Azure Cosmos DB bindings for Azure Functions 1.x

The following example shows an in-process C# function that is invoked when there are inserts or updates in the specified database and collection.

using Microsoft.Azure.Documents;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using System.Collections.Generic;

namespace CosmosDBSamplesV1
{
    public static class CosmosTrigger
    {
        [FunctionName("CosmosTrigger")]
        public static void Run([CosmosDBTrigger(
            databaseName: "ToDoItems",
            collectionName: "Items",
            ConnectionStringSetting = "CosmosDBConnection",
            LeaseCollectionName = "leases",
            CreateLeaseCollectionIfNotExists = true)]IReadOnlyList<Document> documents,
            TraceWriter log)
        {
            if (documents != null && documents.Count > 0)
            {
                log.Info($"Documents modified: {documents.Count}");
                log.Info($"First document Id: {documents[0].Id}");
            }
        }
    }
}

The following example shows an Azure Cosmos DB trigger binding in a function.json file and a JavaScript function that uses the binding. The function writes log messages when Azure Cosmos DB records are modified.

Here's the binding data in the function.json file:

{
    "type": "cosmosDBTrigger",
    "name": "documents",
    "direction": "in",
    "leaseCollectionName": "leases",
    "connectionStringSetting": "<connection-app-setting>",
    "databaseName": "Tasks",
    "collectionName": "Items",
    "createLeaseCollectionIfNotExists": true
}

Here's the JavaScript code:

    module.exports = async function (context, documents) {
        context.log('First document Id modified : ', documents[0].id);
    }

For in-process C# class libraries, use the CosmosDBTrigger attribute.

The attribute's constructor takes the database name and collection name. For information about those settings and other properties that you can configure, see Trigger - configuration. Here's a CosmosDBTrigger attribute example in a method signature:

    [FunctionName("DocumentUpdates")]
    public static void Run(
        [CosmosDBTrigger("database", "collection", ConnectionStringSetting = "myCosmosDB")]
    IReadOnlyList<Document> documents,
        TraceWriter log)
    {
        ...
    }

For a complete example, see Trigger - C# example.

Attributes are not supported by JavaScript.

This section contains the following examples:

• Queue trigger, look up ID from JSON
• HTTP trigger, look up ID from query string
• HTTP trigger, look up ID from route data
• HTTP trigger, look up ID from route data, using SqlQuery
• HTTP trigger, get multiple docs, using SqlQuery
• HTTP trigger, get multiple docs, using DocumentClient

The examples refer to a simple ToDoItem type:

namespace CosmosDBSamplesV1
{
    public class ToDoItem
    {
        public string Id { get; set; }
        public string Description { get; set; }
    }
}

Queue trigger, look up ID from JSON

The following example shows a C# function that retrieves a single document. The function is triggered by a queue message that contains a JSON object. The queue trigger parses the JSON into an object named ToDoItemLookup, which contains the ID to look up. That ID is used to retrieve a ToDoItem document from the specified database and collection.

namespace CosmosDBSamplesV1
{
    public class ToDoItemLookup
    {
        public string ToDoItemId { get; set; }
    }
}

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;

namespace CosmosDBSamplesV1
{
    public static class DocByIdFromJSON
    {
        [FunctionName("DocByIdFromJSON")]
        public static void Run(
            [QueueTrigger("todoqueueforlookup")] ToDoItemLookup toDoItemLookup,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection",
                Id = "{ToDoItemId}")]ToDoItem toDoItem,
            TraceWriter log)
        {
            log.Info($"C# Queue trigger function processed Id={toDoItemLookup?.ToDoItemId}");

            if (toDoItem == null)
            {
                log.Info($"ToDo item not found");
            }
            else
            {
                log.Info($"Found ToDo item, Description={toDoItem.Description}");
            }
        }
    }
}

HTTP trigger, look up ID from query string

The following example shows a C# function that retrieves a single document. The function is triggered by an HTTP request that uses a query string to specify the ID to look up. That ID is used to retrieve a ToDoItem document from the specified database and collection.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using System.Net;
using System.Net.Http;

namespace CosmosDBSamplesV1
{
    public static class DocByIdFromQueryString
    {
        [FunctionName("DocByIdFromQueryString")]
        public static HttpResponseMessage Run(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)]HttpRequestMessage req,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection",
                Id = "{Query.id}")] ToDoItem toDoItem,
            TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");
            if (toDoItem == null)
            {
                log.Info($"ToDo item not found");
            }
            else
            {
                log.Info($"Found ToDo item, Description={toDoItem.Description}");
            }
            return req.CreateResponse(HttpStatusCode.OK);
        }
    }
}

HTTP trigger, look up ID from route data

The following example shows a C# function that retrieves a single document. The function is triggered by an HTTP request that uses route data to specify the ID to look up. That ID is used to retrieve a ToDoItem document from the specified database and collection.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using System.Net;
using System.Net.Http;

namespace CosmosDBSamplesV1
{
    public static class DocByIdFromRouteData
    {
        [FunctionName("DocByIdFromRouteData")]
        public static HttpResponseMessage Run(
            [HttpTrigger(
                AuthorizationLevel.Anonymous, "get", "post",
                Route = "todoitems/{id}")]HttpRequestMessage req,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection",
                Id = "{id}")] ToDoItem toDoItem,
            TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");

            if (toDoItem == null)
            {
                log.Info($"ToDo item not found");
            }
            else
            {
                log.Info($"Found ToDo item, Description={toDoItem.Description}");
            }
            return req.CreateResponse(HttpStatusCode.OK);
        }
    }
}

Skip input examples

HTTP trigger, look up ID from route data, using SqlQuery

The following example shows a C# function that retrieves a single document. The function is triggered by an HTTP request that uses route data to specify the ID to look up. That ID is used to retrieve a ToDoItem document from the specified database and collection.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using System.Collections.Generic;
using System.Net;
using System.Net.Http;

namespace CosmosDBSamplesV1
{
    public static class DocByIdFromRouteDataUsingSqlQuery
    {
        [FunctionName("DocByIdFromRouteDataUsingSqlQuery")]
        public static HttpResponseMessage Run(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post",
                Route = "todoitems2/{id}")]HttpRequestMessage req,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection",
                SqlQuery = "select * from ToDoItems r where r.id = {id}")] IEnumerable<ToDoItem> toDoItems,
            TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");
            foreach (ToDoItem toDoItem in toDoItems)
            {
                log.Info(toDoItem.Description);
            }
            return req.CreateResponse(HttpStatusCode.OK);
        }
    }
}

Skip input examples

HTTP trigger, get multiple docs, using SqlQuery

The following example shows a C# function that retrieves a list of documents. The function is triggered by an HTTP request. The query is specified in the SqlQuery attribute property.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using System.Collections.Generic;
using System.Net;
using System.Net.Http;

namespace CosmosDBSamplesV1
{
    public static class DocsBySqlQuery
    {
        [FunctionName("DocsBySqlQuery")]
        public static HttpResponseMessage Run(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)]
                HttpRequestMessage req,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection",
                SqlQuery = "SELECT top 2 * FROM c order by c._ts desc")]
                IEnumerable<ToDoItem> toDoItems,
            TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");
            foreach (ToDoItem toDoItem in toDoItems)
            {
                log.Info(toDoItem.Description);
            }
            return req.CreateResponse(HttpStatusCode.OK);
        }
    }
}

Skip input examples

HTTP trigger, get multiple docs, using DocumentClient (C#)

The following example shows a C# function that retrieves a list of documents. The function is triggered by an HTTP request. The code uses a DocumentClient instance provided by the Azure Cosmos DB binding to read a list of documents. The DocumentClient instance could also be used for write operations.

using Microsoft.Azure.Documents.Client;
using Microsoft.Azure.Documents.Linq;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using System;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;

namespace CosmosDBSamplesV1
{
    public static class DocsByUsingDocumentClient
    {
        [FunctionName("DocsByUsingDocumentClient")]
        public static async Task<HttpResponseMessage> Run(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)]HttpRequestMessage req,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection")] DocumentClient client,
            TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");

            Uri collectionUri = UriFactory.CreateDocumentCollectionUri("ToDoItems", "Items");
            string searchterm = req.GetQueryNameValuePairs()
                .FirstOrDefault(q => string.Compare(q.Key, "searchterm", true) == 0)
                .Value;

            if (searchterm == null)
            {
                return req.CreateResponse(HttpStatusCode.NotFound);
            }

            log.Info($"Searching for word: {searchterm} using Uri: {collectionUri.ToString()}");
            IDocumentQuery<ToDoItem> query = client.CreateDocumentQuery<ToDoItem>(collectionUri)
                .Where(p => p.Description.Contains(searchterm))
                .AsDocumentQuery();

            while (query.HasMoreResults)
            {
                foreach (ToDoItem result in await query.ExecuteNextAsync())
                {
                    log.Info(result.Description);
                }
            }
            return req.CreateResponse(HttpStatusCode.OK);
        }
    }
}

This section contains the following examples:

• Queue trigger, look up ID from JSON
• HTTP trigger, look up ID from query string
• HTTP trigger, look up ID from route data
• Queue trigger, get multiple docs, using SqlQuery

Queue trigger, look up ID from JSON

The following example shows an Azure Cosmos DB input binding in a function.json file and a JavaScript function that uses the binding. The function reads a single document and updates the document's text value.

Here's the binding data in the function.json file:

{
    "name": "inputDocumentIn",
    "type": "documentDB",
    "databaseName": "MyDatabase",
    "collectionName": "MyCollection",
    "id" : "{queueTrigger_payload_property}",
    "partitionKey": "{queueTrigger_payload_property}",
    "connection": "MyAccount_COSMOSDB",
    "direction": "in"
},
{
    "name": "inputDocumentOut",
    "type": "documentDB",
    "databaseName": "MyDatabase",
    "collectionName": "MyCollection",
    "createIfNotExists": false,
    "partitionKey": "{queueTrigger_payload_property}",
    "connection": "MyAccount_COSMOSDB",
    "direction": "out"
}

The configuration section explains these properties.

Here's the JavaScript code:

    // Change input document contents using Azure Cosmos DB input binding, using context.bindings.inputDocumentOut
    module.exports = async function (context) {
        context.bindings.inputDocumentOut = context.bindings.inputDocumentIn;
        context.bindings.inputDocumentOut.text = "This was updated!";
    };

HTTP trigger, look up ID from query string

The following example shows a JavaScript function that retrieves a single document. The function is triggered by an HTTP request that uses a query string to specify the ID to look up. That ID is used to retrieve a ToDoItem document from the specified database and collection.

Here's the function.json file:

{
  "bindings": [
    {
      "authLevel": "anonymous",
      "name": "req",
      "type": "httpTrigger",
      "direction": "in",
      "methods": [
        "get",
        "post"
      ]
    },
    {
      "name": "$return",
      "type": "http",
      "direction": "out"
    },
    {
      "type": "documentDB",
      "name": "toDoItem",
      "databaseName": "ToDoItems",
      "collectionName": "Items",
      "connection": "CosmosDBConnection",
      "direction": "in",
      "Id": "{Query.id}"
    }
  ],
  "disabled": true
}

Here's the JavaScript code:

module.exports = async function (context, req, toDoItem) {
    context.log('JavaScript queue trigger function processed work item');
    if (!toDoItem)
    {
        context.log("ToDo item not found");
    }
    else
    {
        context.log("Found ToDo item, Description=" + toDoItem.Description);
    }
};

HTTP trigger, look up ID from route data

The following example shows a JavaScript function that retrieves a single document. The function is triggered by an HTTP request that uses a query string to specify the ID to look up. That ID is used to retrieve a ToDoItem document from the specified database and collection.

Here's the function.json file:

{
  "bindings": [
    {
      "authLevel": "anonymous",
      "name": "req",
      "type": "httpTrigger",
      "direction": "in",
      "methods": [
        "get",
        "post"
      ],
      "route":"todoitems/{id}"
    },
    {
      "name": "$return",
      "type": "http",
      "direction": "out"
    },
    {
      "type": "documentDB",
      "name": "toDoItem",
      "databaseName": "ToDoItems",
      "collectionName": "Items",
      "connection": "CosmosDBConnection",
      "direction": "in",
      "Id": "{id}"
    }
  ],
  "disabled": false
}

Here's the JavaScript code:

module.exports = async function (context, req, toDoItem) {
    context.log('JavaScript queue trigger function processed work item');
    if (!toDoItem)
    {
        context.log("ToDo item not found");
    }
    else
    {
        context.log("Found ToDo item, Description=" + toDoItem.Description);
    }
};

Queue trigger, get multiple docs, using SqlQuery

The following example shows an Azure Cosmos DB input binding in a function.json file and a JavaScript function that uses the binding. The function retrieves multiple documents specified by a SQL query, using a queue trigger to customize the query parameters.

The queue trigger provides a parameter departmentId. A queue message of { "departmentId" : "Finance" } would return all records for the finance department.

Here's the binding data in the function.json file:

{
    "name": "documents",
    "type": "documentdb",
    "direction": "in",
    "databaseName": "MyDb",
    "collectionName": "MyCollection",
    "sqlQuery": "SELECT * from c where c.departmentId = {departmentId}",
    "connection": "CosmosDBConnection"
}

The configuration section explains these properties.

Here's the JavaScript code:

    module.exports = async function (context, input) {
        var documents = context.bindings.documents;
        for (var i = 0; i < documents.length; i++) {
            var document = documents[i];
            // operate on each document
        }
    };

In in-process C# class libraries, use the DocumentDB attribute.

The attribute's constructor takes the database name and collection name. For information about those settings and other properties that you can configure, see the following configuration section.

Attributes are not supported by JavaScript.

When the function exits successfully, any changes made to the input document via named input parameters are automatically persisted.

Updates are not made automatically upon function exit. Instead, use context.bindings.<documentName>In and context.bindings.<documentName>Out to make updates. See the input example.

This section contains the following examples:

• Queue trigger, write one doc
• Queue trigger, write docs using IAsyncCollector

The examples refer to a simple ToDoItem type:

namespace CosmosDBSamplesV1
{
    public class ToDoItem
    {
        public string Id { get; set; }
        public string Description { get; set; }
    }
}

Queue trigger, write one doc

The following example shows a C# function that adds a document to a database, using data provided in message from Queue storage.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using System;

namespace CosmosDBSamplesV1
{
    public static class WriteOneDoc
    {
        [FunctionName("WriteOneDoc")]
        public static void Run(
            [QueueTrigger("todoqueueforwrite")] string queueMessage,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection")]out dynamic document,
            TraceWriter log)
        {
            document = new { Description = queueMessage, id = Guid.NewGuid() };

            log.Info($"C# Queue trigger function inserted one row");
            log.Info($"Description={queueMessage}");
        }
    }
}

Queue trigger, write docs using IAsyncCollector

The following example shows a C# function that adds a collection of documents to a database, using data provided in a queue message JSON.

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using System.Threading.Tasks;

namespace CosmosDBSamplesV1
{
    public static class WriteDocsIAsyncCollector
    {
        [FunctionName("WriteDocsIAsyncCollector")]
        public static async Task Run(
            [QueueTrigger("todoqueueforwritemulti")] ToDoItem[] toDoItemsIn,
            [DocumentDB(
                databaseName: "ToDoItems",
                collectionName: "Items",
                ConnectionStringSetting = "CosmosDBConnection")]
                IAsyncCollector<ToDoItem> toDoItemsOut,
            TraceWriter log)
        {
            log.Info($"C# Queue trigger function processed {toDoItemsIn?.Length} items");

            foreach (ToDoItem toDoItem in toDoItemsIn)
            {
                log.Info($"Description={toDoItem.Description}");
                await toDoItemsOut.AddAsync(toDoItem);
            }
        }
    }
}

The following example shows an Azure Cosmos DB output binding in a function.json file and a JavaScript function that uses the binding. The function uses a queue input binding for a queue that receives JSON in the following format:

{
    "name": "John Henry",
    "employeeId": "123456",
    "address": "A town nearby"
}

The function creates Azure Cosmos DB documents in the following format for each record:

{
    "id": "John Henry-123456",
    "name": "John Henry",
    "employeeId": "123456",
    "address": "A town nearby"
}

Here's the binding data in the function.json file:

{
    "name": "employeeDocument",
    "type": "documentDB",
    "databaseName": "MyDatabase",
    "collectionName": "MyCollection",
    "createIfNotExists": true,
    "connection": "MyAccount_COSMOSDB",
    "direction": "out"
}

The configuration section explains these properties.

Here's the JavaScript code:

    module.exports = async function (context) {

      context.bindings.employeeDocument = JSON.stringify({
        id: context.bindings.myQueueItem.name + "-" + context.bindings.myQueueItem.employeeId,
        name: context.bindings.myQueueItem.name,
        employeeId: context.bindings.myQueueItem.employeeId,
        address: context.bindings.myQueueItem.address
      });
    };

In in-process C# class libraries, use the DocumentDB attribute.

The attribute's constructor takes the database name and collection name. For information about those settings and other properties that you can configure, see Output - configuration. Here's a DocumentDB attribute example in a method signature:

    [FunctionName("QueueToDocDB")]
    public static void Run(
        [QueueTrigger("myqueue-items", Connection = "AzureWebJobsStorage")] string myQueueItem,
        [DocumentDB("ToDoList", "Items", Id = "id", ConnectionStringSetting = "myCosmosDB")] out dynamic document)
    {
        ...
    }

For a complete example, see Output.

Attributes are not supported by JavaScript.