Add a data store

Add a data store

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 and add a new file called Pizza.cs.

   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.

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;
       }
   }

3. 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.

Notice the use of static keyword on the service class! Static objects are created only once - whenAPI is called for the first time. It remains in-memory until it is shut down

Build the web API project

Save the files and 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.