Multiple DataKeyNames in GridView

May 7, 2007 by ggraham412

I like GridView, but using it is a sometimes like getting behind the wheel of a 747 without ever flying before.

I have a software tracking report to make that pulls data out of database using an SQLDataSource. Everything in the database is keyed on the computer name, so to make a list of installed applications across the domain, I do a GROUP BY on application name and version in the select statement. The report displays the name, version, and count in a GridView. To get the list of computers where a particular application name and version instance is installed, I query the database on GridView select. But since it’s a GROUP BY, there is no permanent primary key, and so I need to know both the application name and the version for the query.

To get this information in the select handler I thought I’d use
gdvApplications.SelectedRow["name"] gdvApplications.SelectedRow["version"]
but it turns out there are no indexers defined on the SelectedRow. Then I read about DataKeyNames. You can set this property of the GridView to the name(s) of one or more (comma separated) of your columns, and then something will show up in the SelectedValue property. In fact, this is supposed to be used to get PrimeryKey values out of a selected row.
gdvApplications.DataKeyNames = "name,version"; // In Page_Init() or correspondingly //in the aspx/ascx file. (...) gdvApplications. SelectedValue["name"]; gdvApplications.SelectedValue["version"];
Except, er, well, no. There are no indexers defined on SelectedValue either. In fact it is just an object and corresponds only to the first column that is defined in DataKeyNames. To cut to the chase, if you have multiple DataKeyNames defined, here is how you can access them:
gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values["name"]; gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values["version"];
And yet it looks so simple in Visual Studio, you just drag and drop the GridView on your web form like a text box and follow the wizards. I’m glad that it can be done, but why wouldn’t we just have row indexers? Anyway, this is really more of a case of “I let the IDE lead me by the nose (and it led me into a brick wall.)” Not the first time for me…

Update 8/2009

Thank you very much for all of the wonderful comments!

If you liked this post, feel free to find me at Linked In, Gregory Graham, Greater Chicago Area, Banking.

Posted in ASP.Net, Programming | 45 Comments

45 Responses

on May 18, 2007 at 5:46 pm | Reply B. Nguyen

It works! Thanks for the posting. I also tried your first 2 attempts without success. This is very helpful.

Thank you,

BN
on May 25, 2007 at 4:36 pm | Reply Scott

I found this helpful.

Thanks
on September 14, 2007 at 1:36 pm | Reply Zarchi

I found it very useful.
Thanks.
on October 2, 2007 at 2:48 pm | Reply Steve

I am a noob. Can you spell out the context that
gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[”name”];
gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[”version”];

should be placed in?

Thanks!
on November 18, 2007 at 9:36 am | Reply salman

Found a Helpful Article. Thank u.
on December 6, 2007 at 3:28 pm | Reply Jorge

This article has been in my list of most wanted for a while
on December 13, 2007 at 12:13 am | Reply ited

Really helpful article.

Thanks!
on January 22, 2008 at 7:00 pm | Reply Coleen

This really helped me with using multiple DatakeyNames and hidden cells, thank you!
on January 24, 2008 at 2:47 pm | Reply Maulik Patel

Hey, thanks buddy….
This article is very help full to me.
on January 24, 2008 at 8:25 pm | Reply mmoota

hi,

i tried to use the code

gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[”name”];
gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[”version”];

to get the values of the datakeys of the selected row.

it gives me object reference not set to an instance of an object error.

could you tell me why.
on February 10, 2008 at 8:13 pm | Reply SeaDog

Thanks very much for taking the time to post this – it was very helpful!
on February 13, 2008 at 9:06 pm | Reply clop321

I have seen your code on how to get multiple datakeyvalues fromthe row select. How can I pass multiple value back into another control (such as a detailsview). I am using SelectCommand=’SELECT * From “GPT_INTER_ADJUSTMENT_ERR” WHERE LOAD_SEQ_ID = :dkSeqNo’ >

where dkSeqNo is the first datakey value I obtained inside of GridView1_SelectedIndexChanged. Where would I code for additional datakeys inside ?
on February 28, 2008 at 5:34 pm | Reply philip

Why not use gdvApplications.SelectedDataKey.Values["whatever"]?

Saves a step for me.
on March 12, 2008 at 8:59 am | Reply Anthony

Thank you so much~~~
on March 23, 2008 at 1:39 pm | Reply Vijay Vyas

Thanks,

This solution was very useful to us.

Particularly when there is case of multiple columns in Primary Key and you want to retrieve the value of a particulat column.

Once again thanks a lot.
on March 26, 2008 at 1:14 am | Reply David Cho

Thank you. Very helpful.
on April 17, 2008 at 10:06 pm | Reply John

And in the case where I’ve got multiple detailviews based off multiple keys in the selected gridview… where I was using a linqdatasource, but switching to an objectdatasource (gotta start thinking about business rules once you’ve got the prototype working).
I ran into this again and had to figure it out again. If you use the datasource “properties” to edit this (since I just can’t figure out how to write asp directly).
So, based on you name and version, datasources (object and linq) keying off the version from a gridview1, would look like-

Maybe I need to blog this myself to properly knock it in my head so I don’t keep solving the same problem over and over!!!!
Thanks, reading this blog stirred enough braincells so I knew what to do.
john.
on April 17, 2008 at 10:07 pm | Reply John

”

“
on April 29, 2008 at 9:13 am | Reply Preethi

Gud one graham.
Keep posting such commmon scenarios where developers get strucked.
on June 25, 2008 at 11:02 am | Reply Ian

Google on Datakeynames and you came a very well deserved 5th. long may you prosper. Thanks Ian, http://www.ava.co.uk
on June 30, 2008 at 7:31 pm | Reply Syed Shariq

Good article but for work for ASP.NET with VB.NET do these very minor changes

gdvApplications.DataKeyNames = New String() {“name”,”version”}
on July 25, 2008 at 7:08 am | Reply Sajeev

It doesnt work for me..i have been trying to fix this problem for a long time

here is a part of my gridview

<asp:GridView ID=”gvEventsList” runat=”server”
AutoGenerateColumns=”False”
DataSourceID=”odsEventsList”
EmptyDataText=”No Events”
AllowSorting=”true”
DataKeyNames=”EventID,LastUpdatedOn”

And this is my code behind for the object data source deleting event

String eventID = gvEventsList.DataKeys[gvEventsList.SelectedIndex].Values["EventID"].ToString();

but it gives and error ” Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index ”

the problem is that gvEventsList.SelectedIndex is returning a value -1 . Why is it so ?is it somehow related to the link i used in the template field in the gid view ?? can somebosy plz help me out ??
on August 13, 2008 at 4:47 am | Reply Lipu

helpful article.
on August 21, 2008 at 4:04 pm | Reply Paolo Brocco

Hello and thanks for the post… just a question as I’m a newbie…

How am I supposed to use DataKeyNames inside a “manual query”?

e.g. SELECT TCustomer as Client, TFirstName as Name FROM Table

What would be the DataKeyName for the first column, in this case?

TCustomer or Client?

Or none of them (in this case how should the DataKeyName be configured?)?

Thanks for letting me know,

–Paolo
on August 22, 2008 at 8:55 pm | Reply ggraham412

Should be “Client” I suppose. I haven’t tried it though.
on October 1, 2008 at 12:03 am | Reply How To: Get DataKeys value for multiple DataKeyNames in a GridView for ASP.NET 2.0 « HP’s Blog

[...] You can also check a similar kind of article here [...]
on November 20, 2008 at 2:10 am | Reply Rupa

This article was simple and easy to understand!!! Thanks a lot for the effort!!!
on December 13, 2008 at 2:47 pm | Reply Catjedfl

Thanks!,
on December 27, 2008 at 7:27 am | Reply Madhava Manikandan

Hai,

To resolve this issue, try this one

protected void gvPopulate_SelectedIndexChanged(object sender, EventArgs e)
{
TextBox1.Text = “”;
TextBox1.Text = gvPopulate.SelectedPersistedDataKey[0].ToString() + “,” + gvPopulate.SelectedPersistedDataKey[1].ToString();
}

It surely helps you…
on December 28, 2008 at 7:13 pm | Reply newbie

for the other newbies who are struggling with the gridview..
gdvApplications.DataKeyNames = “name,version”;
should have been
gdvApplications.DataKeyNames = new string[]{“name,version”}
on January 6, 2009 at 4:15 pm | Reply Karri

I kept seeing on the Microsoft site that you could define multiple fields in the DataKeyNames but nowhere did it explain how to access them. I was spinning my wheels trying to figure it out. You saved me! Thanks.
on January 16, 2009 at 3:38 am | Reply Aurelian

There is an issue with multiple-field DataKeys in GridView. Delete command of the GridView will pass to the underlying datasource all fields used in data keys as parameters. This throws an error, since most probably the datasource doesn’t have all data key fields as parameters (it ussually is using a single field primary key). Adding fictious parameters to the datasource just to workaround this issue is making dificult to manage the changes in your BLL/DAL.
on February 19, 2009 at 10:58 pm | Reply aWellWisher

Gregory,

You may want to look at this:
http://www.dotnetwatch.com/Multiple-datakeynames-in-gridview2693_MSG.aspx
on March 18, 2009 at 5:11 pm | Reply Howie

Thanks, much appreciated!

I’d just like to point out alternatives to

gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values["name"];

This also works -

gdvApplications.DataKeys[gdvApplications.SelectedIndex].Item["name"];

As well as these less useful versions,
with an integer variable which represents the order of the datakeys -

gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[ipos];

gdvApplications.DataKeys[gdvApplications.SelectedIndex].Item[ipos];
on March 24, 2009 at 7:36 pm | Reply Penny

Very, very helpful when required to work with multiple field primary keys! Thank you so much for posting this!
on April 22, 2009 at 11:03 am | Reply Neil

There is a shortcut version to the same thing, at least where a row is selected:

in VB:
gdvApplications.DataKeys(gdvApplications.SelectedIndex).Values(“name”)

..can be rendered more simply as:
gdvApplications.SelectedDatakey(“name”)

or as per Madhava’s post above:

gdvApplications.SelectedPersistedDatakey(“name”)

Unfortunately, if you are retrieving the key for an unselected row, there seems to be no alternative to the long route, eg in _RowDataBound sub:

GVblog.DataKeys(e.Row.DataItemIndex).Values(“ThreadID”)
on May 10, 2009 at 3:34 pm | Reply Mike Stone

I have to say a big thanks. Your post saved the day. I had to make a change as I was using the RowCommand override and needed to get the index value first. But it works great. Thanks so much. I case it helps someone else I have included my working version here.

protected void gvCustomersListEdit_RowCommand(object source, GridViewCommandEventArgs e)
{
switch (e.CommandName)
{
case “edit_entry”:
//gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values["name"];
ViewState["Edit"] = gv_Vendors.DataKeys[int.Parse(e.CommandArgument.ToString())].Values["VendorKey"];
MultiView1.SetActiveView(editView);
lbl_CustomerKey.Text = ViewState["Edit"].ToString();
break;
}
}
on June 4, 2009 at 11:22 pm | Reply Ravi Madha

Hi,

the correct code to get multiple DataKeyNames is the following:

option 1

stringkey1 = gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values["name"].ToString();

stringkey2 = gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values["version"].ToString();

option 2

stringkey1 = gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[0].ToString();

stringkey2 = gdvApplications.DataKeys[gdvApplications.SelectedIndex].Values[1].ToString();

This both options will retrieve the keys.
on June 5, 2009 at 12:16 pm | Reply robson

Thanks!!!
I spent 2 days, trying gets values from two fields. After I read your article my problem has disapeared in 5 minutes.
on June 26, 2009 at 11:26 am | Reply KeCe

great post….kudos..
on July 3, 2009 at 6:07 am | Reply kheonline

Big Thanks
on July 8, 2009 at 1:13 am | Reply Stumbling through ASP.net « Obscured Info

[...] July 8, 2009 in dotnet One of the humbling (and slightly frustrating) parts of switching technology stacks is learning how to do something you knew by heart in the old tech. Case in point: figuring out which item you selected in a GridView in ASP.net. I had a pattern down cold for this in Java web development. I eventually found the DataKeys property of GridView, but the online help did not describe how to use multiple keys. Thanks to the internet, I found a very helpful answer (and it’s not intuitive) here. [...]
on July 23, 2009 at 3:43 pm | Reply Kavitha

Thank you so much for this post. I spent a couple of days in frustration trying to get my UpdateCommand to work. I followed your suggested method of passing multiple parameters and it worked!
on October 27, 2009 at 12:51 am | Reply Cesar Daniel

Check out the second example:

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.selecteddatakey.aspx
on November 4, 2009 at 3:40 pm | Reply RaeRae

First much thanks for writing this aritcle!!!!!

I found I was able to retrieve the value of the my second datakey by using SelectedValue instead of SelectedIndex.

Me.GridView1.DataKeys(GridView1.SelectedValue).Values(“PublicationId”)

Thanks again for this article