Class Serialization To XML

Question

Given the following class design:

 public class AllUserCollections
    {
        public List<UserCollection> UserCollections { get; set; }

        public AllUserCollections()
        {
            this.UserCollections = new List<UserCollection> ();
        }
    }

    public class UserCollection
    {
        public string UserGroup { get; set; }
        public Dictionary<int,User> Users { get; set; }

        public UserCollection(string userGroup)
        {
            this.UserGroup = userGroup;
            this.Users = new Dictionary<int, User> ();
        }
    }

    public class User
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public string Location { get; set; }
        public AgeGroup UserAgeGroup { get; set; }
    }

    public enum AgeGroup
    {
        Twenties,
        Thirties,
        Fourties,
    }

How can I serialize this to XML using my existing serialization class?

public static class HardDriveService
    {
        private static string docsFolderPath = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
        private const string fileName = "AllUserCollections.xml";
        private static string filePath = Path.Combine(docsFolderPath, fileName);

        private static bool FileExists(string fullFilePath)
        {
            if (File.Exists (fullFilePath)) 
                return true;

            return false;
        }

        public static void Save(AllUserCollections allUserCollections)
        {
            if (FileExists(filePath))
            {
                File.Delete (filePath);
            }

            XmlSerializer serializer = new XmlSerializer(allUserCollections.GetType());
            using(StreamWriter writer = new StreamWriter(filePath))
            {
                serializer.Serialize(writer.BaseStream, allUserCollections);
            }
        }

        public static AllUserCollections Read()
        {
            AllUserCollections allUserCollections = new AllUserCollections();
            XmlSerializer serializer = new XmlSerializer(allUserCollections.GetType());

            if (FileExists(filePath))
            {
                StreamReader reader = new StreamReader(filePath);
                object deserialized = serializer.Deserialize(reader.BaseStream);
                allUserCollections = (AllUserCollections)deserialized;
            }

            return allUserCollections;
        }


    }//End of class.

ISSUES

My code seems to fail on this line -

XmlSerializer serializer = new XmlSerializer(allUserCollections.GetType());

I wonder if it's to do with the class needing to be explicitly marked as "serializable"? How would I do this?

Usage This code will run on an iphone and save/read directly from an app to XML on the iPhone hard drive.

Please start by reading docs: http://msdn.microsoft.com/en-us/library/ms233843.aspx — Samuel, Dec 19 '13 at 12:07
I have edited your title. Please see, "[Should questions include “tags” in their titles?](http://meta.stackexchange.com/questions/19190/)", where the consensus is "no, they should not". — John Saunders, Dec 19 '13 at 12:34
Thanks John Saunders. I find that mildly irritating as it means that someone who is just browsing can't just read the title and think "I know C#, perhaps I can help!" — Goober, Dec 19 '13 at 12:35

score 3 · Accepted Answer · edited May 23 '17 at 11:50

3

XMLSerializer doesn't support Dictionary out of the box. Your UserCollection class has a Dictionary. See this link for a workaround. Why doesn't XmlSerializer support Dictionary?

Other than that the XMLSerializer requires that your classes have default constructors (UserCollection and User don't) and each of them must have the [Serializable] attribute.

edited May 23 '17 at 11:50

Community

1
1

answered Dec 19 '13 at 12:33

StevieB

982
7
15

score 1 · Answer 2 · answered Dec 19 '13 at 12:28

You could use XElement to build up an XML format. You could use them along the following lines:

public static XElement ToXml(this User user)
{
    if (user == null)
    {
        throw new ArgumentException("User can not be null.");
    }

    XElement userElement = new XElement("User");
    userElement.Add(new XElement("ID", user.ID));
    userElement.Add(new XElement("Name", user.Name));
    userElement.Add(new XElement("Location", user.Location));
    userElement.Add(new XElement("UserAgeGroup", user.UserAgeGroup));

    return userElement;
}

public static string ToXml(this UserCollection userCollection)
{
    if (userCollection == null)
    {
        throw new ArgumentException("UserCollection can not be null.");
    }

    XElement userCollectionElement = new XElement("UserCollection");
    userCollectionElement.Add(new XElement("UserGroup", userCollection.UserGroup));
    userCollectionElement.Add(new XElement("Users", 
                                           userCollection.Users.Select(x => new XElement("User", x.ToXml()));

    return userCollectionElement;
}

Calling .ToString() on an XElement should give you an xml-formatted string.

score 0 · Answer 3 · edited May 23 '17 at 12:03

Here you have 2 choices XmlSerializer(which will not work with Dictionary or List type deserialization ) or you can use DataContractSerializer which added in .net 3.0 and has a lot advantages here are few: form this post

optimized for speed (about 10% faster than XmlSerializer, typically)
in "opt-in" - only stuff you specifically mark as [DataMember] will be serialized
doesn't support XML attributes (for speed reasons)

Note : you should add reference to the C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Runtime.Serialization.dll

//to serialize 
        SerializeHelper.Serialize("your filename" ,new AllUserCollections());
// deserialize
        var usertCollections = SerializeHelper.Deserialize<AllUserCollections>("yourfile name"); 


//code 
 [DataContract]
    public class AllUserCollections
    {
        public List<UserCollection> UserCollections { get; set; }

        public AllUserCollections()
        {
            this.UserCollections = new List<UserCollection>();
        }
    }
    [DataContract()]
    public class UserCollection
    {
         [DataMember]
        public string UserGroup { get; set; }

         [DataMember]
        public Dictionary<int, User> Users { get; set; }

        public UserCollection(string userGroup)
        {
            this.UserGroup = userGroup;
            this.Users = new Dictionary<int, User>();
        }
    }
    [DataContract()]
    public class User
    {   [DataMember]
        public int ID { get; set; }
         [DataMember]
        public string Name { get; set; }
         [DataMember]
        public string Location { get; set; }
         [DataMember]
        public AgeGroup UserAgeGroup { get; set; }
    }
     [DataContract]
    public enum AgeGroup
    {
        Twenties,
        Thirties,
        Fourties,
    }
    public  static class  SerializeHelper
    {
         public static void Serialize<T>(string fileName, T obj)
    {
        using (FileStream writer = new FileStream(fileName, FileMode.Create))
        {
         DataContractSerializer ser =
            new DataContractSerializer(typeof(T));
        ser.WriteObject(writer, obj);
        writer.Close();   
        }


    }

    public static T Deserialize<T>(string fileName)
    {
        T des;
        using (FileStream fs = new FileStream(fileName,FileMode.Open))
        {
        XmlDictionaryReader reader =
            XmlDictionaryReader.CreateTextReader(fs, new XmlDictionaryReaderQuotas());
        DataContractSerializer ser = new DataContractSerializer(typeof(T));
        des =
            (T)ser.ReadObject(reader, true);
        reader.Close();
        fs.Close(); 

        }

        return des;
    }
    }

@JohnSaunders I was too busy and have posted the answer fast — BRAHIM Kamel, Dec 19 '13 at 12:45
@JulieShannon: well, I'll be too busy to reverse the downvote until you have time to fix that :-) — John Saunders, Dec 19 '13 at 12:47
@JohnSaunders can you revert your down vote now it's look better now :) — BRAHIM Kamel, Dec 19 '13 at 13:02
I meant `using` blocks on the `FileStream` and anything else that implements `IDisposable`. — John Saunders, Dec 19 '13 at 13:05

score 0 · Answer 4 · answered Dec 19 '13 at 12:49

FULL WORKING SOLUTION

Data Model

using System;
using System.Collections.Generic;

namespace iPhoneHardDriveCRUDPrototype
{
    [Serializable]
    public class AllUserCollections
    {
        public List<UserCollection> UserCollections { get; set; }

        public AllUserCollections()
        {
            this.UserCollections = new List<UserCollection> ();
        }
    }

    [Serializable]
    public class UserCollection
    {
        public string UserGroup { get; set; }
        public SerializableDictionary<int,User> Users { get; set; }

        public UserCollection()
        {
            this.Users = new SerializableDictionary<int, User> ();
        }

        public UserCollection(string userGroup)
        {
            this.UserGroup = userGroup;
            this.Users = new SerializableDictionary<int, User> ();
        }
    }

    [Serializable]
    public class User
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public string Location { get; set; }
        public AgeGroup UserAgeGroup { get; set; }

        public User()
        {

        }
    }

    [Serializable]
    public enum AgeGroup
    {
        Twenties,
        Thirties,
        Fourties,
    }
}

Serializable Dictionary

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

namespace iPhoneHardDriveCRUDPrototype
{
    [XmlRoot("dictionary")] 
    public class SerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, IXmlSerializable 
    { 
        public System.Xml.Schema.XmlSchema GetSchema() 
        { 
            return null; 
        }

        public void ReadXml(System.Xml.XmlReader reader) 
        { 
            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey)); 
            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

            bool wasEmpty = reader.IsEmptyElement; 
            reader.Read();

            if (wasEmpty) 
                return;

            while (reader.NodeType != System.Xml.XmlNodeType.EndElement) 
            { 
                reader.ReadStartElement("item"); 
                reader.ReadStartElement("key"); 
                TKey key = (TKey)keySerializer.Deserialize(reader); 
                reader.ReadEndElement(); 
                reader.ReadStartElement("value"); 
                TValue value = (TValue)valueSerializer.Deserialize(reader); 
                reader.ReadEndElement(); 
                this.Add(key, value); 
                reader.ReadEndElement(); 
                reader.MoveToContent(); 
            } 
            reader.ReadEndElement(); 
        }

        public void WriteXml(System.Xml.XmlWriter writer) 
        { 
            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey)); 
            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

            foreach (TKey key in this.Keys) 
            { 
                writer.WriteStartElement("item"); 
                writer.WriteStartElement("key"); 
                keySerializer.Serialize(writer, key); 
                writer.WriteEndElement(); 
                writer.WriteStartElement("value"); 
                TValue value = this[key]; 
                valueSerializer.Serialize(writer, value); 
                writer.WriteEndElement(); 
                writer.WriteEndElement(); 
            } 
        }



    }//End of Class....
}

Serializer

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

namespace iPhoneHardDriveCRUDPrototype
{
    public static class HardDriveService
    {
        private static string docsFolderPath = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
        private const string fileName = "AllUserCollections.xml";
        private static string filePath = Path.Combine(docsFolderPath, fileName);

        private static bool FileExists(string fullFilePath)
        {
            if (File.Exists (fullFilePath)) 
                return true;

            return false;
        }

        public static void Save(AllUserCollections allUserCollections)
        {
            if (FileExists(filePath))
            {
                File.Delete (filePath);
            }

            XmlSerializer serializer = new XmlSerializer(allUserCollections.GetType());
            using(StreamWriter writer = new StreamWriter(filePath))
            {
                serializer.Serialize(writer.BaseStream, allUserCollections);
            }
        }

        public static AllUserCollections Read()
        {
            AllUserCollections allUserCollections = new AllUserCollections();
            XmlSerializer serializer = new XmlSerializer(allUserCollections.GetType());

            if (FileExists(filePath))
            {
                StreamReader reader = new StreamReader(filePath);
                object deserialized = serializer.Deserialize(reader.BaseStream);
                allUserCollections = (AllUserCollections)deserialized;
            }

            return allUserCollections;
        }


    }//End of class.
}

no it's not a full working solution as you cannot deserialize the dictionary and the List types my solution which use datacontractserializer will work better — BRAHIM Kamel, Dec 19 '13 at 12:53
DataContractSerializer isn't supported by MonoTouch. And yes, the serializable dictionary class I posted does work. — Goober, Dec 19 '13 at 13:00
first you have not added moonotouch tag second DataContractSerializer is supported in Monotouch — BRAHIM Kamel, Dec 19 '13 at 13:17

Class Serialization To XML

4 Answers4