C# 反序列化 XML 文件到列表

Question

我想將 XML 反序列化為對象列表。

這是我的頂級 C# 課程：

[XmlRoot("Events")]
[XmlType("Events")]
[Serializable]
public class WinEventLogList
{

    public WinEventLogList() { Items = new List<WinEventLog>(); }

    [XmlElement("Event")]
    public List<WinEventLog> Items { get; set; }

}

[XmlRoot("Event")]
[XmlType("Event")]
[Serializable]
public class WinEventLog
{

    [XmlElement("System")]
    [JsonPropertyName("system")]
    public EventSystem System { get; set; } = new EventSystem();

    [XmlElement("EventData")]
    [JsonPropertyName("eventData")]
    public EventData EventData { get; set; } = new EventData();

}

這是我需要反序列化的示例 XML：

<?xml version="1.0" encoding="utf-8"?>
<Events>
  <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
    <System>Omitted tags go in here</System>
    <EventData>Omitted tags go in here</EventData>
  </Event>
  <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
    <System>Omitted tags go in here</System>
    <EventData>Omitted tags go in here</Event>
  <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
    <System>Omitted tags go in here</System>
    <EventData>Omitted tags go in here</EventData>
  </Event>
  <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
    <System>Omitted tags go in here</System>
    <EventData>Omitted tags go in here</EventData>
  </Event>
  <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
    <System>Omitted tags go in here</System>
    <EventData>Omitted tags go in here</EventData>
  </Event>
</Events>

這是我嘗試過的兩種不同方法，都來自這個 stackoverflow 問題。

首先，嘗試使用包裝器 class WinEventLogList

using var stream = File.OpenRead("path/to/my/xml/file.xml");
using var reader = new StreamReader(stream);
var serializer = new XmlSerializer(typeof(WinEventLogList));
var list = serializer.Value.Deserialize(reader) as WinEventLogList;
var winEventLogs = list.Items;

然后，嘗試在序列化程序中直接使用普通List 。

using var stream = File.OpenRead("path/to/my/xml/file.xml");
using var reader = new StreamReader(stream);
var serializer = new XmlSerializer(
    typeof(List<WinEventLog>),  
    new XmlRootAttribute("Events"));
var winEventLogs = serializer.Value.Deserialize(reader) as List<WinEventLog>;

在這兩種情況下，生成的winEventLogs變量都是一個空列表。 為什么會這樣？ 如何糾正？

Answer 1

XML 的一個經常被忽視的組件是名稱空間。 它們實際上是 [反] 序列化過程中不可或缺的一部分。
您幾乎就在那里，只需在 object 中指定名稱空間以匹配 XML。

這是一個工作片段：

void Main() {
  using var reader = new StringReader(xmlStr);
  var serializer = new XmlSerializer(typeof(WinEventLogList));
  var list = (WinEventLogList)serializer.Deserialize(reader)!;
  list.Dump();
}

[XmlRoot("Events")]
public class WinEventLogList {
  // Namespaces are extremely important!
  [XmlElement("Event", Namespace="http://schemas.microsoft.com/win/2004/08/events/event")]
  public List<WinEventLog> Items { get; set; } = new();
}

public class WinEventLog {
  [XmlElement] public int System { get; set; }
  [XmlElement] public int EventData { get; set; }
}

string xmlStr = """
<?xml version='1.0' encoding='utf-8'?>
<Events>
  <Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'>
    <System>1</System>  <EventData>2</EventData>
  </Event>
  <Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'>
    <System>3</System>  <EventData>4</EventData>
  </Event>
</Events>
""";