Quickstart in Couchbase with C# and ASP.NET

Learn to build a REST API with Couchbase's C# SDK 3.4 and ASP.NET
See how you can fetch data from Couchbase using SQL++ queries
Explore CRUD operations in action with Couchbase

In this tutorial, you will learn how to connect to a Couchbase Capella cluster to create, read, update, and delete documents and how to write simple parametrized SQL++ queries.

Prerequisites

To run this prebuilt project, you will need:

Couchbase Capella cluster with travel-sample bucket loaded.
- To run this tutorial using a self managed Couchbase cluster, please refer to the appendix.
.NET SDK v6+ installed.
- Ensure that the .Net version is compatible with the Couchbase SDK.
Code Editor installed (Visual Studio Professional, Visual Studio Code, or JetBrains Rider)
Loading Travel Sample Bucket
- If travel-sample is not loaded in your Capella cluster, you can load it by following the instructions for your Capella Cluster:
  - Load travel-sample bucket in Couchbase Capella

Couchbase Capella Configuration

When running Couchbase using Capella, the following prerequisites need to be met.

The application requires the travel-sample bucket to be loaded in the cluster from the Capella UI.
Create the database credentials to access the travel-sample bucket (Read and Write) used in the application.
Allow access to the Cluster from the IP on which the application is running.

App Setup

We will walk through the different steps required to get the application running.

Cloning Repo

git clone https://github.com/couchbase-examples/aspnet-quickstart.git

Install Dependencies

cd src/Org.Quickstart.API
dotnet restore

Dependency Injection Nuget package

The Couchbase SDK for .NET includes a nuget package called Couchbase.Extensions.DependencyInjection which is designed for environments like ASP.NET that takes in a configuration to connect to Couchbase and automatically registers interfaces that you can use in your code to perform full CRUD (create, read, update, delete) operations and queries against the database.

Setup Database Configuration

To know more about connecting to your Capella cluster, please follow the instructions.

Specifically, you need to do the following:

Create the database credentials to access the travel-sample bucket (Read and Write) used in the application.
Allow access to the Cluster from the IP on which the application is running.

All configuration for communication with the database is stored in the appsettings.Development.json file. This includes the connection string, username, password, bucket name and scope name. The default username is assumed to be Administrator and the default password is assumed to be P@$$w0rd12. If these are different in your environment you will need to change them before running the application.

  "Couchbase": {
    "BucketName": "travel-sample",
    "ScopeName": "inventory",
    "ConnectionString": "couchbases://yourassignedhostname.cloud.couchbase.com",
    "Username": "Administrator",
    "Password": "P@ssw0rd12",
    "IgnoreRemoteCertificateNameMismatch": true,
    "HttpIgnoreRemoteCertificateMismatch": true,
    "KvIgnoreRemoteCertificateNameMismatch": true
  }

Note: The connection string expects the couchbases:// or couchbase:// part.

Running The Application

Directly on Machine

At this point, we have installed the dependencies, loaded the travel-sample data and configured the application with the credentials. The application is now ready and you can run it.

cd src/Org.Quickstart.API
dotnet run

Using Docker

Build the Docker image

cd aspnet-quickstart
docker build -t couchbase-aspnet-quickstart .

Run the docker image

cd aspnet-quickstart
docker run -e DB_CONN_STR=<connection_string> -e DB_USERNAME=<user_with_read_write_permission_to_travel-sample_bucket> -e DB_PASSWORD=<password_for_user> -p 8080:8080 couchbase-aspnet-quickstart

You can access the Application on http://localhost:8080/index.html

Verifying the Application

Once the application starts, you can see the details of the application on the logs.

The application will run on port 8080 of your local machine (http://localhost:8080/index.html). You will find the Swagger documentation of the API if you go to the URL in your browser. Swagger documentation is used in this demo to showcase the different API end points and how they can be invoked. More details on the Swagger documentation can be found in the appendix.

Data Model

For this tutorial, we use three collections, airport, airline and route that contain sample airports, airlines and airline routes respectively. The route collection connects the airports and airlines as seen in the figure below. We use these connections in the quickstart to generate airports that are directly connected and airlines connecting to a destination airport. Note that these are just examples to highlight how you can use SQL++ queries to join the collections.

Let Us Review the Code

To begin this tutorial, clone the repo and open it up in the IDE of your choice. Now you can learn about how to create, read, update and delete documents in Couchbase Server.

Code Layout

├── src
│   ├── Org.Quickstart.API
│   │   ├── Controllers
│   │   │   ├── AirlineController.cs
│   │   │   ├── AirportController.cs
│   │   │   └── RouteController.cs
│   │   ├── Models
│   │   │   ├── Airline.cs
│   │   │   ├── Airport.cs
│   │   │   └── Route.cs
│   │   ├── Properties
│   │   │   └── launchSettings.json
│   │   ├── Services
│   │   │   └── InventoryScopeService.cs
│   │   ├── Couchbase.TravelSample.csproj
│   │   ├── Program.cs
│   │   └── appsettings.Development.json
│   └── Org.Quickstart.IntegrationTests
│       ├── ControllerTests
│       │   ├── AirlineTests.cs
│       │   ├── AirportTests.cs
│       │   └── RouteTests.cs  
│       └── Org.Quickstart.IntegrationTests.csproj
├── Org.Quickstart.sln
└── Dockerfile

Org.Quickstart.API.Program:

In order to use the Couchbase.Extensions.DependencyInjection framework, we must first register the service. The Couchbase Services requires the database configuration information, which can be provided by reading the database configuration from the appsettings.Development.json file.

// Register the configuration for Couchbase and Dependency Injection Framework
 builder.Services.Configure<CouchbaseConfig>(config);
 builder.Services.AddCouchbase(config);

The services are added to the DI container. CORS policy is defined to allow specific origins. HttpClient, Controllers, Endpoints API Explorer, and Swagger are also added here. The Swagger setup includes a detailed description of the API.

builder.Services.AddCors(options =>
{
    // ...
});

builder.Services.AddHttpClient();
builder.Services.AddControllers();

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(options =>
{
    // ...
});

The InventoryScopeService is registered as a singleton service in the DI container.

builder.Services.AddSingleton<IInventoryScopeService, InventoryScopeService>();

ASP.NET has an interface called IHostApplicationLifetime that you can add to your Configure method to help with registration of lifetime events. The Couchbase SDK provides the ICouchbaseLifetimeService interface for handling closing the database connections when the application closes. It's best practice to register for the ASP.NET ApplicationStop lifetime event and call the ICouchbaseLifetimeService Close method so that the database connection and resources are closed and removed gracefully. The program logs the Swagger UI address when the application starts.

var lifetime = app.Services.GetRequiredService<IHostApplicationLifetime>();

lifetime.ApplicationStarted.Register(() =>
{
    // ...
});

app.Lifetime.ApplicationStopped.Register(() =>
{
    var cls = app.Services.GetRequiredService<ICouchbaseLifetimeService>();
    cls.Close();
});

The program sets up the middleware pipeline for the application. This includes Swagger, CORS, HTTPS redirection, routing, authorization, and endpoint mapping.

app.UseSwagger();
app.UseSwaggerUI(c => {
    c.SwaggerEndpoint("/swagger/v1/swagger.json", "Couchbase Quickstart API v1"); 
    c.RoutePrefix = string.Empty;
});

if (app.Environment.EnvironmentName == "Testing")
{
    app.UseCors("_devAllowSpecificOrigins");
}

app.UseHttpsRedirection();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
    endpoints.MapControllers();
});

The Couchbase .NET SDK will handle all communications to the database cluster, so you shouldn't need to worry about creating a pool of connections.

This InventoryScopeService class is a service that provides a convenient way to fetch a specific scope from a specific bucket, handling all the necessary validation and error checking.

Airport Entity

For this tutorial, we will focus on the airport entity. The other entities are similar.

We will be setting up a REST API to manage airport documents.

POST Airport – Create a new airport
GET Airport – Read specified airport
PUT Airport – Update specified airport
DELETE Airport – Delete airport
Airport List – Get all airports. Optionally filter the list by country
Direct Connections - Get a list of airports directly connected to the specified airport

For CRUD operations, we will use the Key-Value operations that are built into the Couchbase SDK to create, read, update, and delete a document. Every document will need an ID (similar to a primary key in other databases) to save it to the database. This ID is passed in the URL. For other end points, we will use SQL++ to query for documents.

Airport Document Structure

Our airport document will have an airportname, city, country, faa code, icao code, timezone info and the geographic coordinates. For this demo, we will store all airport information in one document in the airport collection in the travel-sample bucket.

{
  "airportname": "Sample Airport",
  "city": "Sample City",
  "country": "United Kingdom",
  "faa": "SAA",
  "icao": "SAAA",
  "tz": "Europe/Paris",
  "geo": {
    "lat": 48.864716,
    "lon": 2.349014,
    "alt": 92
  }
}

POST Airport

Open the AirportController.cs file and navigate to the Post method.

It takes an id and a request as parameters, where id is the unique identifier for the airport and request contains the data for the new airport. The method extracts the airport object from the request and attempts to insert it into the collection using the InsertAsync method of the Couchbase SDK. If the insertion is successful, it returns a Created result. However, if a document with the same id already exists in the collection, the method catches a DocumentExistsException and returns a Conflict result. For any other exceptions, it logs the error message and returns an InternalServerError result.

public async Task<IActionResult> Post(string id, AirportCreateRequestCommand request)
{
    try
    {
        var collection = await _inventoryScope.CollectionAsync(CollectionName);
        var airport = request.GetAirport();
        await collection.InsertAsync(id, airport);
        return Created($"/api/v1/airport/{id}", airport);
    }
    catch (DocumentExistsException)
    {
        return Conflict($"A document with the ID '{id}' already exists.");
    }
    catch (Exception ex)
    {
        _logger.LogError(ex.Message);
        return StatusCode(StatusCodes.Status500InternalServerError, $"Error: {ex.Message} {ex.StackTrace} {Request.GetDisplayUrl()}");
    }
}

GET Airport

Open the AirportController.cs file and navigate to the GetById method.

This method retrieves an airport document from a collection using its id. It uses the GetAsync method of the Couchbase SDK to fetch the document. If the document exists, it returns the document; otherwise, it returns a NotFound result. Any other exceptions are caught, logged, and an InternalServerError result is returned.

public async Task<IActionResult> GetById(string id)
{
    try
    {
        var collection = await _inventoryScope.CollectionAsync(CollectionName);
        var result = await collection.GetAsync(id);
        var resultAirport = result.ContentAs<Airport>();
        if (resultAirport != null)
        {
            return Ok(resultAirport);
        }
    }
    catch (DocumentNotFoundException)
    {
        return NotFound();
    }
    catch (Exception ex)
    {
        _logger.LogError(ex.Message);
        return StatusCode(StatusCodes.Status500InternalServerError, $"Error: {ex.Message} {ex.StackTrace} {Request.GetDisplayUrl()}");
    }
    return NotFound();
}

PUT Airport

Open the AirportController.cs file and navigate to the Update method.

This method is used to update an existing airport document in the collection. It uses the GetAsync and ReplaceAsync methods from the Couchbase SDK. If the document with the specified id exists, it replaces the document with the new data from the request. If the document does not exist, it returns a NotFound result. Any other exceptions are caught, logged, and an InternalServerError result is returned.

public async Task<IActionResult> Update(string id, AirportCreateRequestCommand request)
{
    try
    {
        var collection = await _inventoryScope.CollectionAsync(CollectionName);
        if (await collection.GetAsync(id) is { } result)
        {
            result.ContentAs<Airport>();
            await collection.ReplaceAsync(id, request.GetAirport());
            return Ok(request);
        }
        else
        {
            return NotFound();
        }
    }
    catch (DocumentNotFoundException)
    {
        return NotFound();
    }
    catch (Exception ex)
    {
        _logger.LogError(ex.Message);
        return StatusCode(StatusCodes.Status500InternalServerError, $"Error: {ex.Message} {ex.StackTrace} {Request.GetDisplayUrl()}");
    }
    return NotFound();
}

DELETE Airport

Open the AirportController.cs file and navigate to the Delete method.

This method used to delete an existing airport document from a Couchbase collection. It uses the GetAsync and RemoveAsync methods from the Couchbase SDK. If the document with the specified id exists, it removes the document from the collection. If the document does not exist, it returns a NotFound result. Any other exceptions are caught, logged, and an InternalServerError result is returned.

public async Task<IActionResult> Delete(string id)
{
    try
    {
        var collection = await _inventoryScope.CollectionAsync(CollectionName);
        var result = await collection.GetAsync(id);
        var resultAirport = result.ContentAs<Airport>();
        if (resultAirport != null)
        {
            await collection.RemoveAsync(id);
            return Ok(id);
        }
        else
        {
            return NotFound();
        }
    }
    catch (DocumentNotFoundException)
    {
        return NotFound();
    }
    catch (Exception ex)
    {
        _logger.LogError(ex.Message);
        return StatusCode(StatusCodes.Status500InternalServerError, ex.Message);
    }
    return NotFound();
}

List Airport

This endpoint retrieves the list of airports in the database. The API has options to specify the page size for the results and country from which to fetch the airport documents.

SQL++ is a powerful query language based on SQL, but designed for structured and flexible JSON documents. We will use a SQL+ query to search for airports with Limit, Offset, and Country option.

Open the AirportController.cs file and navigate to the Delete method. This endpoint is different from the others we have seen before because it makes the SQL++ query rather than a key-value operation. This usually means more overhead because the query engine is involved. For this query, we are using the predefined indices in the travel-sample bucket. We can create an additional index specific for this query to make it perform better.

We need to get the values from the query string for country, limit, and Offset that we will use in our query. These are pulled from the queryParameters.Parameter method.

This end point has two queries depending on the value for the country parameter. If a country name is specified, we retrieve the airport documents for that specific country. If it is not specified, we retrieve the list of airports across all countries. The queries are slightly different for these two scenarios.

We build our SQL++ query using the parameters specified by $ symbol for both these scenarios. The difference between the two queries is the presence of the country parameter in the query. Normally for the queries with pagination, it is advised to order the results to maintain the order of results across multiple queries.

Next, we pass that query to the QueryAsync method. We save the results in a list, items.

This endpoint calls the QueryAsync method defined in the Scope by the Couchbase SDK.

           
           var queryParameters = new Couchbase.Query.QueryOptions();
		   queryParameters.Parameter("limit", limit ?? 10);
		   queryParameters.Parameter("offset", offset ?? 0);

		   string query;
		   if (!string.IsNullOrEmpty(country))
		   {
			   query = $@"SELECT airport.airportname,
                          airport.city,
                          airport.country,
                          airport.faa,
                          airport.geo,
                          airport.icao,
                          airport.tz
                        FROM airport AS airport
                        WHERE lower(airport.country) = $country
                        ORDER BY airport.airportname
                        LIMIT $limit
                        OFFSET $offset";
                    
			   queryParameters.Parameter("country", country.ToLower());
		   }
		   else
		   {
			   query = $@"SELECT airport.airportname,
                              airport.city,
                              airport.country,
                              airport.faa,
                              airport.geo,
                              airport.icao,
                              airport.tz
                            FROM airport AS airport
                            ORDER BY airport.airportname
                            LIMIT $limit
                            OFFSET $offset";
		   }

		   var results = await _inventoryScope.QueryAsync<Airport>(query, queryParameters);
		   var items = await results.Rows.ToListAsync();

		   return items.Count == 0 ? NotFound() : Ok(items);

Direct Connections

This endpoint fetches the airports that can be reached directly from the specified source airport code. This also uses a SQL++ query to fetch the results similar to the List Airport endpoint.

Let us look at the query used here:

SELECT distinct (route.destinationairport)
FROM airport as airport
JOIN route as route on route.sourceairport = airport.faa
WHERE airport.faa = $airport and route.stops = 0
ORDER BY route.destinationairport
LIMIT $limit
OFFSET $offset

We are fetching the direct connections by joining the airport collection with the route collection and filtering based on the source airport specified by the user and by routes with no stops.

Running The Tests

We have defined integration tests using the xunit nuget package for all the API end points. The integration tests use the same database configuration as the application. For the integration tests, we perform the operation using the API and confirm the results by checking the documents in the database. For example, to check the creation of the document by the API, we would call the API to create the document and then read the same document from the database and compare them. After the tests, the documents are cleaned up by calling the DELETE endpoint

To run the standard integration tests, use the following commands:

cd ../Org.Quickstart.IntegrationTests/
dotnet restore 
dotnet build
dotnet test

Appendix

Extending API by Adding New Entity

If you would like to add another entity to the APIs, these are the steps to follow:

Create the new entity (collection) in the Couchbase bucket. You can create the collection using the SDK or via the Couchbase Server interface.
Define the routes inside a new file in the Controllers folder similar to the existing ones like AirportController.cs.
Add the tests for the new routes in a new file in the ControllerTests folder similar to AirportTests.cs.

Running Self Managed Couchbase Cluster

If you are running this quickstart with a self managed Couchbase cluster, you need to load the travel-sample data bucket in your cluster and generate the credentials for the bucket.

You need to update the connection string and the credentials in the appsettings.Development.json file in the source folder.

NOTE: Couchbase must be installed and running prior to running the the ASP.NET app.

Swagger Documentation

Swagger documentation provides a clear view of the API including endpoints, HTTP methods, request parameters, and response objects.

Click on an individual endpoint to expand it and see detailed information. This includes the endpoint's description, possible response status codes, and the request parameters it accepts.

Trying Out the API

You can try out an API by clicking on the "Try it out" button next to the endpoints.

Parameters: If an endpoint requires parameters, Swagger UI provides input boxes for you to fill in. This could include path parameters, query strings, headers, or the body of a POST/PUT request.
Execution: Once you've inputted all the necessary parameters, you can click the "Execute" button to make a live API call. Swagger UI will send the request to the API and display the response directly in the documentation. This includes the response code, response headers, and response body.

Models

Swagger documents the structure of request and response bodies using models. These models define the expected data structure using JSON schema and are extremely helpful in understanding what data to send and expect.

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