Develop Reference

Customizing Filters in ASP.NET Dynamic Data Entities

I'm fairly new to Dynamic Data Entities, and I have couple questions about filters if you could help.
I want to create dynamic search pages that can work for different tables, so I used the QueryableFilterRepeater control
you know its implemented by adding some meta data to the table/class:
[FilterUIHint("Filter-Type")]
public Column City { get; set; }
the filters I add appears at the top of the table's aspx page, A. is it possible to display the filters on a different page or even a pop up window, and when the filters are applied (an OK Button i guess) the result would appear on the original page ?
I tried using the Modal Popup Extender but I also failed, something like:
<asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server"
BackgroundCssClass="Background"
PopupControlID="FilterRepeater"
TargetControlID="btnFilter"
CancelControlID="btnClose"
OkControlID="btnOk">
</asp:ModalPopupExtender>
The ToolkitScriptManager contradicted with the DynamicDataManager
My second question :
B. is it possible to add multiple filters to the same column using the [FilterUIHint("Filter-Type")] meta data ?
Thank you so much for your time.

okay, so i just added a panel around my filter, and assigned that panel to the modal and all worked i got my filters as a pop up window .

Creating binding in codebehind

I have this type of code in aspx but wish to generate it in code behind. What would be the equivalent?
<uc1:editformcontrol ID="EditFormControl1" runat="server" CategoryID=' <%#Bind("CategoryID") %>' />
The question pertains mainly to the binding

It's difficult to say without knowing your data model. What kind of data source are you using? You could try adding this line to the Page_Load method:
int categoryId;
categoryId = WHEREEVER YOU'RE STORING THIS VALUE...
EditFormControl1.CategoryID = categoryId;

Usually, you override the OnDataBound event on your control and bind the data there.
See here one example.

Dynamically adding controls to a Templated User Control?

A few weeks back I created a Templated User Control, for the most part based on the example here:
http://msdn.microsoft.com/en-us/library/36574bf6(v=VS.90).aspx
The difference is that I did not implement the "MessageContainer" class as I wanted just an empty template that I could add whatever controls I wanted to at design time.
This TUC has been working great, but I ran into a scenario I hadn't anticipated when I created the thing. The need to dynamically add this TUC to a page, which means that I would need to dynamically add the controls within the template of the TUC as well.
I found another example here on how to dynamically create a Template and add it to the Templated Control:
http://msdn.microsoft.com/en-us/library/y0h809ak(v=vs.71).aspx
This second example article discusses only the "DataList, Repeater, and DataGrid controls" but I figure since I am using the ITemplate interface here, it should be the same thing.
However, I am unable to get this to work, I keep getting an "Object reference not set to an instance of an object." error when I attempt to populate the TUC.
Here's what I am doing....
Like the example above I created an ITemplate class:
public class XPCTemplate : ITemplate
{
private readonly Control _control;
public XPCTemplate(Control control)
{
_control = control;
}
public void InstantiateIn(Control container)
{
container.Controls.Add(_control);
}
}
Then, in the test page code-behind I attempt to load up and display the TUC dynamically:
ExpandCollapseRegion xpcRegion; // The Templated User Control
protected void Page_Load(object sender, EventArgs e)
{
PlaceHolder ph;
// .... code here to dynamically create some labels, textboxes, etc. ....
// Create an instance of the TUC
xpcRegion = new ExpandCollapseRegion();
// Pass into the TUC's template the controls dynamically created above
xpcRegion.LayoutTemplate = new XPCTemplate(ph);
// add the dynamic TUC to the page
phDynamicUC.Controls.Add(xpcRegion);
phDynamicUC.Controls.Add(new LiteralControl("<br />"));
}
Test page HTML Source:
<body>
<form id="form1" runat="server">
<div>
Dynamically Loading User Control
<br />
<asp:PlaceHolder ID="phDynamicUC" runat="server" />
</div>
</form>
</body>
When I run the page, I get the "Object reference not set to an instance of an object" error on the "container.Controls.Add(_control);" line of the XPCTemplate class. When I debug the test page and TUC control, the code of the TUC receives the XPCTemplate into its LayoutTemplate during the TUC's Page_Init() method, but when the InstantiateIn() event back in the XPCTemplate fires immediately afterwards, the "container" argument is NULL.
I'm not sure why this is happening, it's like the InstantiateIn() method of the XPCTemplate class is trying to actually set the PlaceHolder control within the TUC rather than just passing the contents. Maybe this is supposed to be the way and I am missing something on the TUC side to allow this behavior?
This is the first TUC I have created and likewise the first time trying to dynamically fill/load it, so I am sure I am missing something needed to accomplish this. Any help is greatly appreciated.
-- Andrew

Found the solution to the problem, which was how I was loading the TUC.
Incorrect:
xpcRegion = new ExpandCollapseRegion();
Correct:
xpcRegion = (ExpandCollapseRegion)LoadControl("ExpandCollapseRegion.ascx");
Making this simple change took care of the problem. Also, found that I could forego the need for a custom ITemplate class by using the CompiledTemplateBuilder() method. Really simplifies the code.
-- Andrew

I believe the problem is that you haven't instantiated your PlaceHolder ph that you are passing into your template. So, the line it is complaining on is because it can't add the control to the PlaceHolder because it is null/nothing.
Also, I believe you're going to need to put your placeholder somewhere. Otherwise, you're adding items to a container that is never added to the page.

Building Dynamic UI with C#?

I need to expose some input fields based on what properties I find for particular types in an assembly.
I'm not sure how common an approach like that is. Perhaps there are easier ways. Maybe on the client side instead of server.
If anyone knows of a good way of doing something like this, I would appreciate the help.
Create input controls accordingly and simple add control to some div container? I'm not sure if it would be more complex than that.
I'll need to somehow add css classes to the controls as I build them so they get placed nicely; that might get tricky.

This all sounds like standard asp.net development. Any good tutorial should be able to help you. For the asp server controls, you use the CssClass property to set the class for the control.
Here is the asp.net tutorial from the W3C Schools.

I assume you will use reflection to figure out what properties entity has, then you would based on the type of the property create an input field. You would have to dynamically create control to handle input in code behind. Make sure you give that control and id. You will have to recreate these controls on the post back. This looks to me like dynamic property editor. There might be some free ones, google for it.

If the UI doesn't have to be completely dynamic you could include all the controls in the markup with any optional ones set to Visible="false". Then, selectively enable the appropriate controls in your code-behind. For example:
Default.aspx
<asp:Button ID="EvenButton" runat="server" Text="Even" Visible="false" />
<asp:Button ID="OddButton" runat="server" Text="Odd" Visible="false" />
Default.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
String msg = "A message to count";
if (msg.Length % 2 == 0)
{
// Enable the Even Button
EvenButton.Visible = true;
}
else
{
OddButton.Visible = true;
}
}
The advantage of this method is that you can lay things out with the appropriate CSS easily in the markup. If, on the other hand, your UI is much more dynamic than this, you'll probably have to resort to dynamically creating controls in the code-behind and adding them to the page via calls to Controls.Add(). This way, however, is harder to layout. And you have to deal with things like re-wiring any event handlers on each postback.
Hope that helps.

I ended up leveraging jQuery.
I laid out a simple markup with the basic layout I would need.
For creating controls dynamically, I did it all in javascript using jQuery methods.
This of course requires that you return some data set to the UI intelligently enough to render it.

FindControl doesn't work with bind server tag, why?

I have a FindControl in OnLoad event to find my button on page i.e.:
protected override void OnLoad(EventArgs e)
{
DataBind();
control button = Page.FindControl("myButton");
}
on my aspx page I have
<asp:Button runat="server" ID="myButton" />
If I only have this, everything works, when I pass in the OnLoad, button is not null and I can execute what I want. The problem is when I add dynamic text in my aspx:
<asp:Button runat="server" ID="myButton" Text='<%# "Here is my dynamic text pulled from a XML" %>' />
Then the FindControl finds nothing and the button is null.
Adding a binding server tag on aspx isn't suppose to delay anything right? When I inspect the Page object I have some controls in Controls collection, but I'm unable to find myButton.
Any idea on what I am doing wrong?
EDIT
People seem to think that my code example is my real code but it isn't, So I use FindControl because I need to since I have nested controls and I cannot access it directly and I use binding because the dynamic text I'm putting is inside a ContentTemplate which I can override in other page aspx.
The question I asked was more specific to the fact that I have traced the problem where my FindControl returns null because a newly implement behaviour which is the binding.
Improving the code example isn't a solution or an explanation to the fact that if I put a <%# %> tag in my aspx page, the FindControl in the OnLoad event return null.
EDIT 2
the bind tag alone seems to not be the culprit but the DataBind() to populate them. Whether or not I have bind tag, putting DataBind() before the FindControl makes the myButton to be null. Correction in code example was made.

In here MSDN says that :
PreRender : Each data bound control whose
DataSourceID property is set calls its
DataBind method.
It looks like you're not using DataSourceID of your data bound control, but moving your FindControl code to PreRender event might help.

The Page.FindControl() method will only search the imediate collection of controls that are associated with Page. It will not recurse down the entire control tree, so if your button is contained within another control it will not be found. You would need to call the FindControl method on the containing control.

If you want to access a button on your page, you can directly refer to the button as -
this.myButton
And as far as assigning values is concerned, you can do it like this in your server code -
this.myButton.Text = "Dynamic Text";
<%# xyz %> is only used when you are databinding the controls, for e.g. in a DataGrid, GridView, etc.

In your override dont you want to call base.OnLoad(e) in your method first ?