C# C实体框架和存储库模式

使用工作单元和存储库模式，我有以下几点：

public interface IDatabaseFactory<C> : IDisposable
{
    C Get();
    void Set(string connectionString);
}

public interface IUnitOfWork<C>
{
    ICustomerRepository Customers { get; }
    //etc...

    void Commit();
    void ChangeDatabase(string connectionString);
    string GetConnectionString(Database database);
}

public interface ICustomerRepository : IRepository<Customer> { }

以及实施：

public class CustomerRepository : Repository<MyDbContext, Customer>, ICustomerRepository
{
    public CustomerRepository (IDatabaseFactory<MyDbContext> databaseFactory) 
        : base(databaseFactory) { }
}

public class UnitOfWork<C> : IUnitOfWork<C> where C : DbContext, IMyDbContext
{
    private readonly IDatabaseFactory<C> databaseFactory;

    private C dataContext;

    public UnitOfWork(IDatabaseFactory<C> databaseFactory)
    {
        this.databaseFactory = databaseFactory;
    }

    private ICustomerRepository customerRepository;
    public ICustomerRepository Customers
    {
        get { return customerRepository?? (customerRepository = new CustomerRepository((IDatabaseFactory<MyDbContext>)databaseFactory)); }
    }

    private void ClearRespositories()
    {
        customerRepository = null;
    }

    protected C DataContext
    {
        get { return dataContext ?? (dataContext = databaseFactory.Get()); }
    }

    public string GetConnectionString(Model.Database database)
    {
    }

    public void ChangeDatabase(string connectionString)
    {
    }

    public void Commit()
    {
    }
}

我的模型有不少于250个主要实体，使用上述模式，这些实体需要相同数量的存储库，并且每一个都是工作类单元中的一个属性

我的典型服务层类别是：

public class CustomerService : BaseService, ICustomerService
{
    private ICustomerRepository customerRepository;

    public CustomerService(IUnitOfWork<MyDbContext> unitOfWork) : base(unitOfWork) { }

    public override void ChangeDatabase(string connectionString)
    {
        base.ChangeDatabase(connectionString);
        customerRepository = unitOfWork.Customers;
    }
}

我的应用程序有一个db上下文，该上下文用于使用相同上下文的不同数据库。当用户登录系统时，他可以选择一个数据库，这将相应地设置uow类的数据上下文

我已经将存储库添加到UoW类中，以便所有存储库都具有相同的UoW

---

这是正确的方法还是有更好的方法？

您可以使用通用存储库模式。这可以通过非常特定的域查询进行扩展。然后，DI容器可以创建所需的特定存储库，并且可以针对所有数据类使用它

如果对代码有任何疑问，请随时提问

我会给你我的VB.net代码，希望它有用：

这是您将要使用的界面。保存和检索必须从IEntity继承的类

Public Interface IRepository
    Function GetEntity(Of T As {EntityObject, IEntity})(id As Integer) As T

    Function GetAll(Of T As {EntityObject, IEntity})() As IEnumerable(Of T)

    Sub Add(Of T As {EntityObject, IEntity})(entity As T)
    Sub Remove(Of T As EntityObject)(entity As T)
    Sub Attach(Of T As EntityObject)(entity As T)
    Sub Update(Of T As {EntityObject, IEntity})(entity As T)

    Function ExecuteQuery(Of T As {EntityObject, IEntity})(query As IQuery(Of T)) As IQueryResult(Of T)
    Function ExecuteQuery(Of T As {EntityObject, IEntity}, TResult)(query As IQuery(Of T, TResult)) As IQueryResult(Of TResult)
End Interface

必须在数据对象中实现的接口 您也可以在PK中使用其他then int：

Public Interface IEntity
    Property Id As Int32
End Interface

在IQuery对象中，为数据的特定查询实现以下功能：

Public Interface IQuery(Of T As {EntityObject, IEntity})
    Function Execute(ByVal objectSet As ObjectSet(Of T)) As IQueryResult(Of T)
End Interface

Public Interface IQuery(Of T As {EntityObject, IEntity}, TResult)
    Function Execute(ByVal objectSet As ObjectSet(Of T)) As IQueryResult(Of TResult)
End Interface

您将要处理的查询结果是可扩展的

Public Interface IQueryResult(Of T)
    Function UniqueResult() As T
    Function List() As IEnumerable(Of T)
End Interface

Public Class LinqResult(Of T)
    Implements IQueryResult(Of T)
    Private ReadOnly _query As IQueryable(Of T)

    Public Sub New(query As IQueryable(Of T))
        _query = query
    End Sub

    Protected Overridable Function ExpandQuery(query As IQueryable(Of T)) As IQueryable(Of T)
        Return query
    End Function

    Public Function UniqueResult() As T Implements IQueryResult(Of T).UniqueResult
        Dim result = ExpandQuery(_query).SingleOrDefault()
        If result Is Nothing Then
            Throw New EntityNotFoundException(Of T)()
        End If
        Return result
    End Function
    Public Function List() As IEnumerable(Of T) Implements IQueryResult(Of T).List
        Return ExpandQuery(_query).ToList()
    End Function
End Class

您的ObjectcontextRepository，IRepository的实际实现

Public Class EntityObjectContextRepository
    Implements IRepository

    Private ReadOnly Property _context As ObjectContext
        Get
            Return UnitOfWork.Current
        End Get
    End Property


    Public Sub Add(Of T As {EntityObject, IEntity})(entity As T) Implements IRepository.Add
        _context.CreateObjectSet(Of T)().AddObject(entity)
    End Sub

    Public Sub Attach(Of T As EntityObject)(entity As T) Implements IRepository.Attach
        _context.Attach(entity)
        '_context.CreateObjectSet(Of T)().Attach(entity)
    End Sub

    Public Sub Update(Of T As {EntityObject, IEntity})(ByVal entity As T) Implements IRepository.Update
        _context.CreateObjectSet(Of T)().Attach(entity)
        _context.ObjectStateManager.ChangeObjectState(entity, EntityState.Modified)
    End Sub

    Public Function ExecuteQuery(Of T As {EntityObject, IEntity})(query As IQuery(Of T)) As IQueryResult(Of T) Implements IRepository.ExecuteQuery
        Return query.Execute(_context.CreateObjectSet(Of T))
    End Function

    Public Function ExecuteQuery(Of T As {EntityObject, IEntity}, TResult)(ByVal query As IQuery(Of T, TResult)) As IQueryResult(Of TResult) Implements IRepository.ExecuteQuery
        Return query.Execute(_context.CreateObjectSet(Of T))
    End Function

    Public Function GetAll(Of T As {EntityObject, IEntity})() As IEnumerable(Of T) Implements IRepository.GetAll
        Return _context.CreateObjectSet(Of T).ToList().Where(Function(c) c.EntityState <> EntityState.Deleted)
    End Function

    Public Function GetEntity(Of T As {EntityObject, IEntity})(id As Integer) As T Implements IRepository.GetEntity
        Dim entity = _context.CreateObjectSet(Of T)().SingleOrDefault(Function(x) x.Id = id)
        Return ReturnEntityWhenItExists(entity)
    End Function

    Public Sub Remove(Of T As EntityObject)(entity As T) Implements IRepository.Remove
        _context.DeleteObject(entity)
    End Sub

    Private Function ReturnEntityWhenItExists(Of T As {EntityObject, IEntity})(ByVal entity As T) As T
        If entity IsNot Nothing AndAlso entity.EntityState <> EntityState.Deleted Then
            Return entity
        End If
        Throw New EntityNotFoundException(Of T)()
    End Function
End Class

查询的一个示例：

Public Class GetAllBuildingsQuery
Implements IQuery(Of DataAccess.Building, BuildingDto)

Public Function Execute(ByVal objectSet As ObjectSet(Of Building)) As IQueryResult(Of BuildingDto) Implements IQuery(Of Building, BuildingDto).Execute
    Dim query = objectSet.Select(Function(g) New BuildingDto() With {.Description = g.Name, .Id = g.Id})
    Return New LinqResult(Of BuildingDto)(query)
End Function
End Class

如何在服务调用中实现它：

Public Class EmployeeService
    Implements IEmployeeService


    Private ReadOnly _repository As IRepository
    Public Sub New(ByVal repository As IRepository)
        _repository = repository
    End Sub

    Public Function GetAllEmployees() As IEnumerable(Of EmployeeOverviewDto) Implements IEmployeeService.GetAllEmployees
        Dim employees = _repository.ExecuteQuery(EmployeeQueries.GetAllEmployeesForOverview()).List()
        Return employees
    End Function
End Class

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考虑不同的方法，使用通用存储库不一定是一个好方法，请参见域驱动的设计和我的应用程序有一个DB上下文，你的意思是你不在你的应用程序生命周期中处理一次你的上下文吗？这不是一个聪明的主意。有没有想过不使用这些？问题明确地说是C，这是VB.NET。。。我知道它们是相关的，但仍然如此。@anaximander:我知道问题是c，但我愿意分享我的代码。Juts不会努力把这个翻译成c。如果答案不正确，我会删除它。始终是一个有用的工具

Public Class EmployeeService
    Implements IEmployeeService


    Private ReadOnly _repository As IRepository
    Public Sub New(ByVal repository As IRepository)
        _repository = repository
    End Sub

    Public Function GetAllEmployees() As IEnumerable(Of EmployeeOverviewDto) Implements IEmployeeService.GetAllEmployees
        Dim employees = _repository.ExecuteQuery(EmployeeQueries.GetAllEmployeesForOverview()).List()
        Return employees
    End Function
End Class