使用 IOption 的类的实例化

Question

在 ASP.NET Core 2.1 中，我有一个使用 IOptions 接口发送电子邮件的类，如下所示：

public class Email
{
    private readonly ManuelaIbiEmail manuelaIbiEmail;

    public Email(IOptions<ManuelaIbiEmail> manuelaIbiEmail)
    {
        this.manuelaIbiEmail.Username = manuelaIbiEmail.Value.Username;
        this.manuelaIbiEmail.Password = manuelaIbiEmail.Value.Password;
    }

    public async Task SendAsync(Contato contato)
    {
        var smtpClient = new SmtpClient
        {
            Host = "smtp.sendgrid.net",
            Port = 587,
            EnableSsl = true,
            Credentials = new NetworkCredential(manuelaIbiEmail.Username, manuelaIbiEmail.Password)
        };

        using (var message = new MailMessage(contato.Email, "manuelaibi66@gmail.com")
        {
            Subject = "Email de Manuela Ibi Nutrição Integrada",
            Body = $"{contato.Comentario}\nTelefone: {contato.Telefone}"
        })
        {
            await smtpClient.SendMailAsync(message);
        }
    }
}

这个类必须在控制器中用类似“var whatever = new Email(???);”的行来实例化为了可以调用 SendAsync 方法。

但这里的大局是我迷失在这个初始化中。我只是不知道在“Email(something)”中调用什么。

只是，提供更多信息以防万一：

系统应该从 Secrets 中读取用户名、密码，因此我在 Startup.cs 中有以下行：

services.Configure<ManuelaIbiEmail>(Configuration.GetSection("ManuelaIbiEmail"));

ManuelaIbiEmail 是一个非常简单的 POCO 类：

public class ManuelaIbiEmail
{
    public string Username { get; set; }
    public string Password { get; set; }
}

控制器看起来像：

public class ContactController : Controller
{
    private readonly ManuelaIbiEmail manuelaIbiEmail;

    public IActionResult Contact()
    {
        return View(new Contato());
    }

    [HttpPost]
    public async Task<IActionResult> ContactAsync(Contato contato)
    {
        var email = new Email();
        email.SendAsync(contato);

        return Ok();
    }
}

如果有人能告诉我我缺少什么，我将不胜感激。

提前谢谢你

Answer 1

依赖注入的全部意义在于不要那样做。

您可以通过属性将其注入方法中：

public class ContactController : Controller
{
    public IActionResult Contact()
    {
        return View(new Contato());
    }

    [HttpPost]
    public async Task<IActionResult> ContactAsync(Contato contato, [FromServices]Email email)
    {
        email.SendAsync(contato);

        return Ok();
    }
}

或者通过构造函数注入：

public class ContactController : Controller
{
    private readonly EMail email;

    public ContactController(Email email)
    {
        this.email = email;
    }

    public IActionResult Contact()
    {
        return View(new Contato());
    }

    [HttpPost]
    public async Task<IActionResult> ContactAsync(Contato contato)
    {
        email.SendAsync(contato);

        return Ok();
    }
}

Answer 2

只需通过构造函数注入Email：

public class ContactController : Controller
{
    public ContactController(Email email)
    {
        Email = email;
    }

    public Email Email { get; }

    public IActionResult Contact()
    {
        return View(new Contato());
    }

    [HttpPost]
    public async Task<IActionResult> ContactAsync(Contato contato)
    {
        Email.SendAsync(contato);

        return Ok();
    }
}

Answer 3

理想情况下，您不希望通过手动初始化Email 将控制器与实现问题紧密耦合，因为类应该依赖于抽象而不是具体。

抽象电子邮件类

public interface IEmail {
    Task SendAsync(Contato contato);
}

public class Email: IEmail {
    //...omitted for brevity
}

您可以通过构造函数注入将其注入控制器

public class ContactController : Controller {
    private readonly IEmail email;

    public ContactController(IEmail email) {
        this.email = email;
    }

    public IActionResult Contact() {
        return View(new Contato());
    }

    [HttpPost]
    public async Task<IActionResult> ContactAsync(Contato contato) {        
        await email.SendAsync(contato);
        return Ok();
    }
}

一旦配置正确

services.AddTransient<IEmail, Email>();

容器将在创建注入对象图时解析所有依赖项。

Answer 4

我的提议：

Create IOption 实例并使用此实例初始化您的类电子邮件

using Microsoft.Extensions.Options;

var mail = new ManuelaIbiEmail() { Username= "", Password="" };
IOptions<ManuelaIbiEmail> options = Options.Create(mail);
var email = new Email(options);