z_mainplan record_spec = ResourceWrapper.CurrentDomainContext.z_mainplans.FirstOrDefault(r => r.id_spec == 3);

 List<z_mainplan> record_spec = ResourceWrapper.CurrentDomainContext.z_mainplans.Where(r => r.id_spec == ID_spec).ToList();

public static ArrayList Plan_id_block = new ArrayList();

Plan_id_block.Add(record_spec.ToArray());

z_mainplan record = Plan_id_block[i] as z_mainplan;

 z_mainplan record = record_spec[i] as z_mainplan;
                                z_mainplan record_block = record as z_mainplan;
                                if (record != null)
                                {
                                    arr[i] = record_block.id_block;
                                {

    private void Del_block_Click(object sender, RoutedEventArgs e)
        {
            for (int i = 0; i < 2; i++)
            {
                Parameter p = new Parameter();
                p.Value = OpenPlan.arr[i];
                p.ParameterName = "Idx";
                z_main_block_procDomainDataSource.QueryParameters.Add(p);
                z_main_block_procDomainDataSource.Load();
                z_main_block_procDomainDataSource.QueryParameters.Clear();
            }
        }

<riaControls:DomainDataSource AutoLoad="True" d:DesignData="{d:DesignInstance my:z_main_block_proc_Result, CreateList=true}" 
                                      Height="0" Name="z_main_block_procDomainDataSource" 
                                      QueryName="Getz_main_block_procQuery" 
                                      DomainContext="{StaticResource DomainContext}" Width="0" Margin="0,0,651,40">
        </riaControls:DomainDataSource>

   public IQueryable<z_main_block_proc_Result> Getz_main_block_proc(int Idx)
        {
            return this.ObjectContext.z_main_block_proc(0).AsQueryable<z_main_block_proc_Result>().Where(r => r.indx ==Idx);
        }