我正试图找到一种方法来简化一些代码，我希望从一种方法获取具有不同结构的数据。
我有以下代码：
public class VmOne
{
private ObservableCollection<Structure1> GetFirstStructCollection()
{
var myList = new List<Structure1>();
myList.Add(new Structure1
{
Id = 1,
Name = "John Doe",
Description = "struct 1 test"
});
myList.Add(new Structure1
{
Id = 2,
Name = "Sally Doe",
Description = "struct 1 test"
});
return new ObservableCollection<Structure1>(myList);
}
private ObservableCollection<Structure2> GetSecondStructCollection()
{
var myList = new List<Structure2>();
myList.Add(new Structure2
{
Id = 1,
Name = "Saphire Doe",
Description = "struct 2 test"
});
myList.Add(new Structure2
{
Id = 2,
Name = "Onyx Doe",
Description = "struct 2 test"
});
return new ObservableCollection<Structure1>(myList);
}
// this wont work....
public ObservableCollection<object> GetDataByIndex(int pIndex)
{
ObservableCollection<object> data;
if (pIndex == 1)
{
data = GetFirstStructCollection();
}
if (pIndex == 2)
{
data = GetSecondStructCollection();
}
return data;
}
}
由
调用public class MyMain
{
public void DoSomething()
{
var job = new VmOne();
var data = job.GetDataByIndex(1);
// .... do something useful with the data
}
}
我无法找到办法做到这一点。可以这样做吗？只需要一点方向。
数据的使用如下，用户选择他们希望维护的学科。每个学科可以有2个或更多与之关联的数据表。他们可以单步执行数据表来执行维护。每张桌子都有自己独特的结构。我想使用一个通用的UI，这样他们只需要选择一个将加载适当的表来维护的规程。
为了做到这一点，我在数组中有表名，当他们从下拉列表中选择时，索引将指向具有表名的数组。然后我想使用索引或表名来调用我的方法来返回数据集合。由于这是一个WPF应用程序，因此数据将在ObservableCollection中返回。
因此该方法将返回ObservableColleciton类型的任意组合....
答案 0 :(得分：2)
我认为你不能按照你想要的方式去做。 如果你定义一个类（t）（vb）或类（c＃），那么你可以创建一个方法dosomething，然后给你一个通用的东西。
我建议定义一个接口，即structure1和structure2实现，并让你的函数返回你的接口的observablecollection。
欢呼声
答案 1 :(得分：0)
你可以尝试沿着这些方向尝试一些东西，虽然你的规格含糊不清，但有点不清楚：
void Main()
{
// call it
VmOne vmOne = new VmOne();
vmOne.GetDataByIndex<Structure1>(GetStructCollection<Structure1>());
// ...
}
// Define other methods and classes here
public class VmOne
{
public ObservableCollection<TStruct> GetStructCollection<TStruct>() where TStruct : class // or base class for the structures if you can do it
{
var myList = new List<TStruct>();
// add to list somehow
return new ObservableCollection<TStruct>(myList);
}
public ObservableCollection<TStruct> GetDataByIndex<TStruct>(System.Action getStructCollection) where TStruct : class
{
ObservableCollection<TStruct> data = getStructCollection<TStruct>();
// ...
return data;
}
}
请记住，这只是您可以尝试做的草图
答案 2 :(得分：0)
你是关于varianza的吗？ ObservableCollection<T>不是共同的，这意味着您可以传递一个ObservableCollection<Tk>，其中Tk是从T继承的。请注意，您可以使用数组执行此操作。
object[] data1 = new Structure1[0]; // is valid becuase array are covariant
ObservableCollection<Structure> data2 = new ObservableCollection<Structure1>(); // compilation error becuase ObservableCollection are not covariant
您可以使用数组，并像这样创建ObservableCollection<object>：
private Structure1[] GetFirstStructCollection()
{
return new[]
{
new Structure1
{
Id = 1,
Name = "John Doe",
Description = "struct 1 test"
},
new Structure1
{
Id = 2,
Name = "Sally Doe",
Description = "struct 1 test"
}
};
}
private Structure2[] GetSecondStructCollection()
{
return new[]
{
new Structure2
{
Id = 1,
Name = "Saphire Doe",
Description = "struct 2 test"
},
new Structure2
{
Id = 2,
Name = "Onyx Doe",
Description = "struct 2 test"
}
};
}
public ObservableCollection<object> GetDataByIndex2(int pIndex)
{
ObservableCollection<object> data = null;
if (pIndex == 1)
{
data = new ObservableCollection<object>(GetFirstStructCollection());
}
if (pIndex == 2)
{
data = new ObservableCollection<object>(GetSecondStructCollection());
}
return data;
}
答案 3 :(得分：0)
您可以使用泛型执行类似于您想要的操作：
class Zoo
{
public ObservableCollection<T> GetData<T>() where T : class
{
if (typeof(T) == typeof(Cat))
return new ObservableCollection<T>(this.GetCatCollection().Cast<T>().ToList());
// or:
// return new ObservableCollection<T>(Cat.GetDefaultCollection().Cast<T>().ToList());
if (typeof(T) == typeof(Dog))
return new ObservableCollection<T>(Dog.GetDefaultCollection().Cast<T>().ToList());
if (typeof(T) == typeof(Lion))
return new ObservableCollection<T>(Lion.GetDefaultCollection().Cast<T>().ToList());
return null;
// pseudo-switch version
//ObservableCollection<T> result = null;
//var @switch = new Dictionary<Type, Action> {
//{ typeof(Cat), () => result = new ObservableCollection<T>(Cat.GetDefaultCollection().Cast<T>().ToList()) },
//{ typeof(Dog), () => result = new ObservableCollection<T>(Dog.GetDefaultCollection().Cast<T>().ToList())},
//{ typeof(Lion), () => result = new ObservableCollection<T>(Lion.GetDefaultCollection().Cast<T>().ToList())}};
//@switch[typeof(T)]();
//return result;
}
private ObservableCollection<Cat> GetCatCollection()
{
ObservableCollection<Cat> list = new ObservableCollection<Cat>();
list.Add(new Cat { CatName = "Cat No. 1" });
list.Add(new Cat { CatName = "Cat No. 2" });
list.Add(new Cat { CatName = "Cat No. 3" });
return list;
}
}
class Cat
{
public string CatName { get; set; }
public static ObservableCollection<Cat> GetDefaultCollection()
{
ObservableCollection<Cat> list = new ObservableCollection<Cat>();
list.Add(new Cat { CatName = "Cat No. 1" });
list.Add(new Cat { CatName = "Cat No. 2" });
list.Add(new Cat { CatName = "Cat No. 3" });
return list;
}
}
class Dog
{
public string DogName { get; set; }
public static ObservableCollection<Dog> GetDefaultCollection()
{
ObservableCollection<Dog> list = new ObservableCollection<Dog>();
list.Add(new Dog { DogName = "Dog No. 1" });
list.Add(new Dog { DogName = "Dog No. 2" });
list.Add(new Dog { DogName = "Dog No. 3" });
return list;
}
}
class Lion
{
public string LionName { get; set; }
public static ObservableCollection<Lion> GetDefaultCollection()
{
ObservableCollection<Lion> list = new ObservableCollection<Lion>();
list.Add(new Lion { LionName = "Lion No. 1" });
list.Add(new Lion { LionName = "Lion No. 2" });
list.Add(new Lion { LionName = "Lion No. 3" });
return list;
}
}
使用示例：
var zoo = new Zoo();
ObservableCollection<Cat> cats = zoo.GetData<Cat>();
ObservableCollection<Dog> dogs = zoo.GetData<Dog>();
ObservableCollection<Lion> lions = zoo.GetData<Lion>();
Console.WriteLine("-------------- Cats:");
cats.ToList().ForEach(cat => Console.WriteLine(cat.CatName));
Console.WriteLine("-------------- Dogs:");
dogs.ToList().ForEach(dog => Console.WriteLine(dog.DogName));
Console.WriteLine("-------------- Lions:");
lions.ToList().ForEach(lion => Console.WriteLine(lion.LionName));
结果：
-------------- Cats:
Cat No. 1
Cat No. 2
Cat No. 3
-------------- Dogs:
Dog No. 1
Dog No. 2
Dog No. 3
-------------- Lions:
Lion No. 1
Lion No. 2
Lion No. 3