Are dynamically loaded controls preserved over a postback?

[Alan Silver]

Hello,

I have a placeholder, which gets a user control added in when the page
first loads. This user control contains a dropdownlist, and I would like
to get hold of the value of this drop down list form the calling page on
postback. Can I do this? If I try and use FindControl on the
placeholder, it can't find the dropdownlist.

I tried...

ShowCategory ctlShowCategory = (ShowCategory)plcCategoryDetails.Controls[0];

(where ShowCategory is the user control) but this gave the error...

System.ArgumentOutOfRangeException: Specified argument was out of the
range of valid values. Parameter name: index

which sounds like the user control wasn't preserved in the placeholder
over the postback.

Any ideas how I do this? Hope this was clear!! TIA

 

[Bruce Barker]

you have to recreate the dynamic comtrol on postback. there is no code in
the placeholder for this.

-- bruce (sqlwork.com)

 

[Alan Silver]

you have to recreate the dynamic comtrol on postback. there is no code in

the placeholder for this.

If I recreate the user control, will the child controls have their
values preserved? The point of this is that I want to get the value of a
dropdownlist in the user control. If the value of that dropdownlist
isn't preserved (ie if recreating the user control resets the child
controls), then I'm wasting my time.

Thanks for the reply.

-- bruce (sqlwork.com)

Hello,

I have a placeholder, which gets a user control added in when the page
first loads. This user control contains a dropdownlist, and I would like
to get hold of the value of this drop down list form the calling page on
postback. Can I do this? If I try and use FindControl on the placeholder,
it can't find the dropdownlist.

I tried...

ShowCategory ctlShowCategory =
(ShowCategory)plcCategoryDetails.Controls[0];

(where ShowCategory is the user control) but this gave the error...

System.ArgumentOutOfRangeException: Specified argument was out of the
range of valid values. Parameter name: index

which sounds like the user control wasn't preserved in the placeholder
over the postback.

Any ideas how I do this? Hope this was clear!! TIA

 

[Guest]

If I recreate the user control, will the child controls have their
values preserved?

Yes and no, depending on which stage of the page's life cycle the child
controls were created.

The following article on the MSDN is very useful in understanding the
ASP.NET View State:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/html/viewstate.asp

Phillip Williams
http://www.societopia.net
http://www.webswapp.com

 

[Alan Silver]

If I recreate the user control, will the child controls have their

Yes and no, depending on which stage of the page's life cycle the child
controls were created.

The following article on the MSDN is very useful in understanding the
ASP.NET View State:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/
html/viewstate.asp

Thanks, that's my bedtime reading sorted out tonight then!!

 

[Bruce Barker]

as long as you recreate all dynamic controls with the same name used on the
render, before page load, then they will receive their postback data. don't
overwrite their values on a postback.

its best to recreate dynamic controls in oninit()

-- bruce (sqlwork.com)

you have to recreate the dynamic comtrol on postback. there is no code in
the placeholder for this.

If I recreate the user control, will the child controls have their values
preserved? The point of this is that I want to get the value of a
dropdownlist in the user control. If the value of that dropdownlist isn't
preserved (ie if recreating the user control resets the child controls),
then I'm wasting my time.

Thanks for the reply.

-- bruce (sqlwork.com)

Hello,

I have a placeholder, which gets a user control added in when the page
first loads. This user control contains a dropdownlist, and I would like
to get hold of the value of this drop down list form the calling page on
postback. Can I do this? If I try and use FindControl on the
placeholder,
it can't find the dropdownlist.

I tried...

ShowCategory ctlShowCategory =
(ShowCategory)plcCategoryDetails.Controls[0];

(where ShowCategory is the user control) but this gave the error...

System.ArgumentOutOfRangeException: Specified argument was out of the
range of valid values. Parameter name: index

which sounds like the user control wasn't preserved in the placeholder
over the postback.

Any ideas how I do this? Hope this was clear!! TIA

 

[Alan Silver]

as long as you recreate all dynamic controls with the same name used on the

render, before page load, then they will receive their postback data. don't
overwrite their values on a postback.

its best to recreate dynamic controls in oninit()
Thanks

-- bruce (sqlwork.com)

you have to recreate the dynamic comtrol on postback. there is no code in
the placeholder for this.

If I recreate the user control, will the child controls have their values
preserved? The point of this is that I want to get the value of a
dropdownlist in the user control. If the value of that dropdownlist isn't
preserved (ie if recreating the user control resets the child controls),
then I'm wasting my time.

Thanks for the reply.

-- bruce (sqlwork.com)

Hello,

I have a placeholder, which gets a user control added in when the page
first loads. This user control contains a dropdownlist, and I would like
to get hold of the value of this drop down list form the calling page on
postback. Can I do this? If I try and use FindControl on the
placeholder,
it can't find the dropdownlist.

I tried...

ShowCategory ctlShowCategory =
(ShowCategory)plcCategoryDetails.Controls[0];

(where ShowCategory is the user control) but this gave the error...

System.ArgumentOutOfRangeException: Specified argument was out of the
range of valid values. Parameter name: index

which sounds like the user control wasn't preserved in the placeholder
over the postback.

Any ideas how I do this? Hope this was clear!! TIA