Lviv .Net User Group. NHibernate

OutlineQ1: What is NHibernate?Q2: Why do I need it?Q3: How does it look like?ConceptsDEMO 1: Hello World!Q4: How can I proceed with it?QueriesMore about mapping, querying, usage patternsDEMO 2: Customer-Orders-Productshttp://andriybuday.blogspot.com/Let see… will we get what we want!

Q1: What is NHibernate?NHibernate is…ORMNew level of Abstractionhttp://andriybuday.blogspot.com/Paradigm mismatch

Q2: Why Do I need it?Because…http://andriybuday.blogspot.com/Development speed increasesReducing database workOptimizes access to DB, so could even perform better than plain ADO.NETYou think in terms of business model, not databaseMore time for real programming

Q2: Why Do I need it?Why do I like NHibernate?http://andriybuday.blogspot.com/MatureFree & Open SourceGood community supportFlexibleAllows you do Domain Driven DesignYou asked for comparison with other ORM…LINQ to SQL doesn’t really lead you to good modelsEntity Framework has better Linq and it is MicrosoftVisit http://ormbattle.net/ for performance numbersGoogle.Search(string.Format“Nhibernate vs. {0}”, yourORM);

Q3: How does it look like?Concepts: Unit of Workhttp://andriybuday.blogspot.com/Kind of “workspace” within which you can do anything you wantA Unit Of Work either success or fails as a unitConceptually like database transactionsIn NHibernate we have ISession which does the sameConceptually we have the same for in ADO.NET as DataSet

Q3: How does it look like?Concepts: ISessionhttp://andriybuday.blogspot.com/Open a sessionWe get it from the session factoryWe do some workSession.Add(…)Session.Delete(…)Commit the sessionSession.Flush(…)

Q3: How does it look like?Concepts: ISessionFactoryhttp://andriybuday.blogspot.com/We are getting our session through this classVery expensive to createOne per database or application

Q3: How does it look like?Concepts: Summaryhttp://andriybuday.blogspot.com/Configuration Class builds Session FactorySession Factory builds SessionSession is used as Unit Of Work to interaction with objects and persist to underlying databasevar sessionFactory = newConfiguration().Configure().BuildSessionFactory(); using (var session = sessionFactory.OpenSession()){var customer = newCustomer(); session.SaveOrUpdate(customer); session.Flush(); }

Q3: How does it look like?Architecture: and look from inside?http://andriybuday.blogspot.com/

Q3: How does it look like?DEMO: Hello World!http://andriybuday.blogspot.com/Just basics… to refresh our minds 

Q4: How can I proceed with it? More on Query APIhttp://andriybuday.blogspot.com/Criteria APIObject oriented queryingICriteria chainingEasy to writeHard to readHQL APIString basedParameterizedSimilar to SQLSpeak in terms of ObjectsMore flexible“from Customer c wherec.FirstName = :firstName”session.CreateCriteria(typeof(Customer)) .Add(Restrictions.Eq("FirstName", "Hello"))

Q4: How can I proceed with it? Mappinghttp://andriybuday.blogspot.com/<hibernate-mappingxmlns="urn:nhibernate-mapping-2.2"default-lazy="true"assembly="LearningNHibernate"namespace="LearningNHibernate"> <classname="Customer"table="Customer"xmlns="urn:nhibernate-mapping-2.2"> <idname="CustomerId"column="CustomerId"type="Int32"> <generatorclass="identity" /> </id> <propertyname="FirstName"column="Firstname"length="50"type="String"> <columnname="Firstname" /> </property> <propertyname="LastName"column="Lastname"length="50"type="String"> <columnname="Lastname" /> </property> </class></hibernate-mapping>publicclassCustomerMap : ClassMap<Customer> {public CustomerMap() { WithTable("Customer"); Id(x => x.CustomerId); Map(x => x.FirstName, "Firstname"); Map(x => x.LastName, "Lastname").WithLengthOf(50); } }

Q4: How can I proceed with it? Fetch strategieshttp://andriybuday.blogspot.com/Lazy loadingDefault for all collectionsMembers are loaded from database when assessedUsually good for performanceSession has to stay OPENEager FetchingUse when you sure you’ll use dataOUTER joins

Q4: How can I proceed with it? Caching, batching, concurrencyhttp://andriybuday.blogspot.com/First level cacheFollowing will run only one SELECTSecond level cacheWithin two sessions you still run one SELECTIt is needed to explicitly turn it on everywhereBatch processing<property name="adonet.batch_size">250</property>Concurrency<version name="Version" column="Version"/> var customer1 = session.Get<Customer>(5);var customer2 = session.Get<Customer>(5);

Q4: How can I proceed with it?http://andriybuday.blogspot.com/Use FluentNhibernate to do not bore developers with XMLCreate wrappers to have NHibernateRepositoryImplement UnitOfWorkVS projectsTwo ways for kick-offFrom database to ObjectsFrom objects to Database

DEMO 2: Mapping, Querying, LazyLoad, etc..http://andriybuday.blogspot.com/Damn it! Let’s write some code again!

Read blog! Follow me! Visit LVIV .NET UG!http://andriybuday.blogspot.com/http://andriybuday.blogspot.com/@andriybudayandriybuday@gmail.comhttp://dotnetug-lviv.blogspot.com/

Linkshttp://andriybuday.blogspot.com/My blog:http://andriybuday.blogspot.comLviv .NET User Group:http://dotnetug-lviv.blogspot.com/NHibernate:Home Page: http://nhibernate.com/Reference: http://www.nhforge.org/doc/nh/en/index.htmlGreat series of screencasts on NHibernate:http://www.summerofnhibernate.com/ORM with NHibernate screen cast (2 hours)http://www.flux88.com/uploads/ORMWithNHibernateScreenCast.wmvTools:Profiler: http://nhprof.com/Fluent NHibernate: http://fluentnhibernate.org/MyGeneration: http://www.mygenerationsoftware.com/

Lviv .Net User Group. NHibernate

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