I've got a VM class below that's being used to wire up a view to my ADO.NET Entity Data Model, utilizing a P_BUDGET class. This works fine, gets my data, makes everything pretty. I have about 15-20 pages that are all going to be based on the same structure as this, and the code is going开发者_StackOverflow社区 to be virtually identical except for the EntityType (P_BUDGET, P_ACCOUNT, P_CIRCUIT, etc etc). I feel like there should be a way to abstract this out, but I tried, and failed miserably! I also feel like I should be able to use one view, one viewmodel, and just swap out the entities binding to the GV... I just haven't been able to find a way to variablize the type, which permeates the entire viewmodel.
Appreciate your help,
Scott
public class TestViewModel : ViewModelBase
{
private readonly ODADomainContext _context = new ODADomainContext();
private readonly DomainCollectionView<P_BUDGET> _view;
private readonly DomainCollectionViewLoader<P_BUDGET> _loader;
private readonly EntityList<P_BUDGET> _source;
private bool _isGridEnabled;
/// <summary>
/// Initializes a new instance of the TestViewModel class.
/// </summary>
public TestViewModel()
{
this._source = new EntityList<P_BUDGET>(this._context.P_BUDGETs);
this._loader = new DomainCollectionViewLoader<P_BUDGET>(
this.LoadSampleEntities,
this.OnLoadSampleEntitiesCompleted);
this._view = new DomainCollectionView<P_BUDGET>(this._loader, this._source);
INotifyCollectionChanged notifyingSortDescriptions =
(INotifyCollectionChanged)this.CollectionView.SortDescriptions;
notifyingSortDescriptions.CollectionChanged +=
(sender, e) => this._view.MoveToFirstPage();
using (this.CollectionView.DeferRefresh())
{
this._view.PageSize = 10;
this._view.MoveToFirstPage();
}
}
#region View Properties
public bool IsGridEnabled
{
get
{
return this._isGridEnabled;
}
private set
{
if (this._isGridEnabled != value)
{
this._isGridEnabled = value;
this.RaisePropertyChanged("IsGridEnabled");
}
}
}
public ICollectionView CollectionView
{
get { return this._view; }
}
#endregion
private LoadOperation<P_BUDGET> LoadSampleEntities()
{
this.IsGridEnabled = false;
return this._context.Load(
this._context.GetBudgetsQuery());
}
private void OnLoadSampleEntitiesCompleted(LoadOperation<P_BUDGET> op)
{
this.IsGridEnabled = true;
if (op.HasError)
{
// TODO: handle errors
_view.PageSize = 0;
op.MarkErrorAsHandled();
}
else if (!op.IsCanceled)
{
this._source.Source = op.Entities;
_view.PageSize = 10;
this._view.MoveToFirstPage();
if (op.TotalEntityCount != -1)
{
this._view.SetTotalItemCount(op.TotalEntityCount);
}
}
}
////public override void Cleanup()
////{
//// // Clean own resources if needed
//// base.Cleanup();
////}
}
Try something like this. This is not tested (obviously), not even complied. This also assumes that the EntityTypes (P_BUDGET, P_ACCOUNT, P_CIRCUIT etc.) are not POCOs.
public class TestViewModel<TEntity> : ViewModelBase
{
private readonly ODADomainContext _context = new ODADomainContext();
private readonly DomainCollectionView<TEntity> _view;
private readonly DomainCollectionViewLoader<TEntity> _loader;
private readonly EntityList<TEntity> _source;
private bool _isGridEnabled;
/// <summary>
/// Initializes a new instance of the TestViewModel class.
/// </summary>
public TestViewModel()
{
this._source = new EntityList<TEntity>(this._context.GetEntitySet<TEntity>);
this._loader = new DomainCollectionViewLoader<TEntity>(
this.LoadSampleEntities,
this.OnLoadSampleEntitiesCompleted);
this._view = new DomainCollectionView<TEntity>(this._loader, this._source);
INotifyCollectionChanged notifyingSortDescriptions =
(INotifyCollectionChanged)this.CollectionView.SortDescriptions;
notifyingSortDescriptions.CollectionChanged +=
(sender, e) => this._view.MoveToFirstPage();
using (this.CollectionView.DeferRefresh())
{
this._view.PageSize = 10;
this._view.MoveToFirstPage();
}
}
#region View Properties
public bool IsGridEnabled
{
get
{
return this._isGridEnabled;
}
private set
{
if (this._isGridEnabled != value)
{
this._isGridEnabled = value;
this.RaisePropertyChanged("IsGridEnabled");
}
}
}
public ICollectionView CollectionView
{
get { return this._view; }
}
#endregion
private LoadOperation<TEntity> LoadSampleEntities()
{
this.IsGridEnabled = false;
return this._context.Load(
this._context.GetBudgetsQuery());
}
private void OnLoadSampleEntitiesCompleted(LoadOperation<TEntity> op)
{
this.IsGridEnabled = true;
if (op.HasError)
{
// TODO: handle errors
_view.PageSize = 0;
op.MarkErrorAsHandled();
}
else if (!op.IsCanceled)
{
this._source.Source = op.Entities;
_view.PageSize = 10;
this._view.MoveToFirstPage();
if (op.TotalEntityCount != -1)
{
this._view.SetTotalItemCount(op.TotalEntityCount);
}
}
}
////public override void Cleanup()
////{
//// // Clean own resources if needed
//// base.Cleanup();
////}
}
// http://blog.zoolutions.se/post/2010/04/05/Generic-Repository-for-Entity-Framework-for-Pluralized-Entity-Set.aspx
public static class ObjectContextExtensions
{
internal static EntitySetBase GetEntitySet<TEntity>(this ObjectContext context)
{
EntityContainer container = context.MetadataWorkspace.GetEntityContainer(context.DefaultContainerName, DataSpace.CSpace);
Type baseType = GetBaseType(typeof(TEntity));
EntitySetBase entitySet = container.BaseEntitySets
.Where(item => item.ElementType.Name.Equals(baseType.Name))
.FirstOrDefault();
return entitySet;
}
private static Type GetBaseType(Type type)
{
var baseType = type.BaseType;
if (baseType != null && baseType != typeof(EntityObject))
{
return GetBaseType(type.BaseType);
}
return type;
}
}
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