如何将使用键的 XML 反序列化为对象

Question

I have an ASP.NET core 2.1 MVC project and I am retrieving data from a Serlilog MSSqlServr Sink that stores values in a Properties field as an XML data type. I want to deserialize that data into a viewmodel so I can present the individual elements as data in a view.

Here is an example of the XML from the Properties field in the database Logs table.

<properties>
  <property key="EventId">
    <structure type="">
      <property key="Id">404</property>
    </structure>
  </property>
  <property key="ActionId">0592d9e8-f4fd-459f-96b3-2b787d01a754</property>
  <property key="ActionName">API.Controllers.CompletionsController.GetCompletion (PS.API)</property>
  <property key="RequestId">0HLJ2IL5A9:00000001</property>
  <property key="RequestPath">/api/completions/0</property>
  <property key="CorrelationId" />
  <property key="ConnectionId">0HLJ2IL59</property>
  <property key="MachineName">RD0003FF1</property>
  <property key="ThreadId">117</property>
</properties>

I set up a class for the decoding as follows;

using System.Xml.Serialization;

namespace PS.Models.ApiLogs
{
    [XmlRoot("properties")]
    public class LogProperties
    {

        [XmlElement("SourceContext")]
        public string SourceContext { get; set; }

        [XmlElement("ActionId")]
        public string ActionId { get; set; }

        [XmlElement("ActionName")]
        public string ActionName { get; set; }

        [XmlElement("RequestId")]
        public string RequestId { get; set; }

        [XmlElement("RequestPath")]
        public string RequestPath { get; set; }

        [XmlElement("CorrelationId")]
        public string CorrelationId { get; set; }

        [XmlElement("ConnectionId")]
        public string ConnectionId { get; set; }

        [XmlElement("MachineName")]
        public string MachineName { get; set; }

        [XmlElement("ThreadId")]
        public string ThreadId { get; set; }

    }
}

And in my controller, I have the following code;

        var serializer = new XmlSerializer(typeof(LogProperties));

        LogProperties logProperties;

        using (TextReader reader = new StringReader(log.Properties))
        {
            logProperties = (LogProperties)serializer.Deserialize(reader);
        }

But the logProperties variable does not contain anything, so I assume I have the XML attributes incorrect in the LogProperties class.

I have spent quite a bit of time searching for a solution and I reviewed all of the related posts while entering this question but I am not able to find an example where the XML is using "property key=" or how to deal with a "key=" attribute property (if that is the correct term)

Any ideas?

[UPDATE 2/21/19]

I ended up using @jdweng suggestion as it was the least complex and gave me exactly what I wanted.

I created 2 classes (as I like to keep my class files separated as a personal pref.). The classes are below;

using System.Collections.Generic;
using System.Xml.Serialization;

namespace PS.Models.ApiLogs
{
    [XmlRoot("properties")]
    public class LogProperties
    {
        [XmlElement("property")]
        public List<LogProperty> Property { get; set; }

    }
}

and

using System.Xml.Serialization;

namespace PS.Models.ApiLogs
{
    [XmlRoot("property")]
    public class LogProperty
    {
        [XmlAttribute("key")]
        public string Key { get; set; }
        [XmlText]
        public string Value { get; set; }
    }
}

Then in my Controller, I have the following for the Detail method;

        var response = await _client.GetLogAsync(id, $"api/logs", token);
        if (response == null)
        {
            return NotFound($"Unable to find a record for Log ID [{id}].");
        }

        var log = _mapper.Map<DetailLogViewModel>(response.Record);

        var serializer = new XmlSerializer(typeof(LogProperties));

        LogProperties logProperties;

        using (TextReader reader = new StringReader(log.Properties))
        {
            logProperties = (LogProperties)serializer.Deserialize(reader);
        }

        var logWithProperties = new DetailLogWithPropertiesViewModel
        {
            Id = log.Id,
            Message = log.Message,
            TimeStamp = log.TimeStamp,
            Exception = log.Exception,
            XmlProperties = logProperties 
        };


        return View(logWithProperties);

My DetailLogWithPropertiesViewModel is below;

public class DetailLogWithPropertiesViewModel
{
    public int Id { get; set; }

    [Display(Name = "Message")]
    public string Message { get; set; }

    [Display(Name = "Level")]

    public string Level { get; set; }

    [Display(Name = "Time Stamp")]
    public DateTimeOffset TimeStamp { get; set; }

    [Display(Name = "Exception")]
    public string Exception { get; set; }

    [Display(Name = "Properties")]
    public string Properties { get; set; }

    public LogProperties XmlProperties { get; set; }

}

And the relevant portion of my Detail.cshtml is below;

<div class="card-body ml3 mr3">


    @foreach (var logProperty in Model.XmlProperties.Property)
    {
        <div class="row">
            <div class="col-4 bg-light border border-primary">
                <span class="font-weight-bold">@logProperty.Key</span>
            </div>
            <div class="col-8 bg-secondary border border-left-0 border-primary">
                <span>@logProperty.Value</span>
            </div>
        </div>


    }

</div>

The XML that is generated by Serilog and stored in the MS SQL Database has a variable number of properties, which I now understand are represented as key/value pairs. So this method allows me to ensure that all of the provided properties are displayed in the log viewer of the website.

Answer 1

Try following :

    [XmlRoot("properties")]
    public class LogProperties
    {

        [XmlElement("property")]
        public List<LogProperty> property { get; set; }

    }
    [XmlRoot("property")]
    public class LogProperty
    {
        [XmlAttribute("key")]
        public string key { get; set; }
        [XmlText]
        public string value { get; set; }
    }

Answer 2

1) Copy your XML to clipboard...
2) ...Open Visual Studio and create an empty cs file...
3) ...go to EDIT > Paste Special > XML to classes ( might require ASP.NET webdevelopment to be installed )...
3) ...will result in this code:

/// <remarks/>
[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
[System.Xml.Serialization.XmlRootAttribute(Namespace = "", IsNullable = false)]
public partial class properties
{

    private propertiesProperty[] propertyField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute("property")]
    public propertiesProperty[] property
    {
        get
        {
            return this.propertyField;
        }
        set
        {
            this.propertyField = value;
        }
    }
}

/// <remarks/>
[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
public partial class propertiesProperty
{

    private propertiesPropertyStructure structureField;

    private string[] textField;

    private string keyField;

    /// <remarks/>
    public propertiesPropertyStructure structure
    {
        get
        {
            return this.structureField;
        }
        set
        {
            this.structureField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlTextAttribute()]
    public string[] Text
    {
        get
        {
            return this.textField;
        }
        set
        {
            this.textField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlAttributeAttribute()]
    public string key
    {
        get
        {
            return this.keyField;
        }
        set
        {
            this.keyField = value;
        }
    }
}

/// <remarks/>
[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
public partial class propertiesPropertyStructure
{

    private propertiesPropertyStructureProperty propertyField;

    private string typeField;

    /// <remarks/>
    public propertiesPropertyStructureProperty property
    {
        get
        {
            return this.propertyField;
        }
        set
        {
            this.propertyField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlAttributeAttribute()]
    public string type
    {
        get
        {
            return this.typeField;
        }
        set
        {
            this.typeField = value;
        }
    }
}

/// <remarks/>
[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
public partial class propertiesPropertyStructureProperty
{

    private string keyField;

    private ushort valueField;

    /// <remarks/>
    [System.Xml.Serialization.XmlAttributeAttribute()]
    public string key
    {
        get
        {
            return this.keyField;
        }
        set
        {
            this.keyField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlTextAttribute()]
    public ushort Value
    {
        get
        {
            return this.valueField;
        }
        set
        {
            this.valueField = value;
        }
    }
}

4) Yes, much code o_O. Use an XmlDeserializer(typeof(properties))

Answer 3

If you make a sample instance of your LogProperties class and serialize it like this:

var serializer = new XmlSerializer(typeof(LogProperties));

LogProperties logProperties = new LogProperties() 
{ 
    SourceContext = "MySourceContext",
    ActionId = "MyActionId",
    ActionName = "MyActionName"
};

StringBuilder sb = new StringBuilder();
using (StringWriter writer = new StringWriter(sb))
{
    serializer.Serialize(writer, logProperties);
}

Console.WriteLine(sb.ToString());

This is what you get:

<?xml version="1.0" encoding="utf-16"?>
<properties xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <SourceContext>MySourceContext</SourceContext>
  <ActionId>MyActionId</ActionId>
  <ActionName>MyActionName</ActionName>
</properties>

So the class you have doesn't fit the XML you have very well. It is always useful to try serialization in both directions.

Below is a way you can serialize the XML you have into the class you have (getting a clear separation of your object model and your persistence format). It uses the XDocument class from the System.Xml.Linq namespace.

// Must escape all quotes !
string xmlSample = @"
<properties>
    <property key=""EventId"">
        <structure type = """">
            <property key=""Id"">404</property>
        </structure>
    </property>
    <property key=""ActionId""> 0592d9e8 - f4fd - 459f - 96b3 - 2b787d01a754</property>
    <property key=""ActionName""> API.Controllers.CompletionsController.GetCompletion(PS.API)</property>
    <property key=""RequestId""> 0HLJ2IL5A9: 00000001</property>
    <property key=""RequestPath"">/api/completions/0</property>
    <property key=""CorrelationId"" />
    <property key=""ConnectionId"">0HLJ2IL59</property>
    <property key=""MachineName"">RD0003FF1</property>
    <property key=""ThreadId"">117</property>
</properties>";

StringReader reader = new StringReader(xmlSample);
XDocument xdoc = XDocument.Parse(xmlSample);

LogProperties log = new LogProperties();
foreach (XElement prop in xdoc.Root.Elements())
{
    switch (prop.Attribute("key").Value)
    {
    case "ActionId" : log.ActionId = prop.Value; break;
    case "ActionName" : log.ActionName = prop.Value; break;

    // and so on

    }
}

Note that with this approach:

• you dont need the XML attributes in your class
• you dont need to shape your class to fit the XML (or the other way around)
• you can add your own custom initialization of the LogProperties class (no need for a default constructor anymore)
• you can add your own custom error handling