Azure Cosmos DB: Build a DocumentDB API web app with .NET and the Azure portal

Azure Cosmos DB is Microsoft’s globally distributed multi-model database service. You can quickly create and query document, key/value, and graph databases, all of which benefit from the global distribution and horizontal scale capabilities at the core of Azure Cosmos DB.

This quick start demonstrates how to create an Azure Cosmos DB account, document database, and collection using the Azure portal. You'll then build and deploy a todo list web app built on the DocumentDB .NET API, as shown in the following screenshot.

Todo app with sample data


If you don’t already have Visual Studio 2017 installed, you can download and use the free Visual Studio 2017 Community Edition. Make sure that you enable Azure development during the Visual Studio setup.

If you don't have an Azure subscription, create a free account before you begin.

Create a database account

  1. In a new window, sign in to the Azure portal.
  2. In the left pane, click New, click Databases, and then click Azure Cosmos DB.

    The Azure portal Databases pane

  3. On the New account blade, specify the configuration that you want for the Azure Cosmos DB account.

    With Azure Cosmos DB, you can choose one of four programming models: Gremlin (graph), MongoDB, SQL (DocumentDB), and Table (key-value).

    In this quick-start article we program against the DocumentDB API, so choose SQL (DocumentDB) as you fill out the form. But if you have graph data for a social media app, or key/value (table) data, or data migrated from a MongoDB app, realize that Azure Cosmos DB can provide a highly available, globally distributed database service platform for all your mission-critical applications.

    Complete the fields on the New account blade, using the information in the following screenshot as a guide. When you set up your account, choose unique values that do not match those in the screenshot.

    The new Azure Cosmos DB blade

    Setting Suggested value Description
    ID Unique value A unique name that identifies your Azure Cosmos DB account. The string is appended to the ID you provide to create your URI, so use a unique but identifiable ID. The ID can contain only lowercase letters, numbers, and the hyphen (-) character, and it must contain from 3 through 50 characters.
    API SQL (DocumentDB) We program against the DocumentDB API later in this article.
    Subscription Your subscription The Azure subscription that you want to use for your Azure Cosmos DB account.
    Resource Group The same value as ID The new resource-group name for your account. For simplicity, you can use the same name as your ID.
    Location The region closest to your users The geographic location in which to host your Azure Cosmos DB account. Choose the location that's closest to your users to give them the fastest access to the data.
  4. Click Create to create the account.
  5. On the top toolbar, click Notifications to monitor the deployment process.

    The Azure portal Notifications pane

  6. When the deployment is complete, open the new account from the All Resources tile.

    The DocumentDB account on the All Resources tile

Add a collection

You can now use Data Explorer to create a collection and add data to your database.

  1. In the Azure portal, in the left pane, click Data Explorer.

  2. On the Data Explorer blade, click New Collection, and then provide the following information:

    The Azure portal Data Explorer blade

    Setting Suggested value Description
    Database id Items The ID for your new database. Database names must contain from 1 through 255 characters, and they cannot contain /, \, #, ?, or a trailing space.
    Collection id ToDoList The ID for your new collection. Collection names have the same character requirements as database IDs.
    Storage capacity Fixed (10 GB) Use the default value. This is the storage capacity of the database.
    Throughput 400 RU Use the default value. If you want to reduce latency, you can scale up the throughput later.
    Partition key /userid A partition key that distributes data evenly to each partition. Selecting the correct partition key is important in creating a performant collection. To learn more, see Designing for partitioning.
  3. After you've completed the form, click OK.

Add sample data

You can now add data to your new collection using Data Explorer.

  1. In Data Explorer, the new database appears in the Collections pane. Expand the Items database, expand the ToDoList collection, click Documents, and then click New Documents.

    Create new documents in Data Explorer in the Azure portal

  2. Now add a few documents to the collection with the following structure, where you insert unique values for id in each document and change the other properties as you see fit. Your new documents can have any structure you want as Azure Cosmos DB doesn't impose any schema on your data.

        "id": "1",
        "category": "personal",
        "name": "groceries",
        "description": "Pick up apples and strawberries."

    You can now use queries in Data Explorer to retrieve your data. By default, Data Explorer uses SELECT * FROM c to retrieve all documents in the collection, but you can change that to SELECT * FROM c ORDER BY ASC, to return all the documents in alphabetic ascending order of the name property.

    You can also use Data Explorer to create stored procedures, UDFs, and triggers to perform server-side business logic as well as scale throughput. Data Explorer exposes all of the built-in programmatic data access available in the APIs, but provides easy access to your data in the Azure portal.

Clone the sample application

Now let's clone a DocumentDB API app from github, set the connection string, and run it. You'll see how easy it is to work with data programmatically.

  1. Open a git terminal window, such as git bash, and CD to a working directory.

  2. Run the following command to clone the sample repository.

    git clone
  3. Then open the solution file in Visual Studio.

Review the code

Let's make a quick review of what's happening in the app. Open the DocumentDBRepository.cs file and you'll find that these lines of code create the Azure Cosmos DB resources.

  • The DocumentClient is initialized.

    client = new DocumentClient(new Uri(ConfigurationManager.AppSettings["endpoint"]), ConfigurationManager.AppSettings["authKey"]);`
  • A new database is created.

    await client.CreateDatabaseAsync(new Database { Id = DatabaseId });
  • A new collection is created.

    await client.CreateDocumentCollectionAsync(
        new DocumentCollection { Id = CollectionId },
        new RequestOptions { OfferThroughput = 1000 });

Update your connection string

Now go back to the Azure portal to get your connection string information and copy it into the app.

  1. In the Azure portal, in your Azure Cosmos DB account, in the left navigation click Keys, and then click Read-write Keys. You'll use the copy buttons on the right side of the screen to copy the URI and Primary Key into the web.config file in the next step.

    View and copy an access key in the Azure portal, Keys blade

  2. In Visual Studio 2017, open the web.config file.

  3. Copy your URI value from the portal (using the copy button) and make it the value of the endpoint key in web.config.

    <add key="endpoint" value="FILLME" />

  4. Then copy your PRIMARY KEY value from the portal and make it the value of the authKey in web.config. You've now updated your app with all the info it needs to communicate with Azure Cosmos DB.

    <add key="authKey" value="FILLME" />

Run the web app

  1. In Visual Studio, right-click on the project in Solution Explorer and then click Manage NuGet Packages.

  2. In the NuGet Browse box, type DocumentDB.

  3. From the results, install the Microsoft.Azure.DocumentDB library. This installs the Microsoft.Azure.DocumentDB package as well as all dependencies.

  4. Click CTRL + F5 to run the application. Your app displays in your browser.

  5. Click Create New in the browser and create a few new tasks in your to-do app.

    Todo app with sample data

You can now go back to Data Explorer and see query, modify, and work with this new data.

Review SLAs in the Azure portal

Now that your app is up and running, you'll want to ensure business continuity and watch user access to ensure high availability. You can use the Azure portal to review the availability, latency, throughput, and consistency of your collection.

Each graph that's associated with the Azure Cosmos DB Service Level Agreements (SLAs) provides a line that shows the quota required to meet the SLA and your actual usage, giving you a clear view into your database performance. Additional metrics, such as storage usage and number of requests per minute, are also included in the portal.

  • In the Azure portal, in the left pane, under Monitoring, click Metrics.

    Todo app with sample data

Clean up resources

If you're not going to continue to use this app, delete all resources created by this quickstart in the Azure portal with the following steps:

  1. From the left-hand menu in the Azure portal, click Resource groups and then click the name of the resource you created.
  2. On your resource group page, click Delete, type the name of the resource to delete in the text box, and then click Delete.

Next steps

In this quickstart, you've learned how to create an Azure Cosmos DB account, create a collection using the Data Explorer, and run a web app. You can now import additional data to your Cosmos DB account.