Quickstart: Build an ASP.NET web app using Azure Cosmos DB SQL API account

Azure Cosmos DB is Microsoft’s globally distributed, highly available, 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 SQL API account, database, and container using the Azure portal. You'll then build and deploy an ASP.NET To-do List web app built on the SQL .NET API, as shown in the following screenshot.

This quick start uses Version 3.0+ of the Azure Cosmos DB .NET SDK.

Todo app with sample data


If you don’t already have Visual Studio 2019 installed, you can download and use the free Visual Studio 2019 Community Edition. Make sure that you enable the Azure development workload during the Visual Studio setup.

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

You can Try Azure Cosmos DB for free without an Azure subscription, free of charge and commitments. Or, you can use the Azure Cosmos DB Emulator with a URI of https://localhost:8081. The Primary Key is provided in Authenticating requests.

Create a database account

  1. In a new browser window, sign in to the Azure portal.

  2. Click Create a resource > Databases > Azure Cosmos DB.

    The Azure portal Databases pane

  3. In the Create Azure Cosmos DB Account page, enter the settings for the new Azure Cosmos DB account.

    Setting Value Description
    Subscription Your subscription Select the Azure subscription that you want to use for this Azure Cosmos DB account.
    Resource Group Create new

    Enter a unique name
    Select Create New, then enter a new resource-group name for your account. For simplicity, you can use the same name as your Account Name.
    Account Name Enter a unique name Enter a unique name to identify your Azure Cosmos DB account. Because documents.azure.com is appended to the ID that you provide to create your URI, use a unique ID.

    The ID can only contain lowercase letters, numbers, and the hyphen (-) character, and it must be between 3 and 31 characters in length..
    API Core (SQL) The API determines the type of account to create. Azure Cosmos DB provides five APIs: SQL (document database), Gremlin (graph database), MongoDB (document database), Table API, and Cassandra API. Each API currently requires you to create a separate account.

    Select Core (SQL) because in this article you will create a document database and query using SQL syntax.

    Learn more about the SQL API
    Location Select the region closest to your users Select a geographic location to host your Azure Cosmos DB account. Use the location that's closest to your users to give them the fastest access to the data.
    Enable geo-redundancy Leave blank This creates a replicated version of your database in a second (paired) region. Leave this blank.
    Multi-region writes Leave blank This enables each of your database regions to be both a read and write region. Leave this blank.

    Then click Review + create. You can skip the Network and Tags section.

    The new account page for Azure Cosmos DB

    Review the summary information and click Create.

    The account verification summary page

  4. The account creation takes a few minutes. Wait for the portal to display the Your deployment is complete message and click Go to resource.

    The account successfully created page

  5. The portal will now display the Congratulations! Your Azure Cosmos DB account was created page.

    The Azure portal Notifications pane

Add a collection

You can now use the Data Explorer tool in the Azure portal to create a database and collection.

  1. Click Data Explorer > New Collection.

    The Add Collection area is displayed on the far right, you may need to scroll right to see it.

    The Azure portal Data Explorer, Add Collection blade

  2. In the Add collection page, enter the settings for the new collection.

    Setting Suggested value Description
    Database id Tasks Enter Tasks as the name for the new database. Database names must contain from 1 through 255 characters, and they cannot contain /, \, #, ?, or a trailing space.
    Collection id Items Enter Items as the name for your new collection. Collection ids have the same character requirements as database names.
    Provision database throughput Leave blank Azure Cosmos DB can provision throughput at either the database level (all collections in a database share the same throughput) or at the collection level. Leave blank to provision throughput at the collection level for this particular collection.
    Storage capacity Unlimited Choose the Storage capacity of Unlimited.
    Partition key /category Enter "/category" as the partition key. Setting a partition key allows Azure Cosmos DB to scale your collection to meet the storage and throughput needs of your application. In general, a good choice of partition key is one that has a wide range of distinct values, and results in an even distribution of storage and request volume across your workload. Learn more about partitioning.
    Throughput 400 RU/s Change the throughput to 400 request units per second (RU/s). If you want to reduce latency, you can scale up the throughput later.

    In addition to the preceding settings, you can optionally add Unique keys for the collection. Let's leave the field empty in this example. Unique keys provide developers with the ability to add a layer of data integrity to the database. By creating a unique key policy while creating a collection, you ensure the uniqueness of one or more values per partition key. To learn more, refer to the Unique keys in Azure Cosmos DB article.

    Click OK.

    Data Explorer displays the new database and collection.

    The Azure portal Data Explorer, showing the new database and collection

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 Tasks database, expand the Items collection, click Documents, and then click New Documents.

    Create new documents in Data Explorer in the Azure portal

  2. Now add a document to the collection with the following structure.

        "id": "1",
        "category": "personal",
        "name": "groceries",
        "description": "Pick up apples and strawberries.",
        "isComplete": false
  3. Once you've added the json to the Documents tab, click Save.

    Copy in json data and click Save in Data Explorer in the Azure portal

  4. Create and save one more document where you insert a unique value for the id property, 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.

Query your data

You can use queries in Data Explorer to retrieve and filter your data.

  1. At the top of the Documents tab in Data Explorer, review the default query SELECT * FROM c. This query retrieves and displays all documents in the collection in ID order.

    Default query in Data Explorer is SELECT * FROM c

  2. To change the query, select Edit Filter, replace the default query with ORDER BY c._ts DESC, and then select Apply Filter.

    Change the default query by adding ORDER BY c._ts DESC and clicking Apply Filter

    The modified query displays the documents in descending order based on their time stamp, so now your second document is listed first.

    Changed query to ORDER BY c._ts DESC and clicking Apply Filter

If you're familiar with SQL syntax, you can enter any supported SQL queries in the query predicate box. You can also use Data Explorer to create stored procedures, UDFs, and triggers for server-side business logic.

Data Explorer provides easy Azure portal access to all of the built-in programmatic data access features available in the APIs. You also use the portal to scale throughput, get keys and connection strings, and review metrics and SLAs for your Azure Cosmos DB account.

Clone the sample application

Now let's switch to working with code. Let's clone a SQL API app from GitHub, set the connection string, and run it.

  1. Open a command prompt, create a new folder named git-samples, then close the command prompt.

    md "C:\git-samples"
  2. Open a git terminal window, such as git bash, and use the cd command to change to the new folder to install the sample app.

    cd "C:\git-samples"
  3. Run the following command to clone the sample repository. This command creates a copy of the sample app on your computer.

    git clone https://github.com/Azure-Samples/cosmos-dotnet-todo-app.git
  4. Open the todo.sln solution file in Visual Studio.

Review the code

This step is optional. If you're interested in learning how the database resources are created in the code, you can review the following snippets. Otherwise, you can skip ahead to Update your connection string.

Note, if you are familiar with the previous version of the .NET SDK, you may be used to seeing the terms 'collection' and 'document.' Because Azure Cosmos DB supports multiple API models, version 3.0+ of the .NET SDK uses the generic terms 'container' and 'item.' A container can be a collection, graph, or table. An item can be a document, edge/vertex, or row, and is the content inside a container. Learn more about databases, containers, and items.

The following snippets are all taken from the ToDoItemService.cs file.

  • The CosmosClient is initialized on lines 68 - 69.

    CosmosConfiguration config = new CosmosConfiguration(Endpoint, PrimaryKey);
    client = new CosmosClient(config);
  • A new database is created on line 71.

    CosmosDatabase database = await client.Databases.CreateDatabaseIfNotExistsAsync(DatabaseId);
  • A new container is created on line 72 with partition key "/category."

    CosmosContainer container = await database.Containers.CreateContainerIfNotExistsAsync(ContainerId, "/category");

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 select Keys, and then select 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, 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 primarykey in web.config.

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

  5. Then update the database and container value to match the name of the database and container you created earlier. You've now updated your app with all the info it needs to communicate with Azure Cosmos DB.

    <add key="database" value="Tasks" />

    <add key="container" value="Items" />

Run the web app

  1. In the Solution Explorer, right click on your new console application project, which is under your Visual Studio solution, and then click Manage NuGet Packages...

    Screenshot of the Right Clicked Menu for the Project

  2. In the NuGet tab, click Browse, and type Microsoft.Azure.Cosmos in the search box.

  3. Within the results, find Microsoft.Azure.Cosmos and click Install. The package ID for the Azure Cosmos DB SQL API Client Library is Microsoft Azure Cosmos DB Client Library.

    Screenshot of the NuGet Menu for finding Azure Cosmos DB Client SDK

    If you get a message about reviewing changes to the solution, click OK. If you get a message about license acceptance, click I accept.

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

  5. Select Create New in the browser and create a few new tasks in your to-do app. You should also see the tasks you created in Add sample data

    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

The Azure portal monitors your Cosmos DB account throughput, storage, availability, latency, and consistency. Charts for metrics associated with an Azure Cosmos DB Service Level Agreement (SLA) show the SLA value compared to actual performance. This suite of metrics makes monitoring your SLAs transparent.

To review metrics and SLAs:

  1. Select Metrics in your Cosmos DB account's navigation menu.

  2. Select a tab such as Latency, and select a timeframe on the right. Compare the Actual and SLA lines on the charts.

    Azure Cosmos DB metrics suite

  3. Review the metrics on the other tabs.

Clean up resources

When you're done with your web app and Azure Cosmos DB account, you can delete the Azure resources you created so you don't incur more charges. To delete the resources:

  1. In the Azure portal, select Resource groups on the far left. If the left menu is collapsed, select Expand button to expand it.

  2. Select the resource group you created for this quickstart.

    Metrics in the Azure portal

  3. In the new window, select Delete resource group.

    Metrics in the Azure portal

  4. In the next window, type the name of the resource group to delete, and then select Delete.

Next steps

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