How to get data from session variable?

Question

0.00/5 (No votes)

See more:

I am trying build a function, when I check a checkbox control, i create cart session which stories list of data and from that data, I would like to get product_id.

when I try to execute the below function, I get a cast exception error on the line below:

System.InvalidCastException: Unable to cast object of type 'System.Collections.Generic.List`1[System.String]' to type 'System.String'.

string data = (string)Session["Cart"];

I tried calling data from the checkbox variable as well, but i also kept getting another error, informing me that the input format is incorrect.
Whole Method:

C#

protected void AddToCart_Click(object sender, EventArgs e)
{
    var selectedProducts = GridView1.Rows.Cast<GridViewRow>()
      .Where(row => ((CheckBox)row.FindControl("SelectedProducts")).Checked)
      .Select(row => GridView1.DataKeys[row.RowIndex].Value.ToString()).ToList();
    if (Session["Cart"] == null)
    {
        Session["Cart"] = selectedProducts;
    }
    else
    {
        List<String> cart = new List<String>();
        cart = (List<string>)Session["Cart"];
       // cart.Add(Session["Cart"]);
        foreach (var product in selectedProducts)
            cart.Add(product);
        Session["Cart"] = cart;
    }
    foreach (GridViewRow row in GridView1.Rows)
    {
        CheckBox cb = (CheckBox)row.FindControl("SelectedProducts");
        if (cb.Checked)
            cb.Checked = true;

            {
              string data = (string)Session["Cart"];
                Label1.Text = data.ToString();

                // Access chb.Text;
                //int num = Convert.ToInt32(cb.Text);
               // Label1.Text = num.ToString();
            }
    }
}

Any help, would be very much appreciated.
Many thanks

Posted 24-Nov-14 3:35am

miss786

Add a Solution

Comments

Kornfeld Eliyahu Peter 24-Nov-14 9:44am

It seams Session["Cart"] has the type List<t> - it can not be casted into a single string!!!

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2014-11-24T03:54:00

Why would you expect it to convert a List of strigns to a string for you?
If you wrote this:

C#

List<string> list = new List<string>();
string s = (string) list;

You would expect an error woudln;t you?
So when you do this:

C#

            var selectedProducts = GridView1.Rows.Cast<gridviewrow>()
              .Where(row => ((CheckBox)row.FindControl("SelectedProducts")).Checked)
              .Select(row => GridView1.DataKeys[row.RowIndex].Value.ToString()).ToList();
            if (Session["Cart"] == null)
            {
                Session["Cart"] = selectedProducts;
...
                      string data = (string)Session["Cart"];</gridviewrow>

That is exactly what your are trying to do!
Try getting the list from the session instead?

C#

List<string> data = (List<string>)Session["Cart"];</string></string>

Asim Ghazanfar · Answer 2 · 2014-11-26T06:52:00

Solution 2

Assign Data
Session["Cart"] = selectedProducts;

Retrieve Data
string data = (string)Session["Cart"];

Posted 26-Nov-14 6:52am

Asim Ghazanfar