SingleObjectViewModel.vb

Imports System
Imports System.ComponentModel
Imports System.ComponentModel.DataAnnotations
Imports System.Collections.Generic
Imports System.Linq
Imports System.Linq.Expressions
Imports DevExpress.Mvvm
Imports DevExpress.Mvvm.POCO
Imports DevExpress.Mvvm.DataAnnotations
Imports PersonalOrganizer.Common.Utils
Imports PersonalOrganizer.Common.DataModel
Namespace PersonalOrganizer.Common.ViewModel
  ''' <summary>
  ''' The base class for POCO view models exposing a single entity of a given type and CRUD operations against this entity. 
  ''' This is a partial class that provides the extension point to add custom properties, commands and override methods without modifying the auto-generated code.
  ''' </summary>
  ''' <typeparam name="TEntity">An entity type.</typeparam>
  ''' <typeparam name="TPrimaryKey">A primary key value type.</typeparam>
  ''' <typeparam name="TUnitOfWork">A unit of work type.</typeparam>
  Public Partial MustInherit Class SingleObjectViewModel(Of TEntity As Class, TPrimaryKey, TUnitOfWork As IUnitOfWork)
    Inherits SingleObjectViewModelBase(Of TEntity, TPrimaryKey, TUnitOfWork)    
    ''' <summary>
    ''' Initializes a new instance of the SingleObjectViewModel class.
    ''' </summary>
    ''' <param name="unitOfWorkFactory">A factory used to create the unit of work instance.</param>
    ''' <param name="getRepositoryFunc">A function that returns the repository representing entities of a given type.</param>
    ''' <param name="getEntityDisplayNameFunc">An optional parameter that provides a function to obtain the display text for a given entity. If ommited, the primary key value is used as a display text.</param>
    Protected Sub New(ByVal unitOfWorkFactory As IUnitOfWorkFactory(Of TUnitOfWork), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TEntity, TPrimaryKey)), Optional ByVal getEntityDisplayNameFunc As Func(Of TEntity, Object) = Nothing)
      MyBase.New(unitOfWorkFactory, getRepositoryFunc, getEntityDisplayNameFunc)
    End Sub
  End Class  
  ''' <summary>
  ''' The base class for POCO view models exposing a single entity of a given type and CRUD operations against this entity. 
  ''' It is not recommended to inherit directly from this class. Use the SingleObjectViewModel class instead.
  ''' </summary>
  ''' <typeparam name="TEntity">An entity type.</typeparam>
  ''' <typeparam name="TPrimaryKey">A primary key value type.</typeparam>
  ''' <typeparam name="TUnitOfWork">A unit of work type.</typeparam>
  <POCOViewModel> _
  Public MustInherit Class SingleObjectViewModelBase(Of TEntity As Class, TPrimaryKey, TUnitOfWork As IUnitOfWork)
    Implements ISupportParameter, IDocumentContent, ISingleObjectViewModel(Of TEntity, TPrimaryKey)
    Private _DocumentOwner As IDocumentOwner
    Private _PrimaryKey As TPrimaryKey
    Private _UnitOfWorkFactory As IUnitOfWorkFactory(Of TUnitOfWork)
    Private _title As Object
    Protected ReadOnly getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TEntity, TPrimaryKey))
    Protected ReadOnly getEntityDisplayNameFunc As Func(Of TEntity, Object)
    Private _entityInitializer As Action(Of TEntity)
    Private _isEntityNewAndUnmodified As Boolean
    Private ReadOnly _lookUpViewModels As Dictionary(Of String, IDocumentContent) = New Dictionary(Of String, IDocumentContent)()    
    ''' <summary>
    ''' Initializes a new instance of the SingleObjectViewModelBase class.
    ''' </summary>
    ''' <param name="unitOfWorkFactory">A factory used to create the unit of work instance.</param>
    ''' <param name="getRepositoryFunc">A function that returns repository representing entities of a given type.</param>
    ''' <param name="getEntityDisplayNameFunc">An optional parameter that provides a function to obtain the display text for a given entity. If ommited, the primary key value is used as a display text.</param>
    Protected Sub New(ByVal unitOfWorkFactory As IUnitOfWorkFactory(Of TUnitOfWork), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TEntity, TPrimaryKey)), ByVal getEntityDisplayNameFunc As Func(Of TEntity, Object))
      Me._UnitOfWorkFactory = unitOfWorkFactory
      Me.getRepositoryFunc = getRepositoryFunc
      Me.getEntityDisplayNameFunc = getEntityDisplayNameFunc
      UnitOfWork = UnitOfWorkFactory.CreateUnitOfWork()
      If Me.IsInDesignMode() Then
        Me.Entity = Me.Repository.FirstOrDefault()
      Else
        OnInitializeInRuntime()
      End If
    End Sub    
    ''' <summary>
    ''' The display text for a given entity used as a title in the corresponding view.
    ''' </summary>
    ''' <returns></returns>
    Public ReadOnly Property Title As Object
      Get
        Return _title
      End Get
    End Property    
    ''' <summary>
    ''' An entity represented by this view model.
    ''' Since SingleObjectViewModelBase is a POCO view model, this property will raise INotifyPropertyChanged.PropertyEvent when modified so it can be used as a binding source in views.
    ''' </summary>
    ''' <returns></returns>
    Public Overridable Property Entity As TEntity    
    ''' <summary>
    ''' Updates the Title property value and raises CanExecute changed for relevant commands.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the UpdateCommand property that can be used as a binding source in views.
    ''' </summary>
    <Display(AutoGenerateField := False)> _
    Public Sub Update()
      _isEntityNewAndUnmodified = False
      UpdateTitle()
      UpdateCommands()
    End Sub    
    ''' <summary>
    ''' Saves changes in the underlying unit of work.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the SaveCommand property that can be used as a binding source in views.
    ''' </summary>
    Public Overridable Sub Save()
      SaveCore()
    End Sub    
    ''' <summary>
    ''' Determines whether entity has local changes that can be saved.
    ''' Since SingleObjectViewModelBase is a POCO view model, this method will be used as a CanExecute callback for SaveCommand.
    ''' </summary>
    Public Overridable Function CanSave() As Boolean
      Return Entity IsNot Nothing AndAlso Not HasValidationErrors() AndAlso NeedSave()
    End Function    
    ''' <summary>
    ''' Saves changes in the underlying unit of work and closes the corresponding view.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the SaveAndCloseCommand property that can be used as a binding source in views.
    ''' </summary>
    <Command(CanExecuteMethodName := "CanSave")> _
    Public Sub SaveAndClose()
      If SaveCore() Then
        Close()
      End If
    End Sub    
    ''' <summary>
    ''' Saves changes in the underlying unit of work and create new entity.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the SaveAndNewCommand property that can be used as a binding source in views.
    ''' </summary>
    <Command(CanExecuteMethodName := "CanSave")> _
    Public Sub SaveAndNew()
      If SaveCore() Then
        Reload(createNew := True)
      End If
    End Sub    
    ''' <summary>
    ''' Reset entity local changes.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the ResetCommand property that can be used as a binding source in views.
    ''' </summary>
    <Display(Name := "Reset Changes")> _
    Public Sub Reset()
      Dim confirmationResult As MessageResult = MessageBoxService.ShowMessage(CommonResources.Confirmation_Reset, CommonResources.Confirmation_Caption, MessageButton.OKCancel)
      If confirmationResult = MessageResult.OK Then
        Reload()
      End If
    End Sub    
    ''' <summary>
    ''' Determines whether entity has local changes.
    ''' Since SingleObjectViewModelBase is a POCO view model, this method will be used as a CanExecute callback for ResetCommand.
    ''' </summary>
    Public Function CanReset() As Boolean
      Return NeedReset()
    End Function    
    ''' <summary>
    ''' Deletes the entity, save changes and closes the corresponding view if confirmed by a user.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the DeleteCommand property that can be used as a binding source in views.
    ''' </summary>
    Public Overridable Sub Delete()
      If MessageBoxService.ShowMessage(String.Format(CommonResources.Confirmation_Delete, GetType(TEntity).Name), GetConfirmationMessageTitle(), MessageButton.YesNo) <> MessageResult.Yes Then
        Return
      End If
      Try
        OnBeforeEntityDeleted(PrimaryKey, Entity)
        Repository.Remove(Entity)
        UnitOfWork.SaveChanges()
        Dim primaryKeyForMessage As TPrimaryKey = PrimaryKey
        Dim entityForMessage As TEntity = Entity
        Entity = Nothing
        OnEntityDeleted(primaryKeyForMessage, entityForMessage)
        Close()
      Catch e As DbException
        MessageBoxService.ShowMessage(e.ErrorMessage, e.ErrorCaption, MessageButton.OK, MessageIcon.[Error])
      End Try
    End Sub    
    ''' <summary>
    ''' Determines whether the entity can be deleted.
    ''' Since SingleObjectViewModelBase is a POCO view model, this method will be used as a CanExecute callback for DeleteCommand.
    ''' </summary>
    Public Overridable Function CanDelete() As Boolean
      Return Entity IsNot Nothing AndAlso Not IsNew()
    End Function    
    ''' <summary>
    ''' Closes the corresponding view.
    ''' Since SingleObjectViewModelBase is a POCO view model, an instance of this class will also expose the CloseCommand property that can be used as a binding source in views.
    ''' </summary>
    Public Sub Close()
      If Not TryClose() Then
        Return
      End If
      If DocumentOwner IsNot Nothing Then
        DocumentOwner.Close(Me)
      End If
    End Sub
    Protected ReadOnly Property UnitOfWorkFactory As IUnitOfWorkFactory(Of TUnitOfWork)
      Get
        Return _UnitOfWorkFactory
      End Get
    End Property
    Protected Property UnitOfWork As TUnitOfWork
    Protected Overridable Function SaveCore() As Boolean
      Try
        Dim isNewEntity As Boolean = IsNew()
        If Not isNewEntity Then
          Repository.SetPrimaryKey(Entity, PrimaryKey)
          Repository.Update(Entity)
        End If
        OnBeforeEntitySaved(PrimaryKey, Entity, isNewEntity)
        UnitOfWork.SaveChanges()
        Reload()
        OnEntitySaved(PrimaryKey, Entity, isNewEntity)
        Return True
      Catch e As DbException
        MessageBoxService.ShowMessage(e.ErrorMessage, e.ErrorCaption, MessageButton.OK, MessageIcon.[Error])
        Return False
      End Try
    End Function
    Protected Overridable Sub OnBeforeEntitySaved(ByVal primaryKey As TPrimaryKey, ByVal entity As TEntity, ByVal isNewEntity As Boolean)
    End Sub
    Protected Overridable Sub OnEntitySaved(ByVal primaryKey As TPrimaryKey, ByVal entity As TEntity, ByVal isNewEntity As Boolean)
      Messenger.[Default].Send(New EntityMessage(Of TEntity, TPrimaryKey)(primaryKey, If(isNewEntity, EntityMessageType.Added, EntityMessageType.Changed)))
    End Sub
    Protected Overridable Sub OnBeforeEntityDeleted(ByVal primaryKey As TPrimaryKey, ByVal entity As TEntity)
    End Sub
    Protected Overridable Sub OnEntityDeleted(ByVal primaryKey As TPrimaryKey, ByVal entity As TEntity)
      Messenger.[Default].Send(New EntityMessage(Of TEntity, TPrimaryKey)(primaryKey, EntityMessageType.Deleted))
    End Sub
    Protected Overridable Sub OnInitializeInRuntime()
      Messenger.[Default].Register(Of EntityMessage(Of TEntity, TPrimaryKey))(Me, Sub(ByVal x) OnEntityMessage(x))
      Messenger.[Default].Register(Of SaveAllMessage)(Me, Sub(ByVal x) Save())
      Messenger.[Default].Register(Of CloseAllMessage)(Me, Sub(ByVal x) OnClosing(x))
    End Sub
    Protected Overridable Sub OnEntityMessage(ByVal message As EntityMessage(Of TEntity, TPrimaryKey))
      If Entity Is Nothing Then
        Return
      End If
      If message.MessageType = EntityMessageType.Deleted AndAlso Object.Equals(message.PrimaryKey, PrimaryKey) Then
        Close()
      End If
    End Sub
    Protected Overridable Sub OnEntityChanged()
      If Entity IsNot Nothing AndAlso Repository.HasPrimaryKey(Entity) Then
        _PrimaryKey = Repository.GetPrimaryKey(Entity)
        RefreshLookUpCollections(True)
      End If
      Update()
    End Sub
    Protected ReadOnly Property Repository As IRepository(Of TEntity, TPrimaryKey)
      Get
        Return getRepositoryFunc(UnitOfWork)
      End Get
    End Property
    Protected ReadOnly Property PrimaryKey As TPrimaryKey
      Get
        Return _PrimaryKey
      End Get
    End Property
    Protected ReadOnly Property MessageBoxService As IMessageBoxService
      Get
        Return Me.GetRequiredService(Of IMessageBoxService)()
      End Get
    End Property
    Protected Overridable Sub OnParameterChanged(ByVal parameter As Object)
      _entityInitializer = TryCast(parameter, Action(Of TEntity))
      If _entityInitializer IsNot Nothing Then
        CreateAndInitializeEntity()
        _isEntityNewAndUnmodified = True
      Else
        If TypeOf parameter Is TPrimaryKey Then
          Entity = Repository.Find(CType(parameter, TPrimaryKey))
        Else
          Entity = Nothing
        End If
      End If
    End Sub
    Protected Overridable Function CreateEntity() As TEntity
      Return Repository.Create()
    End Function
    Private Sub UpdateTitle()
      If Entity Is Nothing Then
        _title = Nothing
      Else
        If IsNew() Then
          _title = GetTitleForNewEntity()
        Else
          _title = GetTitle(GetState() = EntityState.Modified)
        End If
      End If
      Me.RaisePropertyChanged(Function(ByVal x) x.Title)
    End Sub
    Protected Overridable Sub UpdateCommands()
      Me.RaiseCanExecuteChanged(Sub(ByVal x) x.Save())
      Me.RaiseCanExecuteChanged(Sub(ByVal x) x.SaveAndClose())
      Me.RaiseCanExecuteChanged(Sub(ByVal x) x.SaveAndNew())
      Me.RaiseCanExecuteChanged(Sub(ByVal x) x.Delete())
      Me.RaiseCanExecuteChanged(Sub(ByVal x) x.Reset())
    End Sub
    Private Sub CreateAndInitializeEntity()
      Dim entity = CreateEntity()
      If _entityInitializer IsNot Nothing Then
        _entityInitializer(entity)
      End If
      Me.Entity = entity
    End Sub
    Protected Sub Reload(Optional ByVal createNew As Boolean = False)
      If IsNew() Then
        createNew = True
      End If
      If createNew Then
        CreateAndInitializeEntity()
      Else
        Entity = Repository.Reload(Entity)
      End If
      OnEntityChanged()
      Me.RaisePropertyChanged(Function(ByVal x) x.Entity)
      If createNew Then
        _isEntityNewAndUnmodified = True
      End If
    End Sub
    Protected ReadOnly Property DocumentOwner As IDocumentOwner
      Get
        Return _DocumentOwner
      End Get
    End Property
    Protected Overridable Sub OnDestroy()
      Messenger.[Default].Unregister(Me)
      RefreshLookUpCollections(False)
    End Sub
    Protected Overridable Function TryClose() As Boolean
      If HasValidationErrors() Then
        Dim warningResult As MessageResult = MessageBoxService.ShowMessage(CommonResources.Warning_SomeFieldsContainInvalidData, CommonResources.Warning_Caption, MessageButton.OKCancel)
        Return warningResult = MessageResult.OK
      End If
      If Not NeedReset() Then
        Return True
      End If
      Dim result As MessageResult = MessageBoxService.ShowMessage(CommonResources.Confirmation_Save, GetConfirmationMessageTitle(), MessageButton.YesNoCancel)
      If result = MessageResult.Yes Then
        Return SaveCore()
      End If
      Return result <> MessageResult.Cancel
    End Function
    Protected Overridable Sub OnClosing(ByVal message As CloseAllMessage)
      If Not message.Cancel Then
        message.Cancel = Not TryClose()
      End If
    End Sub
    Protected Overridable Function GetConfirmationMessageTitle() As String
      Return GetTitle()
    End Function
    Protected Function IsNew() As Boolean
      Return GetState() = EntityState.Added
    End Function
    Protected Overridable Function NeedSave() As Boolean
      If Entity Is Nothing Then
        Return False
      End If
      Dim state As EntityState = GetState()
      Return state = EntityState.Modified OrElse state = EntityState.Added
    End Function
    Protected Overridable Function NeedReset() As Boolean
      Return NeedSave() AndAlso Not _isEntityNewAndUnmodified
    End Function
    Protected Overridable Function HasValidationErrors() As Boolean
      Dim dataErrorInfo As IDataErrorInfo = TryCast(Entity, IDataErrorInfo)
      Return dataErrorInfo IsNot Nothing AndAlso IDataErrorInfoHelper.HasErrors(dataErrorInfo)
    End Function
    Private Function GetTitle(ByVal entityModified As Boolean) As String
      Return GetTitle() + (If(entityModified, CommonResources.Entity_Changed, String.Empty))
    End Function
    Protected Overridable Function GetTitleForNewEntity() As String
      Return GetType(TEntity).Name + CommonResources.Entity_New
    End Function
    Protected Overridable Function GetTitle() As String
      Return (GetType(TEntity).Name + " - " + Convert.ToString(If(getEntityDisplayNameFunc IsNot Nothing, getEntityDisplayNameFunc(Entity), PrimaryKey))).Split(New String() { "" + vbCr + "","" + vbLf + "" }, StringSplitOptions.RemoveEmptyEntries).FirstOrDefault()
    End Function
    Protected Function GetState() As EntityState
      Try
        Return Repository.GetState(Entity)
      Catch e As InvalidOperationException
        Repository.SetPrimaryKey(Entity, PrimaryKey)
        Return Repository.GetState(Entity)
      End Try
    End Function
    Protected Overridable Sub RefreshLookUpCollections(ByVal raisePropertyChanged As Boolean)
      Dim values = _lookUpViewModels.ToArray()
      _lookUpViewModels.Clear()
      For Each item In values
        item.Value.OnDestroy()
        If raisePropertyChanged Then
          CType(Me, IPOCOViewModel).RaisePropertyChanged(item.Key)
        End If
      Next
    End Sub
    Protected Function GetDetailsCollectionViewModel(Of TViewModel, TDetailEntity As Class, TDetailPrimaryKey, TForeignKey)(ByVal propertyExpression As Expression(Of Func(Of TViewModel, CollectionViewModel(Of TDetailEntity, TDetailPrimaryKey, TUnitOfWork))), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TDetailEntity, TDetailPrimaryKey)), ByVal foreignKeyExpression As Expression(Of Func(Of TDetailEntity, TForeignKey)), ByVal setMasterEntityKeyAction As Action(Of TDetailEntity, TPrimaryKey), Optional ByVal projection As Func(Of IRepositoryQuery(Of TDetailEntity), IQueryable(Of TDetailEntity)) = Nothing) As CollectionViewModel(Of TDetailEntity, TDetailPrimaryKey, TUnitOfWork)
      Return GetCollectionViewModelCore(Of CollectionViewModel(Of TDetailEntity, TDetailPrimaryKey, TUnitOfWork), TDetailEntity, TDetailEntity, TForeignKey)(propertyExpression, foreignKeyExpression, Function() CollectionViewModel(Of TDetailEntity, TDetailPrimaryKey, TUnitOfWork).CreateCollectionViewModel(UnitOfWorkFactory, getRepositoryFunc, projection, CreateForeignKeyPropertyInitializer(setMasterEntityKeyAction, PrimaryKey), True))
    End Function
    Protected Function GetDetailProjectionsCollectionViewModel(Of TViewModel, TDetailEntity As Class, TDetailProjection As Class, TDetailPrimaryKey, TForeignKey)(ByVal propertyExpression As Expression(Of Func(Of TViewModel, CollectionViewModel(Of TDetailEntity, TDetailProjection, TDetailPrimaryKey, TUnitOfWork))), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TDetailEntity, TDetailPrimaryKey)), ByVal foreignKeyExpression As Expression(Of Func(Of TDetailEntity, TForeignKey)), ByVal setMasterEntityKeyAction As Action(Of TDetailEntity, TPrimaryKey), Optional ByVal projection As Func(Of IRepositoryQuery(Of TDetailEntity), IQueryable(Of TDetailProjection)) = Nothing) As CollectionViewModel(Of TDetailEntity, TDetailProjection, TDetailPrimaryKey, TUnitOfWork)
      Return GetCollectionViewModelCore(Of CollectionViewModel(Of TDetailEntity, TDetailProjection, TDetailPrimaryKey, TUnitOfWork), TDetailEntity, TDetailProjection, TForeignKey)(propertyExpression, foreignKeyExpression, Function() CollectionViewModel(Of TDetailEntity, TDetailProjection, TDetailPrimaryKey, TUnitOfWork).CreateProjectionCollectionViewModel(UnitOfWorkFactory, getRepositoryFunc, projection, CreateForeignKeyPropertyInitializer(setMasterEntityKeyAction, PrimaryKey), True))
    End Function
    Protected Function GetReadOnlyDetailsCollectionViewModel(Of TViewModel, TDetailEntity As Class, TForeignKey)(ByVal propertyExpression As Expression(Of Func(Of TViewModel, ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailEntity, TUnitOfWork))), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IReadOnlyRepository(Of TDetailEntity)), ByVal foreignKeyExpression As Expression(Of Func(Of TDetailEntity, TForeignKey)), Optional ByVal projection As Func(Of IRepositoryQuery(Of TDetailEntity), IQueryable(Of TDetailEntity)) = Nothing) As ReadOnlyCollectionViewModel(Of TDetailEntity, TUnitOfWork)
      Return GetCollectionViewModelCore(Of ReadOnlyCollectionViewModel(Of TDetailEntity, TUnitOfWork), TDetailEntity, TDetailEntity, TForeignKey)(propertyExpression, foreignKeyExpression, Function() ReadOnlyCollectionViewModel(Of TDetailEntity, TUnitOfWork).CreateReadOnlyCollectionViewModel(UnitOfWorkFactory, getRepositoryFunc, projection))
    End Function
    Protected Function GetReadOnlyDetailProjectionsCollectionViewModel(Of TViewModel, TDetailEntity As Class, TDetailProjection As Class, TForeignKey)(ByVal propertyExpression As Expression(Of Func(Of TViewModel, ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailProjection, TUnitOfWork))), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IReadOnlyRepository(Of TDetailEntity)), ByVal foreignKeyExpression As Expression(Of Func(Of TDetailEntity, TForeignKey)), ByVal projection As Func(Of IRepositoryQuery(Of TDetailEntity), IQueryable(Of TDetailProjection))) As ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailProjection, TUnitOfWork)
      Return GetCollectionViewModelCore(Of ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailProjection, TUnitOfWork), TDetailEntity, TDetailProjection, TForeignKey)(propertyExpression, foreignKeyExpression, Function() ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailProjection, TUnitOfWork).CreateReadOnlyProjectionCollectionViewModel(UnitOfWorkFactory, getRepositoryFunc, projection))
    End Function
    Protected Function GetLookUpEntitiesViewModel(Of TViewModel, TLookUpEntity As Class, TLookUpEntityKey)(ByVal propertyExpression As Expression(Of Func(Of TViewModel, IEntitiesViewModel(Of TLookUpEntity))), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TLookUpEntity, TLookUpEntityKey)), Optional ByVal projection As Func(Of IRepositoryQuery(Of TLookUpEntity), IQueryable(Of TLookUpEntity)) = Nothing) As IEntitiesViewModel(Of TLookUpEntity)
      Return GetLookUpProjectionsViewModel(propertyExpression, getRepositoryFunc, projection)
    End Function
    Protected Overridable Function GetLookUpProjectionsViewModel(Of TViewModel, TLookUpEntity As Class, TLookUpProjection As Class, TLookUpEntityKey)(ByVal propertyExpression As Expression(Of Func(Of TViewModel, IEntitiesViewModel(Of TLookUpProjection))), ByVal getRepositoryFunc As Func(Of TUnitOfWork, IRepository(Of TLookUpEntity, TLookUpEntityKey)), ByVal projection As Func(Of IRepositoryQuery(Of TLookUpEntity), IQueryable(Of TLookUpProjection))) As IEntitiesViewModel(Of TLookUpProjection)
      Return GetEntitiesViewModelCore(Of IEntitiesViewModel(Of TLookUpProjection), TLookUpProjection)(propertyExpression, Function() LookUpEntitiesViewModel(Of TLookUpEntity, TLookUpProjection, TLookUpEntityKey, TUnitOfWork).Create(UnitOfWorkFactory, getRepositoryFunc, projection))
    End Function
    Private Shared Function CreateForeignKeyPropertyInitializer(Of TDetailEntity As Class, TForeignKey)(ByVal setMasterEntityKeyAction As Action(Of TDetailEntity, TPrimaryKey), ByVal masterEntityKey As TForeignKey) As Action(Of TDetailEntity)
      Return Sub(ByVal x) setMasterEntityKeyAction(x, CType(CType(masterEntityKey, Object), TPrimaryKey))
    End Function
    Private Function GetCollectionViewModelCore(Of TViewModel As ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailProjection, TUnitOfWork), TDetailEntity As Class, TDetailProjection As Class, TForeignKey)(ByVal propertyExpression As LambdaExpression, ByVal foreignKeyExpression As Expression(Of Func(Of TDetailEntity, TForeignKey)), ByVal createViewModelCallback As Func(Of TViewModel)) As TViewModel
      Return GetEntitiesViewModelCore(Of TViewModel, TDetailProjection)(propertyExpression, Function() CreateAndInitializeCollectionViewModel(Of TViewModel, TDetailEntity, TDetailProjection, TForeignKey)(createViewModelCallback, foreignKeyExpression))
    End Function
    Private Function CreateAndInitializeCollectionViewModel(Of TViewModel As ReadOnlyCollectionViewModel(Of TDetailEntity, TDetailProjection, TUnitOfWork), TDetailEntity As Class, TDetailProjection As Class, TForeignKey)(ByVal createViewModelCallback As Func(Of TViewModel), ByVal foreignKeyExpression As Expression(Of Func(Of TDetailEntity, TForeignKey))) As TViewModel
      Dim lookUpViewModel As TViewModel = createViewModelCallback().SetParentViewModel(Me)
      lookUpViewModel.FilterExpression = ExpressionHelper.GetValueEqualsExpression(foreignKeyExpression, CType(CType(PrimaryKey, Object), TForeignKey))
      Return lookUpViewModel
    End Function
    Private Function GetEntitiesViewModelCore(Of TViewModel As IEntitiesViewModel(Of TDetailEntity), TDetailEntity As Class)(ByVal propertyExpression As LambdaExpression, ByVal createViewModelCallback As Func(Of TViewModel)) As TViewModel
      Dim result As IDocumentContent = Nothing
      Dim propertyName As String = ExpressionHelper.GetPropertyName(propertyExpression)
      If Not _lookUpViewModels.TryGetValue(propertyName, result) Then
        result = createViewModelCallback()
        _lookUpViewModels(propertyName) = result
      End If
      Return CType(result, TViewModel)
    End Function
    Private Property Parameter As Object Implements ISupportParameter.Parameter
      Get
        Return Nothing
      End Get
      Set
        OnParameterChanged(value)
      End Set
    End Property
    Private ReadOnly Property Title_Impl As Object Implements IDocumentContent.Title
      Get
        Return Title
      End Get
    End Property
    Private Sub OnClose(ByVal e As CancelEventArgs) Implements IDocumentContent.OnClose
      e.Cancel = Not TryClose()
    End Sub
    Private Sub OnDestroy_Impl() Implements IDocumentContent.OnDestroy
      OnDestroy()
    End Sub
    Private Property DocumentOwner_Impl As IDocumentOwner Implements IDocumentContent.DocumentOwner
      Get
        Return DocumentOwner
      End Get
      Set
        _DocumentOwner = value
      End Set
    End Property
    Private ReadOnly Property Entity_Impl As TEntity Implements ISingleObjectViewModel(Of TEntity, TPrimaryKey).Entity
      Get
        Return Entity
      End Get
    End Property
    Private ReadOnly Property PrimaryKey_Impl As TPrimaryKey Implements ISingleObjectViewModel(Of TEntity, TPrimaryKey).PrimaryKey
      Get
        Return PrimaryKey
      End Get
    End Property
  End Class
End Namespace