ObservableCollection of objects containing Lists

Question

I am using an ObservableCollection for databinding as ItemsSource for DataGrid. Collection contains complex type objects. One of this type properties is a List of strings.

Just for now I see that when I update this List property from code nothing changes in the UI (the primary binding works fine). So, my question is: is it an expected behaviour? Maybe I should not use List as part of the type, but also use an ObservableCollection?

Update

Mode is set to OneWay.

Jehof is correct, however, you may also need to use a HierarchicalDataTemplate (depending on view). — Danny Varod, Jun 21 '11 at 07:43
Type should expose ICollection or another interface as property, backing field should implement INotifyCollectionChanged, such as ObservableCollection. — Danny Varod, Jun 21 '11 at 07:47

score 2 · Answer 1 · answered Jun 21 '11 at 07:31

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Use a collection, instead of List, that implementes the interface INotifyCollectionChanged (like ObservableCollection). Then changes to the collection get populated to the ui.

answered Jun 21 '11 at 07:31

Jehof

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score 0 · Answer 2 · answered Jun 21 '11 at 07:33

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When you are updateding your list u have to call INotifyPropertyChange other wise UI wont get update the list result..

INotifyPropertyChange is the indication that here some changes occurred in the items source so update it.

answered Jun 21 '11 at 07:33

Syeda

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Won't help, since comparison with old value will be the same. Also the external collection did not change - no need to update its view (performance) inner collection is the one that must implement **INotifyCollectionChanged**. – Danny Varod Jun 21 '11 at 07:39
@Dammy: INotifyCollectionChanged will work no doubt.. But i worked with property using INotifyCollectionChanged for binding it works for me. The way i knew i told.. – Syeda Jun 21 '11 at 08:04

score 0 · Answer 3 · edited May 23 '17 at 10:33

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This might help as well:

ObservableCollection that also monitors changes on the elements in collection

edited May 23 '17 at 10:33

Community

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answered Jun 21 '11 at 08:16

Marc

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score 0 · Accepted Answer · answered Jun 21 '11 at 10:18

Yes it is expected behaviour. The observable collection only notifies of changes to its own contents - that is add, delete, reorder.

What you are looking at is a change to an element in the observablecollection - if you want to see your changes to the class you put in, your element has to implement INotifyPropertyChanged.

So currently: If your list property on you complex object changes you won't see it, however if you change that too to be an observablecollection you could see changes to that collection in a sub-itemscontrol like a combobox - but not if you change the collection object to another one - so if you do not implement INotifyPropertyChanged you should set the collectionproperty before the binding is applied.

That's just what I've done an hour earlier - ObservableCollection instead of List + INotifyPropertyObject on the whole structure (shame on me, I should have thought of it earlier). I mark you answer as a solution to my problem. — 26071986, Jun 21 '11 at 10:33

ObservableCollection of objects containing Lists

4 Answers4