Challenge? [De-]Serialise a class derived from DataTable.

6 Nov 2006 4:33 PM

Phill W.

OK, I've asked nicely before; now I'm going to throw down the gauntlet
to anyone brave enough to take it up.

In VB'2005, can anyone write me a class that inherits from
System.Data.DataTable, add it to a System.Data.DataSet (a /normal/ one,
/not/ a subclass), serialise the whole lot to, say, a file and then
deserialise the whole shooting match back into the classes they started
with? (All my attempts seem to lose all the Type information on the
DataTable-derived calss in the serialisation process).

I've tried to do this repeatedly (in VB'2003 and '2005) with no success.

I'm not looking for the page and pages of XML Schema "stuff" created by
a Strongly-typed Dataset (although I'm afraid that's where I'll wind
up). I'm /trying/ to get a Strongly-Typed DataTable that can exist
within any old DataSet.

Is this possible in VB'2005? (It wasn't in '2003).

TIA,
Phill W.

7 Nov 2006 7:56 AM

Michel Posseth [MCP]

Have you tried binary serialization ?

i use this to serialize anny .Net object to a sql server database ( Classes
, structures ) when i deserialize them i get them back in the original
state .

<code >
Imports System.Runtime.Serialization.Formatters.Binary

add this attribute to the serializable class
<Serializable()> _

--- methods

''' <summary>
    ''' maakt van een byte array een object
    ''' </summary>
    ''' <param name="Argdata">de ruwe binaire data </param>
    ''' <returns></returns>
    Private Function DeSerialize(ByVal Argdata() As Byte) As Object
        Dim m As New MemoryStream(Argdata)
        Dim b As New BinaryFormatter()
        m.Seek(0, 0) 'start
        Return b.Deserialize(m)
    End Function
    ''' <summary>
    ''' Maakt van een Object (foo) een byte array .
    ''' </summary>
    ''' <param name="Argdata">argdata als foo object</param>
    ''' <returns></returns>
    Private Function Serialize(ByVal Argdata As Object) As Byte()
        Dim b As New BinaryFormatter
        Dim m As New MemoryStream
        b.Serialize(m, Argdata)
        m.Seek(0, 0) 'start
        Return m.ToArray
    End Function

</code >

With these methods i could store ( until sofar ) every .Net object in SQL
server
( you could also write the binary data   out to a file and read it back
from a file )

I hope this helps you in the right direction

regards

Michel Posseth [MCP]

Show quoteHide quote

"Phill W." wrote:

> OK, I've asked nicely before; now I'm going to throw down the gauntlet
> to anyone brave enough to take it up.
>
> In VB'2005, can anyone write me a class that inherits from
> System.Data.DataTable, add it to a System.Data.DataSet (a /normal/ one,
> /not/ a subclass), serialise the whole lot to, say, a file and then
> deserialise the whole shooting match back into the classes they started
> with? (All my attempts seem to lose all the Type information on the
> DataTable-derived calss in the serialisation process).
>
> I've tried to do this repeatedly (in VB'2003 and '2005) with no success.
>
> I'm not looking for the page and pages of XML Schema "stuff" created by
> a Strongly-typed Dataset (although I'm afraid that's where I'll wind
> up). I'm /trying/ to get a Strongly-Typed DataTable that can exist
> within any old DataSet.
>
> Is this possible in VB'2005? (It wasn't in '2003).
>
> TIA,
> Phill W.
>

7 Nov 2006 10:49 AM

Michel Posseth [MCP]

When i rethink this ....

i believe this is never going to work with a standard dataset

as the deserialize method needs a type that is the same as the serialized
object

and a standard dataset type is not the same as a dataset with a custom
table , so the deserialization will probably crash on the custom table ...

so i guess you can only do this with standard datatypes or a custom wrapper

I for instance write my own custom datat types to a database
however when i retrieve the values for serialization i can use this custom
type as my serialization template

in the case of a dataset that holds a custom datatable you miss the mask for
this custom datatable for correct deserialization .

Hmmm , :-| ,,, Interesting .......

i guess that if you used a class as wrapper , with an object array to hold
the custom datatables you would not have anny problem, this way you should
first cast the wrapper wich would give you the class with datatables as
objects , now you could cast these objects to your custom tables

Well i guess i picked up the gloves , but need to throw the towel in the
ring for the original task :-)

regards

Michel

Show quoteHide quote

"Michel Posseth [MCP]" wrote:

> Have you tried binary serialization ?
>
>
> i use this to serialize anny .Net object to a sql server database ( Classes
> , structures ) when i deserialize them i get them back in the original
> state .
>
>
> <code >
> Imports System.Runtime.Serialization.Formatters.Binary
>
> add this attribute to the serializable class
> <Serializable()> _
>
> --- methods
>
> ''' <summary>
>     ''' maakt van een byte array een object
>     ''' </summary>
>     ''' <param name="Argdata">de ruwe binaire data </param>
>     ''' <returns></returns>
>     Private Function DeSerialize(ByVal Argdata() As Byte) As Object
>         Dim m As New MemoryStream(Argdata)
>         Dim b As New BinaryFormatter()
>         m.Seek(0, 0) 'start
>         Return b.Deserialize(m)
>     End Function
>     ''' <summary>
>     ''' Maakt van een Object (foo) een byte array .
>     ''' </summary>
>     ''' <param name="Argdata">argdata als foo object</param>
>     ''' <returns></returns>
>     Private Function Serialize(ByVal Argdata As Object) As Byte()
>         Dim b As New BinaryFormatter
>         Dim m As New MemoryStream
>         b.Serialize(m, Argdata)
>         m.Seek(0, 0) 'start
>         Return m.ToArray
>     End Function
>
> </code >
>
>
> With these methods i could store ( until sofar ) every .Net object in SQL
> server
> ( you could also write the binary data   out to a file and read it back
> from a file )
>
>
> I hope this helps you in the right direction
>
> regards
>
> Michel Posseth [MCP]
>
>
> "Phill W." wrote:
>
> > OK, I've asked nicely before; now I'm going to throw down the gauntlet
> > to anyone brave enough to take it up.
> >
> > In VB'2005, can anyone write me a class that inherits from
> > System.Data.DataTable, add it to a System.Data.DataSet (a /normal/ one,
> > /not/ a subclass), serialise the whole lot to, say, a file and then
> > deserialise the whole shooting match back into the classes they started
> > with? (All my attempts seem to lose all the Type information on the
> > DataTable-derived calss in the serialisation process).
> >
> > I've tried to do this repeatedly (in VB'2003 and '2005) with no success.
> >
> > I'm not looking for the page and pages of XML Schema "stuff" created by
> > a Strongly-typed Dataset (although I'm afraid that's where I'll wind
> > up). I'm /trying/ to get a Strongly-Typed DataTable that can exist
> > within any old DataSet.
> >
> > Is this possible in VB'2005? (It wasn't in '2003).
> >
> > TIA,
> >     Phill W.
> >

7 Nov 2006 3:40 PM

Phill W.

Michel Posseth [MCP] wrote:

> When i rethink this ....
> i believe this is never going to work with a standard dataset as the
> deserialize method needs a type that is the same as the serialized
> object and a standard dataset type is not the same as a dataset with
> a custom table, so the deserialization will probably crash on the
> custom table ...
>
> so i guess you can only do this with standard datatypes or a custom wrapper
.. . .
> in the case of a dataset that holds a custom datatable you miss the mask for
> this custom datatable for correct deserialization .

And therein lies my problem... :-(

> Hmmm , :-| ,,, Interesting .......

"Veeerry interesting" (says the german chap in the helmet hiding behind
the potted plant) "but Stupid"... Why should a class derived from
DataTable [de-]serialise any differently to any other class?

> Well i guess i picked up the gloves , but need to throw the towel in the
> ring for the original task :-)

Ah well; at least I have a nice new towel in exchange for my old
gloves... :-)

Thanks anyway.
Phill W.