Weird Code problem - serialisation (I'll spell it the proper way!!"0

[psycik]

Yeah mine too. I've been playing with a settings class, and have effectively had to implement the following:

Code:

List<Server> servers;

[XmlIgnore()]
[Browsable(false)]
public List<Server> Servers { get; set }


public Server[] ServerArray { get return this.servers.ToArray(); }

This is kinda an example. So this code is in a settings class.

If I serialise the List<Server> object directly it works.
But trying to serialise the Settings class (which this internal list) fails - unless I do what I've done here and convert it to an array.

[whurlston]

I do it slightly different:

Code:

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace XmlTests
{
    [System.Xml.Serialization.XmlRootAttribute("settings", Namespace = "", IsNullable = false)]
    public partial class Settings
    {
        private List<Server> servers = new List<Server>();

        public Settings() { }

        //[System.Xml.Serialization.XmlArrayItem("server", typeof(Server), Form=System.Xml.Schema.XmlSchemaForm.Unqualified), System.Xml.Serialization.XmlArray("servers", Form=System.Xml.Schema.XmlSchemaForm.Unqualified)]
        [System.Xml.Serialization.XmlElementAttribute("server", Form = System.Xml.Schema.XmlSchemaForm.Unqualified)]
        public List<Server> Servers
        {
            get
            {
                return this.servers;
            }
            set
            {
                this.servers = value;
            }
        }

        public void WriteTo(string FileName)
        {
            FileInfo fi = new FileInfo(FileName);
            using (System.IO.FileStream fs = fi.Create())
            {
                using (System.Xml.XmlTextWriter txw = new System.Xml.XmlTextWriter(fs, Encoding.GetEncoding("ISO-8859-1")))
                {
                    System.Xml.Serialization.XmlSerializerNamespaces customNamespace = new System.Xml.Serialization.XmlSerializerNamespaces(); customNamespace.Add("", "");
                    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(this.GetType());
                    txw.Formatting = System.Xml.Formatting.Indented;
                    txw.Indentation = 2;
                    txw.WriteStartDocument();
                    serializer.Serialize(txw, this, customNamespace);
                }
            }
        }

        public void ReadFrom(string FileName)
        {
            FileInfo fi = new FileInfo(FileName);
            if (fi.Exists)
            {
                using (System.IO.FileStream fs = fi.OpenRead())
                {
                    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(this.GetType());
                    System.Xml.XmlReaderSettings rs = new System.Xml.XmlReaderSettings();
                    rs.ProhibitDtd = false;
                    rs.XmlResolver = null;
                    System.Xml.XmlReader reader = System.Xml.XmlReader.Create(fs, rs);
                    Settings tmp = (Settings)serializer.Deserialize(reader);
                    this.Servers = tmp.Servers;
                }
            }
        }
    }

    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
    public partial class Server
    {
        private string name = string.Empty;

        public Server() { }
        public Server(string Name) { this.name = Name; }

        [System.Xml.Serialization.XmlElementAttribute("name")]
        public string Name
        {
            get { return this.name; }
            set { this.name = value; }
        }
    }

}

produces/reads the following:

Code:

<?xml version="1.0" encoding="iso-8859-1"?>
<settings>
  <server>
    <name>Test Server</name>
  </server>
  <server>
    <name>Test Server 2</name>
  </server>
</settings>

uncommenting the XmlArrayItem line (and removing the XmlElementAttribute line below it) groups the server list (adds a "<servers>" tag around the list of "<server>":

Code:

<?xml version="1.0" encoding="iso-8859-1"?>
<settings>
  <servers>
    <server>
      <name>Test Server</name>
    </server>
    <server>
      <name>Test Server 2</name>
    </server>
  </servers>
</settings>

[imilne]

Just as an aside, you might find this interesting reading regarding the spelling of serialization: http://en.wikipedia.org/wiki/Oxford_spelling

These kind of little annoyances cause me no end of hassle, because my day job involves visualization/visualisation.

Iain

[psycik]

@whurlston I'll have a toodle with that. Apart from some of the switches etc you had, my serialise method was pretty similar.

Although I ran it as a static method rather than a class method.

[whurlston]

Static should work too. I do that with some of my serializations. I just put that one together as a quick example.

[psycik]

That's what I expected, but I always kept getting the inner exception of "Object reference not found" and it doesn't tell you what what empty.

Setting the List to non null made not difference.

[whurlston]

These work in the above Settings class:

Code:

public static void WriteTo(Settings settings, string FileName)
        {
            FileInfo fi = new FileInfo(FileName);
            using (System.IO.FileStream fs = fi.Create())
            {
                using (System.Xml.XmlTextWriter txw = new System.Xml.XmlTextWriter(fs, Encoding.GetEncoding("ISO-8859-1")))
                {
                    System.Xml.Serialization.XmlSerializerNamespaces customNamespace = new System.Xml.Serialization.XmlSerializerNamespaces(); customNamespace.Add("", "");
                    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(settings.GetType());
                    txw.Formatting = System.Xml.Formatting.Indented;
                    txw.Indentation = 2;
                    txw.WriteStartDocument();
                    serializer.Serialize(txw, settings, customNamespace);
                }
            }
        }

        public static Settings ReadFromStatic(string FileName)
        {
            try
            {
                FileInfo fi = new FileInfo(FileName);
                if (fi.Exists)
                {
                    using (System.IO.FileStream fs = fi.OpenRead())
                    {
                        System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(Settings));
                        System.Xml.XmlReaderSettings rs = new System.Xml.XmlReaderSettings();
                        rs.ProhibitDtd = false;
                        rs.XmlResolver = null;
                        System.Xml.XmlReader reader = System.Xml.XmlReader.Create(fs, rs);
                        Settings tmp = (Settings)serializer.Deserialize(reader);
                        return tmp;
                    }
                }
            }
            catch { }
            return null;
        }

The WriteTo method includes a Settings parameter since you can use "this" in a static method. The ReadFromStatic method (renamed so as not to conflict with the non-static method) returns a Settings object or null if serialization fails.

Code:

XmlTests.Settings settings = new XmlTests.Settings();
            settings.Servers = new List<XmlTests.Server>();
            settings.Servers.Add(new XmlTests.Server("Test Server"));
            settings.Servers.Add(new XmlTests.Server("Test Server 2"));

            // Non-Static methods
            settings.WriteTo("settings.xml");
            XmlTests.Settings settings2 = new XmlTests.Settings();
            settings2.ReadFrom("settings.xml");
            //These last two could actually be combined  a constructor: XmlTests.Settings settings2 = new XmlTests.Settings("settings.xml");


            // Static methods
            XmlTests.Settings.WriteTo(settings, "settings.xml");
            XmlTests.Settings settings2 = XmlTests.Settings.ReadFromStatic("settings.xml");

[whurlston]

Well that was one of those "Doh" moments. You said it worked in a form but not a plugin and guess where I tested all the above code. :o

I do have code that works though (I used it for my original Netflix plugin). As soon as I find it, I'll let you know what the differences are.

I did however track down what is throwing the error. When the serializer is disposed, it references a null object. Unfortunately, that is in the System.Xml.dll file and not something we can readily fix.

[psycik]

Great to see its not just me then getting the error.

[whurlston]

I checked my old netflix code and I do it the same way so I'm not sure why it doesn't work now. Strangely, the following code works:

Code:

[XmlRoot(IsNullable = false, Namespace = "")]
    public class Lists
    {
        private List<string> _Locations = new List<string>();

        [XmlArrayItem("Url", Form = XmlSchemaForm.Unqualified)]
        [XmlArray("Locations")]
        public List<string> Locations
        {
            get
            {
                return this._Locations;
            }
            set
            {
                this._Locations = value;
            }
        }

        public void ReadFrom(string FileName)
        {
            XmlSerializer xmlSerializer = new XmlSerializer(this.GetType());
            FileStream fileStream = new FileStream(FileName, FileMode.Open);
            if (fileStream.Length > 0L)
            {
                XmlReader xmlReader = XmlReader.Create((System.IO.Stream)fileStream, new XmlReaderSettings()
                {
                    ProhibitDtd = false,
                    XmlResolver = (XmlResolver)null
                });
                this._Locations = ((Lists)xmlSerializer.Deserialize(xmlReader)).Locations;
                fileStream.Close();
            }
            else
                fileStream.Close();
        }

        public void WriteTo(string FileName)
        {
            XmlSerializerNamespaces namespaces = new XmlSerializerNamespaces();
            namespaces.Add("", "");
            XmlTextWriter xmlTextWriter = new XmlTextWriter(FileName, Encoding.GetEncoding("ISO-8859-1"));
            XmlSerializer xmlSerializer = new XmlSerializer(this.GetType());
            xmlTextWriter.Formatting = Formatting.Indented;
            xmlTextWriter.Indentation = 2;
            xmlTextWriter.WriteStartDocument();
            xmlSerializer.Serialize((XmlWriter)xmlTextWriter, (object)this, namespaces);
            xmlTextWriter.Close();
        }
    }

The only real difference being is that the list contains strings and not a class.