DAO和存储库之间有什么区别 [英] what is the difference between the DAO and repositery

问题描述

DAO和repositery之间有什么区别，它们是如何在项目中使用的。

以及DAL，DAO，Repositery之间的关系是什么。

what is the difference between the DAO and repositery , how they are used in the project..
and also what is the relation between DAL,DAO,Repositery.

推荐答案

DAO是数据持久性的抽象。存储库是对象集合的抽象。



DAO将被认为更接近数据库，通常以表为中心。存储库将被视为更接近域，仅处理聚合根。可以使用DAO实现存储库，但是你不会做相反的事情。



此外，存储库通常是一个较窄的接口。它应该只是一个对象的集合，具有Get（id），Find（ISpecification），Add（Entity）。类似于Update的方法适用于DAO，但不适用于存储库 - 使用存储库时，通常会通过单独的UnitOfWork跟踪对实体的更改。



看起来确实如此通常看到实际上称为存储库的实现更多的是DAO，因此我认为它们之间存在一些混淆。





请参阅以下链接了解更多信息

http://msdn.microsoft .com / zh-CN / magazine / dd419654.aspx [ ^ ]

http://www.codeinsanity.com/ SystemMessages / FileNotFound.aspx [ ^ ]

http://blog.fedecarg.com/2009/03/15/domain-driven-design-the-repository/ [ ^ ]



http://devlicio.us/blogs /casey/archive/2009/02/20/ddd-the-repository-pattern.aspx [ ^ ]

DAO is an abstraction of data persistence. Repository is an abstraction of a collection of objects.

DAO would be considered closer to the database, often table-centric. Repository would be considered closer to the Domain, dealing only in Aggregate Roots. A Repository could be implemented using DAO''s, but you wouldn''t do the opposite.

Also, a Repository is generally a narrower interface. It should be simply a collection of objects, with a Get(id), Find(ISpecification), Add(Entity). A method like Update is appropriate on a DAO, but not a Repository - when using a Repository, changes to entities would usually be tracked by separate UnitOfWork.

It does seem common to see implementations called a Repository that are really more of a DAO, and hence I think there is some confusion about the difference between them.


see below links for more info
http://msdn.microsoft.com/en-us/magazine/dd419654.aspx[^]
http://www.codeinsanity.com/SystemMessages/FileNotFound.aspx[^]
http://blog.fedecarg.com/2009/03/15/domain-driven-design-the-repository/[^]

http://devlicio.us/blogs/casey/archive/2009/02/20/ddd-the-repository-pattern.aspx[^]

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