Sorting Linq Query Objects

[Neo]

I have a Linq Query stored in session and bound to a gridview like this:

Code:

gvResults.DataSource = persons gvResults.DataBind() Session("PERSONS") = persons

Each Time a user clicks a column header, I would like to sort the query. This would be the normal way I would do it if it was a dataTable stored in session:

Code:

Dim dt As DataTable = Session("PERSONS") Dim dv As DataView = New DataView(dt) dv.Sort = sortEx 'Save back to Session so paging functionality remains Session("PERSONS") = dv.ToTable() gvResults.DataSource = Session("PERSONS") gvResults.DataBind()

What is the alternative way to make this work with LINQ?

[PetarP]

Hello Michael,
in the sorting event of the grid you can do a query similar to this one:

IObjectScope scope = ObjectScopeProvider1.GetNewObjectScope();
IQueryable<Offer> result = from c in scope.Extent<Offer>()
               .OrderBy(e.SortExpression.ToString())
                           select c;
GridView1.DataSource = result.ToList();
GridView1.DataBind();

Please do not hesitate to contact us if you face any further difficulties.

Kind regards,
PetarP
the Telerik team

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[Jay]

I'm using Q3 2009 SP 1 and this syntax won't compile.  I can use a function parameter so that it looks like

from a in Scope.Extent<T>().OrderBy(order => "Id")
                                    select a;

but this produces the following runtime error.

Unable to cast object of type 'Telerik.OpenAccess.Query.Context' to type 'OpenAccessRuntime.DataObjects.query.Node'.

What's going on?  What am I doing wrong?

[Damyan Bogoev]

Hello Jay,

You should slightly modify the binding query in the following way:

from a in Scope.Extent<T>().OrderBy(order => order.Id) select a;

I think that will help you.

All the best,
Damyan Bogoev
the Telerik team

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[Jay]

Unfortunately that doesn't allow me to do what I want to do -- which is to sort dynamically.

[Damyan Bogoev]

Hello Jay,

Unfortunately at the moment Telerik OpenAccess ORM does not support dynamic expressions inside an OrderBy clause. This functionality is on our to-do list and will be part of the product in the future.
Your current option is to use the solution provided by Petar and pass the SortExpression to the OrderBy clause.

Greetings,
Damyan Bogoev
the Telerik team

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[Jay]

Any update on the dynamic expressions inside the order by clause?  Is this featured getting any closer to being implemented?

[Damyan Bogoev]

Hello Jay,

You could try this code library example. It demonstrates how to use OpenAccess with Dynamic Linq. Additional useful information with regard to Dynamic Linq and OpenAccess can be found here.
Hope that helps.

Greetings,
Damyan Bogoev
the Telerik team