Serializing into an XML file a Hashtable

[Victor Paraschiv]

I need to serialize into an XML file a hashtable.
From MSDN at XmlSerializer:
http://msdn.microsoft.com/library/de...classtopic.asp

I implemented the indexable property and the add function but I'm still
getting the following exception:"The type System.Collecti ons.Hashtable
is not supported because it implements IDictionary."
My code for Item and Add add-on looks like this:

[Serializable]
public class DaysArchive
{
 
public class HashTableItems
{
private IDictionaryEnumerator HashEntries;
public HashTableItems()
{
}
 
public  void Initialize(Hashtable table)
{
HashEntries = table.GetEnumerator();
}
 
public System.Collections.DictionaryEntry this[string key]
{
get
{
HashEntries.Reset();
HashEntries.MoveNext();
while ((string)HashEntries.Key != key)
{
HashEntries.MoveNext();
}
return new DictionaryEntry(HashEntries.Key,HashEntries.Value);
}
}
}
 
public readonly HashTableItems Item;
public Hashtable archive;
 
public DaysArchive()
{
archive = new Hashtable();
this.Item = new HashTableItems();
this.Item.Initialize(archive);
}
 
public void AddItem(string Name, bool offline)
{
if (archive.ContainsKey(Name) == false)
archive.Add(Name,offline);
}
 
public bool GetKeyValue(string Name)
{
if (archive.ContainsKey(Name) == false)
throw new Exception("Key could not be found!");
 
IDictionaryEnumerator days_enum = archive.GetEnumerator();
 
 
days_enum.MoveNext();
while (((string)days_enum.Key != Name)&&(days_enum.MoveNext()));
 
return (bool)days_enum.Value;
}
 
public bool IsKeyInCollection(string Name)
{
return archive.ContainsKey(Name);
}
 
public void Add(System.Collections.DictionaryEntry cel)
{
archive.Add(cel.Key,cel.Value);
}
}
 

[bart_deboeck]

Hi Victor,

I am probably missing something, what do you use HashTableItems for ?
What is the role of this part of the code :

HashEntries.Res et();
HashEntries.Mov eNext();
while ((string)HashEn tries.Key != key)
{
HashEntries.Mov eNext();
}

Are you trying to check the existence of a key ? Such type of
functionality is implemented by a Hashtable.

What is the role of DaysArchive ? Do you want to store (Name,
offline) pairs ? A Hashtable should be sufficient for this type of
functionality.
Please feel free to contact me if you need any more information.

Regards,
Bart

http://www.xenopz.com/blog/bartdeboeck/

[Victor Paraschiv]

Hi Bart,

HashTableItems is a custom made class which I use to define the suport
for the Item indexed property. I make an instance of this class and I
return it in the get method of the Item property.

My goal is to serialize the Hashtable into an XML file. I you try to
serialize a hashtable the XmlSerializer throws an exception that says
Hashtable impelements IDictionary. Now I wrote my own class which has
an internal Hashtable. In the hash I store a string wich is the name of
a file and a boolean variable which represents the state of the file
data (if it was obtain from a the realtime-market or tha data was
aquired when the market was offline)
I modiffied the implementation of the whole DaysArchive class as follows
but I still get an exception that says "You must implement the default
accessor for DaysArchive because it inherits ICollection"
I still have not a clue what am I supposed to do next.

Thank you very much for your support.

public class DaysArchive:ICollection,IEnumerable
{
private Hashtable archive;
private HashItems hashitems;
 
public DaysArchive()
{
archive  = new Hashtable();
hashitems = new HashItems();
hashitems.Refresh( archive);
}
 
#region implementations for ICollection & IEnumerable
 
public int Count
{
get
{
return archive.Count;
}
}
 
 
public bool IsSynchronized
{
get
{
return archive.IsSynchronized;
}
}
 
 
public object SyncRoot
{
get
{
return archive.SyncRoot;
}
}
 
 
public void CopyTo(    Array array,int index)
{
archive.CopyTo(array,index);
}
 
 
public IEnumerator GetEnumerator()
{
return archive.GetEnumerator();
}
 
 
#endregion
 
public bool ContainsKey(string Name)
{
return archive.ContainsKey(Name);
}
 
 
public void Add(DictionaryEntry cel)
{
archive.Add(cel.Key,cel.Value);
hashitems.Refresh(archive);
}
 
 
public void Add(object key, object value)
{
archive.Add(key,value);
hashitems.Refresh( archive);
}
 
 
public class HashItems
{
Hashtable hash;
 
public HashItems(Hashtable hash)
{
this.hash = hash;
}
public HashItems()
{
}
 
public DictionaryEntry this[int index]
{
get
{
IDictionaryEnumerator enumerator = hash.GetEnumerator();
 
enumerator.MoveNext();
 
while(index>0)
{
enumerator.MoveNext();
index--;
}
return new DictionaryEntry(enumerator.Key,enumerator.Value);
}
}
 
public void Refresh( Hashtable hash)
{
this.hash = hash;
}
 
public int Count
{
get
{
return hash.Count;
}
}
}
 
 
public HashItems Item
{
get
{
return hashitems;
}
}
}
 

[bart_deboeck]

Hi Victor,

Thanks for the extra info. I'll take a look at your question with the
extra info tomorrow.

cu,
Bart

http://www.xenopz.com/blog/bartdeboeck/

Victor Paraschiv schreef:

Hi Bart,

HashTableItems is a custom made class which I use to define the suport
for the Item indexed property. I make an instance of this class and I
return it in the get method of the Item property.

My goal is to serialize the Hashtable into an XML file. I you try to
serialize a hashtable the XmlSerializer throws an exception that says
Hashtable impelements IDictionary. Now I wrote my own class which has
an internal Hashtable. In the hash I store a string wich is the name of
a file and a boolean variable which represents the state of the file
data (if it was obtain from a the realtime-market or tha data was
aquired when the market was offline)
I modiffied the implementation of the whole DaysArchive class as follows
but I still get an exception that says "You must implement the default
accessor for DaysArchive because it inherits ICollection"
I still have not a clue what am I supposed to do next.

Thank you very much for your support.

     public class DaysArchive:ICollection,IEnumerable
     {
         private Hashtable archive;
         private HashItems hashitems;

         public DaysArchive()
         {
             archive  = new Hashtable();
             hashitems = new HashItems();
             hashitems.Refresh( archive);
         }

         #region implementations for ICollection & IEnumerable

         public int Count
         {
             get
             {
                 return archive.Count;
             }
         }


         public bool IsSynchronized
         {
             get
             {
                 return archive.IsSynchronized;
             }
         }


         public object SyncRoot
         {
             get
             {
                 return archive.SyncRoot;
             }
         }


         public void CopyTo(    Array array,int index)
         {
             archive.CopyTo(array,index);
         }


         public IEnumerator GetEnumerator()
         {
             return archive.GetEnumerator();
         }


         #endregion

         public bool ContainsKey(string Name)
         {
             return archive.ContainsKey(Name);
         }


         public void Add(DictionaryEntry cel)
         {
             archive.Add(cel.Key,cel.Value);
             hashitems.Refresh(archive);
         }


         public void Add(object key, object value)
         {
             archive.Add(key,value);
             hashitems.Refresh( archive);
         }


         public class HashItems
         {
             Hashtable hash;

             public HashItems(Hashtable hash)
             {
                 this.hash = hash;
             }
             public HashItems()
             {
             }

             public DictionaryEntry this[int index]
             {
                 get
                 {
                     IDictionaryEnumerator enumerator = hash.GetEnumerator();

                     enumerator.MoveNext();

                     while(index>0)
                     {
                         enumerator.MoveNext();
                         index--;
                     }
                     return new DictionaryEntry(enumerator.Key,enumerator.Value);
                 }
             }

             public void Refresh( Hashtable hash)
             {
                 this.hash = hash;
             }

             public int Count
             {
                 get
                 {
                     return hash.Count;
                 }
             }
         }


         public HashItems Item
         {
             get
             {
                 return hashitems;
             }
         }
     }
 

[bart_deboeck]

Hi Victor,

This link http://www.thecodeproject.com/csharp/hash_ser.asp is not an
answer, it might, however, provide a few hints.

Regards,
Bart

http://www.xenopz.com/blog/bartdeboeck/

[Victor Paraschiv]

Problem solved. I discarded everything was written in MSDN library at
XmlSerializer.
I've built a custom class that contains internally a Hashtable and
inherits ICollection and IEnumerable. I added then an indexer which
returns the hashtableitem at the given index. That's all!

Victor Paraschiv

ba**********@ho tmail.com wrote:

Hi Victor,

This link http://www.thecodeproject.com/csharp/hash_ser.asp is not an
answer, it might, however, provide a few hints.

Regards,
Bart

http://www.xenopz.com/blog/bartdeboeck/