[英]Mongo DB - Issue with a List<string> Nested in a Dictionary<string, object>- c# Driver
I'm getting the following error when retrieving a document from MongoDB:从 MongoDB 检索文档时出现以下错误:
"Unable to determine actual type of object to deserialize. NominalType is System.Object and BsonType is Array."
“无法确定要反序列化的 object 的实际类型。NominalType 是 System.Object,BsonType 是 Array。”
The object that I'm serializing has a Dictionary<string, object>
property.我正在序列化的 object 具有
Dictionary<string, object>
属性。 I can put a simple string in the Dictionary and pull it out without getting an error, but if there is a List<string>
then I get the deserialization error.我可以在 Dictionary 中放入一个简单的字符串并将其拉出而不会出现错误,但如果存在
List<string>
则会出现反序列化错误。
I'm using the official c# driver (v 1.1).我正在使用官方的 c# 驱动程序(v 1.1)。 I can query the document just fine using Mongo shell, so I'm pretty it's an issue with MongoDB.Bson.
我可以使用 Mongo shell 很好地查询文档,所以我很高兴这是 MongoDB.Bson 的问题。
Any suggestions/workarounds?有什么建议/解决方法吗?
Code sample as requested:根据要求的代码示例:
Example object being saved to MongoDB:示例 object 被保存到 MongoDB:
public class WebUser
{
public int _id;
private DateTime startTime;
private DateTime stopTime;
private string browser;
private string sessionID;
private string ip;
public List<PageView> PageViews;
public Dictionary<string, Object> Session;
public Save(){/*Data access code here*/}
public static Single(int id){/*Data access code here*/}
}
Data Access Code:数据访问代码:
public T Single<T>(int id) where T : class, new()
{
var server = MongoServer.Create(ConnectionString);
var db = server.GetDatabase(DBName);
var collection = db.GetCollection<T>(typeof(T).Name);
var value = collection.FindOneById(id);
server.Disconnect();
return value;
}
This works just fine:这工作得很好:
var wu = WebUser.single(1);
wu.Session.Add("string key", "value");
wu.Session.Add("int key", 1);
wu.Save();
wu = WebUser.single(1);
This is where I get an error:这是我收到错误的地方:
var wu = WebUser.single(1);
wu.Session.Add("list of values", new List<string>() { "yada", "yada 2", "yada 3" });
wu.Save();
//deserialize error on the retrieve below
wu = WebUser.single(1);
I think the following simple example reproduces the issue.我认为以下简单示例重现了该问题。 Use class:
使用 class:
public class C {
public ObjectId Id;
public object Obj;
}
and the following test code:和以下测试代码:
collection.RemoveAll();
var c = new C { Obj = new int[] { 1, 2, 3 } };
collection.Insert(c);
var r = collection.FindOneAs<C>(); // fails
The problem is that the document was serialized as:问题是文档被序列化为:
> db.test.find()
{ "_id" : ObjectId("4e15b931e447ad6a54eb0114"), "Obj" : [ 1, 2, 3 ] }
>
and the value for "Obj" has no type information, so the deserializer doesn't know what class to instantiate for "Obj".并且“Obj”的值没有类型信息,因此反序列化器不知道要为“Obj”实例化什么 class。
I've create a JIRA ticket for this:我为此创建了一张 JIRA 票证:
https://jira.mongodb.org/browse/CSHARP-263 https://jira.mongodb.org/browse/CSHARP-263
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