使用强类型的XSD错误deserialising XML文档 [英] Error deserialising XML document with strongly typed XSD

问题描述

我遇到一个很烦人的问题，而试图用deserialise XmlSerializer.Deserialize（）方法的特定的XML文档。

I am running into quite an annoying issue while trying to deserialise a specific XML document using XmlSerializer.Deserialize() method.

基本上，我有一个强类型的XSD DOUBLE类型的元素。当试图deserialise元素有特定的XML文档，我得到了一贯的System.FormatException：输入字符串的不正确的格式。异常是因为特定文件中，元素不具有价值。

Basically, I have a strongly typed XSD with an element of type double. When trying to deserialise the element for a specific XML document, I get the usual "System.FormatException: Input string was not in a correct format." exception because in that specific document, the element does not have a value.

下面是为您的书呆子在那里一些代码。

Here is some code for you nerds out there.

的示例XML文档：

<TrackInfo>
  <Name>Barcelona</Name>
  <Length>4591</Length>
  <AverageSpeed />
</TrackInfo>

XSD：

<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="TrackInfo">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Name" type="xs:string" />
      <xs:element name="Length" type="xs:double" default="0.0" />
      <xs:element name="AverageSpeed" type="xs:double" default="0.0" />
    </xs:sequence>
  </xs:complexType>
</xs:element>

TrackInfo类：

[Serializable]
public class TrackInfo
{
  private string name = string.Empty;
  private double length = 0.0;
  private double averageSpeed = 0.0;

  [XmlElement]
  public string Name
  { ... }

  [XmlElement]
  public double Length
  { ... }

  [XmlElement]
  public double AverageSpeed
  { ... }
}

样品deserialisation代码：

XmlDocument xmlDocument = new XmlDocument();
xmlDocument.Load("TrackInfo.xml");

// Deserialise XML string into TrackInfo object
byte[] buffer = ASCIIEncoding.UTF8.GetBytes(xmlDocument.InnerXml);
MemoryStream stream = new MemoryStream(buffer);
System.Xml.XmlReader reader = new System.Xml.XmlTextReader(stream);

XmlSerializer xSerializer = new System.Xml.Serialization.XmlSerializer(typeof(TrackInfo));
TrackInfo trackInfo = (TrackInfo)xSerializer.Deserialize(reader);

我知道deserialisation例外来自于一个事实，一个空字符串不能转换为double。我也知道这一点，因为有效，空字符串是一个完全可以接受的值的默认值没有分配给AverageSpeed。

I know that the deserialisation exception comes from the fact that an empty string cannot be converted to a double. I also know that the default value is not assigned to AverageSpeed because, effectively, an empty string is a perfectly acceptable value.

有一种简单的方式来默认双值0.0（或任何其他类型）deserialising时，如果一个空字符串值在XML文档中发现了什么？
理想情况下，我想，以避免实施ISerializable的，因为我不觉得自己是这一天的休息花费入地狱燃烧坑（即实施了ISerializable约一百班）。

Is there an easy way to default double values to 0.0 (or any other type) when deserialising if an empty string value is found in the XML document? Ideally, I would like to avoid implementing ISerializable because I don't really feel like spending the rest of the day into the burning pit of hell (i.e. implementing ISerializable for about a hundred classes).

干杯！
让 - 米歇尔·

Cheers! Jean-Michel

推荐答案

您可以指定像

    [XmlElement]
    [System.ComponentModel.DefaultValueAttribute(0.0)]
    public double AverageSpeed
    { ... }

/编辑：好吧，怪beaviour在这里。无论我设定为它总是域值的属性值：

/edit: ok, strange beaviour here. Whatever I set as value in the Attribute it's always the fields value:

private double averageSpeed = 2.0;

但没有异常发生。

But no exception occurs.

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