Check whether the checkbox is checked or not - ASP.NET

I have the following code:

(some.aspx.cs)

        if(Page.IsPostBack)
        {
        bool apple2 = false;
        bool pizza2 = false;
        bool orange2 = false;
        if (apple.Checked)
            apple2 = true;
        if (pizza.Checked)
            pizza2 = true;
        if (orange.Checked)
            orange2 = true;
        }

(some.aspx)

     <tr>
     <td>Food:</td>
     <td>Apple <input type="checkbox" name="food" id="apple" value="apple" runat="server" />Pizza <input type="checkbox" name="food" id="pizza" value="pizza" runat="server" />Orange <input type="checkbox" name="food" id="orange" value开发者_运维知识库="orange" runat="server" /></td>
 </tr>

Now, i send the Boolean variables to SQL database. The problem is only with unchecked boxes. I mean, when you check some checkboxes it sends it as true (and that's right) but when i uncheck them it remains the same (true).

Addition: Why too little? here's a query...nothing special here

string q = string.Format(@"UPDATE tblUsers SET ......., apple='{8}', orange='{9}' WHERE id='{10}'", ...., apple2, orange2, id);
lib.sql_query(q); // using my sql library...

the datatype is bit....i tried also with string...but no success

P.S. - i also tried with Request.Form["apple"], and the uncheck worked...but unfortunately the check didn't...when i check the checkbox it throws me an error:

Conversion failed when converting the varchar value 'on' to data type bit. 

Somebody?

So after a long time of combinations and other stuff it worked...Without any javascripts and hidden fields... that's the .cs code

        bool apple2 = (Request.Form["apple"] == "on") ? true : false;
        bool orange2 = (Request.Form["orange"] == "on") ? true : false;
        bool pizza2 = (Request.Form["pizza"] == "on") ? true : false;

Unchecked checkboxes are not submitted when a form is posted. You will have to write a workaround.

One method would be to have a hidden field that is populated via the javascript of the checkbox.

Firstly I would tidy your code up at the beginning the if statements are unnecessary:

if (Page.IsPostback)
{
    bool appleSelected = apple.Checked;
    bool pizzaSelected = pizza.Checked;
    bool orangeSelected = orange.Checked;
}

Have you tried using the CheckBox class instead of input?

<asp:CheckBox id="apple" value="apple" runat="server" Checked="True|False" />
<asp:CheckBox id="pizza" value="pizza" runat="server" Checked="True|False" />
<asp:CheckBox id="orange" value="orange" runat="server" Checked="True|False" />

It should work since the datatype is bit...at least when you pass the bool to a stored procedure.

Since you have the SQL update statement in your code, try converting the bool to a 0 or 1.

Int16 iApple = (apple2) ? 1 : 0;
Int16 iOrange = (orange2) ? 1 : 0;
string query = string.Format(@"UPDATE tblUsers SET ......., apple='{8}', orange='{9}'    WHERE id='{10}'", ...., iApple, iOrange, id);
lib.sql_query(q);

using System.Data.SqlClient;
using System.Data;

public partial class _Default : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection("Data Source=RND3 " + "\\" + " SQLEXPRESS;Initial Catalog=SSSolutionFiles;Integrated Security=True");
    public void displaygrid()
    {
        SqlDataAdapter da = new SqlDataAdapter("select * from userfile", con);
        DataSet ds = new DataSet();
        da.Fill(ds, "p");
        GridView1.DataSource = ds.Tables["p"];
        GridView1.DataBind();
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        //Label1.Text = txtUserName.Text + "<br>" + txtPassword.Text + "<br>" + txtConfirmPassword.Text + "<br>" + txtConfirmationNumber.Text;
        displaygrid();
        if (!IsPostBack)
            BindDropDownListData();
    }

    public void BindDropDownListData()
    {
        //SqlConnection con = new SqlConnection("Data Source=RND3 " + "\\" + " SQLEXPRESS;Initial Catalog=SSSolutionFiles;Integrated Security=True");
        //SqlConnection mySqlConnection = new SqlConnection();
        {
            try
            {
                con.Open();
                SqlCommand mySqlCommand = new SqlCommand("Select username from userfile ", con);
                SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter(mySqlCommand);
                DataSet myDataSet = new DataSet();
                mySqlDataAdapter.Fill(myDataSet);
                //DropDownList1.DataSource = myDataSet;
                //DropDownList1.DataTextField = "username";
                //DropDownList1.DataValueField = "username";
                //DropDownList1.DataBind();
                CheckBoxList1.DataSource = myDataSet;
                CheckBoxList1.DataTextField = "username";
                CheckBoxList1.DataValueField = "username";
                CheckBoxList1.DataBind();
            }
            catch (Exception ex)
            {
                Label1.Text = ex.Message;
            }
            finally
            {
                con.Close();
            }
        }
    }
    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        SqlCommand cmd = new SqlCommand("insert into userfile values('" + txtUserName.Text + "','" + txtPassword.Text + "','" + txtConfirmPassword.Text + "','" + txtConfirmationNumber.Text + "')", con);
        con.Open();
        cmd.ExecuteScalar();
        displaygrid();
        BindDropDownListData();
    }
    protected void btnUpdate_Click(object sender, EventArgs e)
    {
        SqlCommand cmd = new SqlCommand("update userfile set confirmnumber='" + txtConfirmationNumber.Text + "', password='" + txtPassword.Text + "',confirmpassword='" + txtConfirmPassword.Text + "' where username='" + txtUserName.Text + "' ", con);
        con.Open();
        cmd.ExecuteScalar();
        displaygrid();
    }
    protected void btnDelete_Click(object sender, EventArgs e)
    {
        SqlCommand cmd = new SqlCommand("delete from userfile where username='" + txtUserName.Text + "' ", con);
        con.Open();
        cmd.ExecuteScalar();
        displaygrid();
        BindDropDownListData();
    }
    protected void btnClear_Click(object sender, EventArgs e)
    {
        txtConfirmationNumber.Text = "";
        txtUserName.Text = "";
        txtConfirmPassword.Text = "";
        txtPassword.Text = "";
    }
    protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
    {
        if (CheckBox1.Checked == true)
        {
            foreach (ListItem checkboxitems in CheckBoxList1.Items)
            {
                checkboxitems.Selected = true;
            }
        }
        else if (CheckBox1.Checked == false)
        {
            foreach (ListItem listItem in CheckBoxList1.Items)
            {
                listItem.Selected = false;
            }
        }
    }
}

THis is actually more accurate to get the checked values for an input field with runat="server".

string isAppleChecked = apple.Attributes["checked"] != null && apple.Attributes["checked"] == "checked" ? "{true}" : "{false}";