在C＃中将参数传递给Func <>的最佳方法是什么？

Question

我有以下代码：

public void Test(Request request, Func<IEnumerable<Building>> buildings) 
{ 
    vm.Buildings = Helper.GenerateDropdownList(request.BuildingId,() => buildings()); 
} 

我现在想要一个额外的参数传递给buildings()回调

public void Test(Request request, Func<IEnumerable<Building>> buildings) 
{ 
    var cityId = GetCity(); 
    vm.Buildings = Helper.GenerateDropdownList(request.BuildingId,() => buildings(cityId)); 
} 

什么是输入该参数的正确方法？

Answer 1

您的buildings代表需要是Func<T, TResult>而不是Func<TResult>。

假设cityId是int：

public void Test(Request request, Func<int, IEnumerable<Building>> buildings) 
{ 
    var cityId = GetCity(); 
    m.Buildings = Helper.GenerateDropdownList(request.BuildingId, 
              () => buildings(cityId)); 
}