Question

我只是在寻找一些关于其他人在使用EF4时管理其背景的行为的反馈。我正在创建一个MVC应用程序，使用（我认为:)）工作单元，服务层，存储库，EF4 w / POCO技术。

我的控制器利用UOW服务，然后利用存储库从EF获取POCO。

这是否正确实施？

看看下面，感谢任何反馈！

控制器

Public Class MyController
    Function ListCustomers() As ActionResult
        Dim _UOW = New UnitOfWork
        Dim _Service = New CustomerService(_UOW)
        Dim _Model = New CustomersViewModel
        _Model.Customers = _Service.GetCustomers
        _UOW.Dispose()

        Return View(_Model)
    End Function
End Class

工作单元

Public Interface IUnitOfWork
    Property Context As GTGContext
    Sub Committ()

End Interface

Public Class UnitOfWork
    Implements IDisposable, IUnitOfWork

    Public Property Context As Domain.GTGContext Implements IUnitOfWork.Context

    Public Sub New()
        _Context = New GTGContext

    End Sub

    Public Sub Committ() Implements IUnitOfWork.Committ
        _Context.SaveChanges()

    End Sub

#Region "IDisposable Support"

    Private _IsDisposed As Boolean

    Protected Overridable Sub Dispose(ByVal Disposing As Boolean)
        If (Not _IsDisposed) Then
            If (Disposing) Then
                If (_Context IsNot Nothing) Then
                    _Context.Dispose()
                End If
            End If

            'TODO: Free unmanaged resources (unmanaged objects) and override Finalize() below.
        End If

        _IsDisposed = True

    End Sub

    'TODO: Override Finalize() only if Dispose(ByVal disposing As Boolean) above has code to free unmanaged resources.
    'Protected Overrides Sub Finalize()
    '    Dispose(False)
    '    MyBase.Finalize()
    'End Sub

    Public Sub Dispose() Implements IDisposable.Dispose
        Dispose(True)
        GC.SuppressFinalize(Me)

    End Sub

#End Region

End Class

服务

Public Class CustomerService
    Private _UOW As IUnitOfWork
    Private _Repo As Repository(Of Customer)

    Public Sub New(UOW As IUnitOfWork)
        _UOW = UOW
        _Repo = New Repository(Of Customer)(_UOW)
    End Sub

    Public Function GetCustoemrs() As IQueryable(Of Customer)
        ' Any Business Logic Here
        Return _Repo.GetCustomers()
    End Function

End Class

存储库

Imports System.Data.Objects

Namespace Repositories
    Public Interface IRepository(Of T As Class)
        ReadOnly Property ObjectSet As IObjectSet(Of T)
        ReadOnly Property UnitOfWork As IUnitOfWork
        Function Query(ByVal Expression As Expressions.Expression(Of Func(Of T, Boolean))) As IQueryable(Of T)
        Function GetFirst(ByVal Expression As Expressions.Expression(Of Func(Of T, Boolean))) As T
        Function GetSingle(ByVal Expression As Expressions.Expression(Of Func(Of T, Boolean))) As T
        Sub Add(ByVal Entity As T)
        Sub Attach(ByVal Entity As T)
        Sub Delete(ByVal Entity As T)
        Sub SaveChanges()

    End Interface

    Public Class Repository(Of T As Class)
        Implements IRepository(Of T)

#Region "Private Members/Properties"

        Private _ObjectSet As IObjectSet(Of T)
        Private ReadOnly Property ObjectSet As System.Data.Objects.IObjectSet(Of T) Implements IRepository(Of T).ObjectSet
            Get
                If (_ObjectSet Is Nothing) Then
                    _ObjectSet = UnitOfWork.Context.CreateObjectSet(Of T)()
                End If
                Return _ObjectSet
            End Get
        End Property

        Private _UnitOfWork As IUnitOfWork
        Private ReadOnly Property UnitOfWork As IUnitOfWork Implements IRepository(Of T).UnitOfWork
            Get
                Return _UnitOfWork
            End Get
        End Property

#End Region

#Region "Constructor(s)"

        Public Sub New(ByVal UnitOfWork As IUnitOfWork)
            If (UnitOfWork Is Nothing) Then
                Throw New ArgumentNullException("UnitOfWork")
            End If
            _UnitOfWork = UnitOfWork

        End Sub

#End Region

#Region "IRepository(Of T)"

        Public Sub Add(ByVal Entity As T) Implements IRepository(Of T).Add
            ObjectSet.AddObject(Entity)

        End Sub

        Public Sub Attach(ByVal Entity As T) Implements IRepository(Of T).Attach
            ObjectSet.Attach(Entity)
            UnitOfWork.Context.ObjectStateManager.ChangeObjectState(Entity, EntityState.Modified)

        End Sub

        Public Sub Delete(ByVal Entity As T) Implements IRepository(Of T).Delete
            ObjectSet.DeleteObject(Entity)

        End Sub

        Public Function GetFirst(ByVal Expression As System.Linq.Expressions.Expression(Of System.Func(Of T, Boolean))) As T Implements IRepository(Of T).GetFirst
            Return ObjectSet.FirstOrDefault(Expression)

        End Function

        Public Function GetSingle(ByVal Expression As System.Linq.Expressions.Expression(Of System.Func(Of T, Boolean))) As T Implements IRepository(Of T).GetSingle
            Return ObjectSet.SingleOrDefault(Expression)

        End Function

        Public Function Query(ByVal Expression As System.Linq.Expressions.Expression(Of System.Func(Of T, Boolean))) As System.Linq.IQueryable(Of T) Implements IRepository(Of T).Query
            Return ObjectSet.Where(Expression)

        End Function

        Public Sub SaveChanges() Implements IRepository(Of T).SaveChanges
            UnitOfWork.Committ()

        End Sub

#End Region

    End Class
End Namespace

Answer 1

让我告诉你，我在很长一段时间内采取了什么方法，特别是在StackOverflow上，我很痛苦：）

我决定实施这篇关于管理对象上下文的精彩文章（注意允许多个上下文的修改版本）。

http://dotnetslackers.com/articles/ado_net/Managing-Entity-Framework-ObjectContext-lifespan-and-scope-in-n-layered-ASP-NET-applications.aspx

然后我实施了外墙，如：

public class MyEntityFacade : FacadeBase<MyEntities, MyEntity>
{
    public object GetAll()
    {
        return this.ObjectContext.MyEntities.ToList();
    }

    public bool HasChild(int parentId)
    {
        return this.ObjectContext.MyEntityChild.Any(c => c.parentId == parentId);
    }
}

当然，它已经老了，但男孩哦，男孩，它有效！

请参阅，所有服务层/工作单元/存储库的东西是你最终必须编写一堆很多代码来支持它（当然EF4应该减少代码膨胀！）。每次添加新实体时，猜猜是什么？更繁琐的代码膨胀。

通过上面的方法，我将所有的Facade / unit of work支持代码填充到一个可重用的类库中，我所要做的就是编写我的外观代码，它只关注实际执行某些操作的代码 - 而且它适用于多种情境。

为我工作......哦，不要嘲笑我使用“立面”这个词。我从未真正去过学校;）

谢谢，理查德

P.S。祝周末愉快！

实体框架4上下文？

1 个答案: