DevForce Community Forum : Bindable LINQ query

Bindable LINQ query : The ObservableCollection is bindable,...

Tue, 07 Sep 2010 18:33:21 -700

Author: sbelini
Subject: 2112
Posted: 07-Sep-2010 at 6:33pm

The ObservableCollection is bindable, but it only reflects the changes done to itself.

To monitor to any other changes you might want to use the EntityListManager:

##################

var filter = new Predicate(delegate(Customer aCustomer) {return aCustomer.CompanyName.StartsWith("C");});

var elm = new EntityListManager(mgr, filter, null);

elm.ManageList(bindableList, true);

##################

This way, any changes made to any Customer matching the criteria above with reflect in bindableList (regardless of if it was made in bindableList or not).

Bindable LINQ query : Silvio, your code for ToObservableCollection...

Tue, 07 Sep 2010 15:19:30 -700

Author: kpozin
Subject: 2112
Posted: 07-Sep-2010 at 3:19pm

Silvio, your code for ToObservableCollection does not seem to create any binding to the query. What will cause new items added to the Customers entity set to also appear in bindableList after the bindableList is initialized?

Bindable LINQ query : Hi, DevForce's LINQ-to-Entities...

Tue, 07 Sep 2010 15:12:34 -700

Author: sbelini
Subject: 2112
Posted: 07-Sep-2010 at 3:12pm

Hi,

DevForce's LINQ-to-Entities does support bindable query results indeed.

You can have bidirectional bindable query results by using ObservableCollection.

While the reladedEntityList is not intended to be used to wrap a query (it's intended to be used as the return value of a collection navigation property), you can do that with ObservableCollection as well.

A suggestion would be creating a "ToObservableCollection" extension method, so you could use like this:

##################

var bindableList = _em1.Customers
.Where(c => c.CompanyName.StartsWith("C"))
.ToObservableCollection();

##################

The extension method would look like this (please note that the code below does not do any error checking):

##################

public static ObservableCollection ToObservableCollection(this IEnumerable items) {
var result = new ObservableCollection();
foreach (var each in items) {
result.Add(each);
}
return result;
}

##################

You might also be interested in knowing about the EntityListManager, so you could monitor the entire cache to any changes that could affect bindableList (but made directly into it). You can find more information about the EntityListManager in the DevForce Resource Center.

Bindable LINQ query : Does DevForce's LINQ-to-Entities...

Tue, 31 Aug 2010 15:08:11 -700

Author: kpozin
Subject: 2112
Posted: 31-Aug-2010 at 3:08pm

Does DevForce's LINQ-to-Entities have any support for bindable query results?
That is, if I select some entity objects using LINQ, is there any way to ensure that the collection that holds the result will implement INotifyCollectionChanged and will be bidirectionally bindable?
Is there, for example, a way to wrap a RelatedEntityList around a query?