没有为此对象定义无参数构造函数 - Hangfire调度程序

Question

我刚刚在我的MVC网站上安装了Hangfire包.我创建了一个Startup类

[assembly: OwinStartup(typeof(Website.Startup))]

namespace Website
{
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            Hangfire.ConfigureHangfire(app);
            Hangfire.InitializeJobs();
        }
    }
}

和一个Hangfire课程

public class Hangfire
{
    public static void ConfigureHangfire(IAppBuilder app)
    {
        app.UseHangfire(config =>
        {
            config.UseSqlServerStorage("DefaultConnection");
            config.UseServer();
            config.UseAuthorizationFilters(); 
        });
    }

    public static void InitializeJobs()
    {
        RecurringJob.AddOrUpdate<CurrencyRatesJob>(j => j.Execute(), "* * * * *");
    }
}

另外,我在一个单独的类库中创建了一个新工作

public class CurrencyRatesJob
{
    private readonly IBudgetsRepository budgetsRepository;

    public CurrencyRatesJob(IBudgetsRepository budgetsRepository)
    {
        this.budgetsRepository = budgetsRepository;
    }

    public void Execute()
    {
        try
        {
            var budgets = new BudgetsDTO();
            var user = new UserDTO();

            budgets.Sum = 1;
            budgets.Name = "Hangfire";
            user.Email = "email@g.com";

            budgetsRepository.InsertBudget(budgets, user);
        }
        catch (Exception ex)
        {
            var message = ex.ToString();
            throw new NotImplementedException(message);
        }
    }
}

因此,当我运行应用程序时,在Hangfire的仪表板中,我收到以下错误:

Failed An exception occurred during job activation.
System.MissingMethodException

No parameterless constructor defined for this object.

System.MissingMethodException: No parameterless constructor defined for this object.
   at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
   at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic)
   at System.Activator.CreateInstance(Type type)
   at Hangfire.JobActivator.ActivateJob(Type jobType)
   at Hangfire.Common.Job.Activate(JobActivator activator)

所以,我在这里有点失落.我错过了什么？

Answer 1

您似乎没有将Hangfire连接到您正在使用的IoC容器,因此它使用其默认策略来创建请求的类型,在您的特定示例中,这意味着调用:

System.Activator.CreateInstance(typeof(CurrencyRatesJob));

由于CurrencyRatesJob该类没有默认的无参数构造函数,因此失败并显示您在问题中显示的错误消息.

要将Hangfire连接到IoC基础结构,您需要创建自己的JobActivator类来覆盖该ActivateJob方法,并使用配置的IoC容器来创建所请求的作业类型的实例.

UnityJobActivator可以在此处找到使用Unity作为容器()的示例,可以在此处找到Funqcontainer(FunqJobActivator)的示例.

Hangfire文档中描述了该过程,Hangfire github repo提供了几种容器类型的标准实现