I am trying to use a checkbox control in gridview. Basically the user would enter an Item Description, the Quantity of the Item used, and if it has already been "Sold" out of inventory. The checkbox when checked would indicate the item was sold. Unchecked it can be null or no. I can store the value in the database as 1/2, true/false, yes/no. It doesn't matter.
I have tried using bit type, int, and vchar in my database. And have tried multiple ways of getting the value for the check in C# and cant seem to get it to work.
I've searched all over and have found examples on how to use it to save or delete multiple rows. But I need it to actually store a value in my db.
Here's code i've scavenged from other posts and almost have something working.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
namespace WebApplication1
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
SetInitialRow();
}
}
private void SetInitialRow()
{
DataTable dt = new DataTable();
DataRow dr = null;
dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
dt.Columns.Add(new DataColumn("Column1", typeof(string)));
dt.Columns.Add(new DataColumn("Column2", typeof(string)));
dt.Columns.Add(new DataColumn("Column3", typeof(string)));
dr = dt.NewRow();
dr["RowNumber"] = 1;
dr["Column1"] = string.Empty;
dr["Column2"] = string.Empty;
dr["Column3"] = string.Empty;
dt.Rows.Add(dr);
ViewState["CurrentTable"] = dt;
Gridview1.DataSource = dt;
Gridview1.DataBind();
}
private void AddNewRowToGrid()
{
int rowIndex = 0;
if (ViewState["CurrentTable"] != null)
{
DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
DataRow drCurrentRow = null;
if (dtCurrentTable.Rows.Count > 0)
{
for (int i = 1; i <= dtCurrentTable.Rows.Count; i )
{
TextBox itemDesc = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("txtItemDesc");
TextBox quantity = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("txtQuantity");
CheckBox sold = (CheckBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("alreadySold");
drCurrentRow = dtCurrentTable.NewRow();
drCurrentRow["RowNumber"] = i 1;
dtCurrentTable.Rows[i - 1]["Column1"] = itemDesc.Text;
dtCurrentTable.Rows[i - 1]["Column2"] = quantity.Text;
dtCurrentTable.Rows[i - 1]["Column3"] = sold.Checked.ToString();
rowIndex ;
}
dtCurrentTable.Rows.Add(drCurrentRow);
ViewState["CurrentTable"] = dtCurrentTable;
Gridview1.DataSource = dtCurrentTable;
Gridview1.DataBind();
}
}
else
{
Response.Write("ViewState is null");
}
//Set Previous Data on Postbacks
SetPreviousData();
}
private void SetPreviousData()
{
int rowIndex = 0;
if (ViewState["CurrentTable"] != null)
{
DataTable dt = (DataTable)ViewState["CurrentTable"];
if (dt.Rows.Count > 0)
{
for (int i = 0; i < dt.Rows.Count; i )
{
TextBox itemDesc = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("txtItemDesc");
TextBox quantity = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("txtQuantity");
CheckBox sold = (CheckBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("alreadySold");
itemDesc.Text = dt.Rows[i]["Column1"].ToString();
quantity.Text = dt.Rows[i]["Column2"].ToString();
sold.Checked = dt.Rows[i]["Column3"].ToString().ToUpperInvariant() == "TRUE";
rowIndex ;
}
}
}
}
protected void ButtonAdd_Click(object sender, EventArgs e)
{
AddNewRowToGrid();
}
protected void Save(object sender, System.EventArgs e)
{
if (ViewState["CurrentTable"] != null)
{
DataTable dt = new DataTable();
dt = ViewState["CurrentTable"] as DataTable;
if (dt.Rows.Count > 0)
{
using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString))
{
SqlCommand cmd = null;
foreach (GridViewRow row in Gridview1.Rows)
{
cmd = new SqlCommand("INSERT INTO SampleTest(ItemDesc,Quantity,Sold) VALUES(@Column1,@Column2,@Column3)", con);
string itemDesc = (row.FindControl("txtItemDesc") as TextBox).Text;
string quantity = (row.FindControl("txtQuantity") as TextBox).Text;
CheckBox sold = (row.FindControl("alreadySold") as CheckBox);
if (sold == null)
{
sold.Checked = false;
}
else
{
sold.Checked = true;
}
cmd.Parameters.AddWithValue("@Column1", itemDesc);
cmd.Parameters.AddWithValue("@Column2", quantity);
cmd.Parameters.AddWithValue("@Column3", sold);
con.Open();
cmd.ExecuteNonQuery();
con.Close();
}
//cmd = new SqlCommand("SELECT Column1,Column2,Column3 FROM SampleTest", con);
//SqlDataAdapter da = new SqlDataAdapter(cmd);
//DataTable dt1 = new DataTable();
//da.Fill(dt1);
//this.gvSample.DataSource = dt1;
//this.gvSample.DataBind();
}
}
}
}
}
}
CodePudding user response：
In your save, instead of CheckBox sold try something like:
bool sold = (row.FindControl("alreadySold") as CheckBox)?.Checked ?? false;
So a little explanation on the above:
- as CheckBox can return null.
- the '?' in CheckBox)? is a null conditional check that will prevent a null exception being thrown if it is null.
- the '??' is saying that if the code preceding that is null, instead of assigning null, it assigns 'false'. Now if the code preceding the ?? is not null, then it will set the bool variable value to whatever .Checked actually is (true or false).
Now if your DB allows NULLs in that column and you are fine with that, you can also do:
bool? sold = (row.FindControl("alreadySold") as CheckBox)?.Checked;
^ bool? is a what is called a Nullable value type. Value types can't be null, but nullable value types wrap around a value type and allow it be null.
CodePudding user response：
I'm an idiot. Thank you B.O.B. for explaining what was happening with the null value and the checkbox control. It really helped me understand what was happening. The reason the other things didnt work is because I had a type-o on the checkbox control on the html page. Once I fixed that everything works perfect.