how to change loadoperation.entities?

Question

when i use domainservice's load method to load a query, as it retured the loadoperation.entities collection is readonly

and I can't change it.  what i want to do is fetching entitiesfrom domainservice and bind it to a gridview. i want to remove an entity from gridview and change database. here is my code snipper.

I met two problems:

1: visual studio prompt me that the loadoperation.entities collection is readonly and can't change

2: commandparameter not be passed to viewmodel

Follow is my code snipper:

[view.xaml markup]

<StackPanel >
            <telerik:RadButton Content="Add" Height="Auto" Name="btnAdd" VerticalAlignment="Top"Command="{Binding AddCommand}" />
            <telerik:RadButton Content="Edit" Height="Auto" Name="btnEdit"  Command="{Binding EditCommand}" CommandParameter="{Binding ElementName=departmentGridView,Path=SelectedItem}" />
            <telerik:RadButton Content="Delete" Name="btnDelete" Command="{Binding DeleteCommand}"  CommandParameter="{Binding ElementName=departmentGridView,Path=SelectedItem}" />
        </StackPanel>
        <telerik:RadGridView  
                             HorizontalAlignment="Stretch"
                             VerticalAlignment="Stretch" 
                             ShowGroupPanel="False" 
                             ShowColumnHeaders="True"
                             RowIndicatorVisibility="Collapsed"
                             ItemsSource="{Binding DepartmentTypeList}"
                             Name="departmentTypeGridView" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" AutoGenerateColumns="False" Grid.RowSpan="1" Grid.Row="1">
            <telerik:RadGridView.Columns>
                <telerik:GridViewDataColumn Header="Name" Width="*" DataMemberBinding="{Binding Name}" IsSortable="False" />
            </telerik:RadGridView.Columns>
        </telerik:RadGridView>

[viewmodel code]

private readonly DepartmentTypeContext _DomainContext;

        public DepartmentTypeViewModel()
        {
            this._DomainContext = new DepartmentTypeContext();
            this._DeleteCommand = new DelegateCommand(this.Delete,()=>_DepartmentTypeList!=null && _DepartmentTypeList.CurrentItem!=null?true:false);

            LoadDepartmentType();
        }

        void _DepartmentTypeList_CurrentChanged(object sender, System.EventArgs e)
        {
            (_DeleteCommand as DelegateCommand).RaiseCanExecuteChanged();
        }

        private void LoadDepartmentType()
        {
            _DomainContext.Load<DepartmentType>(_DomainContext.GetDepartmentTypeQuery(),this.LoadCallBack,null);
        }

        private void LoadCallBack(LoadOperation<DepartmentType> lo)
        {
            if (lo.HasError)
            {
                MessageBox.Show(lo.Error.Message);
                return;
            }
            CollectionViewSource dataSource = new CollectionViewSource();
            dataSource.Source = lo.AllEntities;
            DepartmentTypeList = dataSource.View;
            DepartmentTypeList.MoveCurrentToFirst();
            DepartmentTypeList.CurrentChanged += new System.EventHandler(_DepartmentTypeList_CurrentChanged);
        }

        private ICollectionView _DepartmentTypeList;

        public ICollectionView DepartmentTypeList
        {
            get
            {
                return _DepartmentTypeList;
            }
            private set
            {
                if (_DepartmentTypeList != value)
                {
                    _DepartmentTypeList = value;
                    RaisePropertyChanged(() => this.DepartmentTypeList);
                }
            }
        }

        private ICommand _AddCommand;
        public ICommand AddCommand
        {
            get
            {
                return _AddCommand;
            }
            set
            {
                if (_AddCommand != value)
                {
                    this._AddCommand = value;
                    RaisePropertyChanged(() => this._AddCommand);
                }
            }
        }

        private ICommand _EditCommand;
        public ICommand EditCommand
        {
            get
            {
                return _EditCommand;
            }
            set
            {
                if (_EditCommand != value)
                {
                    this._EditCommand = value;
                    RaisePropertyChanged(() => this._EditCommand);
                }
            }
        }

        private ICommand _DeleteCommand;
        public ICommand DeleteCommand
        {
            get
            {
                return _DeleteCommand;
            }
            set
            {
                if (_DeleteCommand != value)
                {
                    _DeleteCommand = value;
                    RaisePropertyChanged(() => this._DeleteCommand);
                }
            }
        }

        private void Delete()
        {
            if (DepartmentTypeList.CurrentItem != null)
            {   
                IList list = DepartmentTypeList.SourceCollection as IList;
                list.Remove(DepartmentTypeList.CurrentItem);
            }
        }

Answer 1

weakinverse

 

With single block

LoadOperation<DepartmentType> lo = _DomainContext.Load(DomainContext.GetDepartmentTypeQuery())

lo.Completed += (s, e) =>

{

    this._DepartmentTypeList = new CollectionView(this._DomainContext.DepartmentType);

    this.RaisePropertyChanged(() => this.DepartmentType);

};

Answer 2

You might find that the EntityList gives you better results. You will find a full list of options at http://blogs.msdn.com/b/kylemc/archive/2010/12/02/collection-binding-options-in-wcf-ria-services-sp1.aspx

Answer 3

thanks for your help