Entity framework 如何在ASP.NET Core 2.0中将选项从Startup.cs传递到DbContextOptions构造函数函数

我正在使用ASP.NET Core 2.0

在Startup.cs我有

services.AddDbContext<MailDBServicesContext>(optionsSqLite =>
        {
            optionsSqLite.UseSqlite("Data Source=Mail.db");
        });

---

例如，只需将

maildbservicecontext

注入控制器或服务类就足够了

public class SomeDataService
{
    private readonly MailDBServicesContext _dbContext;

    public SomeDataService(MailDBServicesContext dbContext)
    {
        _dbContext = dbContext ?? throw new ArgumentNullException(nameof(dbContext));
    }

    public async Task AddMailCounts()
    {
        _dbContext.DbSetMailCountSentErrorMails
            .Add(new MailCountSentErrorMails { CountSentMails = 55 });
        await _dbContext.SaveChangesAsync();
    }
}

其他数据库上下文配置选项在MSDN上的中定义

更新

确保在DI中注册您的服务，即

ConfigureServices

方法

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<ISomeDataService, SomeDataService>();
    services.AddDbContext<MailDBServicesContext>(optionsSqLite =>
    {
        optionsSqLite.UseSqlite("Data Source=Mail.db");
    });

    services.AddMvc();
}

现在，每次加载主页时，都会在

DbSetMailCountSentErrorMails

表中插入一条记录

---

您可以在my.

上找到有效的解决方案。您不必

新建它。让DI为您在类中注入它。抱歉，Shyju，我找不到您如何共享一些代码。我收到错误：{System.NullReferenceException:Object reference未设置为对象的实例。在TestApp.MyServices.MailClass.d__1.MoveNext（）尝试调用时：\ dbContext.DbSetMailCountSentErrorMails.Add（new-MailCountSentErrorMails（）{countSentMails=55}）；我已经更新了我的答案，并在我的GitHub上添加了一个示例。这有帮助吗？非常感谢您的帮助，现在它正在工作！@AG70您应该单击上下投票按钮下的复选标记，将Ignas的答案标记为问题的答案。
public class SomeDataService
{
    private readonly MailDBServicesContext _dbContext;

    public SomeDataService(MailDBServicesContext dbContext)
    {
        _dbContext = dbContext ?? throw new ArgumentNullException(nameof(dbContext));
    }

    public async Task AddMailCounts()
    {
        _dbContext.DbSetMailCountSentErrorMails
            .Add(new MailCountSentErrorMails { CountSentMails = 55 });
        await _dbContext.SaveChangesAsync();
    }
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<ISomeDataService, SomeDataService>();
    services.AddDbContext<MailDBServicesContext>(optionsSqLite =>
    {
        optionsSqLite.UseSqlite("Data Source=Mail.db");
    });

    services.AddMvc();
}

public class HomeController : Controller
{
    private readonly ISomeDataService _dataService;

    public HomeController(ISomeDataService dataService)
    {
        _dataService = dataService ?? throw new ArgumentNullException(nameof(dataService));
    }

    public IActionResult Index()
    {
        _dataService.AddMailCounts();

        return View();
    }
}