Exercise - Add a data store

Completed

Before you start to implement a web API for pizza, you need to have a data store on which you can perform operations.

You need a model class to represent a pizza in inventory. The model contains properties that represent the characteristics of a pizza. The model is used to pass data in the web API and to persist pizza options in the data store.

In this unit, that data store is a simple local in-memory caching service. In a real-world application, you would consider using a database, such as SQL Server, with Entity Framework Core.

Create a pizza model

  1. Run the following command to create a Models folder:

    mkdir Models
    

    Select the Models folder in Visual Studio Code and add a new file called Pizza.cs.

    Screenshot of adding a new file to the Models folder in Visual Studio Code.

    The project root now contains a Models directory with an empty Pizza.cs file. The directory name Models is a convention. The directory name comes from the model-view-controller architecture that the web API uses.

  2. Add the following code to Models/Pizza.cs to define a pizza. Save your changes.

    namespace ContosoPizza.Models;
    
    public class Pizza
    {
        public int Id { get; set; }
        public string? Name { get; set; }
        public bool IsGlutenFree { get; set; }
    }
    

Add a data service

  1. Run the following command to create a Services folder:

    mkdir Services
    

    Select the folder in Visual Studio Code and add a new file called PizzaService.cs.

    Screenshot of Visual Studio Code that shows adding a new file to the Services folder.

  2. Add the following code to Services/PizzaService.cs to create an in-memory pizza data service. Save your changes.

    using ContosoPizza.Models;
    
    namespace ContosoPizza.Services;
    
    public static class PizzaService
    {
        static List<Pizza> Pizzas { get; }
        static int nextId = 3;
        static PizzaService()
        {
            Pizzas = new List<Pizza>
            {
                new Pizza { Id = 1, Name = "Classic Italian", IsGlutenFree = false },
                new Pizza { Id = 2, Name = "Veggie", IsGlutenFree = true }
            };
        }
    
        public static List<Pizza> GetAll() => Pizzas;
    
        public static Pizza? Get(int id) => Pizzas.FirstOrDefault(p => p.Id == id);
    
        public static void Add(Pizza pizza)
        {
            pizza.Id = nextId++;
            Pizzas.Add(pizza);
        }
    
        public static void Delete(int id)
        {
            var pizza = Get(id);
            if(pizza is null)
                return;
    
            Pizzas.Remove(pizza);
        }
    
        public static void Update(Pizza pizza)
        {
            var index = Pizzas.FindIndex(p => p.Id == pizza.Id);
            if(index == -1)
                return;
    
            Pizzas[index] = pizza;
        }
    }
    

    This service provides a simple in-memory data caching service with two pizzas by default. Our web API will use that service for demo purposes. When you stop and start the web API, the in-memory data cache will be reset to the two default pizzas from the constructor of PizzaService.

Build the web API project

Run the following command to build the app:

dotnet build

The build succeeds with no warnings. If the build fails, check the output for troubleshooting information.

In the next unit, you'll create a controller that will use the Pizza model and PizzaService class.