將XML反序列化爲對象返回空值

Question

我想反序列化一個XML文檔，但我使用的代碼每次都返回Null值。

我有這樣

<?xml version="1.0" encoding="utf-8"?> 
<RegistrationOpenData xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://example.gov"> 
<Description>Registration data is collected by ABC XYZ</Description> 
<InformationURL>http://www.example.com/html/hpd/property-reg-unit.shtml</InformationURL> 
<SourceAgency>ABC Department of Housing</SourceAgency> 
<SourceSystem>PREMISYS</SourceSystem> 
<StartDate>2016-02-29T00:03:06.642772-05:00</StartDate> 
<EndDate i:nil="true" /> 
<Registrations> 
<Registration xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> 
<RegistrationID>108260</RegistrationID> 
<BuildingID>4731</BuildingID> 
</Registration> 
</Registrations> 
</RegistrationOpenData> 

一個XML反序列化它，我創建了一個類

using System.Xml.Serialization; 
using System.Xml; 
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.1")] 
[System.SerializableAttribute()] 
[System.Diagnostics.DebuggerStepThroughAttribute()] 
[System.ComponentModel.DesignerCategoryAttribute("code")] 
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://example.gov")] 
[System.Xml.Serialization.XmlRootAttribute(Namespace="http://example.gov", IsNullable=true)] 
public partial class Registration : InfoClass { 

    private long registrationIDField; 
    private bool registrationIDFieldSpecified; 
    private System.Nullable<long> buildingIDField; 
    private bool buildingIDFieldSpecified; 

    public long RegistrationID 
{ 
    get 
    { 
     return this.registrationIDField; 
    } 
    set 
    { 
     this.registrationIDField = value; 
    } 
} 
[System.Xml.Serialization.XmlIgnoreAttribute()] 
public bool RegistrationIDSpecified { 
    get { 
     return this.registrationIDFieldSpecified; 
    } 
    set { 
     this.registrationIDFieldSpecified = value; 
    } 
} 

[System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] 
public System.Nullable<long> BuildingID { 
    get { 
     return this.buildingIDField; 
    } 
    set { 
     this.buildingIDField = value; 
    } 
} 

[System.Xml.Serialization.XmlIgnoreAttribute()] 
public bool BuildingIDSpecified { 
    get { 
     return this.buildingIDFieldSpecified; 
    } 
    set { 
     this.buildingIDFieldSpecified = value; 
    } 
} 

和我使用的代碼

public void Test() 
    { 

     Registration RegistrationVal = null; 
     var xRoot = new XmlRootAttribute(); 
     xRoot.ElementName = "RegistrationOpenData"; 
     xRoot.Namespace = "http://services.hpd.gov"; 
     xRoot.IsNullable = true; 
     var serializer = new XmlSerializer(typeof(Registration), xRoot); 
     using (TextReader reader = new StreamReader(@"D:\sample.xml")) 
      { 
       RegistrationVal = (Registration)serializer.Deserialize(reader); 
      } 
} 

這總是返回空值。 在此先感謝您的幫助。

Answer 1

你的問題是在XML中，因爲它有一個註冊列表。如果你刪除<Registration>和<Registrations>標籤，那麼它的工作原理。你需要Registration和Registrations，因爲在這種情況下，你必須使用Lists。

你能做到這一點就像這個例子（Deserializing nested xml into C# objects）

，並創建自己的類Registrations持有Registration的List元素。

有了這段代碼，它的工作原理。創建一個超類：

[XmlRoot("RegistrationOpenData")] 
public class RegistrationOpenData 
{ 
    [XmlElement("Registrations")] 
    public Registrations Regs { get; set; } 
} 

和Registrations：

[XmlRoot("Registrations")] 
public class Registrations 
{ 
    [XmlElement("Registration")] 
    public List<Registration> Regs { get; set; } 
} 

和Registration應該是和以前一樣。 主要功能應改爲：

static void Main(string[] args) 
{ 
     RegistrationOpenData RegistrationVal = null; 
     var xRoot = new XmlRootAttribute(); 
     xRoot.ElementName = "RegistrationOpenData"; 
     xRoot.Namespace = "http://services.hpd.gov"; 
     xRoot.IsNullable = true; 
     var serializer = new XmlSerializer(typeof(RegistrationOpenData), xRoot); 
     using (TextReader reader = new StreamReader(@"D:\sample.xml")) 
     { 
      RegistrationVal = (RegistrationOpenData)serializer.Deserialize(reader); 
     } 
}