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ORM Concepts in Cosmos DB and Entity Framework Core

Introduction

Object-Relational Mapping (ORM) is a programming technique used to map data between two incompatible types of systems, relational database and object-oriented programming language. ORM is essential when developing an application using a database to store information. In this article, we will discuss ORM concepts in Cosmos DB and Entity Framework Core.

Syntax

To use ORM with Cosmos DB and Entity Framework Core, follow the steps below:

  1. Define the database models and entity classes
  2. Map the entity classes to database collections
  3. Use the DbContext to interact with the database
  4. Query the database with LINQ queries

Example

Consider a scenario where we need to store and retrieve information about customers. We can represent this information in Cosmos DB using a document format as shown below:

{
  "id": "customer-001",
  "name": "John Doe",
  "email": "johndoe@email.com",
  "address": {
    "street": "123 Main St",
    "city": "Anytown",
    "state": "CA",
    "zip": "12345"
  }
}

To map this customer data to an entity class in C#, we can create a Customer class as shown below:

public class Customer
{
    public string Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public Address Address { get; set; }
}

public class Address
{
    public string Street { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string Zip { get; set; }
}

Now, to map this Customer entity class to a Cosmos DB collection, we can create a new DbContext class and define a DbSet<Customer> property as shown below:

public class CustomerDbContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseCosmos(
            "https://your-cosmos-db-endpoint",
            "your-cosmos-db-primary-key",
            "your-database-id"
        );
    }
}

With this setup, we can now use LINQ queries to interact with the customer collection in Cosmos DB:

// Retrieve all customers
var customers = dbContext.Customers.ToList();

// Retrieve a customer by their ID
var customer = dbContext.Customers.FirstOrDefault(c => c.Id == "customer-001");

// Add a new customer
var newCustomer = new Customer { Name = "Jane Doe", Email = "janedoe@email.com" };
dbContext.Customers.Add(newCustomer);
dbContext.SaveChanges();

Explanation

ORM maps object-oriented programming constructs to a relational database schema. With ORM, we can use entity classes to represent database records and retrieve data using LINQ queries. In Cosmos DB, we can use the Entity Framework Core library and the Cosmos DB provider to map C# entity classes to document collections.

Use

ORM is useful in applications that store and retrieve data from a database. ORM automates the process of interacting with a database and abstracts away the need for low-level SQL queries. By using ORM, developers can write higher level code that is easier to maintain and less error-prone.

Important Points

  • ORM is a programming technique used to map data between incompatible systems
  • ORM is essential when developing applications that use a database to store information
  • ORM automates the process of interacting with a database and abstracts away the need for low-level SQL queries
  • Cosmos DB and Entity Framework Core can be used together to implement ORM in C# applications

Summary

In summary, ORM is a powerful programming technique that abstracts away the complexities of interacting with a database. In Cosmos DB and Entity Framework Core, we can use entity classes to represent database records and retrieve data using LINQ queries. By using ORM, developers can focus on writing high-level code that is easier to maintain and less error-prone.

IntegrationData Modeling with Entity Framework Core
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