Re: ListBox DataItemTemplate And Multiple Object Types - WPF Discussion Boards

Re: Binding one DP to another across controls

4-Mar-09 16:48

It won't get hit. But your value will be set. You cannot debug dependency property the normal way. To debug you have some options, See here[^]

MBursill4-Mar-09 18:32

MBursill

4-Mar-09 18:32

Thanks! You hit the nail on the head.

Re: Binding one DP to another across controls

ABitSmart4-Mar-09 18:33

ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 18:33

BlitzPackage4-Mar-09 6:07

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 6:07

Good People,

I have a brief question.

So I have various types of objects with a common base that I need displayed differently - obviously by their type - in a listbox. I already have built several different types of data templates for each one. The question is do I use a value converter or some other strategy.

For example, let's say I have a base Home object. Sub-classes (child objects) include HomeRanch, HomeSplitFoyer, HomeDuplex, HomeTwoFloor, HomeTwoFloorBrick (which actually inherits from HomeTwoFloor), HomeThreeStory, etc... Now, they all inherit the properties and fields of the base home class. In addition they all add a range of their own variables. (All run of the mill object-oriented design concepts.)

In my listbox I need them to each display differently depending on types. I am thinking I need to bind the list box to an ObservableCollection<object> type. However, how do I make it select the proper datatemplate depending on the specific type of object? Thanks for any ideas or help you can provide.

Blitz

Mark Salsbery4-Mar-09 7:37

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 7:37

BlitzPackage wrote:
how do I make it select the proper datatemplate depending on the specific type of object?

That should happen automatically - is it not working?

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

BlitzPackage4-Mar-09 7:51

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 7:51

Thanks Mark.

So, you are saying that if I just use an obeservablecollection of type "object" that it will automatically convert it to the type that the specific datatemplate needs? In other words, it will automatically know that in actuality since datatemplatehomesplitfoyer is for type HomeSplitFoyer and convert it from object to the type it needs?

I actually I haven't tried it yet. I just did not know it could do that automatically so I thought I had to implement it.

Thanks again.

Blitz

Mark Salsbery4-Mar-09 8:15

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 8:15

BlitzPackage wrote:
So, you are saying that if I just use an obeservablecollection of type "object" that it will automatically convert it to the type that the specific datatemplate needs?

Yes.

I use (observable) collections of my base type instead of type "object" - less/no casting
when using the collection in code.

For each item in the collection, the available data templates (up the tree) are searched in order for a
data template with a matching DataType, so if you also have a data template for your base class,
you'll want that one last, otherwise it will be found first and applied to all derived types.
IOW, put your DataTemplate resources in order by DataType, from most derived to base. Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

BlitzPackage4-Mar-09 8:29

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 8:29

Awesome! I can't wait to try it. That's really good. Seems Microsoft may have outdid themselves with this WPF thing.

Thanks,
Blitz

Mark Salsbery4-Mar-09 8:32

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 8:32

DataTemplates are the #1 thing I loved initially about WPF.

I used to spend (waste?) so much time doing it in MFC.
Now I let the framework do all the work Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Mark Salsbery4-Mar-09 8:29

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 8:29

Here's a little example in case I'm not making any sense Smile | :)

<Window x:Class="MyNamespace.TestWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MyNamespace" 
    xmlns:mytypes="clr-namespace:MyTypes;assembly=MyTypes" 
    Title="TestWindow" Height="Auto" Width="Auto" ShowInTaskbar="False" WindowStartupLocation="CenterOwner" >
    <Window.Resources>
        <local:MyBaseTypeList_design  x:Key="MyBaseTypeList_design"/>
        <DataTemplate DataType="{x:Type mytypes:DerivedFromMyBaseType}">
		...
        </DataTemplate>
        <DataTemplate DataType="{x:Type mytypes:MyBaseType}">
		...
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <ListBox ItemsSource="{Binding Source={StaticResource MyBaseTypeList_design}}" />
    </Grid>
</Window>

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

BlitzPackage4-Mar-09 8:42

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 8:42

Thanks, that is also awesome and really helps alot. This way, if I can't do it in blend, I can hand code it.

Blitz

Mark Salsbery4-Mar-09 8:49

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 8:49

Having the static "designer" data helps alot - then you can have
live data to see while designing the DataTemplates.

Cheers!
Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

BlitzPackage4-Mar-09 9:55

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 9:55

What is "the static designer"? Are you talking about how Blend will populate it with some data while you are working on it?

Thanks,
Blitz

Mark Salsbery4-Mar-09 10:01

Re: ListBox DataItemTemplate And Multiple Object Types

4-Mar-09 10:01

Heh sorry, I didn't word that right...

I meant that static resource shown in the xaml sample with the
"_design" suffix on the name. It's just a wrapper around a collection<T>
type that adds a few items to the collection in the constructor.

That way there's data available at design time (can be seen in both Blend and VS)
of the actual types I'm designing data templates for, and I can see them as they'll
look in the listbox.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

BlitzPackage4-Mar-09 10:42

4-Mar-09 10:42

Cool...thanks.

Blitz

WPF ComboBox using Llinq

GomathiR4-Mar-09 1:38

GomathiR

4-Mar-09 1:38

Hi ,

I plaved a combobox and a listbox in a .xaml page. I used LINQ to fill combobox. I want the selected value to be displayed in the textbox. But i am getting object and not the exact value.I used like this,

var value=additem.selectedItem;
text1.text=value.ToString();

Pls help me! Frown | :(

Gomathi R

ABitSmart4-Mar-09 1:52

4-Mar-09 1:52

GomathiR wrote:
text1.text=value.ToString();N/blockquote>
Because you are doing a ToString() on the object. You would need to use the objects porperty value.
e.g.
var value=additem.SelectedItem as YourObject; //YourObject is the object type which is the databound for each item
text1.text = value.PropertyInYourObject;
You can do it in XAML itself also, databinding the Text property of text1. See if this works,
Text = ="{Binding ElementName=additem,Path=SelectedItem}"

BlitzPackage4-Mar-09 10:43

4-Mar-09 10:43

Great answer!

GomathiR4-Mar-09 18:20

GomathiR

4-Mar-09 18:20

Hi,
thank u very much for your help. Its working now. Smile | :)

Gomathi R

ABitSmart4-Mar-09 18:25

Actual experience with WF

4-Mar-09 18:25

Glad to be of help.

Asher Barak3-Mar-09 22:35

Asher Barak

3-Mar-09 22:35

Hi all,

We develop classic business applications (relational DB, GUI etc.). We are considering implementing our business processes using WF.
We consider WF as a means of simplifying development and making maintenance of complicated logic easier (Persisting, multiple async users, etc. are not relevant. The WF replaces a synchronous call to a static method).
During the few weeks we have tested it we found out it does have some quirks and we also learned about the expected, totally different, ver 4 (though we cannot wait for it).
We have not been able to find someone with actual working experience that can tell us weather working with this technology actually pays back.

Can anyone help from their own experience?

Thanks,

Asher

Re: Actual experience with WF

Wes Aday4-Mar-09 7:57

Wes Aday

4-Mar-09 7:57

Asher Barak wrote:
Can anyone help

I don't know that you are going to get very many responses but here's mine. About 2 years ago I had to implement several business processes in MFC. It was a nightmare and took a couple of months to get it worked out. My latest project is using WPF, WCF and WF. I decided to try WF for the processes that I had to do before and see if it would work for us or not. The first workflow took maybe 3 days to create and worked the way I expected the first time out. I have had to add things to it but the core has remained the same since. Worked out really great for me. The second workflow took less than 1 day to create the base. I had to shift to other priorites so it's not quite finished but I expect that I could finish it in a couple of hours. So the WF has worked out fine for me and I think that I am going to stick with it unless I discover some really compelling reason to switch.

The big caveat here is that that I am not using any of the more advanced features of WF as yet. I am just doing some really basic stuff.

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Re: Actual experience with WF

Asher Barak12-Mar-09 0:49

Asher Barak

12-Mar-09 0:49

Thanks,

Asher

Mfc Dll to be hoisted in WPF

VCsamir3-Mar-09 19:02

VCsamir

3-Mar-09 19:02

Hi friends,

I have a MFC dll which i m trying to load in Wpf. My Dll consist of a dialog which i
am trying to embedd in WPF Browser. i have done following steps.

a)Build my dll using /clr option
b)I have created a namespace in DLL and added a class which is being derived from
HWNDHost.
c) i have overridden
protected override HandleRef BuildWindowCore(HandleRef hwndParent)
{
}
in this function i have created a dialog and returning the handle of the window.

In the Main application(WPF) i am adding the reference of the Dll, then creating the object of it and then making it as a child control of WPF panel

my applications gets the handle of the window but it crashes..

Can anyone correct my steps if they are wrong

Thanks in Advance

Regards
Samir Satardekar

Re: Mfc Dll to be hoisted in WPF

ABitSmart3-Mar-09 19:41