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IGanttTask implementation

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GanttView

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Paweł asked on 11 Sep 2012, 06:56 AM

Hi,

I asked about this in other thread but I believe that this deserves for own one.

I'm trying to bind custom objects to RadGanttView. I know that such objects should either inherit from GanttTask class or implement IGanttTask interface.
The first option is very easy - just inherit from GanttTask and add desired properties. When I do that, everything works ok.
Second option isn't so simple - when I'm trying to implement IGanttTask interface, RadGanttView loads and is visible, but when I put mouse cursor over any task, IE debugger window pops up and message is shown:

SCRIPT5022: Unhandled Error in Silverlight Application
Code: 4004
Category: ManagedRuntimeError
Message: System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
ved System.Collections.Generic.Dictionary`2.get_Item(TKey key)
ved System.Windows.ResourceManagerWrapper.GetResourceForUri(Uri xamlUri, Type componentType)

I wonder why is that when I inherit from the class, everything is ok, but when I implement interface, problem occurs. Maybe there are some tricks that I'm not aware of?

Thank you in advance for the answer
Paweł

5 Answers, 1 is accepted

answered on 14 Sep 2012, 06:26 AM

Hi again,

Sorry for delay. I found the cause of error I described in my previous post. Detailed description below:

I have Activity class that represents one task. I'd like to show all of my activities in Gantt chart. There is also no way to inherit from GanttTask, as Activity class inherits from other class. So I decided to implement IGanttTask.

As we know, this interface has members:
Deadline, Dependencies, Description, Duration, Progress and Title which are quite obvious.
But it also derives from other interfaces, such as IDateRange, IResourceContainer, INotifyPropertyChanged, IHierarchicalResource, IHierarchical and IResource, so we have to implement also Relations, End, Start, Resources, TypeKey and Children.

As I couldn't find detailed description of the last properties, I just left them in the most straighforward way, for example:

public IList Resources  { get { return new List<Activity>(); } }
public object TypeKey   { get { return new object(); }}

This kind of implementation was wrong and error was thrown. I couldn't find any description of proper implementation
of IGanttTask, so I used JustDecompile to check how the GanttTask implements IGanttTask. What I found is that 
Resources and TypeKey should be implemented like this:

private IList _Resources;
public IList Resources{ get { return _Resources; } }
 
public object TypeKey{ get { return typeof(IGanttTask); }}

and in ctor, we should add:
 _Resources = new List<IResource>();
 _Resources.Add(this);

When I changed my code accordingly, it started to work, and no exception is thrown.
I wrote this post because I believe that there may be many developers that experienced or will experience this problem
and there is not much documentation available...

Best regards
Paweł

PS: One more thing - where can I report possible bugs in the Gantt chart?

Accepted

answered on 14 Sep 2012, 01:40 PM

Hi Paweł,

First, you are right about the missing documentation about IGanttTask implementation. This topic will be definitely added to the RadGanttView documentation soon.

As to reporting bugs - the most efficient way is to open a Bug Report ticket and explain the issue there. Also in the ticket you can attach a sample project demonstrating exactly the problem.

Of course, you can report bugs in the forums as well. But note that in the forums it is allowed to attach only images. Also most of the time we are checking all the threads, but we do not guarantee 100% reply there.

Kind regards,
Yana
the Telerik team

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