Question

Help with asp.net detailsview control

Asked by: jwoodhams

Hi Everyone,

Please help, I think this should be simple but I am struggling with it. I have a detailsview control that has a drop down list control nested within it. I want to programatically set the value of the dropdownlist control. The line of code I want to use is this:

CType(Me.DetailsView1.FindControl("ddlMonth"), DropDownList).SelectedValue = 12

The problem is that whatever event I choose to put this code in throws a null value exception. I have tried on load, on databind, on itemcreated, none seem to work.

Anyone have any ideas?

Thanks

Jay

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

Plus...

30 Day FREE access, no risk, no obligation
Collaborate with the world's top tech experts
Unlimited access to our exclusive solution database
Never be left without tech help again

Subscribe Now

Asked On: 2009-06-03 at 11:55:53ID24461200
Topic: Programming for ASP.NET
Participating Experts: 2
Points: 500
Comments: 14

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

"The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
"Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
"Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Free Tech Articles

WARNING: 5 Reasons why you should NEVER fix a computer for free.
It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
SCCM OSD Basic troubleshooting
SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
Create a Win7 Gadget
This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
Outlook continually prompting for username and password
There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
Backup Exchange 2010 Information Store using Windows Backup
There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

Avoiding Bugs in Microsoft Access
Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
Top 10 Best New Features in Visio 2010
Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
IT Consultant Business Secrets Revealed
Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
Disaster Recovery and Business Continuity
Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
Organize Your Visio Diagrams with Containers and Lists
Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
How to Us Objects, Properties, Events and Methods in Microsoft Access
Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Watch More

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

by: HBHoffmanPosted on 2009-06-03 at 12:21:14ID: 24540164

I think you want to do this in the ItemCreated event.

Look a the example in the link below, I think you need to tell it where to look for the control ie(header, data row, footer, etc)

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.detailsview.itemcreated.aspx

by: arhamePosted on 2009-06-03 at 12:25:28ID: 24540215

You should do it in the ItemCreated event.... and there you can grab the ddl by casting it and finding it... the following will work:

Dim ddl1 As DropDownList = DirectCast(DetailsView1.FindControl("ddlMonth"), DropDownList)
ddl1.SelectedValue = 12

by: jwoodhamsPosted on 2009-06-03 at 12:33:05ID: 24540292

Thanks, I put the code you suggested in the itemCreated event.

by: jwoodhamsPosted on 2009-06-03 at 12:33:59ID: 24540303

Ooops, I mean, Thanks, I put the code you suggested in the itemCreated event and I still get the same null value exception.

by: arhamePosted on 2009-06-03 at 12:35:21ID: 24540324

Interesting, i setup a little test page and it worked on mine - will you post the rest of your code? For the detailsview and the codebehind.

by: HBHoffmanPosted on 2009-06-03 at 12:36:27ID: 24540335

look at the link I reference above, your control is in one of the row collection of the view not the view itself.

by: arhamePosted on 2009-06-03 at 12:41:51ID: 24540379

It should work as I posted it HBHoffman, I thin something else is going on.

I created a test page that had just a dropdownlist that bound to a state. The database value was 44... on the itemdatabound event, I set the value to 2. When the page rendered it was set to the value of 2. I even created 2 buttons to change the value to 4 and 5, and each button click properly changed the value of the dropdownlist. So it should be able to be accessed as I posted with something simple like the following:


    Protected Sub DetailsView1_ItemCreated(ByVal sender As Object, ByVal e As System.EventArgs) Handles DetailsView1.ItemCreated
        Dim ddl1 As DropDownList = DirectCast(DetailsView1.FindControl("DropDownlist1"), DropDownList)
        ddl1.SelectedValue = 2
    End Sub
 
    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim ddl1 As DropDownList = DirectCast(DetailsView1.FindControl("DropDownlist1"), DropDownList)
        ddl1.SelectedValue = 4
    End Sub
 
    Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim ddl1 As DropDownList = DirectCast(DetailsView1.FindControl("DropDownlist1"), DropDownList)
        ddl1.SelectedValue = 5
    End Sub

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:

Select all Open in new window

by: HBHoffmanPosted on 2009-06-03 at 12:47:20ID: 24540445

So is the issues it's not finding your control or is it not finding the item in your control?

by: jwoodhamsPosted on 2009-06-03 at 13:06:17ID: 24540686

Below is my front page, and my code behind is:

Protected Sub DetailsView1_ItemCreated(ByVal sender As Object, ByVal e As System.EventArgs) Handles DetailsView1.ItemCreated
'Dim ddl1 As DropDownList = DirectCast(DetailsView1.FindControl("ddlMonth"), DropDownList)
'ddl1.SelectedValue = 12

'CType(Me.DetailsView1.FindControl("ddlMonth"), DropDownList).SelectedValue = 12
End Sub

<asp:DetailsView ID="DetailsView1" runat="server" Height="50px" Width="416px" DataSourceID="SqlDataSource2" BackColor="White" BorderColor="#DEDFDE" BorderStyle="None" BorderWidth="1px" CellPadding="4" GridLines="Vertical" AutoGenerateRows="False" DataKeyNames="intEventID" ForeColor="Black">
            <Fields>
                <asp:CommandField ShowEditButton="True" ShowDeleteButton="True" ShowInsertButton="True" />
                <asp:TemplateField HeaderText="Title" ShowHeader="False">
                    <ItemTemplate>
                        
                    </ItemTemplate>
                    <EditItemTemplate>
                        <table width="300">
                            <tr>
                                <td>Title</td>
                                <td>
                        <asp:TextBox ID="Label22" runat="server" Text='<%#Bind("chrTitle") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Category</td>
                                <td>
                        <asp:TextBox ID="Label3" runat="server" Text='<%#Bind("enmCategory") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Start Date</td>
                                <td>
                        <asp:TextBox ID="Label4" runat="server" Text='<%#Bind("dtBeginDate") %>' Width="80px"></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>End Date</td>
                                <td>
                        <asp:TextBox ID="Label5" runat="server" Text='<%#Bind("dtEndDate") %>' Width="80px"></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Location</td>
                                <td>
                        <asp:TextBox ID="Label6" runat="server" Text='<%#Bind("chrLocation") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Time</td>
                                <td>
                        <asp:TextBox ID="Label7" runat="server" Text='<%#Bind("chrTime") %>' Width="80px"></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td style="height: 26px">Description</td>
                                <td style="height: 26px">
                        <asp:TextBox ID="Label8" runat="server" Text='<%#Bind("chrDescription") %>' Height="96px" TextMode="MultiLine" Width="288px"></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Cost</td>
                                <td>
                        <asp:TextBox ID="Label9" runat="server" Text='<%#Bind("chrCost") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Phone</td>
                                <td>
                        <asp:TextBox ID="Label10" runat="server" Text='<%#Bind("chrPhone") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>URL</td>
                                <td>
                        <asp:TextBox ID="Label11" runat="server" Text='<%#Bind("chrURL") %>' Width="264px"></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>First Name</td>
                                <td>
                        <asp:TextBox ID="Label12" runat="server" Text='<%#Bind("chrContactFirstName") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Last Name</td>
                                <td>
                        <asp:TextBox ID="Label14" runat="server" Text='<%#Bind("chrContactLastName") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Organization</td>
                                <td>
                        <asp:TextBox ID="Label15" runat="server" Text='<%#Bind("chrContactOrg") %>'></asp:TextBox>
                                </td>
                                <tr>
                                <td>Contact Phone</td>
                                <td>
                        <asp:TextBox ID="Label16" runat="server" Text='<%#Bind("chrContactPhone") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Contact Email</td>
                                <td>
                        <asp:TextBox ID="Label17" runat="server" Text='<%#Bind("chrContactEMail") %>' Width="272px"></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Accessible</td>
                                <td>
                        <asp:TextBox ID="Label18" runat="server" Text='<%#Bind("bAccessible") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Qtr Calendar</td>
                                <td>
                        <asp:TextBox ID="Label19" runat="server" Text='<%#Bind("bQuarterlyCalendar") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Annual Event</td>
                                <td>
                        <asp:TextBox ID="Label20" runat="server" Text='<%#Bind("bAnnualEvent") %>'></asp:TextBox>
                                </td>
                            </tr>
                            <tr>
                                <td>Month</td>
                                <td>
                        <asp:TextBox ID="Label21" runat="server" Text='<%#Bind("Month") %>'></asp:TextBox>
                        <asp:DropDownList ID="ddlMonth" runat="server" DataSourceID="ddlMonthDataSource" DataTextField="Month" 
                            DataValueField="ID"></asp:DropDownList>
                            <asp:SqlDataSource ID="ddlMonthDataSource" runat="server" 
                            ConnectionString="<%$ ConnectionStrings:dkzdbConnectionString %>" 
                            SelectCommand="SELECT [ID], [Month] FROM [tblMonth]"></asp:SqlDataSource>
                                </td>
                            </tr>
                        </table>
                    </EditItemTemplate>
                </asp:TemplateField>
            </Fields>
            <FooterStyle BackColor="#CCCC99" />
            <RowStyle BackColor="#F7F7DE" />
            <PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
            <HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
            <EditRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
            <AlternatingRowStyle BackColor="White" />
        </asp:DetailsView>

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:
55:
56:
57:
58:
59:
60:
61:
62:
63:
64:
65:
66:
67:
68:
69:
70:
71:
72:
73:
74:
75:
76:
77:
78:
79:
80:
81:
82:
83:
84:
85:
86:
87:
88:
89:
90:
91:
92:
93:
94:
95:
96:
97:
98:
99:
100:
101:
102:
103:
104:
105:
106:
107:
108:
109:
110:
111:
112:
113:
114:
115:
116:
117:
118:
119:
120:
121:
122:
123:
124:
125:
126:
127:
128:
129:
130:
131:
132:
133:
134:
135:
136:
137:
138:

Select all Open in new window

by: arhamePosted on 2009-06-03 at 13:08:58ID: 24540720

Try the following. I think what's happening is it's trying to fire off when the Detailsview is not in edit mode? Since it doesn't have its default mode set to edit....

If DetailsView1.CurrentMode = DetailsViewMode.Edit Then
Dim ddl1 As DropDownList = DirectCast(DetailsView1.FindControl("ddlMonth"), DropDownList)
ddl1.SelectedValue = 12
End If

by: HBHoffmanPosted on 2009-06-03 at 13:14:40ID: 24540801

Your loading the month in the text field and an Id in the value field. Try SelectedText instead of SelectedValue.

by: jwoodhamsPosted on 2009-06-04 at 04:49:07ID: 31588462

thanks, it worked perfectly!

by: jwoodhamsPosted on 2009-06-04 at 05:35:16ID: 24546194

Well, I thought this issue was over but, I was wrong. I have another problem. What I need to do is populate a dropdown list with the all the months of the year. I need the dropdown list to show the current value of the record in the database. The record is stored in number format i.e. 1=January, 2=February, etc. So this solution allows me to set the value, if I hardcode in the number of the month. like right now it is set to 12 for December. I actually need to replace that '12' with the value of the field in the selected record. I know that I could write the code to just go to the database and get it but, that seems redundant since I already have the value. I have an asp:hiddenfield that contains the value I want to use. The problem now, is I cant seem to get that value. I have put it in the itemTemplate of the detailsView, and also the EditItemsTemplate of the Details View. The ItemCreated event fires twice. Once for the ItemTemplate controls, and once for the EditItemTemplate Controls. So, I try to capture the value in EditItems fire, event fire #2, then there is no value because the the DetailsView is in Edit mode. I can capture the value on first fire of the event but the value is gone on the next go around. I tried to put the value in a property which is also re-initalized on the second fire so the value is gone. And I tried to capture the value on the DataBound event but, that event fires after the itemCreated event.

Any more suggestions?

Thanks

Jay

by: arhamePosted on 2009-06-04 at 06:31:49ID: 24546696

Probably best off to post another question, that way if I get busy with work and am unable to respond other people will join in since you can assign them the points.

I think you're left with two options:

1) Since the value I assume isn't associated with the record the Detailsview is pulling, put the hidden field outside of the Detailsview and that way the value it's holding is accessable no matter what mode the detailsview is in.

2) Assign the value to a session variable, again just a different way of storing the value not in the itemTemplate of the detailsview so it can be retrieved when you need it regardless of the mode of the detailsview.

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

For individual users
Instant access to solutions
Ask your tech questions
Start your 30-day Free Trial

Business Accounts

Perfect for organizations
Multiple users
Save over 36%
Create a Business Account

Answer for Membership

Earn free access
Showcase your knowledge
No credit card required
Sign Up to Answer

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...

Question

Help with asp.net detailsview control

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

Programming for ASP.NET

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Need individual assistance?

Our experts are ready to help.

Want to learn from the best?

Read articles from industry experts.

Working on a long term project?

Store your work and research.

What Makes Experts Exchange Unique?

Trusted by the world's most respected brands.

Faithfully serving IT professionals since 1996.

Related Solutions

Free Tech Articles

Cloud Class Webinars

Join the Community

Give a Little. Get a Lot.

Answers

3 Ways to Join

The Experts

The Experts

Testimonials

Testimonials

Testimonials

Business Clients

Business Clients

In the Press

In the Press

In the Press