C# 如何将数据源转换为 List<T>？
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How to Casting DataSource to List<T>?
提问by Cristhian Boujon
I have the following method that load products on a DataGridView
我有以下方法可以在 DataGridView 上加载产品
private void LoadProducts(List<Product> products)
{
Source.DataSource = products; // Source is BindingSource
ProductsDataGrid.DataSource = Source;
}
And now I'm trying to give me back to save them as shows below.
现在我试图让我回来保存它们，如下所示。
private void SaveAll()
{
Repository repository = Repository.Instance;
List<object> products = (List<object>)Source.DataSource;
Console.WriteLine("Este es el número {0}", products.Count);
repository.SaveAll<Product>(products);
notificacionLbl.Visible = false;
}
But I get an InvalidCastExceptionon this line:
但我InvalidCastException在这条线上得到了一个：
List<object> products = (List<object>)Source.DataSource;
So how can I cast the DataSource to an List?
那么如何将 DataSource 转换为 List 呢？
采纳答案by Dave Bish
You can't cast covariantly directly to List;
您不能直接将协变转换为 List；
Either:
任何一个：
List<Product> products = (List<Product>)Source.DataSource;
or:
或者：
List<Object> products = ((List<Product>)Source.DataSource).Cast<object>().ToList();
回答by CubeSchrauber
Your List ist of type List<Product>which is different from List<object>. Try to cast to List<Product>
您的 List 类型List<Product>不同于List<object>. 尝试投射到List<Product>
回答by Tilak
So how can I cast the DataSource to an List?
那么如何将 DataSource 转换为 List 呢？
You have plenty of options
你有很多选择
var products = (List<Product>)Source.DataSource; // products if of type List<Product>
or
或者
List<Object> products = ((IEnumerable)Source.DataSource).Cast<object>().ToList();
or
或者
List<Object> products = ((IEnumerable)Source.DataSource).OfType<object>().ToList();
or
或者
List<Object> products = new List<Object>();
((IEnumerable)Source.DataSource).AsEnumerable().ToList().ForEach( x => products.Add( (object)x));
回答by Cristhian Boujon
Convining the answers This is my solution:
说服答案这是我的解决方案：
private void SaveAll()
{
Repository repository = Repository.Instance;
List<Product> products = (List<Product>)Source.DataSource;
IEnumerable<object> objects = products.Cast<object>();
repository.SaveAll<Product>(objects.ToList<object>());
notificacionLbl.Visible = false;
}
I accept constructive criticisms.
我接受建设性的批评。
