State Management

harry code

7y854Learn iOS Programming

Hi,

I am having a problem in understanding the below code.

it is a task regarding performiong crud operations with out using Data base with help of collections.

i am not able to understand How session is having the values despite not assaigning values to session.

Thank you in advance

class Employee

{

public int eid { get; set; }

public string name { get; set; }

public decimal salary { get; set; }

}

public partial class WebForm1 : System.Web.UI.Page

{

Employee obj = new Employee();

List el = new List();

protected void Page_Load(object sender, EventArgs e)

{

if(!Page.IsPostBack)

{

Session["emp"] = el;

}

el=(List)Session["emp"];

}

protected void Button1_Click(object sender, EventArgs e)

{

obj.eid = int.Parse(TextBox1.Text);

obj.name = TextBox2.Text;

obj.salary = Convert.ToDecimal(TextBox3.Text);

el = (List)Session["emp"];

el.Add(obj);

GridView1.DataSource = el.ToList();

GridView1.DataBind();

}

8 Replies

Know the answer? Post it — somebody with the same question will find it here.

Jignesh Kumar7y ago
Accepted answer
Hi Harry,

You are creating session for reference type. If you do assign anything to that object that will store in session.

Please find below example for the same Session["ValType"] not change after save also
List el = new List();
int val = 10;

protected void Page_Load(object sender, EventArgs e)
{
            if (!Page.IsPostBack)
            {
              //  Session["emp"] = el;
                Session["ValType"] = val;

            }
}

protected void button1_Click(object sender, EventArgs e)
        {
            obj.eid = int.Parse(TextBox1.Text);
            obj.name = TextBox2.Text;
            obj.salary = Convert.ToDecimal(TextBox3.Text);
           // el = (List)Session["emp"];
            el = (List)ViewState["emp"];
            val = 20;
            el.Add(obj);
            GridView1.DataSource = el.ToList();
            GridView1.DataBind();
        }
You try to create one session variable to value type and store in session and check it will not change your session variable
harry code7y ago
@ Jignesh Thank you for the reply.
Laxmidhar Sahoo7y ago
1. protected void Button1_Click(object sender, EventArgs e)
2. {
3. obj.eid = int.Parse(TextBox1.Text);
4. obj.name = TextBox2.Text;
5. obj.salary = Convert.ToDecimal(TextBox3.Text);
7. el.Add(obj);
8. GridView1.DataSource = el.ToList();
9. GridView1.DataBind();
10. Session["emp"] = el;
11. }
12. protected void Page_Load(object sender, EventArgs e)
13. {
14. if(!Page.IsPostBack)
15. {
16. Session["emp"] = el;
17. }
18. else
19. {
20. el=(List)Session["emp"];
21. }
22. }

harry code7y ago

Jignesh Kumar

HI,

Thanky you for the Reply.

One you submit data then you are assigning

el = (List)Session["emp"];

el.Add(obj);

I want to know how are the values getting assigned to Session with out assigning them.

Thank You.

Jignesh Kumar7y ago

Hi Harry,

Web application is stateless so once page is postback then data will loos thier state.

Session is maintain your data during postback.

In your code example you are assigning emp list to session while !PageIsPostback so it will be initially 0 count.

One you submit data then you are assigning

el = (List)Session["emp"];

el.Add(obj);

But Idialy you should write session["emp"] = el;

You can retain your updated data

Sreekanth Reddy7y ago

Okay,

Have a small test by placing your objects

Employee obj = new Employee();

List el = new List();

inside the click event.

Thank you.

harry code7y ago

Hi Srikanth.

Thank you for the reply.

"Here again you needs to assign the el to the session["emp"] for holding the updated list of employees"

i am having confusion here.I did not assignn value to Session in Button_Click method.

still i am able to get list of values.

That is the problem.

Sreekanth Reddy7y ago

In general whenever the page has taken the postback(2nd request), Th previous request details are getting lost.

To avoid that factor your code is taking the help of session.

In 1st call :

If the Employee list is empty, the session be having 0 records in session of type Employee.

In 2nd Call(Means on button click) :

Firstly you are getting the existing Items(currently 0) into one Employee object(In your case el) and adding the current current object to that "el".

Here again you needs to assign the el to the session["emp"] for holding the updated list of employees.

Hope you understood. If not plese come back. Else aaccept the answer.

Thank you.