DataBound ListBox

[anastasia]

I have the following code (this is a snippet):

InitDBConn();
OpenDBConnection();

OleDbCommand cmdRidge = new OleDbCommand("SELECT * FROM
TRDRidgeTypes", oleDbConn);

OleDbDataReader oleRidges= cmdRidge.ExecuteReader();

if (!this.IsPostBack)
{
ddlRidge.DataSource = oleRidges;
ddlRidge.DataMember = "TRDRidgeTypes";
ddlRidge.DataTextField = "RidgeType";
ddlRidge.DataValueField = "RidgeTypeID";
ddlRidge.DataBind();
}


----
This code successfully fills a DropDownList box. However, when the
user selects one of the items and the page is posted to the server
,the SelectedItem property of the List is null and the SelectedIndex i
(-1). I am tearing my hair out because I have found people on the
newsgroup with a similar
problem, but it was due to their not setting data source in the
"this.PostBack =False" condition. I have done that, and it still does
not help me.

I do have ViewState for the control set to True. I tried hardcoding
the ListItems in the HTML and the control values were read correctly.

I am sure I am missing the obvious here..but please help!!

Thanks,
Stacey

[David Waz...]

You don't want to bind the data on post-back.
You are wiping out the results when you bind the data!

only bind when postback is TRUE, or when you know the
content will/should be changing. Otherwise, the viewstate
will handle everything else for you automatically.

email if you need more...

>-----Original Message-----
>I have the following code (this is a snippet):
>
>InitDBConn();
>OpenDBConnection();
>
>OleDbCommand cmdRidge = new OleDbCommand("SELECT * FROM
>TRDRidgeTypes", oleDbConn);
>
>OleDbDataReader oleRidges= cmdRidge.ExecuteReader();
>
>if (!this.IsPostBack)
>{
>ddlRidge.DataSource = oleRidges;
>ddlRidge.DataMember = "TRDRidgeTypes";
>ddlRidge.DataTextField = "RidgeType";
>ddlRidge.DataValueField = "RidgeTypeID";
>ddlRidge.DataBind();
>}
>
>
>----
>This code successfully fills a DropDownList box. However,

when the

>user selects one of the items and the page is posted to

the server

>,the SelectedItem property of the List is null and the

SelectedIndex i

>(-1). I am tearing my hair out because I have found

people on the

>newsgroup with a similar
>problem, but it was due to their not setting data source

in the

>"this.PostBack =False" condition. I have done that, and

it still does

>not help me.
>
>I do have ViewState for the control set to True. I tried

hardcoding

>the ListItems in the HTML and the control values were

read correctly.

>
>I am sure I am missing the obvious here..but please help!!
>
>Thanks,
>Stacey
>.
>

[Jim Blizzard [MSFT]]

Stacey is not binding on the postback--at least not in the code below.
Notice the ! (not) in the IF statement. The code shown says to do the
binding if it's not a postback.

We need to see more of the code. What else happens if it IS a postback?
Do you manually re-populate the dropdownlist if it is a postback. If
that's the case, then that's the problem.

-bliz

--
Jim Blizzard
Sr .NET Developer Evangelist
Microsoft

Your Potential. Our Passion.

This posting is provided "AS IS" with no warranties, and confers no rights.
Please reply to newsgroups only, so that others may benefit. Thanks.


--------------------

>Content-Class: urn:content-classes:message
>From: "David Waz..." <dlw@pickpro.com>
>Sender: "David Waz..." <dlw@pickpro.com>
>References: <fdf3218d.0307021116.34878f84@posting.google.com >
>Subject: DataBound ListBox
>Date: Wed, 2 Jul 2003 20:20:59 -0700
>Lines: 57
>Message-ID: <057501c34112$1f8d8150$a501280a@phx.gbl>
>MIME-Version: 1.0
>Content-Type: text/plain;
> charset="iso-8859-1"
>Content-Transfer-Encoding: 7bit
>X-Newsreader: Microsoft CDO for Windows 2000
>Thread-Index: AcNBEh+LwSBUfYKPT5OjrwgxMvdL4g==
>X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4910.0300
>Newsgroups: microsoft.public.dotnet.framework.aspnet
>Path: cpmsftngxa09.phx.gbl
>Xref: cpmsftngxa09.phx.gbl microsoft.public.dotnet.framework.aspnet:31926
>NNTP-Posting-Host: TK2MSFTNGXA13 10.40.1.165
>X-Tomcat-NG: microsoft.public.dotnet.framework.aspnet
>
>You don't want to bind the data on post-back.
>You are wiping out the results when you bind the data!
>
>only bind when postback is TRUE, or when you know the
>content will/should be changing. Otherwise, the viewstate
>will handle everything else for you automatically.
>
>email if you need more...
>

>>-----Original Message-----
>>I have the following code (this is a snippet):
>>
>>InitDBConn();
>>OpenDBConnection();
>>
>>OleDbCommand cmdRidge = new OleDbCommand("SELECT * FROM
>>TRDRidgeTypes", oleDbConn);
>>
>>OleDbDataReader oleRidges= cmdRidge.ExecuteReader();
>>
>>if (!this.IsPostBack)
>>{
>>ddlRidge.DataSource = oleRidges;
>>ddlRidge.DataMember = "TRDRidgeTypes";
>>ddlRidge.DataTextField = "RidgeType";
>>ddlRidge.DataValueField = "RidgeTypeID";
>>ddlRidge.DataBind();
>>}
>>
>>
>>----
>>This code successfully fills a DropDownList box. However,

>when the

>>user selects one of the items and the page is posted to

>the server

>>,the SelectedItem property of the List is null and the

>SelectedIndex i

>>(-1). I am tearing my hair out because I have found

>people on the

>>newsgroup with a similar
>>problem, but it was due to their not setting data source

>in the

>>"this.PostBack =False" condition. I have done that, and

>it still does

>>not help me.
>>
>>I do have ViewState for the control set to True. I tried

>hardcoding

>>the ListItems in the HTML and the control values were

>read correctly.

>>
>>I am sure I am missing the obvious here..but please help!!
>>
>>Thanks,
>>Stacey
>>.
>>

>

[Gerrod Thomas]

Hi Stacey,

I was having this exact same problem, and it was almost hair-tearing
time for me. My issue turned out to be that I had the drop down list in
a panel, and I had turned ViewState off for that panel. Hence the drop
down list wasn't putting it's stuff into the ViewState, so when the page
loaded back up the list was empty.

So make sure you check -
* That ViewState is enabled for the drop down list
* ViewState is enabled for all parent containers (ie. panels,
placeholders, etc)
* ViewState is enabled for the page

Hope that helps -
gerrod




*** Sent via Developersdex [url]http://www.developersdex.com[/url] ***
Don't just participate in USENET...get rewarded for it!

[gerrod]

Stacey -

No, I'm not binding on post-back either - I am binding on page load
only. But the problem was that since the data was not being put into the
ViewState (since it was disabled by the holding panel), on post back the
drop down list was empty.

gerrod


*** Sent via Developersdex [url]http://www.developersdex.com[/url] ***
Don't just participate in USENET...get rewarded for it!

[anastasia]

hi gerrod:

i was replying to David Waz....

in any case, I tried your suggestion and you were right! Thank you. I
did not have view state set for the document. Don't know how that
happened....

Thanks again!

stacey