Exercise - Add a data store

4 minutes

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 your 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'd consider using a database, such as SQL Server, with Entity Framework Core.

Create a pizza model

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.

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.

Add the following code to Models/Pizza.cs and save your changes. This class defines a pizza.

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

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.

Add the following code to Services/PizzaService.cs and save your changes. This code creates an in-memory pizza data service.

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 uses that service for demo purposes. When you stop and start the web API, the in-memory data cache is 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.

Exercise - Add a data store

Create a pizza model

Add a data service

Build the web API project

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