Book Image

Guide to NoSQL with Azure Cosmos DB

By : Gaston C. Hillar, Daron Yöndem
Book Image

Guide to NoSQL with Azure Cosmos DB

By: Gaston C. Hillar, Daron Yöndem

Overview of this book

Cosmos DB is a NoSQL database service included in Azure that is continuously adding new features and has quickly become one of the most innovative services found in Azure, targeting mission-critical applications at a global scale. This book starts off by showing you the main features of Cosmos DB, their supported NoSQL data models and the foundations of its scalable and distributed architecture. You will learn to work with the latest available tools that simplify your tasks with Cosmos DB and reduce development costs, such as the Data Explorer in the Azure portal, Microsoft Azure Storage Explorer, and the Cosmos DB Emulator. Next, move on to working with databases and document collections. We will use the tools to run schema agnostic queries against collections with the Cosmos DB SQL dialect and understand their results. Then, we will create a first version of an application that uses the latest .NET Core SDK to interact with Cosmos DB. Next, we will create a second version of the application that will take advantage of important features that the combination of C# and the .NET Core SDK provides, such as POCOs and LINQ queries. By the end of the book, you will be able to build an application that works with a Cosmos DB NoSQL document database with C#, the .NET Core SDK, LINQ, and JSON.
Table of Contents (13 chapters)
Title Page
Packt Upsell

Calculating a cross-partition aggregate with an asynchronous LINQ query

The following lines declare the code for the DoesCompetitionWithTitleExistWithLinq asynchronous static method, which builds a LINQ query to count the number of competitions with the received title. In order to compute this aggregate, we must run a cross-partition query, because the title for the competition can be at any location; that is, at any zip code.

Add the following lines to the existing code of the Program.cs file. The code file for the sample is included in the learning_cosmos_db_05_01 folder in the SampleApp2/SampleApp1/Program.cs file:

private static async Task<bool> DoesCompetitionWithTitleExistWithLinq(string competitionTitle) 
    var competitionsCount = await client.CreateDocumentQuery<Competition>(collectionUri, 
        new FeedOptions() 
            EnableCrossPartitionQuery = true, 
            MaxItemCount = 1, 
        .Where(c => c.Title == competitionTitle...