CODEWITHSUNDEEP
c#asp.net
user1915452
user1915452

Reputation: 11

Save selected value of a dropdown list in a global variable

I am trying to save the dropdown list selected value in a glbal variable .. I have lots of country on the dropdown list , whan I choose one of them and press a button :

protected void Button1_Click(object sender, EventArgs e)
    {
        Button2.Enabled = true;
        Button2.Visible = true;
        DropDownList1.Visible = true;

        DropDownList9.Items.Clear();


        if (!Class1.Search_Continent.Equals("-"))
        {
            SqlConnection conn1 = new SqlConnection(@"Data Source=AK-PC\MSSQLSERVER1;Initial Catalog=DB;Integrated Security=True");
            conn1.Open();
            SqlCommand cmd1 = new SqlCommand("Select Country_name FROM Country WHERE Continent_name='" + DropDownList1.SelectedValue + "'", conn1);
            SqlDataReader dr1;
            dr1 = cmd1.ExecuteReader();

            while (dr1.Read())
            { DropDownList9.Items.Add(dr1["Country_name"].ToString() + "\n"); }

            dr1.Close();
            conn1.Close();

}

protected void Button2_Click(object sender, EventArgs e)
    {
        // Redirect to Country page
        Class1.CountryName = DropDownList9.SelectedValue.ToString();
        Response.Redirect("Country.aspx", true);
    }

it doesnt take the selected value ! it always take the first value of the dropdown list ! Please help me !

Upvotes: 0

Views: 2107

Answers (2)

David
David

Reputation: 218877

it always take the first value of the dropdown list

This is very common in web forms if you're populating the data incorrectly. Where are you populating the drop down list? I'm going to guess that you're doing it in Page_Load. I'm also going to guess that you don't have it wrapped in something like if (!IsPostBack). If you put a debugging breakpoint in Page_Load you'll find that it's called in the post-back before Button2_Click is called.

Keep in mind that HTTP is stateless. This means that the entire server-side page object needs to be constructed on each request to the server. Page_Load is part of that construction, and it happens before event handlers do. So what's likely happening is:

  1. User requests initial page.
  2. You populate the drop down list with data.
  3. You display the page to the user.
  4. User selects an option and clicks a button, making a post-back request.
  5. You clobber and re-populate the drop down list, returning it to a default state.
  6. You try to get the selected value, which is now gone.

The most common solution to this problem is to use the aforementioned conditional in Page_Load:

protected void Page_Load(object sender, EventArgs e)
{
    // some initial logic
    if (!IsPostBack)
    {
        // stuff that should only happen when the page first loads
        // for example, populating controls from the database
    }
    // any other logic, etc.
}

The values for the controls shouldn't need to be re-populated with each postback because things like viewstate should keep the necessary data available. (Though if you mess with that at all then you might need to tinker some more.)

Upvotes: 0

rick schott
rick schott

Reputation: 21127

You are probably re-binding the DropDownList9 on postback and losing the SelectedValue.

protected void Page_Load(object sender, EventArgs e)
{
    if(!Page.IsPostback)
    {
       //bind data
    }
}

Upvotes: 1

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