Store unstructured data using Azure Functions and Azure Cosmos DB

Azure Cosmos DB is a great way to store unstructured and JSON data. Combined with Azure Functions, Azure Cosmos DB makes storing data quick and easy with much less code than required for storing data in a relational database.

In Azure Functions, input and output bindings provide a declarative way to connect to external service data from your function. In this article, learn how to update an existing function to add an output binding that stores unstructured data in an Azure Cosmos DB document.

Prerequisites

To complete this tutorial:

This topic uses as its starting point the resources created in Create your first function from the Azure portal. If you haven't already done so, please complete these steps now to create your function app.

Create an Azure Cosmos DB account

You must have an Azure Cosmos DB account that uses the SQL API before you create the output binding.

1. From the Azure portal menu or the Home page, select Create a resource.

2. Search for Azure Cosmos DB. Select Create > Azure Cosmos DB.

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

   Setting	Value	Description
   Subscription	Subscription name	Select the Azure subscription that you want to use for this Azure Cosmos DB account.
   Resource Group	Resource group name	Select a resource group, or select Create new, then enter a unique name for the new resource group.
   Account Name	A unique name	Enter a name to identify your Azure Cosmos DB account. Because documents.azure.cn is appended to the name that you provide to create your URI, use a unique name. The name can contain only lowercase letters, numbers, and the hyphen (-) character. It must be 3-44 characters.
   API	NoSQL	The API determines the type of account to create. Azure Cosmos DB provides five APIs: NoSQL for document databases, Gremlin for graph databases, MongoDB for document databases, Azure Table, and Cassandra. To learn more about the API for NoSQL, see Welcome to Azure Cosmos DB.
   Location	The region closest to your users	Select a geographic location to host your Azure Cosmos DB account. Use the location that is closest to your users to give them the fastest access to the data.
   Capacity mode	Provisioned throughput or Serverless	Select Provisioned throughput to create an account in provisioned throughput mode. Select Serverless to create an account in serverless mode.
   Apply Azure Cosmos DB free tier discount	Apply or Do not apply	With Azure Cosmos DB free tier, you get the first 1000 RU/s and 25 GB of storage for free in an account. Learn more about free tier.
   Limit total account throughput	Selected or not	Limit the total amount of throughput that can be provisioned on this account. This limit prevents unexpected charges related to provisioned throughput. You can update or remove this limit after your account is created.

   You can have up to one free tier Azure Cosmos DB account per Azure subscription and must opt in when creating the account. If you don't see the option to apply the free tier discount, another account in the subscription has already been enabled with free tier.

   

   Note

   The following options are not available if you select Serverless as the Capacity mode:

   • Apply Free Tier Discount
   • Limit total account throughput

4. In the Global Distribution tab, configure the following details. You can leave the default values for this quickstart:

   Setting	Value	Description
   Geo-Redundancy	Disable	Enable or disable multiple-region distribution on your account by pairing your region with a pair region. You can add more regions to your account later.
   Multi-region Writes	Disable	Multi-region writes capability allows you to take advantage of the provisioned throughput for your databases and containers across China.
   Availability Zones	Disable	Availability Zones help you further improve availability and resiliency of your application.

   Note

   The following options are not available if you select Serverless as the Capacity mode in the previous Basics page:

   • Geo-redundancy
   • Multi-region Writes

5. Optionally, you can configure more details in the following tabs:

   • Networking. Configure access from a virtual network.
   • Backup Policy. Configure either periodic or continuous backup policy.
   • Encryption. Use either service-managed key or a customer-managed key.
   • Tags. Tags are name/value pairs that enable you to categorize resources and view consolidated billing by applying the same tag to multiple resources and resource groups.

6. Select Review + create.

7. Review the account settings, and then select Create. It takes a few minutes to create the account. Wait for the portal page to display Your deployment is complete.

   

8. Select Go to resource to go to the Azure Cosmos DB account page.

   

Add an output binding

1. In the Azure portal, navigate to and select the function app you created previously.

2. Select Functions, and then select the HttpTrigger function.

   

3. Select Integration and + Add output.

   

4. Use the Create Output settings as specified in the table:

   

   Setting	Suggested value	Description
   Binding Type	Azure Cosmos DB	Name of the binding type to select to create the output binding to Azure Cosmos DB.
   Document parameter name	taskDocument	Name that refers to the Azure Cosmos DB object in code.
   Database name	taskDatabase	Name of database to save documents.
   Collection name	taskCollection	Name of the database collection.
   If true, creates the Azure Cosmos DB database and collection	Yes	The collection doesn't already exist, so create it.
   Azure Cosmos DB account connection	New setting	Select New, then choose Azure Cosmos DB Account and the Database account you created earlier, and then select OK. Creates an application setting for your account connection. This setting is used by the binding to connection to the database.

5. Select OK to create the binding.

Update the function code

Replace the existing function code with the following code, in your chosen language:

#r "Newtonsoft.Json"

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;

public static IActionResult Run(HttpRequest req, out object taskDocument, ILogger log)
{
    string name = req.Query["name"];
    string task = req.Query["task"];
    string duedate = req.Query["duedate"];

    // We need both name and task parameters.
    if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(task))
    {
        taskDocument = new
        {
            name,
            duedate,
            task
        };

        return (ActionResult)new OkResult();
    }
    else
    {
        taskDocument = null;
        return (ActionResult)new BadRequestResult();
    }
}

module.exports = async function (context, req) {

    // We need both name and task parameters.
    if (req.query.name && req.query.task) {

        // Set the output binding data from the query object.
        context.bindings.taskDocument = req.query;

        // Success.
        context.res = {
            status: 200
        };
    }
    else {
        context.res = {
            status: 400,
            body: "The query options 'name' and 'task' are required."
        };
    }
};

This code sample reads the HTTP Request query strings and assigns them to fields in the taskDocument object. The taskDocument binding sends the object data from this binding parameter to be stored in the bound document database. The database is created the first time the function runs.

Test the function and database

1. Select Test/Run. Under Query, select + Add parameter and add the following parameters to the query string:

   • name
   • task
   • duedate

   

2. Select Run and verify that a 200 status is returned.

   

3. In the Azure portal, search for and select Azure Cosmos DB.

   

4. Choose your Azure Cosmos DB account, then select Data Explorer.

5. Expand the TaskCollection nodes, select the new document, and confirm that the document contains your query string values, along with some additional metadata.

   

You've successfully added a binding to your HTTP trigger to store unstructured data in an Azure Cosmos DB instance.

Clean up resources

In the preceding steps, you created Azure resources in a resource group. If you don't expect to need these resources in the future, you can delete them by deleting the resource group.

From the Azure portal menu or Home page, select Resource groups. Then, on the Resource groups page, select myResourceGroup.

On the myResourceGroup page, make sure that the listed resources are the ones you want to delete.

Select Delete resource group, type myResourceGroup in the text box to confirm, and then select Delete.

Next steps

For more information about binding to an Azure Cosmos DB instance, see Azure Functions Azure Cosmos DB bindings.

• Azure Functions triggers and bindings concepts
  Learn how Functions integrates with other services.
• Azure Functions developer reference
  Provides more technical information about the Functions runtime and a reference for coding functions and defining triggers and bindings.
• Code and test Azure Functions locally
  Describes the options for developing your functions locally.