CODEWITHSUNDEEP
c#asp.net
John
John

Reputation: 19

Dynamically change value of hidden field

For an existing site, I have to pass values in hidden fields from a form that's loaded by different pages (eg. City1.aspx, City2.aspx, City3.aspx, etc.), but they are loaded inside an iframe. I also have to dynamically change the value of at least one of those hidden field (let's call it "source") based on the city page loading it. I am familiar with PHP and JavaScript/JQuery, but I have no idea how to do this in C#.

I've found tutorials on retrieving the file name (sans extension) via JavaScript. I think I can still get the city even if the form is in an iframe, but I'd like to keep to the site's conventions and use C# if possible.

Code snippets or links to possible solutions would be much appreciated.

Upvotes: 1

Views: 6173

Answers (2)

freefaller
freefaller

Reputation: 19953

Disclaimer, I don't know JQuery, so there could be easier ways to do this. I also haven't tested any code...

If you know the exact ID then you can do something like this from the parent page (in a javascript block):

var frame = document.getElementById('myIFrame');
var ctrl = frame.document.getElementById('myControl');
ctrl.value = "New Value";

If you don't know the exact ID's of the controls in the CityX.aspx pages, then you will either need a way for those ID's to be discovered, or you will need to go through all controls within the iframe looking for the correct one. (I say this because if the controls in the iframe pages are held in any sort of ASP.NET structure they will not be called txtMyCtrl (for instance) but possibly something like ct00_txtMyCtrl.)

If you don't know the EXACT control name (because of the ASP.NET structure I mentioned before), you could do something like:

var frame = document.getElementById('myIFrame');
var ctrls = frame.document.getElementByTagName("INPUT");
for(var i=0;i<ctrls.length;i++){
  if(ctrls[i].getAttribute("type")=="hidden" && ctrls[i].id.indexOf("_myControl") != -1){
    ctrls[i].value = "New Value";
    break;
  }
}

Or if you have the ability to update the CityX.aspx pages, then you could have the following in the CityX.aspx page:

function getCtrls(){
  return [document.getElementById("<%=hiddenCtrl.ClientID%>"),
          document.getElementById("<%=anotherHiddenCtrl.ClientID%>")];
}

... and then in your parent page, something like:

var frame = document.getElementById('myIFrame');
var ctrls = frame.document.getCtrls();
for(var i=0;i<ctrls.length;i++){
  ctrls[i].value = "New Value";
}

They're just ideas on a general theme

Upvotes: 1

Aghilas Yakoub
Aghilas Yakoub

Reputation: 28970

if you want modify the value of your input in c# associated to your aspx (Code behind), you must to add attributes runat=server to your input.

use this code in your aspx

<input id="test" type="hidden" runat="server"/>

and in your c#

test.Value = 123; //your value is 123 for example

Upvotes: 2

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