Web Service Data Conversion Problem

[xmail123]

In a web service I am using a SqlDataReader to retrieve the
information to populate an ArrayList.

public ArrayList ReadHistory(int ItemPK)
{
SDrdr = SDcmd.ExecuteRe ader();
ArrayList AL = new ArrayList();

while(SDrdr.Rea d())
{
AL.Add(SDrdr["name"]);
}
return AL;
}

The web service is called from another project.

public ArrayList ReadHistory(int ItemPK)
{
wsrKeyCodeServi ce.KeyCodeInfor mation WSR = new
wsrKeyCodeServi ce.KeyCodeInfor mation();
ArrayList AL =
WSR.ReadKeyCode History(Vehicle PK);
return AL;

The problem is when I build the project I get the following error.
Cannot implicitly convert type 'object[]' to
'System.Collect ions.ArrayList'

When I change the type from ArrayList to Array…

public Array ReadHistory(int ItemPK)
{
wsrKeyCodeServi ce.KeyCodeInfor mation WSR = new
wsrKeyCodeServi ce.KeyCodeInfor mation();
Array AL = WSR.ReadHistory (ItemPK);
return AL;
}
The error goes away.

Apparently when the ArrayList is sent from the web service it is
converted to an Array.

Questions

1. Why does it do this?
2. What do I need to do to get an ArrayList on the receiving side? I
need to be able to resize the array. An Array can't be resized, the
ArrayList can.

Thanks for the help.

[Sami Vaaraniemi]

This is not a C# question but here goes anyway. Comments inline:

<xm******@yahoo .com> wrote in message
news:40******** ******@news.dsl extreme.com...

In a web service I am using a SqlDataReader to retrieve the
information to populate an ArrayList.

public ArrayList ReadHistory(int ItemPK)
{
SDrdr = SDcmd.ExecuteRe ader();
ArrayList AL = new ArrayList();

while(SDrdr.Rea d())
{
AL.Add(SDrdr["name"]);
}
return AL;
}

The web service is called from another project.

public ArrayList ReadHistory(int ItemPK)
{
wsrKeyCodeServi ce.KeyCodeInfor mation WSR = new
wsrKeyCodeServi ce.KeyCodeInfor mation();
ArrayList AL =
WSR.ReadKeyCode History(Vehicle PK);
return AL;

The problem is when I build the project I get the following error.
Cannot implicitly convert type 'object[]' to
'System.Collect ions.ArrayList'

When I change the type from ArrayList to Array.

public Array ReadHistory(int ItemPK)
{
wsrKeyCodeServi ce.KeyCodeInfor mation WSR = new
wsrKeyCodeServi ce.KeyCodeInfor mation();
Array AL = WSR.ReadHistory (ItemPK);
return AL;
}
The error goes away.

Apparently when the ArrayList is sent from the web service it is
converted to an Array.

Questions

1. Why does it do this?
Whatever you return from a WebMethod needs to be serializable to SOAP. The
type ArrayList is not serializable to SOAP so it gets converted to an array
of objects (object[]) which is SOAP serializable (provided the objects in
the array are SOAP serializable).
2. What do I need to do to get an ArrayList on the receiving side? I
need to be able to resize the array. An Array can't be resized, the
ArrayList can.

ArrayList al = new ArrayList(WSR.R eadHistory(Item PK));

Regards,
Sami

[xmail123]

Thank you. That solved it. :)

On Fri, 11 Jun 2004 17:07:51 +0300, "Sami Vaaraniemi"
<sa**********@p leasejippii.fi> wrote:

This is not a C# question but here goes anyway. Comments inline:

<xm******@yaho o.com> wrote in message
news:40******* *******@news.ds lextreme.com...

In a web service I am using a SqlDataReader to retrieve the
information to populate an ArrayList.

public ArrayList ReadHistory(int ItemPK)
{
SDrdr = SDcmd.ExecuteRe ader();
ArrayList AL = new ArrayList();

while(SDrdr.Rea d())
{
AL.Add(SDrdr["name"]);
}
return AL;
}

The web service is called from another project.

public ArrayList ReadHistory(int ItemPK)
{
wsrKeyCodeServi ce.KeyCodeInfor mation WSR = new
wsrKeyCodeServi ce.KeyCodeInfor mation();
ArrayList AL =
WSR.ReadKeyCode History(Vehicle PK);
return AL;

The problem is when I build the project I get the following error.
Cannot implicitly convert type 'object[]' to
'System.Collect ions.ArrayList'

When I change the type from ArrayList to Array.

public Array ReadHistory(int ItemPK)
{
wsrKeyCodeServi ce.KeyCodeInfor mation WSR = new
wsrKeyCodeServi ce.KeyCodeInfor mation();
Array AL = WSR.ReadHistory (ItemPK);
return AL;
}
The error goes away.

Apparently when the ArrayList is sent from the web service it is
converted to an Array.

Questions

1. Why does it do this?

Whatever you return from a WebMethod needs to be serializable to SOAP. The
type ArrayList is not serializable to SOAP so it gets converted to an array
of objects (object[]) which is SOAP serializable (provided the objects in
the array are SOAP serializable).

2. What do I need to do to get an ArrayList on the receiving side? I
need to be able to resize the array. An Array can't be resized, the
ArrayList can.

ArrayList al = new ArrayList(WSR.R eadHistory(Item PK));

Regards,
Sami