Loading Web User Control Dynamically

Hi Experts,

We have a text field in our database which allows users to decide where to place a built usercontrol...

So the text that would be saved could be something like this: <table><tr><td>Use the below form to contact us</td></tr><tr><td>#ContactForm2#</td><tr></table>

when we are displaying the text on the front end we need to replace #ContactForm2# with the relevant control which may be loadcontrol("~/ContactForm2.ascx")

Has anyone done this before? If so, how?

Who is Participating?
ErikVBConnect With a Mentor Commented:
the trick is what happens in the else statement of the select.
so if your html would be very simple, like this: <div>#ContactForm2#</div>, the split would give you a string array with 3 elements:
1: <div>
when you loop through those items, you will create controls as you need them. For the 1st and the 3d item, you would create a new literal control, with the corresponding string as content for the literal. This will be output to the pages as just your plain html (because thats what a literal does.. it just outputs what you put into it)
for the second element you will load your usercontrol, and add that to the page
no iFrames needed and no JavaScript / jQuery either..
i'm not sure about loading controls from a file but you can create and add a control at runtime:

Label l = new Label();
l.Text = "test";

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string.Replace ("#ContactForm2#",usercontrol )
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skrombeenAuthor Commented:
the method: string.Replace ("#ContactForm2#",usercontrol )
does not work, as its expecting a string/char to replace the first part with
you can first parse the string from the database, and create literal controls for the simple html. When you hit a token you recognize, load the correct control. So, in the end, all you will be doing is adding controls to the page. most of them will be litererals, some of them will be your custom user controls. Of course.. do all of this in page.init, otherwise you will lose viewstate...
skrombeenAuthor Commented:
thanks ErikVB, DO you perhaps have a little sample code for me to work from?
yep, i will post that tonight, on my way to a client now...
skrombeenAuthor Commented:
thanks, i'll wait till tonight!
I use a placeholder control.  Then I just use placeholder.controls.add([your control]).

You can just dinamicaly create the control and add it.  Something like this

webusercontrol cntrl = new webusercontrol();
skrombeenAuthor Commented:
Hi Derftoy,

My data will look something like this: <table><tr><td>Use the below form to contact us</td></tr><tr><td>#ContactForm2#</td><tr></table>

and the ## part will be replaced by the user control...I dont see how your code will resolve the issue at hand?
I see what your saying... your building the page dynamicaly and putting the #ContactForm2# in the HTML.  I use the placeholder control and add the usercontrol there as I displayed earlier.  Sorry, I think Erik has what you need... you will need to parse the HTML.
for this simple problem, a simple solution should suffice. You can split the string on your token delimiters, and create controls for the seperate substrings. something like this code. Disclaimer: i typed this from the top of my head, not guaranteed errorfree ;)

dim originalString as string = "<table><tr><td>Use the below form to contact us</td></tr><tr><td>#ContactForm2#</td><tr></table>"

dim splitString as string() = originalString.Split("#"c)
dim NewControl as control
for each subString as string in splitString
    Select Case subString
        Case "ContactForm2"
            newControl = loadcontrol("~/ContactForm2.ascx")
            newControl.ID = me.ID + ContactForm2
        Case else
            newControl = new LiteralControl(substring)
    End Select

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hmm, line 9 should have been:
newControl.ID = me.ID + "ContactForm2 "
<:>if you expect more contactforms to be put in the string, you need to add a counter as well
skrombeenAuthor Commented:
thanks Erik, but your sample would add the control to the form and exclude the <table ... part... or did i miss something?

Do you think i could run some java to move the item from the "temporary location" into the table part?
otherwise, i've been thinking about old dirty iframes...
skrombeenAuthor Commented:
Top Class Erik, thank you! I get it!
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