Using hyperlink to call page: Alternatives?

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CJM - 04 Jul 2007 18:09 GMT

Bit of a noob question... I'm finally starting to move across .ASP.NET from
ASP 3.0, and I'm trying to make the most of .NET rather than simply do what
I did before, albeit with different syntax. I'm converting a simple ASP
application to .NET as a learning vehicle.

I have an application that allows the user to search a simple DB containing
information about machine tooling. The user can search for details of a
specific item or for groups of items that have specific characteristics.

In each case, the application returns the same information, and certain
columns are returned as hyperlinks to allow further searching; for example,
if I search for Retainer #1 I get one record returned, but if I click on
the value in the value in the Tip Width field, the the hyperlink calls the
same page again, but with different search paremters that returns all
Retainers with a similar Tip Width.

Snippet:
<tr>
<td><a href="viewc105.asp?retainer=<%=iRetNo%>"
target="_blank"><%=iRetNo%></td>
<td><a
href="searchc105.asp?searchval=<%=fTipWidth%>&search=Search&SearchField=2"><%=fTipWidth%></a></td>
<td><%=.fields("Thickness")%></td>
<td><%=.fields("Depth")%></td>
<td><%=.fields("Style")%></td>
<td><%=.fields("InternalAngle")%></td>
<td><%=Format3dp(.fields("DevelopedWidth"))%></td>
<td><a
href="searchc105.asp?searchval=<%=fFlange%>&search=Search&SearchField=3"><%=fFlange%></a></td>
</tr>

Now, I know I *could* easily use the same technique in ASP.NET. I'm using a
a GridView control to generate the table, so I've configured several of the
columns as HyperTextField columns.

My first question is whether there are any alternatives to this technique?
Rather than submitting the page, then checking for certain QueryString
fields, is there any better method in ASP.NET? I'm not sure why I think
there may be better methods, but I just have a felling that there might be.

My second question is how to actually construct the table that I want to
render. As I've said, I started using a GridView, but I'm in two minds as to
whether should bind the Gridview to the DataReader that I've created, and
then retrospectively, edit the HypertextField columns to point to the right
hyperlinks; or should I manually construct each row in a While
DBReader.Read() loop. Any thoughts?

The overall problem I have at the moment is that I can imagine a dozen ways
to acheive even the simplest of tasks and all of the received wisdom I've
accumulated in ASP3.0 can only be thrown out of the window. I'm sure I can
achieve everything I want somehow, but I'd rather aim for a slick solution
than a series of ASP3-esque bodges...

Thanks in advance

Chris

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Teemu Keiski - 04 Jul 2007 20:08 GMT

Hi,

in ASP.NEt you wouldn't do redirects such as you did with classic asp, at
least not in same sense. In most cases you'd do a postback which means that
page is posted back to itself (in ASP sense means redirect to itself but in
ASP.NEt page has state which is kept on subsequent postbacks with help of
view state, so it is a lot more than just a redirect).

With GridView for example, you'd get a event raised as a result to that a
Link button is clicked (you'd do it using a LinkButton or ButtonField), and
that event can directly provide arguments related to the row you clicked,
for example ids, column values etc without the need for you check
QueryString manually.

http://asp.net/learn/dataaccess/tutorial28vb.aspx?tabid=63

Signature

Teemu Keiski
AspInsider, ASP.NET MVP
http://blogs.aspadvice.com/joteke
http://teemukeiski.net

> Bit of a noob question... I'm finally starting to move across .ASP.NET
> from ASP 3.0, and I'm trying to make the most of .NET rather than simply
[quoted text clipped - 54 lines]
>
> Chris

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CJM - 05 Jul 2007 15:29 GMT

> With GridView for example, you'd get a event raised as a result to that a
> Link button is clicked (you'd do it using a LinkButton or ButtonField),
[quoted text clipped - 3 lines]
>
> http://asp.net/learn/dataaccess/tutorial28vb.aspx?tabid=63

Teemu,

Thanks for the response.

I'm afraid I've been running around in circles trying to implement what you
suggested, but I'm getting nowhere.

I read the article you suggested, unfortunately it covers everything but
using a LinkButton in a GridView. I can imagine how it will work; when the
linkbutton is click, its handler will update the SearchVal field, and will
select (ie set to 'checked') the appropriate radio button before calling
the original code in the btnSearch_Click sub.

However, I can't even get the LinkButton to display the appropriate value .
How do I bind the LinkButton in the TemplateField to the RetainerNo in the
bound DataReader?

Here's the relevant code snippets:

<asp:GridView ID="GridRetainers" AutoGenerateColumns="False"
runat="server">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="btnRetainer" runat="server"></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField HeaderText="Thick" DataField="Thickness" />
<asp:BoundField HeaderText="Depth" DataField="Depth" />
<asp:BoundField HeaderText="Style" DataField="Style" />
<asp:BoundField HeaderText="Angle" DataField="InternalAngle" />
<asp:BoundField HeaderText="Dev Width" DataField="DevelopedWidth" />
</Columns>
</asp:GridView>

Protected Sub btnSearch_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles btnSearch.Click

Dim oConn As New SqlConnection("...connection string...")
Dim oCmd As New SqlCommand
Dim drRetainers As SqlDataReader

oConn.Open()
With oCmd
.Connection = oConn
.CommandType = Data.CommandType.StoredProcedure

If rdoRetainer.Checked Then
.CommandText = "mnd_ListRetainersByRetNo"
.Parameters.Add("RetainerNo", Data.SqlDbType.VarChar, 10).Value =
SearchVal.Text
End If
If rdoTipWidth.Checked Then
.CommandText = "mnd_ListRetainersByTipWidth"
.Parameters.Add("TipWidth", Data.SqlDbType.VarChar, 10).Value =
SearchVal.Text
End If
If rdoFlange.Checked Then
.CommandText = "mnd_ListRetainersByFlange"
.Parameters.Add("Flange", Data.SqlDbType.VarChar, 10).Value =
SearchVal.Text
End If
End With

drRetainers = oCmd.ExecuteReader
With GridRetainers
.DataSource = drRetainers
.DataBind()
.GridLines = GridLines.None
.CellSpacing = 1

End With
End Sub

Thanks

Chris

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Using hyperlink to call page: Alternatives?

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