Concatenate AppSetting key value into web page control attribute value

dima1954 · December 16th, 2016, 09:01 PM

Hello,
I have a problem with one of my pages. I need to get the key value from my web.config file as a âprefixâ, and concatenate the one with the string. Then assign the resulting string to âmyTableâ attribute of the control. Iâve tried different approaches, but no lack. I am missing something.
This is the ORIGINAL controls' code:

Code:

<cc1:BaseRadioButtonList ID="rblUserRegisterationType" runat="server" myAutoBind="True"
                                                myBoundField="Type" myTable="vUserRegisterationType" myFieldSet="TextField,ValueField"
                                                myOrder="TextField" DataTextField="TextField" DataValueField="ValueField" myShowSelectFromList="True"
                                                RepeatColumns="2" RepeatDirection="Horizontal" OnSelectedIndexChanged="rblUserRegisterationType_OnSelectedIndexChanged"
                                                AutoPostBack="true" myFilter="" Visible="false">
                                            </cc1:BaseRadioButtonList>

I was trying to get the key value from the web.config file like this, and concatenate the one with an existing myTable string "vUserRegisterationType":

Code:

 <%$AppSettings:LinkedServerHtmlPrefix%>

, where in the web.config line is:

Code:

 <add key="LinkedServerHtmlPrefix" value="[FWC-VMSD1].[FWC_Users].[dbo]." />

I need to make my final attribute âmyTableâ looking like this:
myTable="[FWC-VMSD1].[FWC_Users].[dbo].vUserRegisterationType"

Question: how concatenate the string from the web.config and current âvUserRegisterationTypeâ?

Any help will be appreciated.
--Dmitriy

Imar · December 18th, 2016, 10:29 AM

Hi there,

Do you own the BaseRadioButtonList class? If so, you could modify the control and add an additional property for the prefix part and concatenate them inside the control.

As an alternative, you could build a custom ExpressionBuilder:
http://www.4guysfromrolla.com/articles/022509-1.aspx

Cheers,

Imar

dima1954 · December 18th, 2016, 11:04 AM

Hi Imar,
Thanks for the response. Unfortunately this BaseRadioButtonList control class created by 3rd party, and I do not have access to the code. This is why I am trying to concatenate the key value from the web.config file and an existing âmyTableâ attribute name, by using that Expression Builder youâve mentioned someway. Iâve been trying different approaches, but it did not work:

Code:

myTable= <%$AppSettings:LinkedServerHtmlPrefix%> + "vUserRegisterationTypeâ

or

Code:

myTable= <%$ ConfigurationSettings.AppSettings["LinkedServerHtmlPrefix "] %> + "vUserRegisterationTypeâ

or

Code:

myTable= <%= ConfigurationSettings.AppSettings["LinkedServerHtmlPrefix "] %> + "vUserRegisterationTypeâ

or

Code:

myTable= <%# ConfigurationSettings.AppSettings["LinkedServerHtmlPrefix "] %> + "vUserRegisterationTypeâ

I am out of ideasâ¦

Thanks again,
Dmitriy

Imar · December 18th, 2016, 03:00 PM

You need to build your own ExpressionBuilder as explained in the section Creating a Custom Expression Builder Class in the article I linked to.

Alternatively, you could inherit the custom control you have, add your own property, inside that access AppSettings and set the property of the base class.

Cheers,

Imar

mmorgan30 · January 29th, 2017, 09:33 PM

A complex solution to a simple problem is a sign of bad design. why don't you just add the prefix in the declaration of the custom control. its not hard to change on the fly (with out recompiling) if you ever need to change it. after all an aspx page or ascx control is just a configuration file.