Can anyone help out a newbie?RSS

• • Reply
  McQvist

  None

  0 Points

  3 Posts

  Can anyone help out a newbie?

  Nov 18, 2019 09:31 PM|McQvist|LINK

  I am trying another go at ASP.net and C#, and I have run into a problem.

  I am making a very simple CRUD system, showing delays of trains. Everything was working well until I got to the UPDATE part.

  I am getting a "Input string was not in a correct format" error when trying to update my data. I have looked at posts with similar issues, but I could not really relate the solutions to my project.

              <asp:GridView ID="gvDisruptions" runat="server" AutoGenerateColumns="false">
  
                  <Columns>
                      <asp:BoundField Datafield="trainID" HeaderText="trainID" />
                      <asp:BoundField Datafield="delay" HeaderText="delay" />
                      <asp:BoundField Datafield="cancellation" HeaderText="cancellation" />
                      <asp:TemplateField>
                          <ItemTemplate>
                              <asp:LinkButton ID="linkView" runat="server" CommandArgument='<% Eval("routeID") %>' OnClick="link_OnClick">View</asp:LinkButton>
                          </ItemTemplate>
                      </asp:TemplateField>
                  </Columns>
  
              </asp:GridView>

  protected void link_OnClick(object sender,EventArgs e)
          {
              int routeID = Convert.ToInt32((sender as LinkButton).CommandArgument);
              if (sqlCon.State == ConnectionState.Closed)
                  sqlCon.Open();
              SqlDataAdapter sqlData = new SqlDataAdapter("DisruptionsViewByID", sqlCon);
              sqlData.SelectCommand.CommandType = CommandType.StoredProcedure;
              sqlData.SelectCommand.Parameters.AddWithValue("@routeID", routeID);
              DataTable dtbl = new DataTable();
              sqlData.Fill(dtbl);
              sqlCon.Close();
              hfrouteID.Value = routeID.ToString();
              txtTrain.Text = dtbl.Rows[0]["Train"].ToString();
              txtDelay.Text = dtbl.Rows[0]["Delay"].ToString();
              txtCancellation.Text = dtbl.Rows[0]["Cancellation"].ToString();
              btnSave.Text = "Update";
              btnDelete.Enabled = true;
          }

  The problem is this line: int routeID = Convert.ToInt32((sender as LinkButton).CommandArgument);
  
  
  

• • Reply
  PaulTheSmith

  Participant

  1080 Points

  571 Posts

  Re: Can anyone help out a newbie?

  Nov 18, 2019 09:45 PM|PaulTheSmith|LINK

  Do you know how to use breakpoints?

  Put a breakpoint on the line that is giving you the error. (Click in the left hand column in Visual Studio and you will get a red/brown dot and the line will be highlighted In the same colour).

  Now run your program with F5.  After you click the button the execution should stop on the line with the breakpoints.  It will be highlighted in yellow.

  Hold your mouse over "CommandArgument" and you should see what the command argument is.  (If you don't see it hen use the "local" window to find the "sender" parameter and expand it to find the value of the CommandArgument.

  What is the value of "CommandArgument"?  Is it what you expect (which would seem to be an Id of some kind)?  What do you expect?  What do you see?

• • Reply
  mgebhard

  All-Star

  44401 Points

  19195 Posts

  Re: Can anyone help out a newbie?

  Nov 18, 2019 09:48 PM|mgebhard|LINK

  You want to use the RowCommand event of the GridView not the click event.

  https://weblog.west-wind.com/posts/2007/Jun/07/GridView-and-CommandArguments

  There's also the GridView reference docs and Google.

  https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.gridview?view=netframework-4.8

  https://www.aspsnippets.com/Articles/GridView-CRUD-Select-Insert-Edit-Update-Delete-using-Single-Stored-Procedure-in-ASPNet.aspx

• • Reply
  Khuram.Shahz...

  Contributor

  2036 Points

  1025 Posts

  Re: Can anyone help out a newbie?

  Nov 19, 2019 11:51 AM|Khuram.Shahzad|LINK

  Please have a look, its good fro getting started and complete example with code:

  https://www.c-sharpcorner.com/UploadFile/4aae29/complete-crud-operations-in-Asp-Net/

  We cannot solve our problems with the same thinking we used when we created them.
• • Reply
  Fei Han - MS...

  All-Star

  40485 Points

  6231 Posts

  Microsoft

  Re: Can anyone help out a newbie?

  Nov 21, 2019 08:51 AM|Fei Han - MSFT|LINK

  Hi McQvist,

  McQvist

  "Input string was not in a correct format" error

  <ItemTemplate>
     <asp:LinkButton ID="linkView" runat="server" CommandArgument='<% Eval("routeID") %>' OnClick="link_OnClick">View</asp:LinkButton>
  </ItemTemplate>

  The problem is this line: int routeID = Convert.ToInt32((sender as LinkButton).CommandArgument);

  If you debug your code, you can find the actual value of (sender as LinkButton).CommandArgument, it would be "<% Eval("routeID") %>" instead of the value of routeID field. 

  

  You can modify the code like below and check if it can help get expected value from CommandArgument.

  <asp:TemplateField>
      <ItemTemplate>
          <asp:LinkButton ID="linkView" runat="server" CommandArgument='<%#Eval("routeID") %>' OnClick="link_OnClick">View</asp:LinkButton>
      </ItemTemplate>
  </asp:TemplateField>

  With Regards,

  Fei Han

  
  MSDN Community Support
  Please remember to "Mark as Answer" the responses that resolved your issue.