Develop Reference

Looping through controls on a page using a masterpage

I'm trying to perform an operation on every control on a page that is inherited from a masterpage. I don't know how to access the child pages controls. I have tried recursively getting to my controls like this:
private void checkControls(ControlCollection controlcollection)
{
foreach (Control control in controlcollection)
{
if (control.Controls.Count > 0)
{
Debug.WriteLine(control.GetType().ToString());
checkControls(control.Controls);
}
else
{
Debug.WriteLine(control.GetType().ToString());
}
}
The method is called like this:
protected void resettodefault()
{
checkControls(this.Page.Controls);
}
However, the only controls that are printed from this execution are:
ASP.site_master
System.Web.UI.LiteralControl
I would prefer to access my controls directly (without recursion). Otherwise, how can I modify my recursion to get to the desired page's controls?

I would suggest using a base page instead of a master page, this way your logic for iterating over controls (and whatever you will do with that afterwards) is not tied to which master page a page is using.
As far as getting all the controls on the page, because the controls are hierarchical, as is the HTML they represent, so iterating over them recursively makes sense. However if you are dead set on not recursively getting controls something like this should work:
IEnumerable<Control> GetAllControls()
{
var allControls = new List<Control>();
var currentControls = new Queue<Control>();
currentControls.Enqueue(this.Page);
while (currentControls.Count >0)
{
var c = currentControls.Dequeue();
if (!allControls.Contains(c))
{
allControls.Add(c);
if (c.Controls != null && c.Controls.Count > 0)
{
foreach (Control e in c.Controls)
{
currentControls.Enqueue(e);
}
}
}
}
return allControls;
}
The last thing to consider is the lifecycle of the page, and when you iterate over the controls. If you try to walk to control tree too early not all controls may exist.
EDIT: Updated code.
Update
For validation purposes I would highly recommend using the built in validation controls of asp.net. You can read more about them here. This has the added benefit of providing validation on the client, providing faster UI responses and easing the load off the servers.
For resetting all the textboxes. I would recommend creating a new class for this purpose, then calling upon that class when needed instead of messing with the master page:
public class UIControlsHelper
{
public static void ClearTextboxes(Page page)
{
GetAllControls(page)
.Where(x => typeof(TextBox).IsAssignableFrom(x.GetType())
.ToList()
.ForEach(x => (TextBox)x.Text = string.Empty);
}
IEnumerable<Control> GetAllControls(Page page)
// Same as above, but with the page parameter replaced.
}
}
And in any of your pages:
UIControlsHelper.ClearTextboxes(this);

To access the controls in your child page do the following steps:
1-declare a variable of the type you want to access. For example if you want to access a Label in your child page use:
Label lbl_child=this.ContentPlaceHolder1.findcontrol("your label id in child page") as Label;
Now you have your label and you are free to make changes on it. Every change on this control will be reflected on the child control.
ContentPlaceHolder1 is your contentplace holder id so change it with your content id.

public void ClearTextboxes(Page page) {
GetAllControls(page)
.Where(x => typeof(TextBox).IsAssignableFrom(x.GetType()))
.ToList()
.ForEach(x => ((TextBox)x).Enabled=false);
}

Set Properties of User Control on Event Using FindControl

I have a user control that is dynamically loaded in the the page load:
protected void Page_Load(object sender, EventArgs e)
{
MyControl ctl = (MyControl)LoadControl(controlPath);
ctl.ID = "mycontrol";
this.MyControlPlaceHolder.Controls.Add(ctl);
}
Front End of the Page:
<asp:PlaceHolder runat="server" ID="MyControlPlaceHolder"></asp:PlaceHolder>
I have an click event on the page that initiates and postback and calls a method where I'm trying to find the control and set some properties:
MyControl ctl = (MyControl)FindControl("mycontrol");
if (ctl != null){
ctl.MyProperty = true;
Response.Write("success");
}
else
Response.Write("fail");
This is writing fail after the postback, so it seems like I'm doing something incorrectly in finding the control. What is the best way to do this?
EDIT:
I switched it to MyControl ctl = (MyControl)this.MyControlPlaceHolder.FindControl("mycontrol");
This made it so it was finding the control, however, when the control loads after the postback, it appears as though the property is not set.

You have to use a recursive FindControl implementation because FindControl will only find direct childs. Your control is inserted in a naming container at a lower level. A generic FindControlRecurisve from MSDN:
private Control FindControlRecursive(Control rootControl, string controlID)
{
if (rootControl.ID == controlID) return rootControl;
foreach (Control controlToSearch in rootControl.Controls)
{
Control controlToReturn =
FindControlRecursive(controlToSearch, controlID);
if (controlToReturn != null) return controlToReturn;
}
return null;
}
from MSDN
Or, if you only have one specific conatiner like in your sample:
MyControl ctl = this.MyControlPlaceHolder.FindControl("mycontrol");
if (ctl != null){
ctl.MyProperty = true;
Response.Write("success");
}
else
Response.Write("fail");
ViewState enable your control
public class MyControl:Control
{
public bool MyProperty
{
get
{
return ViewState["my"] != null? (bool) ViewState["my"]: false;
}
set
{
ViewState["my"] = value;
}
}
}

Try moving the code to dynamically add the control into Init instead of load. I can't be sure but there are a lot of things that happen between Init and Load and if your control is not present and accounted for it may cause issues like this.

You added the Control in the controls collection of a placeholder.
Apart of what control is your dynamically created control, if you want to looking for your dynamically added control in that way you have to do a recursive search starting from the root (maybe the page), so, if you surf over the net, you could find good solutions for that.
Personally I prefer solutions with: generics support and expressed as extension methods, so you could use the solution everywhere. These are some usefull links
Recursive Find Control with generics
Recursive Find Control with generics by extension method
Recursive Find Control with generics by extension method and linq support/example
hope this helps

How to find a panel and add control to it from it's code behind

In a master page I got a panel which I want to add controls to it from the master page's code behind as follow:
var cphRegionName = this.Page.FindControl("pnlLeft") as Panel;
cphRegionName.Controls.Add(uc);
but I get this error:
Object reference not set to an instance of an object at cphRegionName.Controls.Add(uc);
I have tried all possible other ways, but get the same error.
The reason I user FindControl to access the PANEL is the panel's name is dynamic ("pnlLeft"), reading from Database.

The FindControl method doesn't work recursively. This means that unless your control was added directly to the page, it would not find it.
If you know the container control, use FindControl on that and not on the Page.
If you don't, you could use a a function like this to solve the problem
private Control FindControlRecursive(Control root, string id)
{
if (root.ID == id)
{
return root;
}
foreach (Control c in root.Controls)
{
Control t = FindControlRecursive(c, id);
if (t != null)
{
return t;
}
}
return null;
}

FindControl is not recursive, so you have to make sure you're calling it on the correct container. It doesn't look like the panel is defined at the root based on the null reference.
Try calling FindControl on the parent of the panel

ASP.NET How to access a deeply nested user control on the parent page

I have a login control and at is nested 2 deep in a header control
i.e Page --> Header Control --> Login Control. I cannot get a reference to the control on the page using FindControl. I want to be able to set the visible property of the control like
if (_loginControl != null)
_loginControl.Visible = false;
I ended up using a recursive FindControl method to find the nested control.
public static Control FindControlRecursive(Control root, string id)
{
if (root.ID == id)
{
return root;
}
foreach (Control c in root.Controls)
{
Control t = FindControlRecursive(c, id);
if (t != null)
{
return t;
}
}
return null;
}

Are you needing to disable/hide the User Control from the ASP.NET page it resides on (or does the User Control exist on a master page, say)? If it's in the same page, then in your ASP.NET page's code-behind you'd do:
MyUserControlsID.Visible = false
Where MyUserControl is the ID of your User Control. To determine the ID of your User Control look at the markup of your .aspx page and you will see something like this:
<uc1:UserControlName ID="MyUserControlsID" runat="server" ... />
Happy Programming!

A good way would be to use:
Page.FindControl()
if that yields null, the control is not there.

Try calling this.FindControl("_loginControl") or this.Page.FindControl("_loginControl").
See MSDN for method details:
http://msdn.microsoft.com/en-us/library/system.web.ui.control.findcontrol.aspx

The login control, if it's registered in the markup, will also be an instance member of your codebehind page; you can refer to it from the codebehind class as if it were a normal member, using the same name you provided as the ID (I do recommend using codebehinds for most logic, instead of inlining code in the markup, BTW).
You can also use the FindControl() method of your page, which will search its control subtree for a control with a given ID. That takes longer, so I would recommend the first option unless the logic control is added dynamically and you don't always know it's there.

private List<Control> GetAllNestedUserControl(Control ph)
{
List<Control> Get = new List<Control>();
foreach (var control in ph.Controls)
{
if (control is UserControl)
{
UserControl uc = control as UserControl;
if (uc.HasControls())
{
Get = GetAllNestedUserControl(uc);
}
}
else
{
Control c = (Control)control;
if (!(control is LiteralControl))
{
Get.Add(c);
}
}
}
return Get;
}
just call this code from you any parent page and then get any control by the following code
List<Control> Get = GetAllNestedUserControl(ph);
Label l = (Label)Get.Find(o => o.ID == "lblusername");
l.Text = "changed from master";

Finding controls inside nested master pages

I have a master page which is nested 2 levels. It has a master page, and that master page has a master page.
When I stick controls in a ContentPlaceHolder with the name "bcr" - I have to find the controls like so:
Label lblName =(Label)Master.Master.FindControl("bcr").FindControl("bcr").FindControl("Conditional1").FindControl("ctl03").FindControl("lblName");
Am I totally lost? Or is this how it needs to be done?
I am about to work with a MultiView, which is inside of a conditional content control. So if I want to change the view I have to get a reference to that control right? Getting that reference is going to be even nastier! Is there a better way?
Thanks

Finding controls is a pain, and I've been using this method which I got from the CodingHorror blog quite a while ago, with a single modification that returns null if an empty id is passed in.
/// <summary>
/// Recursive FindControl method, to search a control and all child
/// controls for a control with the specified ID.
/// </summary>
/// <returns>Control if found or null</returns>
public static Control FindControlRecursive(Control root, string id)
{
if (id == string.Empty)
return null;
if (root.ID == id)
return root;
foreach (Control c in root.Controls)
{
Control t = FindControlRecursive(c, id);
if (t != null)
{
return t;
}
}
return null;
}
In your case, I think you'd need the following:
Label lblName = (Label) FindControlRecursive(Page, "lblName");
Using this method is generally much more convenient, as you don't need to know exactly where the control resides to find it (assuming you know the ID, of course), though if you have nested controls with the same name, you'll probably get some strange behavior, so that might be something to watch out for.

Firstly, you should know that MasterPages actually sit inside Pages. So much so that a MasterPage's Load event is actually called after your ASPX's Load event.
This means, the Page object is actually the highest control in the control hierarchy.
So, knowing this, the best way to find any control in such a nested environment, is to write a recursive function that loops through every control and child controls until it finds the one you're looking for. in this case, your MasterPages are actually child controls of the main Page control.
You get to the main Page object from inside any control like this:
C#:
this.Page;
VB.NET
Me.Page
I find that usually, the Control's class FindControl() method is pretty useless, as the enviroment is always nested.
Because if this, I've decided to use .NET's 3.5 new Extension features to extend the Control class.
By using the code below (VB.NET), in say, your AppCode folder, all your controls will now peform a recursive find by calling FindByControlID()
Public Module ControlExtensions
<System.Runtime.CompilerServices.Extension()> _
Public Function FindControlByID(ByRef SourceControl As Control, ByRef ControlID As String) As Control
If Not String.IsNullOrEmpty(ControlID) Then
Return FindControlHelper(Of Control)(SourceControl.Controls, ControlID)
Else
Return Nothing
End If
End Function
Private Function FindControlHelper(Of GenericControlType)(ByVal ConCol As ControlCollection, ByRef ControlID As String) As Control
Dim RetControl As Control
For Each Con As Control In ConCol
If ControlID IsNot Nothing Then
If Con.ID = ControlID Then
Return Con
End If
Else
If TypeOf Con Is GenericControlType Then
Return Con
End If
End If
If Con.HasControls Then
If ControlID IsNot Nothing Then
RetControl = FindControlByID(Con, ControlID)
Else
RetControl = FindControlByType(Of GenericControlType)(Con)
End If
If RetControl IsNot Nothing Then
Return RetControl
End If
End If
Next
Return Nothing
End Function
End Module

Although I love recursion, and agree with andy and Mun, one other approach you may want to consider is to have a strongly typed Master page. All you have to do is add one directive in your aspx page.
Instead of accessing a page's control from your master page, consider accessing a control in your master page from the page itself. This approach makes a lot of sense when you have a header label on your master page, and want to set its value from each page that uses the master.
I'm not 100% sure, but I think this would be simpler technique with nested master pages, as you would just point the VirtualPath to the master containing the control you wish to access. It might prove to be tricky though if you want to access two controls, one in each respective master page.

Here is a code that is more generic and works with a custom condition (that can be a lambda expression!)
Call:
Control founded = parent.FindControl(c => c.ID == "youdId", true);
Control extension
public static class ControlExtensions
{
public static Control FindControl(this Control parent, Func<Control, bool> condition, bool recurse)
{
Control founded = null;
Func<Control, bool> search = null;
search = c => c != parent && condition(c) ? (founded = c) != null :
recurse ? c.Controls.FirstOrDefault(search) != null :
(founded = c.Controls.FirstOrDefault(condition)) != null;
search(parent);
return founded;
}
}

I have used the <%# MasterType VirtualPath="~/MyMaster.master" %> method. I have a property in the main master page then in the detail master page other property with the same name calling the main master property and it works fine.
I have this in the main master page
public string MensajeErrorString
{
set
{
if (value != string.Empty)
{
MensajeError.Visible = true;
MensajeError.InnerHtml = value;
}
else
MensajeError.Visible = false;
}
}
this is just a div element that have to show an error message. I would like to use this same property in the pages with the detail master page(this is nested with the main master).
Then in the detail master I have this
public string MensajeErrorString
{
set
{
Master.MensajeErrorString = value;
}
}
Im calling the main master property from the detail master to create the same behavior.

I just got it working perfectly.
In contentpage.aspx, I wrote the following:
If Master.Master.connectsession.IsConnected Then
my coded comes in here
End If