I try to access the MainContentBlock control from the aspx, but unable to do so.
In the aspx file I have registered both controls:
<uc3:ContentBlock ID="MainContentBlock" runat="server" DynamicParameter="id" DefaultContentID="3951" /></uc3>
<uc3:childshow ID="Childshow" runat="server"/></uc3>
In the code behind for child.ascx
If Me.Parent.Page.FindControl("MainContentBlock") IsNot Nothing AndAlso Me.MainContentBlock.Item.Id = 4357 Then
...
But the error says BC30456: 'MainContentBlock' is not a member of 'child'.
It's almost like the ".parent" part did not work.
However, If I try the following:
If Me.Parent.MainContentBlock IsNot Nothing AndAlso Me.MainContentBlock.Item.Id = 4357 Then
...
It will bring up the error "BC30456: 'MainContentBlock' is not a member of 'System.Web.UI.Control'.
and seems it at least recognized the .parent part again.
confused... please help, thanks.
It's because you're trying to reference MainContentBlock as a property of the child control. When you use Me.MainContentBlock, Me refers to the child control.
You just need to use FindControl, and properly reference the found control:
Dim myBlock As ContentBlock = TryCast(Me.Parent.FindControl("MainContentBlock"), ContentBlock)
If myBlock IsNot Nothing Then
'do things with myBlock
End If
Depending on where the control is located on the page, you may need to find it recursively, but in a simple situation you would just do this:
var pnl = Page.FindControl("MainContentBlock") as Panel; //or whatever it is
if (pnl != null)
{
//your code here
}
Here's a recursive method if you need it:
public Control FindControlRecursive(string controlID, Control parentCtrl)
{
foreach (Control ctrl in parentCtrl.Controls)
{
if (ctrl.ID == controlID)
return ctrl;
FindControlRecursive(controlID, ctrl);
}
return null;
}
And you would call it like this:
var pnl ((PageName)Page).FindControlRecursive("MainContentBlock") as Panel;
FindControl works but the pain is that what you're looking for can be higher then just at parent level. Here is a handy method I use:
public static Control FindControlRecursive(Control root, string id)
{
if (root.ID == id)
return root;
foreach (Control ctl in root.Controls)
{
Control foundCtl = FindControlRecursive(ctl, id);
if (foundCtl != null)
return foundCtl;
}
return null;
}
Related
I'm trying to refer to a dynamically created label's .Text property but can't find a way.
If I try referring to label1.Text it won't let me because it hasn't been created yet.
I'm trying:
Page.FindControl("label" & i.ToString).Text
This doesn't work either, although you can access the control's .ID property that way.
Any ideas?
I'm using Visual Studio Express 2012 For Web.
FindControl returns a System.Web.UI.Control which does not have a .Text property. You need to cast it to a Label. Try this:
Dim label = DirectCast(Page.FindControl("label" & i.ToString()), Label)
label.Text = "foo"
If a control is nested inside other controls, you need to find it recursively. In addition, you want to cast the control to Label control before using Text property.
Here is a helper method. It searches a control recursively.
Helper Method
public static Control FindControlRecursive(Control root, string id)
{
if (root.ID == id)
return root;
return root.Controls.Cast<Control>()
.Select(c => FindControlRecursive(c, id))
.FirstOrDefault(c => c != null);
}
Usage
var myLabel = FindControlRecursive(Page, "label" + i.ToString) as Label;
if(myLabel != null)
{
myLabel.Text = "abc";
}
As per the title, I know the code I've posted below is utter poo, this is why I need your help!
I've put way too many hours into this, and it's either down to inexperience, a bug or I've screwed up somewhere.
I have a user control with a view properties that access the ViewState and two user controls within that display the properties.
Within the page_load of the user control, depending on the value of some of the properties, it will toggle the visibility of the controls within:
public partial class PatientStatus : System.Web.UI.UserControl
{
public string PatientName { get { return ViewState["PatientName"] as string; } set { ViewState["PatientName"] = value; } }
public bool ClinicianView { get { return Convert.ToBoolean(ViewState["ClinicianView"]); } set { ViewState["ClinicianView"] = value; } }
public string RangeTitle { get { return ViewState["RangeTitle"] as string; } set { ViewState["RangeTitle"] = value; } }
public int? RangeLimitNormSys { get { return ViewState["RangeLimitNormSys"] as int?; } set { ViewState["RangeLimitNormSys"] = value; } }
public int? RangeLimitNormDia { get { return ViewState["RangeLimitNormDia"] as int?; } set { ViewState["RangeLimitNormDia"] = value; } }
protected void Page_Load(object sender, EventArgs e)
{
bool ispostback = IsPostBack;
if (ispostback && ((System.Web.UI.WebControls.Repeater)(this.Parent.Parent)).DataSource != null)
{
object itm = ((RepeaterItem)this.Parent).DataItem;
if (itm is AppointmentRow)
{
AppointmentRow row = itm as AppointmentRow;
PatientName = row.Name;
RangeTitle = row.Range;
RangeLimitNormDia = row.RangeLimitNormDia;
RangeLimitNormSys = row.RangeLimitNormSys;
ispostback = false;
}
else if (itm is ReadingRow)
{
ReadingRow row = itm as ReadingRow;
PatientName = row.Name;
RangeTitle = row.Range;
RangeLimitNormDia = row.RangeLimitNormDia;
RangeLimitNormSys = row.RangeLimitNormSys;
ispostback = false;
}
else if (itm is PatientRow)
{
PatientRow row = itm as PatientRow;
PatientName = row.Name;
RangeTitle = row.Range;
RangeLimitNormDia = row.RangeLimitNormDia;
RangeLimitNormSys = row.RangeLimitNormSys;
ispostback = false;
}
}
if (!ispostback)
{
if (!string.IsNullOrWhiteSpace(RangeTitle))
{
placeHolder.Visible = true;
literalNA.Visible = false;
}
}
}
}
Previously the Page_Load event simply contained:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
if (!string.IsNullOrWhiteSpace(RangeTitle))
{
placeHolder.Visible = true;
literalNA.Visible = false;
}
}
}
But on postback, the RangeTitle property was always null, so even when removing the isPostBack statement, it didn't work property.
The only way to resolve it, was to really fudge it by the first block of code.
On the Page_Load of the parent page, and on !isPostBack I'm calling a method that gets and binds data to the repeater. This works fine. But on a postback, i'm calling the same method and for some reason, the user control isn't populating.
Any idea's?
Merry Christmas
Gav
Edit
In response to #jwiscarson
I have a table that is generated via an ASP:Repeater and within the ItemTemplate, I have added a User Control which contains a PlaceHolder and a Literal. Also within the User Control is a number of Properties.
Then on databind I pass across a number of values to the user control (I've tried both OnItemDataBound and inline using Eval). Then on the User Control's Page_Load event, as per the second block of code above, I first check if it's a postback, if not, I then check to see if the Property RangeTitle has a value.
If RangeTitle does not have a value, I then hide the placeholder that contains HTML that would display the RangeTitle and show a literal that displays N/A.
When loading the page for the first time, (!isPostBack) it works fine. But as soon as I create a postback, the User Controls within the repeater all revert to N/A even when their RangeTitle properties had a value.
On debugging, I set a breakpoint in the Page_Load of the User Control. When I first load the page, I can see that my properties have been populated correctly. Then on postback, Page_Load is called on the UserControl and the properties are populated correctly, then Page_Load is called again, but this time, the properties are empty.
i.e.
!isPostBack
UserControl::Page_Load < Correct data
isPostBack
UserControl::Page_Load < Correct data
myButton_Click (bind new data)
UserControl::Page_Load < No data
To make things even more confusing. The method called within myButton_Click to bind the data, is the exact same method called in the Page_Load of the Page to populate the repeater on !isPostBack
Thanks ;)
I would check to make sure that DataItem is accessible in this function. I think you need to listen to the ItemDataBound event and perform this work in that event.
Beyond that, it's difficult to suggest anything else concrete. I don't really understand why you're doing what you're doing (if you have this information in a Repeater, why does it also need to be in ViewState?). If you could explain your rationale for doing this, it might help me and anyone else who visits this question. You say that you're just trying to show/hide some specific items on the page. This is pretty complicated code without a lot of justification for that complication.
As an aside: you really, really need to break this code down and think about what you're trying to accomplish. Here are a few suggestions:
Separate the scopes inside your if and else if statements into functions that return the data you need.
Do not include lines like ((System.Web.UI.WebControls.Repeater)(this.Parent.Parent)).DataSource != null in an if statement. Perform this cast separately and store it in a variable, or write a small function that checks this.
Statements like this.Parent.Parent and other references to Parent controls are code smells, in my opinion. Even on a normal page, this would be a code smell, but what exactly is this.Parent going to reference when you include it in a UserControl?
I have a complex asp.net form,having even 50 to 60 fields in one form like there is Multiview, inside MultiView I have a GridView, and inside GridView I have several CheckBoxes.
Currently I am using chaining of the FindControl() method and retrieving the child ID.
Now, my question is that is there any other way/solution to find the nested control in ASP.NET.
If you're looking for a specific type of control you could use a recursive loop like this one -
http://weblogs.asp.net/eporter/archive/2007/02/24/asp-net-findcontrol-recursive-with-generics.aspx
Here's an example I made that returns all controls of the given type
/// <summary>
/// Finds all controls of type T stores them in FoundControls
/// </summary>
/// <typeparam name="T"></typeparam>
private class ControlFinder<T> where T : Control
{
private readonly List<T> _foundControls = new List<T>();
public IEnumerable<T> FoundControls
{
get { return _foundControls; }
}
public void FindChildControlsRecursive(Control control)
{
foreach (Control childControl in control.Controls)
{
if (childControl.GetType() == typeof(T))
{
_foundControls.Add((T)childControl);
}
else
{
FindChildControlsRecursive(childControl);
}
}
}
}
Late as usual. If anyone is still interested in this there are a number of related SO questions and answers. My version of recursive extension method for resolving this:
public static IEnumerable<T> FindControlsOfType<T>(this Control parent)
where T : Control
{
foreach (Control child in parent.Controls)
{
if (child is T)
{
yield return (T)child;
}
else if (child.Controls.Count > 0)
{
foreach (T grandChild in child.FindControlsOfType<T>())
{
yield return grandChild;
}
}
}
}
All the highlighted solutions are using recursion (which is performance costly). Here is cleaner way without recursion:
public T GetControlByType<T>(Control root, Func<T, bool> predicate = null) where T : Control
{
if (root == null) {
throw new ArgumentNullException("root");
}
var stack = new Stack<Control>(new Control[] { root });
while (stack.Count > 0) {
var control = stack.Pop();
T match = control as T;
if (match != null && (predicate == null || predicate(match))) {
return match;
}
foreach (Control childControl in control.Controls) {
stack.Push(childControl);
}
}
return default(T);
}
FindControl does not search within nested controls recursively. It does only find controls that's NamigContainer is the Control on that you are calling FindControl.
Theres a reason that ASP.Net does not look into your nested controls recursively by default:
Performance
Avoiding errors
Reusability
Consider you want to encapsulate your GridViews, Formviews, UserControls etc. inside of other UserControls for reusability reasons. If you would have implemented all logic in your page and accessed these controls with recursive loops, it'll very difficult to refactor that. If you have implemented your logic and access methods via the event-handlers(f.e. RowDataBound of GridView), it'll be much simpler and less error-prone.
Action Management On Controls
Create below class in base class.
Class To get all controls:
public static class ControlExtensions
{
public static IEnumerable<T> GetAllControlsOfType<T>(this Control parent) where T : Control
{
var result = new List<T>();
foreach (Control control in parent.Controls)
{
if (control is T)
{
result.Add((T)control);
}
if (control.HasControls())
{
result.AddRange(control.GetAllControlsOfType<T>());
}
}
return result;
}
}
From Database:
Get All Actions IDs (like divAction1,divAction2 ....) dynamic in DATASET (DTActions) allow on specific User.
In Aspx:
in HTML Put Action(button,anchor etc) in div or span and give them id like
<div id="divAction1" visible="false" runat="server" clientidmode="Static">
<a id="anchorAction" runat="server">Submit
</a>
</div>
IN CS:
Use this function on your page:
private void ShowHideActions()
{
var controls = Page.GetAllControlsOfType<HtmlGenericControl>();
foreach (DataRow dr in DTActions.Rows)
{
foreach (Control cont in controls)
{
if (cont.ClientID == "divAction" + dr["ActionID"].ToString())
{
cont.Visible = true;
}
}
}
}
Recursively find all controls matching the specified predicate (do not include root Control):
public static IEnumerable<Control> FindControlsRecursive(this Control control, Func<Control, bool> predicate)
{
var results = new List<Control>();
foreach (Control child in control.Controls)
{
if (predicate(child))
{
results.Add(child);
}
results.AddRange(child.FindControlsRecursive(predicate));
}
return results;
}
Usage:
myControl.FindControlsRecursive(c => c.ID == "findThisID");
I decided to just build controls dictionaries. Harder to maintain, might run faster than the recursive FindControl().
protected void Page_Load(object sender, EventArgs e)
{
this.BuildControlDics();
}
private void BuildControlDics()
{
_Divs = new Dictionary<MyEnum, HtmlContainerControl>();
_Divs.Add(MyEnum.One, this.divOne);
_Divs.Add(MyEnum.Two, this.divTwo);
_Divs.Add(MyEnum.Three, this.divThree);
}
And before I get down-thumbs for not answering the OP's question...
Q: Now, my question is that is there any other way/solution to find the nested control in ASP.NET?
A: Yes, avoid the need to search for them in the first place. Why search for things you already know are there? Better to build a system allowing reference of known objects.
https://blog.codinghorror.com/recursive-pagefindcontrol/
Page.FindControl("DataList1:_ctl0:TextBox3");
OR
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;
}
The following example defines a Button1_Click event handler. When invoked, this handler uses the FindControl method to locate a control with an ID property of TextBox2 on the containing page. If the control is found, its parent is determined using the Parent property and the parent control's ID is written to the page. If TextBox2 is not found, "Control Not Found" is written to the page.
private void Button1_Click(object sender, EventArgs MyEventArgs)
{
// Find control on page.
Control myControl1 = FindControl("TextBox2");
if(myControl1!=null)
{
// Get control's parent.
Control myControl2 = myControl1.Parent;
Response.Write("Parent of the text box is : " + myControl2.ID);
}
else
{
Response.Write("Control not found");
}
}
Is it possible to dynamically (and generically) clear the state of all of a user control's child controls? (e.g., all of its TextBoxes, DropDrownLists, RadioButtons, DataGrids, Repeaters, etc -- basically anything that has ViewState)
I'm trying to avoid doing something like this:
foreach (Control c in myUserControl.Controls)
{
if (c is TextBox)
{
TextBox tb = (TextBox)c;
tb.Text = "";
}
else if (c is DropDownList)
{
DropDownList ddl = (DropDownList)c;
ddl.SelectedIndex = -1;
}
else if (c is DataGrid)
{
DataGrid dg = (DataGrid)c;
dg.Controls.Clear();
}
// etc.
}
I'm looking for something like this:
foreach (Control c in myUserControl.Controls)
c.Clear();
...but obviously that doesn't exist. Is there any easy way to accomplish this dynamically/generically?
I was going to suggest a solution similar to Task's except (as sixlettervariables points out) we need to implement it as 1 extension method and essentailly switch on the precise type of the control passed in (i.e. copy your logic that you posted in your question).
public static class ControlExtensions
{
public static void Clear( this Control c )
{
if(c == null) {
throw new ArgumentNullException("c");
}
if (c is TextBox)
{
TextBox tb = (TextBox)c;
tb.Text = "";
}
else if (c is DropDownList)
{
DropDownList ddl = (DropDownList)c;
ddl.SelectedIndex = -1;
}
else if (c is DataGrid)
{
DataGrid dg = (DataGrid)c;
dg.Controls.Clear();
}
// etc....
}
}
It is not particularly elegent looking method but your code in your page/control is now the more succinct
foreach (Control c in myUserControl.Controls) {
c.Clear();
}
and you can of course now call control.Clear() anywhere else in you code.
You can do
foreach (Control c in myUserControl.Controls) {
myUserControl.Controls.Remove(c);
}
Because Controls is just a list, you can call Remove() on it, passing it what you want to remove.
EDIT: Oh I'm sorry, I didn't read it correctly. I don't know of a way to do this, maybe someone here who is good with Reflection could make it where you could do like
foreach (Control c in myUserControl.Controls) {
c = new c.Type.GetConstructor().Invoke();
}
or something, to turn it into a freshly made component.
I haven't tested it, but clearing viewstate for the usercontrol may work. You could expose a custom method on the user control as well:
usercontrol:
public void Clear()
{
this.ViewState.Clear();
}
page:
myUserControlInstance.Clear();
Now again I haven't tested. It's possible this will only clear the StateBag for the UserControl container, and not its nested/child controls.. if the above doesn't work you could try using recursion to walk down the control tree to clear viewstate for all children:
usercontrol:
public void Clear()
{
ClearViewState(this.Controls);
}
private void ClearViewState(ControlCollection cc)
{
foreach(Control c in cc)
{
if(c.HasControls())
{
//clear the child controls first
ClearViewState(c.Controls);
}
//then clear the control itself
c.ViewState.Clear();
}
}
page:
myUserControlInstance.Clear();
Just an idea. I haven't tested it but I think in theory it could work. One implication would be to call Clear at the correct point in the page/controls lifecycle, otherwise it may not work.
Hope this helps!
myUserControl.Controls.ToList().ForEach(c => myUserControl.Controls.Remove(c));
However, be careful, because you modify the iterating list. This could lead to some strange behaviour.
Setting EnableViewState="false" on the individual controls might save you the work, if it doesn't cause other problems for you in this instance.
What about the Control.ClearChildViewState method?
MSDN states
Deletes the view-state information for all the server control's child controls.
I have never used this though. So I am unsure if it will help you. Sounds good though, I think :)
Why not do as you suggest:
foreach (Control c in myUserControl.Controls)
c.Clear();
And then implement Clear:
public static class UserController
{
public static void Clear( this Control c )
{
c.Controls.Clear();
}
public static void Clear( this TextBox c )
{
c.Text = String.Empty;
}
}
That should do it.
What I am trying to do is accessing Page Controls at Page_Load, and make a database query, and make controls visible or not visible.
Here is the Code:
foreach (Control thiscontrol in ContentPlaceHolderBody.Controls) {
try {
if (thiscontrol.ID.Contains("TextBox") || thiscontrol.ID.Contains("Label")) {
string dummy = thiscontrol.ID;
bool IsValid = db.Roles.Any(a => a.controlName == dummy);
if (IsValid == false)
thiscontrol.Visible = false;
}
else if (thiscontrol.ID.Contains("UpdatePanel")) {
foreach (Control UPcontrols in ((UpdatePanel)thiscontrol).ContentTemplateContainer.Controls) {
if (UPcontrols.ID.Contains("TextBox") || UPcontrols.ID.Contains("DropDownList")) {
bool UPIsValid = db.Roles.Any(a => a.controlName == UPcontrols.ID);
if (UPIsValid == false)
UPcontrols.Visible = false;
}
}
}
}
catch { }
}
My Problem is with the UPcontrols! It should retrieve the controls within the UpdatePanel, but the thing is it doesn't do its job, except in the debug mode!
When I add a breakpoint, everything is OK, but when I run the web application, it doesn't find any components within the UpdatePanel...
Try this one:
ControlCollection cbb = updatepanel1.Controls;
ControlCollection cb = cbb[0].Controls;
initialize_Controls(cb);
public void initialize_Controls(ControlCollection objcontrls)
{
foreach (Control tb in objcontrls) {
if (tb is TextBox)
((TextBox)tb).Text = "";
if (tb is Panel) {
ControlCollection cbcll = tb.Controls;
foreach (Control tbb in cbcll) {
if (tbb is TextBox)
((TextBox)tbb).Text = "";
}
}
}
}
First find controls from updatepanel i.e ContentTemplate, then find controls from contentTemplate which contain all controls in it.
This seems like a very bizarre design. That is, using control IDs for such purposes is rather unusual.
Nevertheless, you need a recursive method here to do a deep walk of every control on the page. Your method will not work if the UpdatePanel is contained within another control.
Have a check on this article
http://www.codeproject.com/Articles/24178/The-magical-effects-of-the-UpdatePanel-control-in