create new directories.

  2. Open a command shell. Run the following command to connect to MongoDB on default port 27017. Remember to replace <data_directory_path> with the directory you chose in the previous step.

    mongod --dbpath <data_directory_path>

  3. Open another command shell instance. Connect to the default test database by running the following command:

    mongosh

  4. Run the following command in a command shell:

    use BookStore

    A database named BookStore is created if it doesn't already exist. If the database does exist, its connection is opened for transactions.

  5. Create a Books collection using following command:

    db.createCollection('Books')

    The following result is displayed:

    { "ok" : 1 }

  6. Define a schema for the Books collection and insert two documents using the following command:

    db.Books.insertMany([{ "Name": "Design Patterns", "Price": 54.93, "Category": "Computers", "Author": "Ralph Johnson" }, { "Name": "Clean Code", "Price": 43.15, "Category": "Computers","Author": "Robert C. Martin" }])

    A result similar to the following is displayed:

    {
    "acknowledged" : true,
    "insertedIds" : [
        ObjectId("61a6058e6c43f32854e51f51"),
        ObjectId("61a6058e6c43f32854e51f52")
     ]
 }

    Note

    The ObjectIds shown in the preceding result won't match those shown in your command shell.

  7. View the documents in the database using the following command:

    db.Books.find().pretty()

    A result similar to the following is displayed:

    {
     "_id" : ObjectId("61a6058e6c43f32854e51f51"),
     "Name" : "Design Patterns",
     "Price" : 54.93,
     "Category" : "Computers",
     "Author" : "Ralph Johnson"
 }
 {
     "_id" : ObjectId("61a6058e6c43f32854e51f52"),
     "Name" : "Clean Code",
     "Price" : 43.15,
     "Category" : "Computers",
     "Author" : "Robert C. Martin"
 }

    The schema adds an autogenerated _id property of type ObjectId for each document.

Create the ASP.NET Core web API project

  1. Go to File > New > Project.

  2. Select the ASP.NET Core Web API project type, and select Next.

  3. Name the project BookStoreApi, and select Next.

  4. Select the .NET 6.0 (Long-term support) framework and select Create.

  5. In the Package Manager Console window, navigate to the project root. Run the following command to install the .NET driver for MongoDB:

    Install-Package MongoDB.Driver

Add an entity model

  1. Add a Models directory to the project root.

  2. Add a Book class to the Models directory with the following code:

    using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;

namespace BookStoreApi.Models;

public class Book
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string? Id { get; set; }

    [BsonElement("Name")]
    public string BookName { get; set; } = null!;

    public decimal Price { get; set; }

    public string Category { get; set; } = null!;

    public string Author { get; set; } = null!;
}

    In the preceding class, the Id property is:

    • Required for mapping the Common Language Runtime (CLR) object to the MongoDB collection.
    • Annotated with [BsonId] to make this property the document's primary key.
    • Annotated with [BsonRepresentation(BsonType.ObjectId)] to allow passing the parameter as type string instead of an ObjectId structure. Mongo handles the conversion from string to ObjectId.

    The BookName property is annotated with the [BsonElement] attribute. The attribute's value of Name represents the property name in the MongoDB collection.

Add a configuration model

  1. Add the following database configuration values to appsettings.json:

    {
    "BookStoreDatabase": {
        "ConnectionString": "mongodb://localhost:27017",
        "DatabaseName": "BookStore",
        "BooksCollectionName": "Books"
    },
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft.AspNetCore": "Warning"
        }
    },
    "AllowedHosts": "*"
}

  2. Add a BookStoreDatabaseSettings class to the Models directory with the following code:

    namespace BookStoreApi.Models;

public class BookStoreDatabaseSettings
{
    public string ConnectionString { get; set; } = null!;

    public string DatabaseName { get; set; } = null!;

    public string BooksCollectionName { get; set; } = null!;
}

    The preceding BookStoreDatabaseSettings class is used to store the appsettings.json file's BookStoreDatabase property values. The JSON and C# property names are named identically to ease the mapping process.

  3. Add the following highlighted code to Program.cs:

    var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.Configure<BookStoreDatabaseSettings>(
    builder.Configuration.GetSection("BookStoreDatabase"));

    In the preceding code, the configuration instance to which the appsettings.json file's BookStoreDatabase section binds is registered in the Dependency Injection (DI) container. For example, the BookStoreDatabaseSettings object's ConnectionString property is populated with the BookStoreDatabase:ConnectionString property in appsettings.json.

  4. Add the following code to the top of Program.cs to resolve the BookStoreDatabaseSettings reference:

    using BookStoreApi.Models;

Add a CRUD operations service

  1. Add a Services directory to the project root.

  2. Add a BooksService class to the Services directory with the following code:

    using BookStoreApi.Models;
using Microsoft.Extensions.Options;
using MongoDB.Driver;

namespace BookStoreApi.Services;

public class BooksService
{
    private readonly IMongoCollection<Book> _booksCollection;

    public BooksService(
        IOptions<BookStoreDatabaseSettings> bookStoreDatabaseSettings)
    {
        var mongoClient = new MongoClient(
            bookStoreDatabaseSettings.Value.ConnectionString);

        var mongoDatabase = mongoClient.GetDatabase(
            bookStoreDatabaseSettings.Value.DatabaseName);

        _booksCollection = mongoDatabase.GetCollection<Book>(
            bookStoreDatabaseSettings.Value.BooksCollectionName);
    }

    public async Task<List<Book>> GetAsync() =>
        await _booksCollection.Find(_ => true).ToListAsync();

    public async Task<Book?> GetAsync(string id) =>
        await _booksCollection.Find(x => x.Id == id).FirstOrDefaultAsync();

    public async Task CreateAsync(Book newBook) =>
        await _booksCollection.InsertOneAsync(newBook);

    public async Task UpdateAsync(string id, Book updatedBook) =>
        await _booksCollection.ReplaceOneAsync(x => x.Id == id, updatedBook);

    public async Task RemoveAsync(string id) =>
        await _booksCollection.DeleteOneAsync(x => x.Id == id);
}

    In the preceding code, a BookStoreDatabaseSettings instance is retrieved from DI via constructor injection. This technique provides access to the appsettings.json configuration values that were added in the Add a configuration model section.

  3. Add the following highlighted code to Program.cs:

    var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.Configure<BookStoreDatabaseSettings>(
    builder.Configuration.GetSection("BookStoreDatabase"));

builder.Services.AddSingleton<BooksService>();

    In the preceding code, the BooksService class is registered with DI to support constructor injection in consuming classes. The singleton service lifetime is most appropriate because BooksService takes a direct dependency on MongoClient. Per the official Mongo Client reuse guidelines, MongoClient should be registered in DI with a singleton service lifetime.

  4. Add the following code to the top of Program.cs to resolve the BooksService reference:

    using BookStoreApi.Services;

The BooksService class uses the following MongoDB.Driver members to run CRUD operations against the database:

  • MongoClient: Reads the server instance for running database operations. The constructor of this class is provided the MongoDB connection string:

    public BooksService(
    IOptions<BookStoreDatabaseSettings> bookStoreDatabaseSettings)
{
    var mongoClient = new MongoClient(
        bookStoreDatabaseSettings.Value.ConnectionString);

    var mongoDatabase = mongoClient.GetDatabase(
        bookStoreDatabaseSettings.Value.DatabaseName);

    _booksCollection = mongoDatabase.GetCollection<Book>(
        bookStoreDatabaseSettings.Value.BooksCollectionName);
}

  • IMongoDatabase: Represents the Mongo database for running operations. This tutorial uses the generic GetCollection<TDocument>(collection) method on the interface to gain access to data in a specific collection. Run CRUD operations against the collection after this method is called. In the GetCollection<TDocument>(collection) method call:

    • collection represents the collection name.
    • TDocument represents the CLR object type stored in the collection.

GetCollection<TDocument>(collection) returns a MongoCollection object representing the collection. In this tutorial, the following methods are invoked on the collection:

  • DeleteOneAsync: Deletes a single document matching the provided search criteria.
  • Find<TDocument>: Returns all documents in the collection matching the provided search criteria.
  • InsertOneAsync: Inserts the provided object as a new document in the collection.
  • ReplaceOneAsync: Replaces the single document matching the provided search criteria with the provided object.

Add a controller

Add a BooksController class to the Controllers directory with the following code:

using BookStoreApi.Models;
using BookStoreApi.Services;
using Microsoft.AspNetCore.Mvc;

namespace BookStoreApi.Controllers;

[ApiController]
[Route("api/[controller]")]
public class BooksController : ControllerBase
{
    private readonly BooksService _booksService;

    public BooksController(BooksService booksService) =>
        _booksService = booksService;

    [HttpGet]
    public async Task<List<Book>> Get() =>
        await _booksService.GetAsync();

    [HttpGet("{id:length(24)}")]
    public async Task<ActionResult<Book>> Get(string id)
    {
        var book = await _booksService.GetAsync(id);

        if (book is null)
        {
            return NotFound();
        }

        return book;
    }

    [HttpPost]
    public async Task<IActionResult> Post(Book newBook)
    {
        await _booksService.CreateAsync(newBook);

        return CreatedAtAction(nameof(Get), new { id = newBook.Id }, newBook);
    }

    [HttpPut("{id:length(24)}")]
    public async Task<IActionResult> Update(string id, Book updatedBook)
    {
        var book = await _booksService.GetAsync(id);

        if (book is null)
        {
            return NotFound();
        }

        updatedBook.Id = book.Id;

        await _booksService.UpdateAsync(id, updatedBook);

        return NoContent();
    }

    [HttpDelete("{id:length(24)}")]
    public async Task<IActionResult> Delete(string id)
    {
        var book = await _booksService.GetAsync(id);

        if (book is null)
        {
            return NotFound();
        }

        await _booksService.RemoveAsync(id);

        return NoContent();
    }
}

The preceding web API controller:

  • Uses the BooksService class to run CRUD operations.
  • Contains action methods to support GET, POST, PUT, and DELETE HTTP requests.
  • Calls CreatedAtAction in the Create action method to return an HTTP 201 response. Status code 201 is the standard response for an HTTP POST method that creates a new resource on the server. CreatedAtAction also adds a Location header to the response. The Location header specifies the URI of the newly created book.

Test the web API

  1. Build and run the app.

  2. Navigate to https://localhost:<port>/api/books, where <port> is the automatically assigned port number for the app, to test the controller's parameterless Get action method. A JSON response similar to the following is displayed:

    [
  {
    "id": "61a6058e6c43f32854e51f51",
    "bookName": "Design Patterns",
    "price": 54.93,
    "category": "Computers",
    "author": "Ralph Johnson"
  },
  {
    "id": "61a6058e6c43f32854e51f52",
    "bookName": "Clean Code",
    "price": 43.15,
    "category": "Computers",
    "author": "Robert C. Martin"
  }
]

  3. Navigate to https://localhost:<port>/api/books/{id here} to test the controller's overloaded Get action method. A JSON response similar to the following is displayed:

    {
  "id": "61a6058e6c43f32854e51f52",
  "bookName": "Clean Code",
  "price": 43.15,
  "category": "Computers",
  "author": "Robert C. Martin"
}

Configure JSON serialization options

There are two details to change about the JSON responses returned in the Test the web API section:

  • The property names' default camel casing should be changed to match the Pascal casing of the CLR object's property names.
  • The bookName property should be returned as Name.

To satisfy the preceding requirements, make the following changes:

  1. In Program.cs, chain the following highlighted code on to the AddControllers method call:

    var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.Configure<BookStoreDatabaseSettings>(
    builder.Configuration.GetSection("BookStoreDatabase"));

builder.Services.AddSingleton<BooksService>();

builder.Services.AddControllers()
    .AddJsonOptions(
        options => options.JsonSerializerOptions.PropertyNamingPolicy = null);

    With the preceding change, property names in the web API's serialized JSON response match their corresponding property names in the CLR object type. For example, the Book class's Author property serializes as Author instead of author.

  2. In Models/Book.cs, annotate the BookName property with the [JsonPropertyName] attribute:

    [BsonElement("Name")]
[JsonPropertyName("Name")]
public string BookName { get; set; } = null!;

    The [JsonPropertyName] attribute's value of Name represents the property name in the web API's serialized JSON response.

  3. Add the following code to the top of Models/Book.cs to resolve the [JsonProperty] attribute reference:

    using System.Text.Json.Serialization;

  4. Repeat the steps defined in the Test the web API section. Notice the difference in JSON property names.

Add authentication support to a web API

ASP.NET Core Identity adds user interface (UI) login functionality to ASP.NET Core web apps. To secure web APIs and SPAs, use one of the following:

Duende Identity Server is an OpenID Connect and OAuth 2.0 framework for ASP.NET Core. Duende Identity Server enables the following security features:

  • Authentication as a Service (AaaS)
  • Single sign-on/off (SSO) over multiple application types
  • Access control for APIs
  • Federation Gateway

Important

Duende Software might require you to pay a license fee for production use of Duende Identity Server. For more information, see Migrate from ASP.NET Core 5.0 to 6.0.

For more information, see the Duende Identity Server documentation (Duende Software website).

Additional resources

This tutorial creates a web API that runs Create, Read, Update, and Delete (CRUD) operations on a MongoDB NoSQL database.

In this tutorial, you learn how to:

  • Configure MongoDB
  • Create a MongoDB database
  • Define a MongoDB collection and schema
  • Perform MongoDB CRUD operations from a web API
  • Customize JSON serialization

View or download sample code (how to download)

Prerequisites

Configure MongoDB

If using Windows, MongoDB is installed at C:\Program Files\MongoDB by default. Add C:\Program Files\MongoDB\Server\<version_number>\bin to the Path environment variable. This change enables MongoDB access from anywhere on your development machine.

Use the mongo Shell in the following steps to create a database, make collections, and store documents. For more information on mongo Shell commands, see Working with the mongo Shell.

  1. Choose a directory on your development machine for storing the data. For example, C:\BooksData on Windows. Create the directory if it doesn't exist. The mongo Shell doesn't create new directories.

  2. Open a command shell. Run the following command to connect to MongoDB on default port 27017. Remember to replace <data_directory_path> with the directory you chose in the previous step.

    mongod --dbpath <data_directory_path>

  3. Open another command shell instance. Connect to the default test database by running the following command:

    mongo

  4. Run the following command in a command shell:

    use BookstoreDb

    A database named BookstoreDb is created if it doesn't already exist. If the database does exist, its connection is opened for transactions.

  5. Create a Books collection using following command:

    db.createCollection('Books')

    The following result is displayed:

    { "ok" : 1 }

  6. Define a schema for the Books collection and insert two documents using the following command:

    db.Books.insertMany([{'Name':'Design Patterns','Price':54.93,'Category':'Computers','Author':'Ralph Johnson'}, {'Name':'Clean Code','Price':43.15,'Category':'Computers','Author':'Robert C. Martin'}])

    The following result is displayed:

    {
  "acknowledged" : true,
  "insertedIds" : [
    ObjectId("5bfd996f7b8e48dc15ff215d"),
    ObjectId("5bfd996f7b8e48dc15ff215e")
  ]
}

    Note

    The ID's shown in this article will not match the IDs when you run this sample.

  7. View the documents in the database using the following command:

    db.Books.find({}).pretty()

    The following result is displayed:

    {
  "_id" : ObjectId("5bfd996f7b8e48dc15ff215d"),
  "Name" : "Design Patterns",
  "Price" : 54.93,
  "Category" : "Computers",
  "Author" : "Ralph Johnson"
}
{
  "_id" : ObjectId("5bfd996f7b8e48dc15ff215e"),
  "Name" : "Clean Code",
  "Price" : 43.15,
  "Category" : "Computers",
  "Author" : "Robert C. Martin"
}

    The schema adds an autogenerated _id property of type ObjectId for each document.

The database is ready. You can start creating the ASP.NET Core web API.

Create the ASP.NET Core web API project

  1. Go to File > New > Project.

  2. Select the ASP.NET Core Web Application project type, and select Next.

  3. Name the project BooksApi, and select Create.

  4. Select the .NET Core target framework and ASP.NET Core 3.0. Select the API project template, and select Create.

  5. Visit the NuGet Gallery: MongoDB.Driver to determine the latest stable version of the .NET driver for MongoDB. In the Package Manager Console window, navigate to the project root. Run the following command to install the .NET driver for MongoDB:

    Install-Package MongoDB.Driver -Version {VERSION}

Add an entity model

  1. Add a Models directory to the project root.

  2. Add a Book class to the Models directory with the following code:

    using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;

namespace BooksApi.Models
{
    public class Book
    {
        [BsonId]
        [BsonRepresentation(BsonType.ObjectId)]
        public string Id { get; set; }

        [BsonElement("Name")]
        public string BookName { get; set; }

        public decimal Price { get; set; }

        public string Category { get; set; }

        public string Author { get; set; }
    }
}

    In the preceding class, the Id property is:

    • Required for mapping the Common Language Runtime (CLR) object to the MongoDB collection.
    • Annotated with [BsonId] to make this property the document's primary key.
    • Annotated with [BsonRepresentation(BsonType.ObjectId)] to allow passing the parameter as type string instead of an ObjectId structure. Mongo handles the conversion from string to ObjectId.

    The BookName property is annotated with the [BsonElement] attribute. The attribute's value of Name represents the property name in the MongoDB collection.

Add a configuration model

  1. Add the following database configuration values to appsettings.json:

    {
  "BookstoreDatabaseSettings": {
    "BooksCollectionName": "Books",
    "ConnectionString": "mongodb://localhost:27017",
    "DatabaseName": "BookstoreDb"
  },
  "Logging": {
    "IncludeScopes": false,
    "Debug": {
      "LogLevel": {
        "Default": "Warning"
      }
    },
    "Console": {
      "LogLevel": {
        "Default": "Warning"
      }
    }
  }
}

  2. Add a BookstoreDatabaseSettings.cs file to the Models directory with the following code:

    namespace BooksApi.Models
{
    public class BookstoreDatabaseSettings : IBookstoreDatabaseSettings
    {
        public string BooksCollectionName { get; set; }
        public string ConnectionString { get; set; }
        public string DatabaseName { get; set; }
    }

    public interface IBookstoreDatabaseSettings
    {
        string BooksCollectionName { get; set; }
        string ConnectionString { get; set; }
        string DatabaseName { get; set; }
    }
}

    The preceding BookstoreDatabaseSettings class is used to store the appsettings.json file's BookstoreDatabaseSettings property values. The JSON and C# property names are named identically to ease the mapping process.

  3. Add the following highlighted code to Startup.ConfigureServices:

    public void ConfigureServices(IServiceCollection services)
{
    // requires using Microsoft.Extensions.Options
    services.Configure<BookstoreDatabaseSettings>(
        Configuration.GetSection(nameof(BookstoreDatabaseSettings)));

    services.AddSingleton<IBookstoreDatabaseSettings>(sp =>
        sp.GetRequiredService<IOptions<BookstoreDatabaseSettings>>().Value);

    services.AddControllers();
}

    In the preceding code:

    • The configuration instance to which the appsettings.json file's BookstoreDatabaseSettings section binds is registered in the Dependency Injection (DI) container. For example, a BookstoreDatabaseSettings object's ConnectionString property is populated with the BookstoreDatabaseSettings:ConnectionString property in appsettings.json.
    • The IBookstoreDatabaseSettings interface is registered in DI with a singleton service lifetime. When injected, the interface instance resolves to a BookstoreDatabaseSettings object.

  4. Add the following code to the top of Startup.cs to resolve the BookstoreDatabaseSettings and IBookstoreDatabaseSettings references:

    using BooksApi.Models;

Add a CRUD operations service

  1. Add a Services directory to the project root.

  2. Add a BookService class to the Services directory with the following code:

    using BooksApi.Models;
using MongoDB.Driver;
using System.Collections.Generic;
using System.Linq;

namespace BooksApi.Services
{
    public class BookService
    {
        private readonly IMongoCollection<Book> _books;

        public BookService(IBookstoreDatabaseSettings settings)
        {
            var client = new MongoClient(settings.ConnectionString);
            var database = client.GetDatabase(settings.DatabaseName);

            _books = database.GetCollection<Book>(settings.BooksCollectionName);
        }

        public List<Book> Get() =>
            _books.Find(book => true).ToList();

        public Book Get(string id) =>
            _books.Find<Book>(book => book.Id == id).FirstOrDefault();

        public Book Create(Book book)
        {
            _books.InsertOne(book);
            return book;
        }

        public void Update(string id, Book bookIn) =>
            _books.ReplaceOne(book => book.Id == id, bookIn);

        public void Remove(Book bookIn) =>
            _books.DeleteOne(book => book.Id == bookIn.Id);

        public void Remove(string id) => 
            _books.DeleteOne(book => book.Id == id);
    }
}

    In the preceding code, an IBookstoreDatabaseSettings instance is retrieved from DI via constructor injection. This technique provides access to the appsettings.json configuration values that were added in the Add a configuration model section.

  3. Add the following highlighted code to Startup.ConfigureServices:

    public void ConfigureServices(IServiceCollection services)
{
    services.Configure<BookstoreDatabaseSettings>(
        Configuration.GetSection(nameof(BookstoreDatabaseSettings)));

    services.AddSingleton<IBookstoreDatabaseSettings>(sp =>
        sp.GetRequiredService<IOptions<BookstoreDatabaseSettings>>().Value);

    services.AddSingleton<BookService>();

    services.AddControllers();
}

    In the preceding code, the BookService class is registered with DI to support constructor injection in consuming classes. The singleton service lifetime is most appropriate because BookService takes a direct dependency on MongoClient. Per the official Mongo Client reuse guidelines, MongoClient should be registered in DI with a singleton service lifetime.

  4. Add the following code to the top of Startup.cs to resolve the BookService reference:

    using BooksApi.Services;

The BookService class uses the following MongoDB.Driver members to run CRUD operations against the database:

  • MongoClient: Reads the server instance for running database operations. The constructor of this class is provided the MongoDB connection string:

    public BookService(IBookstoreDatabaseSettings settings)
{
    var client = new MongoClient(settings.ConnectionString);
    var database = client.GetDatabase(settings.DatabaseName);

    _books = database.GetCollection<Book>(settings.BooksCollectionName);
}

  • IMongoDatabase: Represents the Mongo database for running operations. This tutorial uses the generic GetCollection<TDocument>(collection) method on the interface to gain access to data in a specific collection. Run CRUD operations against the collection after this method is called. In the GetCollection<TDocument>(collection) method call:

    • collection represents the collection name.
    • TDocument represents the CLR object type stored in the collection.

GetCollection<TDocument>(collection) returns a MongoCollection object representing the collection. In this tutorial, the following methods are invoked on the collection:

  • DeleteOne: Deletes a single document matching the provided search criteria.
  • Find<TDocument>: Returns all documents in the collection matching the provided search criteria.
  • InsertOne: Inserts the provided object as a new document in the collection.
  • ReplaceOne: Replaces the single document matching the provided search criteria with the provided object.

Add a controller

Add a BooksController class to the Controllers directory with the following code:

using BooksApi.Models;
using BooksApi.Services;
using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;

namespace BooksApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class BooksController : ControllerBase
    {
        private readonly BookService _bookService;

        public BooksController(BookService bookService)
        {
            _bookService = bookService;
        }

        [HttpGet]
        public ActionResult<List<Book>> Get() =>
            _bookService.Get();

        [HttpGet("{id:length(24)}", Name = "GetBook")]
        public ActionResult<Book> Get(string id)
        {
            var book = _bookService.Get(id);

            if (book == null)
            {
                return NotFound();
            }

            return book;
        }

        [HttpPost]
        public ActionResult<Book> Create(Book book)
        {
            _bookService.Create(book);

            return CreatedAtRoute("GetBook", new { id = book.Id.ToString() }, book);
        }

        [HttpPut("{id:length(24)}")]
        public IActionResult Update(string id, Book bookIn)
        {
            var book = _bookService.Get(id);

            if (book == null)
            {
                return NotFound();
            }

            _bookService.Update(id, bookIn);

            return NoContent();
        }

        [HttpDelete("{id:length(24)}")]
        public IActionResult Delete(string id)
        {
            var book = _bookService.Get(id);

            if (book == null)
            {
                return NotFound();
            }

            _bookService.Remove(id);

            return NoContent();
        }
    }
}

The preceding web API controller:

  • Uses the BookService class to run CRUD operations.
  • Contains action methods to support GET, POST, PUT, and DELETE HTTP requests.
  • Calls CreatedAtRoute in the Create action method to return an HTTP 201 response. Status code 201 is the standard response for an HTTP POST method that creates a new resource on the server. CreatedAtRoute also adds a Location header to the response. The Location header specifies the URI of the newly created book.

Test the web API

  1. Build and run the app.

  2. Navigate to https://localhost:<port>/api/books to test the controller's parameterless Get action method. The following JSON response is displayed:

    [
  {
    "id":"5bfd996f7b8e48dc15ff215d",
    "bookName":"Design Patterns",
    "price":54.93,
    "category":"Computers",
    "author":"Ralph Johnson"
  },
  {
    "id":"5bfd996f7b8e48dc15ff215e",
    "bookName":"Clean Code",
    "price":43.15,
    "category":"Computers",
    "author":"Robert C. Martin"
  }
]

  3. Navigate to https://localhost:<port>/api/books/{id here} to test the controller's overloaded Get action method. The following JSON response is displayed:

    {
  "id":"{ID}",
  "bookName":"Clean Code",
  "price":43.15,
  "category":"Computers",
  "author":"Robert C. Martin"
}

Configure JSON serialization options

There are two details to change about the JSON responses returned in the Test the web API section:

  • The property names' default camel casing should be changed to match the Pascal casing of the CLR object's property names.
  • The bookName property should be returned as Name.

To satisfy the preceding requirements, make the following changes:

  1. Json.NET has been removed from ASP.NET shared framework. Add a package reference to Microsoft.AspNetCore.Mvc.NewtonsoftJson.

  2. In Startup.ConfigureServices, chain the following highlighted code on to the AddControllers method call:

    public void ConfigureServices(IServiceCollection services)
{
    services.Configure<BookstoreDatabaseSettings>(
        Configuration.GetSection(nameof(BookstoreDatabaseSettings)));

    services.AddSingleton<IBookstoreDatabaseSettings>(sp =>
        sp.GetRequiredService<IOptions<BookstoreDatabaseSettings>>().Value);

    services.AddSingleton<BookService>();

    services.AddControllers()
        .AddNewtonsoftJson(options => options.UseMemberCasing());
}

    With the preceding change, property names in the web API's serialized JSON response match their corresponding property names in the CLR object type. For example, the Book class's Author property serializes as Author.

  3. In Models/Book.cs, annotate the BookName property with the following [JsonProperty] attribute:

    [BsonElement("Name")]
[JsonProperty("Name")]
public string BookName { get; set; }

    The [JsonProperty] attribute's value of Name represents the property name in the web API's serialized JSON response.

  4. Add the following code to the top of Models/Book.cs to resolve the [JsonProperty] attribute reference:

    using Newtonsoft.Json;

  5. Repeat the steps defined in the Test the web API section. Notice the difference in JSON property names.

Add authentication support to a web API

ASP.NET Core Identity adds user interface (UI) login functionality to ASP.NET Core web apps. To secure web APIs and SPAs, use one of the following:

IdentityServer4 is an OpenID Connect and OAuth 2.0 framework for ASP.NET Core. IdentityServer4 enables the following security features:

  • Authentication as a Service (AaaS)
  • Single sign-on/off (SSO) over multiple application types
  • Access control for APIs
  • Federation Gateway

For more information, see Welcome to IdentityServer4.

Next steps

For more information on building ASP.NET Core web APIs, see the following resources: