Setting values of UserControls used multiple times on a page

[Grant Ord]

I have a pages which use the same UserControl multiple times on the same page
- they have different IDs though. The UserControl contains a number of select
lists.

After databinding each select list in each control to a datasource, which
happens correctly, I then set the Value property for each select list to a
known value obtained from a query.

The problem is that only the last Control loaded actually gets its value set
when the page is displayed.

Can anyone tell me what is wrong?

 

[Steven Cheng[MSFT]]

Hi Grant,

Thanks for your posting. From your description, you've an asp.net page
which contains serveral instance of a certain ASP.NET ASCX user control
which also contains some dropdownlist controls. And when you bind some
datasource to those dropdownlists and set a initial selectedValue for them,
you found only the last one you set take effect, yes?

As for this problem, I'm not sure whether the problem is something
concerned to how you loaded control or the code logic in your ascx user
control. Are you put the UserControls onto page staticaly or use
Page.LoadControl to load them dynamically. In addition, I suggest that you
try make a simple repro page and provide some code of your control(could be
a simplified version) and test page so that we can look a bit more deep
into it . thanks.

Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)

 

[Grant Ord]

Hi Steve
Thanks for your response.
Here is an abbreviated code extract - I think it contains all the relevant
code and illustrates what is happening.
The control is used four times on the hosting page.
Each control contains seven HtmlSelects and one HtmlInputHidden.
In essence Fill() and Page.DataBind() works fine - the content of three of
the HtmlSelects should be different in each control, and it is, so the
databinding is being correctly applied to each individual control.
MakeSelection() only is only effective for the last control to go through
the foreach loop on the hosting page.
On the first three there is no 'selected' property in the html for the
options for the HtmlSelects LvlCncrnTypID, IsSupNdID, SupTypID but there is
on the last one.
I've stepped through the whole process in the dubugger and everything
executes identically for each control.


In the hosting aspx.cs page:

private void Page_Load(object sender, System.EventArgs e)
{
Mentl = (VSDWeShefSSL.inc.Support)LoadControl("../inc/Support.ascx");
Mentl.TblID = TblIDs.MentalHealth;
Mentl.ID = "Mentl";
CtlsPH.Controls.Add(Mentl);
Genrl = (VSDWeShefSSL.inc.Support)LoadControl("../inc/Support.ascx");
Genrl.TblID = TblIDs.GeneralHealth;
Genrl.ID = "Genrl";
CtlsPH.Controls.Add(Genrl);
Dentl = (VSDWeShefSSL.inc.Support)LoadControl("../inc/Support.ascx");
Dentl.TblID = TblIDs.DentalHealth;
Dentl.ID = "Dentl";
CtlsPH.Controls.Add(Dentl);
Sight = (VSDWeShefSSL.inc.Support)LoadControl("../inc/Support.ascx");
Sight.TblID = TblIDs.SightHealth;
Sight.ID = "Sight";
CtlsPH.Controls.Add(Sight);

foreach (VSDWeShefSSL.inc.Support c in CtlsPH.Controls)
{
c.RegID = NewReg;
}
}

In the control ascx.cs page:
public class Support : System.Web.UI.UserControl
{
protected System.Web.UI.HtmlControls.HtmlSelect LvlCncrnTypID;
protected System.Web.UI.HtmlControls.HtmlSelect IsSupNdID;
protected System.Web.UI.HtmlControls.HtmlSelect SupTypID;
protected System.Web.UI.HtmlControls.HtmlSelect AgencyID;
protected System.Web.UI.HtmlControls.HtmlSelect BasicAgencyID;
protected System.Web.UI.HtmlControls.HtmlSelect SpeclAgencyID;
protected System.Web.UI.HtmlControls.HtmlSelect RehabAgencyID;
protected System.Web.UI.HtmlControls.HtmlInputHidden SupList;

private DataTable dt;

private void Page_PreRender(object sender, System.EventArgs e)
{
AgencyID.Attributes["onchange"] = "onchange" + this.ID + "_AgencyID();";
BindPagedData();

}

private void BindPagedData()
{
Fill();
Page.DataBind();
MakeSelection();
}

private void Fill()
{
LvlCncrnTypID.DataSource =
VSDWeShefSSL.DDLData.HardCodeLists.LvlCncrnTyp();
LvlCncrnTypID.DataValueField = "LvlCncrnTypID";
LvlCncrnTypID.DataTextField = "LvlCncrnTyp";
IsSupNdID.DataSource = VSDWeShefSSL.DDLData.HardCodeLists.IsSupNd();
IsSupNdID.DataValueField = "IsSupNdID";
IsSupNdID.DataTextField = "IsSupNd";
string rehabSupTyp = SupTyp.TblIDs.ToString();
SupTypID.DataSource = VSDWeShefSSL.DDLData.HardCodeLists.SupTyp();
SupTypID.DataValueField = "SupTypID";
SupTypID.DataTextField = "SupTyp";
AgencyID.DataSource = GetAgencyID();
AgencyID.DataValueField = "AgencyID";
AgencyID.DataTextField = "Organisation";
BasicAgencyID.DataSource = GetSupTypAgencyID(G.SUP_TYP_BASIC_ADVICE);
BasicAgencyID.DataValueField = "AgencyID";
BasicAgencyID.DataTextField = "Organisation";
SpeclAgencyID.DataSource = GetSupTypAgencyID(G.SUP_TYP_SPECIALIST_ADVICE);
SpeclAgencyID.DataValueField = "AgencyID";
SpeclAgencyID.DataTextField = "Organisation";
RehabAgencyID.DataSource =
GetSupTypAgencyID(G.SUP_TYP_REHABILITATION_SERVICE);
RehabAgencyID.DataValueField = "AgencyID";
RehabAgencyID.DataTextField = "Organisation";
dt = (DataTable)GetSelection();
SupList.Value = (dt.Rows[0]["SupList"] != null) ?
dt.Rows[0]["SupList"].ToString() : "";
}

private void MakeSelection()
{
if (dt.Rows.Count > 0)
{
LvlCncrnTypID.Value = (dt.Rows[0]["LvlCncrnTypID"] != null) ?
dt.Rows[0]["LvlCncrnTypID"].ToString() : "";
IsSupNdID.Value = (dt.Rows[0]["IsSupNdID"] != null) ?
dt.Rows[0]["IsSupNdID"].ToString() : "";
SupTypID.Value = (dt.Rows[0]["SupTypID"] != null) ?
dt.Rows[0]["SupTypID"].ToString() : "";
}
else
{
LvlCncrnTypID.Value = "";
IsSupNdID.Value = "";
SupTypID.Value = "";

}

}

public ICollection GetSupTypAgencyID(int supTypID)
{
..........
DataView dv = new DataView(dt);
return dv;
}
public ICollection GetAgencyID()
{
.............
DataView dv = new DataView(dt);
return dv;
}
public DataTable GetSelection()
{
DataSet lists = new DataSet();
DataTable dt = new DataTable();
..........
return dt;
}
}

#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);
}
private void InitializeComponent()
{
this.PreRender += new System.EventHandler(this.Page_PreRender);
}
#endregion
}

 

[Steven Cheng[MSFT]]

Hi Grant,

Thanks for your response. Just have a look at the code you provided, I
think the problem is likely due to the
"Page.DataBind" you called in each UserControl's PreRender event. Your
UserControl's PreRender is like below:

private void Page_PreRender(object sender, System.EventArgs e)
{
//I remove the function call stack
Fill();
Page.DataBind();
MakeSelection();
}

So when you have multi UserControls and each control will call PreRender
before Page Render out and the Page.DataBind() will recursively fire all
its sub controls' DataBind(), that means the sequence will be something
like: (suppose we have loaded 4 UserControls)

Page_PreRender ....

---------Control1-------------
***Control1 PreRender

***Page.DataBind();

*******Control1 DataBind()
*******Control2 DataBind()
*******Control3 DataBind()
*******Control4 DataBind()

***MakeSelection();

---------Control2-------------
***Control2 PreRender

***Page.DataBind();

*******Control1 DataBind()
*******Control2 DataBind()
*******Control3 DataBind()
*******Control4 DataBind()

***MakeSelection();


........



Then, we can see that since the Page.DataBind make all the 4 UserControls
rebind the data(the dropdownlist) , so only the final DropDownList's
assigned SelectedIndex will remain, others' are lost.
Do you think so?

Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)

 

[Grant Ord]

Hi Steve

Thanks for your help.
Your explanation did highlight the issue for me.
I moved the databinding code into a Page_Load function and called the
controles value selections from a PreRender function, that way the bound
values weren't lost.

 

[Steven Cheng[MSFT]]

You're welcome Grant,

Glad that my suggestions are of assistance.
Have a good day!

Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)