homework.md

Homework for week 6

Let's take a look at a simple endpoint:

app.MapGet("/users2", async (IConfiguration configuration) =>
{
    // starting from C# 8 you no longer need inner {}
    using var connection = new MySqlConnection(configuration.GetConnectionString("Default"));

    var users = await connection.QueryAsync<User>("SELECT user FROM mysql.user");
    return users;
});

We want to move this code to a class paired with an interface. Create a new file and name it Users.cs. Start a file with a namespace:

namespace HackYourFuture.Week6;

Everything will be written after the namespace declaration. Then, move the User class or record (whichever you have) to the file. From now on, we keep adding to the file.

Let's introduce the interface:

public interface IUserRepository
{
    Task<IEnumerable<User>> GetUsers();
}

Then, the class that implements it is typically written as:

public class UserRepository : IUserRepository
{
    private string connectionString;

    public UserRepository(IConfiguration configuration)
    {
        this.connectionString = configuration.GetConnectionString("Default");
    }

    public Task<IEnumerable<User>> GetUsers()
    {
        using var connection = new MySqlConnection(connectionString);

        var users = await connection.QueryAsync<User>("SELECT user FROM mysql.user");
        return users;
    }
}

Then, we need to register it in the Program.cs:

builder.Services.AddScoped<IUserRepository, UserRepository>();

Don't forget to add using HackYourFuture.Week6; to the top of the file.

Finally! We can rewrite the original endpoint to:

app.MapGet("/users", async (IUserRepository userRepository) =>
{
    return await userRepository.GetUsers();
});

Task

Following the recipe above, move the rest of the code in the appropriate file.

Keep in mind that all methods concerning users go to Users.cs file while methods for dealing with Product go to Products.cs file.

In larger projects we keep interface in a separate file from the class and the file name is named as the interface or class in it.