遇到 CS0310 错误时如何在构造函数中使用参数

Question

我为调度作业创建了以下抽象：

public abstract class BaseJob
{
    public string? JobId { get; set; }
}

public interface IJobData
{ }

public interface IJob<in TJobData> where TJobData : IJobData
{
    Task ExecuteAsync(TJobData jobData);
}

我使用工厂创建工作：

public class JobCreator<TJob, TJobData>
    where TJob : IJob<TJobData>, new()
    where TJobData : IJobData
{
    public async Task ExecuteAsync(TJobData jobData)
    {
        var job = new TJob();
        await job.ExecuteAsync(jobData);
    }
}

示例实现：

public record ForgotPasswordJobData() : IJobData;

public class ForgotPasswordJob: BaseJob, IJob<ForgotPasswordJobData>
{
    private readonly IMailService _mailer;

    public ForgotPasswordJob(IMailer mailer)
    {
        _mailer = mailer;
    }

    public Task ExecuteAsync(ForgotPasswordJobData jobData)
    {
       // Do something
       // Send mail
    }
}

这是一个作业的排队方式：

JobClient.Enqueue<JobCreator<ForgotPasswordJob, ForgotPasswordJobData>>(job => job.ExecuteAsync(jobData));

因为 ForgetPasswordJob 没有无参数构造函数，所以我得到一个 CS0310 错误，这就是说

“ForgotPasswordJob”类型必须是非抽象类型，具有公共 无参数构造函数，以便将其用作参数“参数” 在泛型类型或方法 'JobCreator'

如何在 IJob 的实现中使用依赖项？

Answer 1

您需要告诉您的JobCreater 如何实例化TJob：

public class JobCreator<TJob, TJobData>
where TJob : IJob<TJobData>
where TJobData : IJobData
{
    public async Task ExecuteAsync(Func<TJob> createJob, TJobData jobData)
    {
        var job = createJob();
        await job.ExecuteAsync(jobData);
    }
}


var mailService = new MailService();
JobClient.Enqueue<JobCreator<ForgotPasswordJob, ForgotPasswordJobData>>(
    job => job.ExecuteAsync(() => new ForgotPasswordJob(mailService), jobData));

---

虽然我不确定JobCreator 是否真的有必要

您可以更改您的 JobClient 以接受已经实例化的作业，考虑到它不依赖 Enqueue 中的任何内容：

void Enqueue<TJob, TJobData>(TJob job, TJobData jobData)
where TJob : IJob<TJobData>
where TJobData : IJobData
{
    // ...
    Task jobTask = job.ExecuteAsync(jobData);
    // ...
}

var forgotPasswordJob = new ForgotPasswordJob(new MailService());
JobClient.Enqueue(forgotPasswordJob, jobData);