CODEWITHSUNDEEP
c#generics
Adam Levitt
Adam Levitt

Reputation: 10476

C# Extend Generic Class in Method call

I'm trying to write a method that passes a generic argument that will extend a class with a generic argument, but I don't want to have to pass a second generic argument to the method. Is there a way to achieve what I'm trying to do without passing two generic arguments?

// this base doesn't work because it expects a BaseReportViewModel<D> 
// I don't want to have to pass in two generic arguments from the child controller
// this is what I don't want to do: this.ReportView<Report1ViewModel, Report1Data>(viewModel);
// I want to ONLY have to pass in a single generic argument. 

public class BaseController {
  // the below line won't compile because it expects a generic type to be passed to BaseReportViewModel<>
  public ActionResult ReportView<T>(T viewModel) where T : BaseReportViewModel {
    viewModel.ReportGroup = this.ReportGroup;
    viewModel.ReportTitle = this.ReportTitle;
    return this.View(viewModel);
  }
}

public class ChildController {  
  var viewModel = new Report1ViewModel();               
  viewModel.Data = new Report1Data();
  return this.ReportView<Report1ViewModel>(viewModel);            
}

public class BaseReportViewModel<T> : BaseViewModel where T : ReportBaseData {
  public string ReportGroup { get; set; }
  public string ReportTitle { get; set; }
  public T Data { get; set; }
}

public class Report1ViewModel : BaseReportViewModel<Report1Data> {
}

public class Report1Data : BaseReportData {
}

Upvotes: 3

Views: 239

Answers (1)

Alexei Levenkov
Alexei Levenkov

Reputation: 100527

I think you want something like this 

public ActionResult ReportView<T>(BaseReportViewModel<T> viewModel) 
    where T : ReportBaseData

Side note: You also should not need to pass type in this.ReportView<Report1ViewModel>(viewModel); call, just ReportView(viewModel); should be enough as type should be derived from the argument.

Upvotes: 4

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