Edit

Share via

Azure DocumentDB input binding for Azure Functions

Important

The Azure DocumentDB extension is currently in preview. At this time, only .NET apps that use the legacy in-process model are supported.

The Azure DocumentDB input binding in Azure Functions lets you retrieve one or more documents from your database. This article explains how to configure and use the input binding with C# code examples, including querying collections and working with the MongoDB client.

Prerequisites

Example

This example shows an HTTP trigger function for an HTTP GET request. The function then uses an input binding to query the target Azure DocumentDB collection for documents that match the filter { "price": { "$gte": 150 }}:

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.Azure.WebJobs.Extensions.AzureCosmosDb.Mongo;
using System.Collections.Generic;
using MongoDB.Bson;

public static class DocumentDBInput
{
    [FunctionName(nameof(DocumentDBInput))]
    public static async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Function, "GET", Route = null)]
        HttpRequest request,
        [CosmosDBMongo(databaseName: "<database-name>",
                        collectionName: "<collection-name>",
                        ConnectionStringSetting = "<name-of-app-setting>",
                        QueryString = "{{ \"price\": {{ \"$gte\": 150 }} }}")]
        IEnumerable<BsonDocument> documents,
        ILogger logger)
    {
        logger.LogInformation("C# Azure DocumentDB function queried a collection.");

        return new OkObjectResult(documents);
    }
}

Alternatively, use a C# record or class type to represent documents returned from the collection:

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.Azure.WebJobs.Extensions.AzureCosmosDb.Mongo;
using System.Collections.Generic;
using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;

public static class DocumentDBInput
{
    [FunctionName(nameof(DocumentDBInput))]
    public static async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Function, "GET", Route = null)]
        HttpRequest request,
        [CosmosDBMongo(databaseName: "<database-name>",
                        collectionName: "<collection-name>",
                        ConnectionStringSetting = "<name-of-app-setting>",
                        QueryString = "{{ \"price\": {{ \"$gte\": 150 }} }}")]
        IEnumerable<ProductDocument> products,
        ILogger logger)
    {
        logger.LogInformation("C# Azure DocumentDB function queried a collection.");

        return new OkObjectResult(products);
    }
}

public sealed record ProductDocument(
    [property: BsonId]
    [property: BsonRepresentation(BsonType.ObjectId)] string id,
    string name,
    string category,
    int quantity,
    decimal price,
    bool sale
);

Attributes

This table describes the binding configuration properties of the CosmosDBMongoTrigger attribute.

Parameter Description
FunctionId (Optional) The ID of the trigger function.
DatabaseName (Optional) The name of the database targeted by the input.
CollectionName (Optional) The name of the collection in the database targeted by the input.
ConnectionStringSetting The name of an app setting or setting collection that specifies how to connect to the Azure DocumentDB cluster.
QueryString Defines the Mongo query expression used by the input binding return documents from the database. The query supports Azure Functions binding parameters.

Note

The QueryString parameter needs to be escaped with double curly brackets to account for Azure Function's built-in parameter binding. For more information, see binding expressions and patterns.

Usage

Use the CosmosDBMongo attribute to retrieve a set of documents from the collection:

[FunctionName(nameof(DocumentDBInput))]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "GET", Route = null)]
    HttpRequest request,
    [CosmosDBMongo(databaseName: "<database-name>",
                    collectionName: "<collection-name>",
                    ConnectionStringSetting = "<name-of-app-setting>")]
    IEnumerable<BsonDocument> documents,
    ILogger logger)
{
    logger.LogInformation("C# Azure DocumentDB function queried a collection.");

    return new OkObjectResult(documents);
}

Alternatively, work directly with the MongoDB client in your function code:

[FunctionName(nameof(DocumentDBInput))]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "GET", Route = null)]
    HttpRequest request,
    [CosmosDBMongo(ConnectionStringSetting = "<name-of-app-setting>")]
    IMongoClient client,
    ILogger logger)
{
    logger.LogInformation("C# Azure DocumentDB function got a client.");

    IMongoDatabase database = client.GetDatabase("<database-name>");

    IMongoCollection<BsonDocument> collection = database.GetCollection<BsonDocument>("<collection-name>");

    BsonDocument filter = []; // Empty filter to get all documents

    long count = await collection.CountDocumentsAsync(filter);

    return new OkObjectResult(new
    {
        documentsInCollection = count
    });
}
  • Last updated on