Develop Reference

ObjectListView editing doesn't work

I'm trying to create a simple listbox with ObjectListView (WinForm, C#). The goal is to have a single value (a double) and a check box.
I want to be able to edit the double value by Single Click, so here are the relevant lines of code from my MyWindow.Designer.cs file (i've left out the default values for efficiency):
this.olvDepths = new BrightIdeasSoftware.ObjectListView();
this.olvColumn1 = ((BrightIdeasSoftware.OLVColumn)(new BrightIdeasSoftware.OLVColumn()));
...
this.olvDepths.CellEditActivation = BrightIdeasSoftware.ObjectListView.CellEditActivateMode.SingleClick;
this.olvDepths.CheckBoxes = true;
this.olvDepths.CheckedAspectName = "IsDefault";
this.olvDepths.FullRowSelect = true;
//
// olvColumn1
//
this.olvColumn1.AspectName = "Depth";
this.olvColumn1.Text = "";
this.olvColumn1.IsEditable = true;
I then create a list of my class (ShieldingEntry) and use the olvDepths.SetObjects() with the list. My ShieldingEntry class looks like this:
public class ShieldingEntry
{
public double Depth { get; set; }
public bool IsDefault { get; set; }
}
However, when I click the field, it doesn't go into edit mode. I've also tried the DoubleClick, SingleClickAlways, and F2Only modes and they don't work either.
The Checkbox works fine.
************** I have additional information *********************
I've pulled and build the ObjectListView source, so I could step through it.
I put a breakpoint in the OLV StartCellEdit method and it gets called and appears to setup and select the control appropriately. It just never appears...
As I noted in the comments on the answer below, I've got this control on a tabbed dialog, and if I switch to another tab, then back, the control works fine.
What am I missing?

I've used ObjectListView before, and here is what I had to do:
Handle the CellEditStarting event. This event is raised when the cell goes into edit mode. Since OLV doesn't really have built-in editors, you have to make your own. Then handle the CellEditFinishing event to validate the data before putting it back into your model.
So first, handling the CellEditStarting event:
private void objlv_CellEditStarting(object sender, CellEditEventArgs e)
{
//e.Column.AspectName gives the model column name of the editing column
if (e.Column.AspectName == "DoubleValue")
{
NumericUpDown nud = new NumericUpDown();
nud.MinValue = 0.0;
nud.MaxValue = 1000.0;
nud.Value = (double)e.Value;
e.Control = nud;
}
}
This creates your editing control. If you want to make sure the size is right, you can set the size of the control (in this case a NumericUpDown) to the cell bounds using e.CellBounds from the event object.
This will show the editor when you click in the cell. Then you can handle the editor finished event to validate the data:
private void objlv_CellEditFinishing(object sender, CellEditEventArgs e)
{
if (e.Column.AspectName == "DoubleValue")
{
//Here you can verify data, if the data is wrong, call
if ((double)e.NewValue > 10000.0)
e.Cancel = true;
}
}
I don't think handling it is required, but its good practice to validate data from the user.
The editing control in the CellEditStarting event can be any control, even a user defined one. I've used a lot of user defined controls (like textboxes with browse buttons) in the cell editor.
[Edit]
I uploaded an example here dropbox link that seems to work. Might not be in the exact view as needed, but seems to do the job.

For anyone else with this problem. I had it specifically when trying to edit a 'null' value in a decimal? on the OLV on a tab page. Solution for me was to set UseCustomSelectionColors to 'False'. I didn't look elsewhere to see if it was reported as a bug. Seems like a bug.

The visible property of a Label act as read only

I have a label within a user control:
<asp:Label runat="server" ID="lblRemainingPlacesMessage" Visible="false" />
I want to setup its visibility to true:
protected void Page_Load(object sender, EventArgs e) {
lblRemainingPlacesMessage.Visible = true;
}
However, the label is still hidden.
What's is puzzling me, is that the property can't be changed, even in the immediate window, or the debugger local watch:
(immediate window)
lblRemainingPlacesMessage.Visible
false
lblRemainingPlacesMessage.Visible = true
true
lblRemainingPlacesMessage.Visible
false
What can explain that my Visible property can't be changed?
I have no exception. Just a NOOP like operation...
My app has the viewstate enabled. Most of all, I have other label in the page, that works perfectly!
Don't know if its matter, but I dynamically instantiate my user control within my owner page using:
protected override void CreateChildControls()
{
m_VisualControl = (MyUserControl)Page.LoadControl(_ascxPath);
Controls.Add(m_VisualControl);
}
The app uses ASP.Net WebForms with .net 3.5 SP1, and I use Visual Studio 2012 Premium.

Yuriy Galanter's comment put me on the right track.
Simply, my immediate parent was not visible. And I suppose the visible property of a control combines the control ancestors visibility.
Sometimes simple problem have simple resolution :)

1) You should create any dynamic UserControl at OnInit or you will not be able to use ViewState:
2) Expose the label property that you wan't to change as property of the UserControl
public bool HiddeMyLabel
{
set { lblRemainingPlacesMessage.Visible = value; }
get { lblRemainingPlacesMessage.Visible; }
}
3) You should ever use OnPreRender from the page to change any control property.
protected override void OnPreRender(EventArgs e)
{
MyUserControl.HiddeMyLabel = false;
}
4) If you still having issues, remove the hidden attribute manually:
public bool HiddeMyLabel
{
set
{
if(value)
lblRemainingPlacesMessage.Attributes.Add("style", "display:none");
else
lblRemainingPlacesMessage.Attributes.Add("style", "display:block");
}
}

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

Access parent DIV of user-control (ascx) from its code behind

From within the code-behind of an ASP .NET web user-control (ascx) I need to get access (at runtime) to its parent, a div element. The aim is simple as to modify the visibility of the mentioned parent div.
I can not touch so much of the web-page code so I'd need a solution requiring only modifications in the user-control's code behind.
So in the HTML "part" of the code of the web page I have this:
<div id="parentDIV" runat="server">
<uc:MyUserControl ID="myUserControlInstance" runat="server" />
</div>
I'd like to do in the code behind of the user-control something like this:
this.Container.Visible = false;
Note that I'm not asking if it is a good practise or not to do this.
EDIT:
The user-control code behind does not "know" about the ID of the parent DIV.

I would hide it on the client. Decorate your user control container (div?) with a class like "awesomeUserControl". Then emit some javascript using the ScriptManager object to hide the parent like this:
ScriptManager.RegisterStartupScript(this, this.GetType(), "HideMyAwesomeUserControl", "$('.awesomeUserControl').parent().hide();", true);

The better way...
What you should do is to create a custom event in your user control, to which your container will subscribe - very much like subscribing to a button event, only this is your custom control. This event passes information to your container which can then discern from it what it needs, such as whether or not the div should/not be visible.
It might look something like:
protected void Page_Load(object sender, EventArgs e)
{
this.myuserControl.Update += new MyUserControlUpdateEventHandler(myuserControl_Update);
}
void myuserControl_Update(object sender, MyuserControlEventArgs e)
{
this.parentDiv.visible = !e.ShouldHideUI;
}
This method will decouple your parent with the user control, i.e. your user control doesn't have to have any knowledge at all of the parent's controls, nor should it.
If you are curious, here is a rough example of how your user control will define such an event:
public class MyuserControlEventArgs : EventArgs
{
public bool ShouldHideUI { get;set;}
public MyuserControlEventArgs (bool shouldHideUI)
{
this.ShouldHideUI = shouldHideUI;
}
}
public delegate void MyUserControlUpdateEventHandler(object sender, MyuserControlEventArgs e);
public event MyUserControlUpdateEventHandler Update;
protected void OnUpdate(MyuserControlEventArgs e)
{
if (Update!= null)
Update(this, e);
}
Your user control will simply need to call OnUpdate whenever it feels its subscribers need to know about it.
The Quick and Dirty way...
If you need quick and dirty, then try this (inside your user control):
TheParentControl parentControl = (TheParentControl)this.Parent;
parentControl.ParentDiv.Visible = true;
The key is to cast to the appropriate type (apparently your user control would know what type of parent it has), then set the parent's property. You might expose your div as a property in the parent control. Note, that parent could be ANY control (page, FooControl, BarControl, whatever) whose control collection your user control resides. Once you get a handle to the parent, you can even FindControl() to find a control by name.

You're almost there....
this.Parent.Visible = false;

When all controls get rendered, the HTML Parent child controls can be determined like below.
I am using while loop, so in case you add some other intermediate control, it may not give crash or unexpected results.
public Control ParentControl
{
get
{
Control ctl = this.Parent;
while (true)
{
if (ctl == null) break;
if (ctl.ID.Equals("parentDIV"))
{
break;
}
ctl = ctl.Parent;
}
return ctl;
}
}
if(ParentControl != null)
ParentControl.Visible = true|false;

Am I missing something, it sounds like you have a usercontrol and an aspx page (both have code behind's).
The user control appears to have been added to the aspx page, wrapped in a div. YOu've made the div control runat server (though you can still do this via htmlcontrol).
All you ned to do to manage the div is:
parentDIV.visible = false;
or whatever you need to do with the div.
Why does the UC code behind need to know about the APSX pages DIV, it doesn't.

Dynamically adding Content blocks to Masterpage fails after Master.FindControl

I've encountered an odd problem that doesn't make any sense to me. I am trying to dynamically set up MasterPage Content controls on a page. I have it working nicely with the following code:
protected override void OnPreInit(EventArgs e)
{
base.OnPreInit(e);
MasterPageFile = "~/MasterPages/Default.master";
string existantContentPlaceHolderID = "ContentPlaceHolder1";
string nonExistantContentPlaceHolderID = "foo";
//Control c = Master.FindControl(existantContentPlaceHolderID);
//Control c1 = Master.FindControl(nonExistantContentPlaceHolderID);
TextBox t = new TextBox
{
Text = "Text"
};
ITemplate iTemplate = new GenericITemplate(container => container.Controls.Add(t));
AddContentTemplate(existantContentPlaceHolderID, iTemplate);
}
public delegate void InstantiateTemplateDelegate(Control container);
public class GenericITemplate : ITemplate
{
private readonly InstantiateTemplateDelegate m_instantiateTemplate;
public void InstantiateIn(Control container)
{
m_instantiateTemplate(container);
}
public GenericITemplate(InstantiateTemplateDelegate instantiateTemplate)
{
m_instantiateTemplate = instantiateTemplate;
}
}
This works great, except I want to be able to double-check that the contentPlaceHolderIDs exist on the MasterPage before calling AddContentTemplate as the Page will throw an error if you add a Content control that points to a non-existing ContentPlaceHolder.
The problem I am having is that in the above example when I call one of the commented Master.FindControl lines, the TextBox no longer renders.
Does anyone have any ideas why this might be... I cannot makes heads or tails of what is going on.
Thanks,
Max

The problem is that AddContentTemplate just records its parameters in a hashtable ready to be combined with the master page instance when it is created. Calling it after the master page has been created won't do anything, and reading the Master property causes the master page to be created.
The best way I can see around this is to create a separate instance of the master page with LoadControl, which you can inspect without affecting the page's own Master property...
MasterPage testMaster = (MasterPage) LoadControl( MasterPageFile );
Control c = testMaster.FindControl(existantContentPlaceHolderID);
There's some overhead in creating a second instance, but it's not immediately obvious to me whether it will be worth worrying about.