passing arraylist

[Celine]

is it possible to pass an arraylist from one page to another page? If yes how?
(I'm using asp.net and c#)

 

[Morten Wennevik]

Hi Celine,

Yes, you can pass any object between pages. Just store them as Session or Application objects.

Session["List"] = myArrayList;

someArrayList = (ArrayList)Session["List"];

 

[Celine]

Hi Morten, Thank you for your answer but I am getting an error
message: "Object reference not set to an instance of an object."

I am trying to build a pictures gallery. For that I display in
datalist thumbnails(form1) which the user can clicked to display a
larger picture. As the larger images are displayed in another web
form(form2) I need to store the pictures numbers the user has already
selected and display them back again on the first page(form1).
My code is as follow:
private void Page_Load(object sender, System.EventArgs e)
{
if(!Page.IsPostBack)
{
BindGrid();

someArrayList = (ArrayList)Session["List"];
for(int i=0;i<someArrayList.Count;i++)
{
PicsDDL.Items.Add(someArrayList.ToString());
}
}
}

private void DataList1_ItemCommand(object source,
System.Web.UI.WebControls.DataListCommandEventArgs e)
{


if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==
ListItemType.AlternatingItem)
{
Label Lbl=(Label)e.Item.FindControl("NameLbl");
Button Btn=(Button)e.Item.FindControl("addBtn");
ImageButton imBtn=(ImageButton)e.Item.FindControl("imageBtn");
if(e.CommandName=="select")
{
for(int i=0;i<PicsDDL.Items.Count;i++)
{
arrayPics.Add(PicsDDL.Items.Text);
}

Session["List"] = arrayPics;
}
if(e.CommandName=="AddToBasket")
{
PicsDDL.Items.Add( Lbl.Text);
}
}

I would really appreciate if you can help me. I am really confused
because when I try to access the array on the form2(where larger
pictures are displayed) I get no error message. It is only when I try
to access it on form1.
Celine

 

[Morten Wennevik]

Hi Celine,

You need to store some list under the "List" name when you start the session.
I'm not sure this will work (not too familiar with web programs) but you could try

if(Session["List"] != null)
{
//there is a list available
someArrayList = (ArrayList)Session["List"];
}
else
{
Session["List"] = new ArrayList();
}

Note that the name "List" could be anything, so you could store several list under different names.

 

[Celine]

Hi Morten, Thank you for so much your help. Everything is working fine now!!
Celine

Hi Morten, Thank you for your answer but I am getting an error
message: "Object reference not set to an instance of an object."

I am trying to build a pictures gallery. For that I display in
datalist thumbnails(form1) which the user can clicked to display a
larger picture. As the larger images are displayed in another web
form(form2) I need to store the pictures numbers the user has already
selected and display them back again on the first page(form1).
My code is as follow:
private void Page_Load(object sender, System.EventArgs e)
{
if(!Page.IsPostBack)
{
BindGrid();

someArrayList = (ArrayList)Session["List"];
for(int i=0;i<someArrayList.Count;i++)
{
PicsDDL.Items.Add(someArrayList.ToString());
}
}
}

private void DataList1_ItemCommand(object source,
System.Web.UI.WebControls.DataListCommandEventArgs e)
{


if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==
ListItemType.AlternatingItem)
{
Label Lbl=(Label)e.Item.FindControl("NameLbl");
Button Btn=(Button)e.Item.FindControl("addBtn");
ImageButton imBtn=(ImageButton)e.Item.FindControl("imageBtn");
if(e.CommandName=="select")
{
for(int i=0;i<PicsDDL.Items.Count;i++)
{
arrayPics.Add(PicsDDL.Items.Text);
}

Session["List"] = arrayPics;
}
if(e.CommandName=="AddToBasket")
{
PicsDDL.Items.Add( Lbl.Text);
}
}

I would really appreciate if you can help me. I am really confused
because when I try to access the array on the form2(where larger
pictures are displayed) I get no error message. It is only when I try
to access it on form1.
Celine

Hi Celine,

Yes, you can pass any object between pages. Just store them as Session or Application objects.

Session["List"] = myArrayList;

someArrayList = (ArrayList)Session["List"];