[RESOLVED] Populating a client text area from server code

[FishGuy]

Hello,

I have a .net user control which gets some data from the database in the controls load event, once it has this data I want it to populate a html text area on the same control.

I have looked at many examples of how to populate client controls from server side code but not ones on a user control.

So far I have the following in script blocks at the start of my markup.

 function AddText(elementid, txtval) {     var txtArea = document.getElementByID ( elementid );     if ( txtArea )     {       txtArea.value = txtval;     }  }

and after I have retreived the data base in my controls load method I have the following

if (!Page.ClientScript.IsStartupScriptRegistered("AddText"))
                {
                    Page.ClientScript.RegisterStartupScript
                        (this.GetType(), "AddText", "AddText('txtArea', '" + aOutline1.Overview + "');", true);
                }

When I run the code the function gets called and appears to pass the correct values in, however it throws this error

Microsoft JScript runtime error: Object doesn't support this property or method

when it hits the code document.getElementByID ( elementid );

I guess this may have something to do with it being on a user control?

Anyone able to help at all.

[motil]

you have syntax error here

getElementByID 

The "D" should be lower case:

getElementById

[FishGuy]

Thanks, I dont work much with Javascript and mainy copy things off the web to suit my needs, I had completely forgotten it was case sensitive and just trusted the code I found.

[motil]

Ok no problem, I just have to say about something you wrote:

I guess this may have something to do with it being on a user control?

I see this types of mistakes coming a lot from people, you must to understand that ASP.NET controls (whatever it be) ending up rendering as native HTML, there is NO such thing ASP.NET controls or elements after your code is being rendered and handed back to the client browser, so what ever ASP.NET controls you use, javascript will be able to understand and use it if you get them properly.

just keep that in mind

[FishGuy]

Thanks, the reason for confusion is all our page content has to sit in the user controls, this is so we can port our controls on to other web pages quickly i.e. into a CMS page without having to alter the page content.

It is causing me problems though, i.e. control communication.

I have a control on one page which has some public properties, on the click of a button(on the control) it takes you to another page also with a user control. I want the second user control to be able to get the value from the user control on the previous page.

I am trying to do this via a crosspagepostback. However I cannot seem to get the value because when I try and cast the control as the control type required it doesnt recognise it as a type so wont build.

Outline ctrla = (Outline)Page.PreviousPage.FindControl("Outlines1");
            
            //if (ctrla != null)
            //{
             
            //    OutlineID = ctrla.outlineID;
            //    this.lblCourseCode.Text =  OutlineID;
}

even though I have referenced the first control in my markup

<%@ Register src="../../usercontrols/Outlines.ascx" tagname="Outlines" tagprefix="uc2" %>

[motil]

are you using master page ?

[FishGuy]

Yes we are, could this be affecting it?

[motil]

of course it, you think you can handle it or should I'll scrap example for you ?

[FishGuy]

I have no idea what the difference would be if you could show me an example please.

[motil]

ok, I'll write one down soon

[motil]

Ok let me explain how to retrieve you control property value when using master page:

first i created a new website and add this very basic control that only has label:

MyControls.ascx

<&#37;@ Control Language="C#" AutoEventWireup="true" CodeFile="MyControl.ascx.cs" Inherits="MyControl" %>
<asp:Label ID="lblPropertyValue" runat="server" Text="Label"></asp:Label>

in the code behind I added property to fill that label:

MyControls.cs

 public partial class MyControl : System.Web.UI.UserControl
    {
        private string _MyProperty;

        public string MyProperty
        {
            set
            {
                this._MyProperty = value;
            }

            get
            {
                return this._MyProperty;
            }
        }
        protected void Page_Load(object sender, EventArgs e)
        {
            lblPropertyValue.Text = this.MyProperty;
        }
    }

So now I have control that called "MyControl" and a string property with the name of "MyProperty", I added to the control to the source page along with a button that will do the post back

Default.aspx

    <uc1:MyControl ID="MyControl1" runat="server" MyProperty="My Property" />
    <asp:Button ID="Button1" runat="server" PostBackUrl="~/Default2.aspx" Text="Button" />

so the button is set to post back to Default2.aspx:

Default2.aspx

 if (Page.PreviousPage != null)
        {

            // now here all the dirty work is been done

            // first you need to get your master page ContentPlaceHolder control which holds your Custom Control
            // and here is how you do that.
            // Note my Master page ContentPlaceHolder Control ID is "MainContent" change it if it's different
            // in your master page
            ContentPlaceHolder BodyContent = (ContentPlaceHolder)PreviousPage.Master.FindControl("MainContent");

            // once we have the ContentPlaceHolderControl we can get our custom control
            // change this "controls_mycontrol_ascx" to your custom control class name 
            ASP.controls_mycontrol_ascx test = (ASP.controls_mycontrol_ascx)BodyContent.FindControl("MyControl1");
            Trace.Warn(test.MyProperty);
        

        }

of course I didn't made more checks for null values which you should do, if you have anymore question we are here to help.

Note:There are more ways to get the controls like drilling down the controls tree but I Decided to show you the most basic method since this methods helps to understand
how things built and why you need to do it all of this.

[FishGuy]

That is excellent thankyou so much, it worked exactly as you said with code below.

  ContentPlaceHolder BodyContent = (ContentPlaceHolder)Page.PreviousPage.Master.FindControl("maincontent");
            ASP.usercontrols_courses_ascx test = (ASP.usercontrols_courses_ascx)BodyContent.FindControl("Courses1");
          
                        
           
             
                courseCode = test.courseCode;
                this.lblCourseCode.Text = courseCode;

Thanks again.

[motil]

No problem at all, Glad to hear everything working now