From Class to Linq : Queries in Silverlight (which...

Fri, 23 Jul 2010 11:23:35 -700

Author: GregD
Subject: 1996
Posted: 23-Jul-2010 at 11:23am

Queries in Silverlight (which I assume you're using since you posted in this forum) must be asynchronous unless directed against the local cache. So the basic query would look something like this:


      var vendorsQuery = entityManager.Vendors

        .OrderBy(v => v.VendorName);

      _em1.ExecuteQueryAsync(vendorsQuery, GotVendors, null);

...

    private void GotVendors(EntityQueryOperation op) {

      ObservableCollection vendors = 

        new ObservableCollection();

      op.Results.ForEach(v => vendors.Add(v));

    }

or using the anonymous method syntax,


      var vendorsQuery = entityManager.Vendors

        .OrderBy(v => v.VendorName);

      entityManager.ExecuteQueryAsync(vendorsQuery, op => {

        ObservableCollection vendors =

          new ObservableCollection();

        op.Results.ForEach(v => vendors.Add(v));

      },

      null);

    }

If you want write a FetchVendors method, you'll need to pass it a callback method so it can "phone" your calling method back when the results have been returned from the asynchronous query operation. For an example of that, see the GetEmployeeWithTotalOrderRevenueAsyncMethod() mini-demo in the Silvermight MiniDemos solution for Object Persistence, described here:

DevForce 2010 Documentation � Business Object Persistence � Code Sample - Mini-Demos (Silverlight)

From Class to Linq : I used to write a retrieval query...

Thu, 22 Jul 2010 16:43:22 -700

Author: BillG
Subject: 1996
Posted: 22-Jul-2010 at 4:43pm

I used to write a retrieval query like this

EntityList customers = myPM.GetEntities(query);

And then I would pass the customers object to a data grid.

How do I do the same in Linq

This is what I have so far:

private readonly TicketWareEntities entityManager = TicketWareEntities.DefaultManager;

public ObservableCollection<Vendor> Vendors { get; private set; }

public ????? FetchVendors()

{

var query = from Vendor in entityManager.Vendors

orderby Vendor.VendorName

select Vendor;

????? = entityManager.ExecuteQuery<Vendor>(query);

return ?????

}

DevForce Community Forum : From Class to Linq

From Class to Linq : Queries in Silverlight (which...

From Class to Linq : I used to write a retrieval query...