How to Schedule Cosmos DB Data Processing With Azure Functions

This is the seventh part in a series of articles.

You can perform scheduled/batch processing of Azure Cosmos DB data by making use of timer triggers in Azure Functions.

Timer triggers allow you to set up a function to execute periodically based on set schedule.

For example the following attribute will cause the function to be executed once per day at  22:00 hours:

[TimerTrigger("0 0 22 * * *")]

As an example, in this series we’ve been using the domain of pizza delivery. Suppose that once per day the manager wanted an SMS with the total sales for the day.

To accomplish this we can combine a timer trigger, cosmos DB input binding, and a Twilio SMS output binding. In this example, the CosmosDB input binding is bound to an instance of DocumentClient. This allows us to perform more complex queries against Cosmos DB as we saw in part 2 of this series.

Once we have a DocumentClient instance, we can use LINQ to query Cosmos DB:

DateTime startOfToday = DateTime.Today;
DateTime endOfToday = startOfToday.AddDays(1).AddTicks(-1); 

decimal totalValueOfTodaysOrders = 
    client.CreateDocumentQuery<Order>(ordersCollectionUri, options)
         .Where(order => order.OrderDate >= startOfToday && order.OrderDate <= endOfToday)
         .Sum(order => order.OrderTotal);

The preceding query gets the total value or orders that have todays date, where order documents look like the following:

[
    {
        "id": "3",
        "StoreId": 2,
        "OrderTotal": 10.25,
        "OrderDate": "2019-06-06T17:17:17.7251173Z",
        "_rid": "Vg08AKOQeVQBAAAAAAAAAA==",
        "_self": "dbs/Vg08AA==/colls/Vg08AKOQeVQ=/docs/Vg08AKOQeVQBAAAAAAAAAA==/",
        "_etag": "\"00000000-0000-0000-1c2d-b2a092fd01d5\"",
        "_attachments": "attachments/",
        "_ts": 1559801067
    },
    {
        "id": "4",
        "StoreId": 2,
        "OrderTotal": 10.25,
        "OrderDate": "2019-06-06T18:18:18.7251173Z",
        "_rid": "Vg08AKOQeVQCAAAAAAAAAA==",
        "_self": "dbs/Vg08AA==/colls/Vg08AKOQeVQ=/docs/Vg08AKOQeVQCAAAAAAAAAA==/",
        "_etag": "\"00000000-0000-0000-1c37-77f607ea01d5\"",
        "_attachments": "attachments/",
        "_ts": 1559805263
    },
    {
        "id": "1",
        "StoreId": 1,
        "OrderTotal": 100,
        "OrderDate": "2019-06-06T14:14:14.7251173Z",
        "_rid": "Vg08AKOQeVQBAAAAAAAACA==",
        "_self": "dbs/Vg08AA==/colls/Vg08AKOQeVQ=/docs/Vg08AKOQeVQBAAAAAAAACA==/",
        "_etag": "\"00000000-0000-0000-1c2d-a87985f501d5\"",
        "_attachments": "attachments/",
        "_ts": 1559801050
    },
    {
        "id": "2",
        "StoreId": 1,
        "OrderTotal": 25.87,
        "OrderDate": "2019-06-06T16:16:16.7251173Z",
        "_rid": "Vg08AKOQeVQCAAAAAAAACA==",
        "_self": "dbs/Vg08AA==/colls/Vg08AKOQeVQ=/docs/Vg08AKOQeVQCAAAAAAAACA==/",
        "_etag": "\"00000000-0000-0000-1c2d-aef57e8c01d5\"",
        "_attachments": "attachments/",
        "_ts": 1559801061
    }
]

Once the total order value has been calculated, a Twilio SMS can be created and written to the Twilio output binding.

The complete listing is as follows:

using System;
using System.Linq;
using Microsoft.Azure.Documents.Client;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;
using Twilio.Rest.Api.V2010.Account;
using Twilio.Types;

namespace DontCodeTiredDemosV2.CosmosDemos
{
    public static class DailySales
    {
        [FunctionName("DailySales")]
        public static void Run(
            [TimerTrigger("0 0 22 * * *")]TimerInfo myTimer,            
            [CosmosDB(ConnectionStringSetting = "pizzaConnection")] DocumentClient client,
            [TwilioSms(AccountSidSetting = "TwilioAccountSid", AuthTokenSetting = "TwilioAuthToken", From = "%TwilioFromNumber%")
                ] out CreateMessageOptions messageToSend,
            ILogger log)
        {
            log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");

            Uri ordersCollectionUri = UriFactory.CreateDocumentCollectionUri(databaseId: "pizza", collectionId: "orders");

            var options = new FeedOptions { EnableCrossPartitionQuery = true }; // Enable cross partition query

            DateTime startOfToday = DateTime.Today;
            DateTime endOfToday = startOfToday.AddDays(1).AddTicks(-1); 

            decimal totalValueOfTodaysOrders = 
                client.CreateDocumentQuery<Order>(ordersCollectionUri, options)
                      .Where(order => order.OrderDate >= startOfToday && order.OrderDate <= endOfToday)
                      .Sum(order => order.OrderTotal);


            var messageText = $"Total sales for today: {totalValueOfTodaysOrders}";

            log.LogInformation(messageText);

            var managersMobileNumber = new PhoneNumber(Environment.GetEnvironmentVariable("ManagersMobileNumber"));

            var mobileMessage = new CreateMessageOptions(managersMobileNumber)
            {
                Body = messageText
            };

            messageToSend = mobileMessage;
        }
    }
}

In the preceding code, notice the From = "%TwilioFromNumber%" element of the [TwilioSms] binding, the %% means that the from number will be read from configuration, e.g. local.settings.json in the development environment. Similarly, notice the phone number that the SMS is sent to is read from configuration: var managersMobileNumber = new PhoneNumber(Environment.GetEnvironmentVariable("ManagersMobileNumber"));

Now once per day at 10pm the function will run and send an SMS to the manager giving him the days sales figures.

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