创建一个新的AnonymousType实例 [英] Create a new AnonymousType instance
问题描述
我正在尝试创建一个AnonymousType实例,如下所示:
I'm trying to create an AnonymousType instance looks like:
new { Channel = g.Key.Channel, Comment = g.Key.Comment, Count = g.Count() }
在黑暗中,.NET使用带有三个参数的构造函数创建一个AnonymousType:String, String, Int32
.
On the dark, .NET creates an AnonymousType with a constructor that takes three arguments: String, String, Int32
.
为了创建这种匿名类型T的新实例,我要做:
In order to create a new instance of this anonymous type, T, I do:
object[] args = new object[3];
args[0] = "arg1";
args[1] = "arg2";
args[2] = 200;
(T)Activator.CreateInstance(typeof(T), args);
.NET转储了我
其他信息:在'<> f__AnonymousType2`3 [[System.String,...],[System.String,...],[System.Int32,...]]'中找不到构造函数.
Additional information: Constructor not found in '<>f__AnonymousType2`3[[System.String, ...],[System.String, ...],[System.Int32, ...]]'.
我不知道为什么CreateInstance
试图调用类似[[],[],[]]的构造函数!
I don't know why CreateInstance
is trying to call a constructor like [[],[],[]]!
范围
真正的范围很难解释:
我创建了一个Linq提供程序.该提供程序将Linq句子翻译为我的服务器方法.当我收到json信息时,我需要将此信息投影到指定的Type用户.在这种情况下:
I've created a Linq provider. This provider translates Linq sentences to my server methods. When I receive json information I need to project this information to whichever Type user has specified. In this case:
var enumerable = UIContainer.UIController.Instance.getDigitalInputs()
.GroupBy(di => new { Channel = di.Channel, Comment = di.Comment })
.Select(g => new { Channel = g.Key.Channel, Comment = g.Key.Comment, Count = g.Count() });
因此,我需要将每个json项目投影到new { Channel = g.Key.Channel, Comment = g.Key.Comment, Count = g.Count() })
.最后,我需要创建这种匿名类型的实例.
So, I need to project each json item to a new { Channel = g.Key.Channel, Comment = g.Key.Comment, Count = g.Count() })
. At the end I need to create an instance of this anonymous type.
所以:
// make the HTTP request
IRestResponse response = (IRestResponse) this.client.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams, authSettings);
if (((int)response.StatusCode) >= 400) {
throw new ApiException (response.StatusCode, "Error calling Search: " + response.Content, response.Content);
}
Newtonsoft.Json.Linq.JArray feeds = Newtonsoft.Json.Linq.JArray.Parse(response.Content);
if (feeds.Any())
{
PropertyDescriptorCollection dynamicProperties = TypeDescriptor.GetProperties(feeds.First());
foreach (dynamic feed in feeds)
{
object[] args = new object[dynamicProperties.Count];
int i = 0;
foreach (PropertyDescriptor prop in dynamicProperties)
{
args[i++] = prop.GetValue(feed);
}
//args[0] = "";
//args[1] = "";
//args[2] = 2;
yield return (T)Activator.CreateInstance(typeof(T), args);
}
}
推荐答案
不确定从哪里获取T
,但是如果您使用前一个变量的匿名类型,则代码可以正常工作:
Not sure where you obtain T
, but the code works fine if you use the anonymous type from the previous variable:
var x = new { Channel = "Channel", Comment = "Comment", Count = 1 };
object[] args = new object[3];
args[0] = "arg1";
args[1] = "arg2";
args[2] = 200;
var y = Activator.CreateInstance(x.GetType(), args);
(然后回复Luaan:.NET使用匿名类型的构造函数,请参见IL:)
(And in to reply to Luaan: .NET uses a constructor for anonymous types, see the IL:)
.method public hidebysig specialname rtspecialname
instance void .ctor(!'<Channel>j__TPar' Channel,
!'<Comment>j__TPar' Comment,
!'<Count>j__TPar' Count) cil managed
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