Get started with Azure Cosmos DB for NoSQL using .NET
APPLIES TO: 
NoSQL
This article shows you how to connect to Azure Cosmos DB for NoSQL using the .NET SDK. Once connected, you can perform operations on databases, containers, and items.
Package (NuGet) | Samples | API reference | Library source code | Give Feedback
Prerequisites
- An Azure account with an active subscription. Create an account for free.
- Azure Cosmos DB for NoSQL account. Create a API for NoSQL account.
- .NET 6.0 or later
- Azure Command-Line Interface (CLI) or Azure PowerShell
Set up your project
Create a new .NET application by using the dotnet new command with the console template.
dotnet new console
Import the Microsoft.Azure.Cosmos NuGet package using the dotnet add package command.
dotnet add package Microsoft.Azure.Cosmos
Build the project with the dotnet build command.
dotnet build
Connect to Azure Cosmos DB for NoSQL
To connect to the API for NoSQL of Azure Cosmos DB, create an instance of the CosmosClient class. This class is the starting point to perform all operations against databases.
To connect to your API for NoSQL account using Microsoft Entra, use a security principal. The exact type of principal will depend on where you host your application code. The table below serves as a quick reference guide.
| Where the application runs | Security principal |
|---|---|
| Local machine (developing and testing) | User identity or service principal |
| Azure | Managed identity |
| Servers or clients outside of Azure | Service principal |
Import Azure.Identity
The Azure.Identity NuGet package contains core authentication functionality that is shared among all Azure SDK libraries.
Import the Azure.Identity NuGet package using the dotnet add package command.
dotnet add package Azure.Identity
Rebuild the project with the dotnet build command.
dotnet build
In your code editor, add using directives for Azure.Core and Azure.Identity namespaces.
using Azure.Core;
using Azure.Identity;
Create CosmosClient with default credential implementation
If you're testing on a local machine, or your application will run on Azure services with direct support for managed identities, obtain an OAuth token by creating a DefaultAzureCredential instance.
For this example, we saved the instance in a variable of type TokenCredential as that's a more generic type that's reusable across SDKs.
// Credential class for testing on a local machine or Azure services
TokenCredential credential = new DefaultAzureCredential();
Create a new instance of the CosmosClient class with the COSMOS_ENDPOINT environment variable and the TokenCredential object as parameters.
// New instance of CosmosClient class using a connection string
using CosmosClient client = new(
accountEndpoint: Environment.GetEnvironmentVariable("COSMOS_ENDPOINT")!,
tokenCredential: credential
);
Build your application
As you build your application, your code will primarily interact with four types of resources:
The API for NoSQL account, which is the unique top-level namespace for your Azure Cosmos DB data.
Databases, which organize the containers in your account.
Containers, which contain a set of individual items in your database.
Items, which represent a JSON document in your container.
The following diagram shows the relationship between these resources.
Hierarchical diagram showing an Azure Cosmos DB account at the top. The account has two child database nodes. One of the database nodes includes two child container nodes. The other database node includes a single child container node. That single container node has three child item nodes.
Each type of resource is represented by one or more associated .NET classes. Here's a list of the most common classes:
| Class | Description |
|---|---|
CosmosClient |
This class provides a client-side logical representation for the Azure Cosmos DB service. The client object is used to configure and execute requests against the service. |
Database |
This class is a reference to a database that may, or may not, exist in the service yet. The database is validated server-side when you attempt to access it or perform an operation against it. |
Container |
This class is a reference to a container that also may not exist in the service yet. The container is validated server-side when you attempt to work with it. |
The following guides show you how to use each of these classes to build your application.
| Guide | Description |
|---|---|
| Create a database | Create databases |
| Create a container | Create containers |
| Read an item | Point read a specific item |
| Query items | Query multiple items |