Srange Object error

[chris]

Hi tere, I have a seperate class called Author:

using System;

namespace DocumentControl
{
/// <summary>
/// Summary description for Author.
/// </summary>
public class Author
{
private string strReport = "";
private string strIssue = "";
private string strAuthors = "";

public Author(string strReport, string strIssue, string strAuthors)
{
this.strReport = strReport;
this.strIssue = strIssue;
this.strAuthors = strAuthors;
}

public string StrReports
{
set
{
strReport = value;
}
get
{
return strReport;
}
}

public string StrIssue
{
set
{
strIssue = value;
}
get
{
return strIssue;
}
}

public string StrAuthor
{
set
{
strAuthors = value;
}
get
{
return strAuthors;
}
}


}
}

I declare the object in the parent class:

private Author objAuthor = null;

I create the object on a Button Event whcih works fine and the values are in
the object.

private void AddAuthor(objec t source,
System.Web.UI.W ebControls.Data GridCommandEven tArgs e)
{
objAuthor = new Author(e.Item.C ells[2].Text, e.Item.Cells[6].Text,
e.Item.Cells[12].Text);
}

Now I try to access the object from a different Button Click event:

private void ButtonAddAuthor _Click(object sender, System.EventArg s e)
{
TextBox3.Text = objAuthor.StrRe ports;
TextBox4.Text = objAuthor.StrIs sue;
TextBox5.Text = objAuthor.StrAu thor;
}

But I get the error: Object reference not set to an instance of an object

Why can't I access the objects content? What is wrong? Thanks a lot for any
feedback

Chris

[Dmytro Lapshyn [MVP]]

Re: Srange Object error

Hi Chris,

The Web page class is not retained between subsequent HTTP requests. When
you first click the button and thus make a postback to the server, your
code-behind class is instantiated, an instance of the Author class gets
initialized in the event handler, but as long as this request is processed,
the whole instance of the code-behind class is recycled.

When you click the other button, a completely new instance of the
code-behind class is created, in which objAuthor is initialized to the null
reference, thus giving you the error.

If you need to retain an instance of a class between requests, you can store
it in the Session object (will work on per-used basis), in the Application
object, or in the Cache. Each scenario has its advantages and drawbacks, I
think you should refer to ASP .NET MSDN docs for more details.

--
Sincerely,
Dmytro Lapshyn [Visual Developer - Visual C# MVP]


"chris" <chris@discussi ons.microsoft.c om> wrote in message
news:62A891E0-D94D-4497-B696-180966B1B541@mi crosoft.com...[color=blue]
> Hi tere, I have a seperate class called Author:
>
> using System;
>
> namespace DocumentControl
> {
> /// <summary>
> /// Summary description for Author.
> /// </summary>
> public class Author
> {
> private string strReport = "";
> private string strIssue = "";
> private string strAuthors = "";
>
> public Author(string strReport, string strIssue, string strAuthors)
> {
> this.strReport = strReport;
> this.strIssue = strIssue;
> this.strAuthors = strAuthors;
> }
>
> public string StrReports
> {
> set
> {
> strReport = value;
> }
> get
> {
> return strReport;
> }
> }
>
> public string StrIssue
> {
> set
> {
> strIssue = value;
> }
> get
> {
> return strIssue;
> }
> }
>
> public string StrAuthor
> {
> set
> {
> strAuthors = value;
> }
> get
> {
> return strAuthors;
> }
> }
>
>
> }
> }
>
> I declare the object in the parent class:
>
> private Author objAuthor = null;
>
> I create the object on a Button Event whcih works fine and the values are
> in
> the object.
>
> private void AddAuthor(objec t source,
> System.Web.UI.W ebControls.Data GridCommandEven tArgs e)
> {
> objAuthor = new Author(e.Item.C ells[2].Text, e.Item.Cells[6].Text,
> e.Item.Cells[12].Text);
> }
>
> Now I try to access the object from a different Button Click event:
>
> private void ButtonAddAuthor _Click(object sender, System.EventArg s e)
> {
> TextBox3.Text = objAuthor.StrRe ports;
> TextBox4.Text = objAuthor.StrIs sue;
> TextBox5.Text = objAuthor.StrAu thor;
> }
>
> But I get the error: Object reference not set to an instance of an object
>
> Why can't I access the objects content? What is wrong? Thanks a lot for
> any
> feedback
>
> Chris[/color]