将 BsonArray 映射到列表在 POCO [英] Mapping a BsonArray to a List<> in a POCO

问题描述

我使用的是 本教程了解如何将 Mongo 数据库中的文档映射到 POCO 对象.

I was using this tutorial to learn about mapping documents in a Mongo database to POCO objects.

我的文档是这样设置的:

My documents are setup like this:

{
  "VehicleEntry" : [
      {
          "BatteryStatus" : "GOOD",
          "VehicleStatus" : "PASSED"
      }, 
      {
          "BatteryStatus" : "GOOD",
          "VehicleStatus" : "PASSED"
      }
  ],
  "project_id" : "1234"
}

要注意的主要事情是我在每个文档中都有一个名为 VehicleEntry 的数组.我已经设置了 POCO 来匹配这样的文档:

The main thing to notice about this is that I have an array inside of each document called VehicleEntry. I have setup POCOs to match the documents like this:

public class VehicleEntry : MongoEntity
{
    [BsonElement("@Date")]
    public String Date { get; set; }

    [BsonElement("@Time")]
    public String Time { get; set; }

    [BsonElement("@Vin")]
    public String Vin { get; set; }

    [BsonElement("@Year")]
    public String Year { get; set; }

    [BsonElement("@Body")]
    public String Body { get; set; }

    [BsonExtraElements]
    public BsonDocument ExtraElements { get; set; }
}

public class VehicleDataUpload : MongoEntity
{
    public VehicleDataUpload()
    {
        VehicleEntries = new List<VehicleEntry>();
    }

    [BsonElement("project_id")]
    public String ProjectId { get; set; }

    [BsonElement("VehicleEntry")]
    public List<VehicleEntry> VehicleEntries { get; set; }

    [BsonExtraElements]
    public BsonDocument ExtraElements { get; set; }
}

为了测试这一点，我写了一个简单的行来提取使用给定项目标识符找到的第一个文档:

To test this, I wrote one simple line that pulls for the first document found with a given project identifier:

var collection = database.GetCollection<VehicleDataUpload>("vehicleCollection");
var firstProj = collection.AsQueryable().Where(i => i.ProjectId.Equals("myProjIdentifier")).First();

但是，当我运行它时，出现以下异常:

However, when I run it I get the following exception:

附加信息:反序列化类 CARRSMongoTest.VehicleDataUpload 的 VehicleEntries 属性时出错:无法反序列化 BsonType 'Document' 中的 'List'.

Additional information: An error occurred while deserializing the VehicleEntries property of class CARSMongoTest.VehicleDataUpload: Cannot deserialize a 'List' from BsonType 'Document'.

我认为这很简单，因为 VehicleEntry 的类型无法转换为 List<> 对象，但我不知道该怎么做它.当它应该将 VehicleEntry 视为数组类型时，我有点困惑为什么它在错误消息中说类型文档".

I think this is pretty straight forward, as the type of VehicleEntry cannot be converted to a List<> object, but I'm not sure how to do it. I'm a little confused why it says type 'Document' in the error message, when it should treat VehicleEntry as an Array type.

如何将数组映射到 POCO 的属性?

How can I map the array to a property of the POCO?

编辑我已尝试更改 VehicleEntry，使其不从 MongoEntity 扩展，但错误仍然存​​在.

EDIT I have tried changing VehicleEntry so it doesn't extend from MongoEntity, but the error still persists.

推荐答案

好吧，我意识到这失败的原因是因为我的错误.我们的大多数项目都会有多个车辆条目，但碰巧的是，我正在测试的项目在 XML 中只有一个，因此反序列化将其转换为 Document，而不是 BsonArray.

Well, I realized that the reason this was failing was because of an error on my end. Most of our projects will have multiple vehicle entries, but by chance the one I was testing with only had one in the XML, so the deserialization converted it to a Document, not to a BsonArray.

上面的代码可以工作，假设 VehicleEntry 字段实际上是 BsonArray 类型，驱动程序会将其映射到 List 对象.

The above code will work, assuming the VehicleEntry field is in fact of type BsonArray, the driver will map it to a List object.

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