DataBound ListBox

[anastasia]

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

InitDBConn();
OpenDBConnectio n();

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

OleDbDataReader oleRidges= cmdRidge.Execut eReader();

if (!this.IsPostBa ck)
{
ddlRidge.DataSo urce = oleRidges;
ddlRidge.DataMe mber = "TRDRidgeTypes" ;
ddlRidge.DataTe xtField = "RidgeType" ;
ddlRidge.DataVa lueField = "RidgeTypeI D";
ddlRidge.DataBi nd();
}


----
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.PostB ack =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...]

DataBound ListBox

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...
[color=blue]
>-----Original Message-----
>I have the following code (this is a snippet):
>
>InitDBConn() ;
>OpenDBConnecti on();
>
>OleDbCommand cmdRidge = new OleDbCommand("S ELECT * FROM
>TRDRidgeTypes" , oleDbConn);
>
>OleDbDataReade r oleRidges= cmdRidge.Execut eReader();
>
>if (!this.IsPostBa ck)
>{
>ddlRidge.DataS ource = oleRidges;
>ddlRidge.DataM ember = "TRDRidgeTypes" ;
>ddlRidge.DataT extField = "RidgeType" ;
>ddlRidge.DataV alueField = "RidgeTypeI D";
>ddlRidge.DataB ind();
>}
>
>
>----
>This code successfully fills a DropDownList box. However,[/color]
when the[color=blue]
>user selects one of the items and the page is posted to[/color]
the server[color=blue]
>,the SelectedItem property of the List is null and the[/color]
SelectedIndex i[color=blue]
>(-1). I am tearing my hair out because I have found[/color]
people on the[color=blue]
>newsgroup with a similar
>problem, but it was due to their not setting data source[/color]
in the[color=blue]
>"this.PostBa ck =False" condition. I have done that, and[/color]
it still does[color=blue]
>not help me.
>
>I do have ViewState for the control set to True. I tried[/color]
hardcoding[color=blue]
>the ListItems in the HTML and the control values were[/color]
read correctly.[color=blue]
>
>I am sure I am missing the obvious here..but please help!!
>
>Thanks,
>Stacey
>.
>[/color]

[Jim Blizzard [MSFT]]

RE: DataBound ListBox

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.


--------------------[color=blue]
>Content-Class: urn:content-classes:message
>From: "David Waz..." <dlw@pickpro.co m>
>Sender: "David Waz..." <dlw@pickpro.co m>
>References: <fdf3218d.03070 21116.34878f84@ posting.google. com>
>Subject: DataBound ListBox
>Date: Wed, 2 Jul 2003 20:20:59 -0700
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>
>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...
>[color=green]
>>-----Original Message-----
>>I have the following code (this is a snippet):
>>
>>InitDBConn( );
>>OpenDBConnect ion();
>>
>>OleDbComman d cmdRidge = new OleDbCommand("S ELECT * FROM
>>TRDRidgeTypes ", oleDbConn);
>>
>>OleDbDataRead er oleRidges= cmdRidge.Execut eReader();
>>
>>if (!this.IsPostBa ck)
>>{
>>ddlRidge.Data Source = oleRidges;
>>ddlRidge.Data Member = "TRDRidgeTypes" ;
>>ddlRidge.Data TextField = "RidgeType" ;
>>ddlRidge.Data ValueField = "RidgeTypeI D";
>>ddlRidge.Data Bind();
>>}
>>
>>
>>----
>>This code successfully fills a DropDownList box. However,[/color]
>when the[color=green]
>>user selects one of the items and the page is posted to[/color]
>the server[color=green]
>>,the SelectedItem property of the List is null and the[/color]
>SelectedInde x i[color=green]
>>(-1). I am tearing my hair out because I have found[/color]
>people on the[color=green]
>>newsgroup with a similar
>>problem, but it was due to their not setting data source[/color]
>in the[color=green]
>>"this.PostBac k =False" condition. I have done that, and[/color]
>it still does[color=green]
>>not help me.
>>
>>I do have ViewState for the control set to True. I tried[/color]
>hardcoding[color=green]
>>the ListItems in the HTML and the control values were[/color]
>read correctly.[color=green]
>>
>>I am sure I am missing the obvious here..but please help!!
>>
>>Thanks,
>>Stacey
>>.
>>[/color]
>[/color]