asp.net get table cell text - asp.net

Question

I'm developping an asp.net Web application.
I have a table and I add rows/cells to the table through code :
<asp:Table ID="Table2" runat="server" Style="table-layout:auto;" GridLines="Both">
<asp:TableRow runat="server" Enabled="False" Font-Bold="True" HorizontalAlign="Center" VerticalAlign="Top" BackColor="#FF704C" ForeColor="Black">
<asp:TableCell runat="server">Famille</asp:TableCell>
<asp:TableCell runat="server">Editeur</asp:TableCell>
<asp:TableCell runat="server">Référence</asp:TableCell>
<asp:TableCell runat="server">Solutions</asp:TableCell>
<asp:TableCell runat="server">Nature</asp:TableCell>
<asp:TableCell runat="server">Unité</asp:TableCell>
<asp:TableCell runat="server">Usage</asp:TableCell>
<asp:TableCell runat="server">Version</asp:TableCell>
<asp:TableCell runat="server">PP net (€)</asp:TableCell>
<asp:TableCell runat="server">Quantité</asp:TableCell>
</asp:TableRow>
</asp:Table>
--
Dim tfp As New TextFieldParser(My.Settings.FilePath)
tfp.Delimiters = New String() {My.Settings.Delimiter}
tfp.TextFieldType = FieldType.Delimited
tfp.ReadLine() ' skip header
Dim Ligne As Integer = 0
While tfp.EndOfData = False
Dim fields = tfp.ReadFields()
Dim trow As New TableRow
Ligne = Ligne + 1
For i = 0 To 8
Dim tcell As New TableCell
tcell.Controls.Add(New LiteralControl(fields(i)))
trow.Cells.Add(tcell)
Next
Table2.Rows.Add(trow)
End While
Later in code, after the user click on a button, I want to get the text which is in the cell, but I always get an empty string.
MyCell = table2.rows(3).Cells(2)
? Mycell.text
""
How can I get the text which is inside the cell ?
Thank you

Answer 1

Ok, the main issue, is that the asp.net "table" has ONE huge big nasty issue.
Asp.net tables do NOT have viewstate nor persistence. So, in code when you add some rows, they are objects added - but NOT with viewstate.
So, your code would have to RE-RUN every time!!!!
In other words, if you run some code to add a row, you have to save that "list" or object of additions, and then on each page load - re-create, and re-add that data each time.
As a result, you are MUCH ,but I mean REALLY BEYOND WORLD poverty better off to use a control with persistence (viewstate) build in.
EVEN in that case where you want to persist the data, I STRONG suggest you persist ONLY the data table used (note how I said the data table - NOT the markup, nor the HTML markup table).
And we do not yet need to have a database to do this!!!
Of course I grasp this is just for learning, but at the end of the day? That data needs to be placed in a database. You then do the data adding, deleting, manipulation, processing against the database. If you need to show updated data as a result (say adding a new row to the database), YOU THEN RE-BIND the control on the form.
so, keep the concept of working with the data 100% separate from the control or so called UI (the web page).
Again, I 100% grasp the goal of learning, and starting out simple. The problem, is that eventually, that data WILL and NEEDS to be in a table. This will allow data base operations, or at the VERY least allow you to use code to add rows, reference a column etc.
so, I suggest you use a GridView, and THEN also create a data table (in code behind).
So, our markup now becomes this:
<asp:GridView ID="GridView1" runat="server" CssClass="table" Width="50%"
ShowHeaderWhenEmpty="true" HeaderStyle-BackColor="LightGray">
</asp:GridView>
<br />
<asp:Button ID="Button1" runat="server" Text="Add new row" CssClass="btn" />
And now our code to create the table, and also code for the add button.
We have this now:
Dim rstData As New DataTable
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
' first page load - create a table,
' send to our grid
CreateTable
LoadGrid
Session("rstData") = rstData
Else
rstData = Session("rstData")
End If
End Sub
Sub CreateTable()
rstData.Columns.Add("Famille")
rstData.Columns.Add("Editeur")
rstData.Columns.Add("Référence")
rstData.Columns.Add("Solutions")
rstData.Columns.Add("Nature")
rstData.Columns.Add("Unité", GetType(Integer))
rstData.Columns.Add("Usage")
rstData.Columns.Add("Version", GetType(Double))
rstData.Columns.Add("PP Net(€)", GetType(Double))
rstData.Columns.Add("Quantité", GetType(Double))
End Sub
Sub LoadGrid()
GridView1.DataSource = rstData
GridView1.DataBind()
End Sub
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' add a new row to our table
Dim MyNewRow As DataRow = rstData.NewRow
MyNewRow("Famille") = "this is test" ' example refernce by colum name
MyNewRow(1) = "My Editeur" ' example refernce by colum index
rstData.Rows.Add(MyNewRow) ' send new row to the table
LoadGrid() ' re-display grid to show this new row
End Sub
And when I run above, click the button, I now see this:
Note how we had much less markup, but of course a bit of extra code. However, if that table comes from a database, then we did not even have the code to "create" the table, since in most cases, that table and data would be in a database.
Other advantages?
Well, I can now format the grid, increase column lengths, even drop in a image control, or whatever I like.
In above, I did let the grid load the data table, and format the column widths, but you will often of course want to control the column widths, settings, and even what kind of control to use here.
In fact, if you have a boatload of custom controls on the grid you want, then often I suggest using a ListView in place of GridView (the hard part and learning curve is to learn when and what control to use - you have so many to choose from!!!).
So, I suggest the above.
You can then say I want the 2nd row, and cell like this:
rstData.Rows(1).Item("Famile")
rstData.Rows(1).Item(0)
Again, you can reference column(s) by number (index) or by name.
And say I want even MORE control, then say I have a grid like this:
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="ID" CssClass="table" >
<Columns>
<asp:BoundField DataField="Fighter" HeaderText="Fighter" />
<asp:BoundField DataField="Engine" HeaderText="Engine" />
<asp:BoundField DataField="Thrust" HeaderText="Thrust" />
<asp:BoundField DataField="Description" HeaderText="Description" />
<asp:TemplateField HeaderText="Preview">
<ItemTemplate>
<asp:Image ID="Image2" runat="server" ImageUrl = '<%# Eval("ImagePath") %>' Width="140" />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="View">
<ItemTemplate>
<asp:Button ID="cmdView" runat="server" Text="View" CssClass="btn"
CommandArgument = '<%# Eval("ImagePath") %>' OnClick="cmdView_Click" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Note how we now have AutoGenerateColumns = false. That's because I want to "control" each column such as width, etc. And I wanted a image control in that "table".
So, my code to load up the above is now this:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
LoadGridF()
End If
End Sub
Sub LoadGridF()
Using conn As New SqlConnection(My.Settings.TEST4)
Using cmdSQL As New SqlCommand("SELECT * FROM Fighters", conn)
conn.Open()
Dim rstData = New DataTable
rstData.Load(cmdSQL.ExecuteReader)
GridView1.DataSource = rstData
GridView1.DataBind()
End Using
End Using
End Sub
And now I get this: