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  • NHibernate 2 Beginner's Guide Book

    - by Ricardo Peres
    Packt Publishing has recently released a new book on NHibernate: NHibernate 2 Beginner's Guide, by Aaron Cure. I am now reading the final version, which Packt Publishing was kind enough to provide me, and I will soon write about it. I can tell you for now that Fabio Maulo was one of the reviewers, which certainly raises the expectations. In the meanwhile, there's a free chapter you can download, which hopefully will get you interested in it; you can get it from here.

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  • NHibernate Tools

    - by Ricardo Peres
    Felice Pollano is the author of a two great new tools for working with NHibernate: NH Workbench: an IDE for writing HQL queries against a model db2hbm: generation of .hbm.xml files from a database (currently only SQL Server, more to come) I suggest you give them a try and give Felix your feedback!

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  • NHibernate Pitfalls: Fetch and Paging

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. NHibernate allows you to force loading additional references (many to one, one to one) or collections (one to many, many to many) in a query. You must know, however, that this is incompatible with paging. It’s easy to see why. Let’s say you want to get 5 products starting on the fifth, you can issue the following LINQ query: 1: session.Query<Product>().Take(5).Skip(5).ToList(); Will product this SQL in SQL Server: 1: SELECT 2: TOP (@p0) product1_4_, 3: name4_, 4: price4_ 5: FROM 6: (select 7: product0_.product_id as product1_4_, 8: product0_.name as name4_, 9: product0_.price as price4_, 10: ROW_NUMBER() OVER( 11: ORDER BY 12: CURRENT_TIMESTAMP) as __hibernate_sort_row 13: from 14: product product0_) as query 15: WHERE 16: query.__hibernate_sort_row > @p1 17: ORDER BY If, however, you wanted to bring as well the associated order details, you might be tempted to try this: 1: session.Query<Product>().Fetch(x => x.OrderDetails).Take(5).Skip(5).ToList(); Which, in turn, will produce this SQL: 1: SELECT 2: TOP (@p0) product1_4_0_, 3: order1_3_1_, 4: name4_0_, 5: price4_0_, 6: order2_3_1_, 7: product3_3_1_, 8: quantity3_1_, 9: product3_0__, 10: order1_0__ 11: FROM 12: (select 13: product0_.product_id as product1_4_0_, 14: orderdetai1_.order_detail_id as order1_3_1_, 15: product0_.name as name4_0_, 16: product0_.price as price4_0_, 17: orderdetai1_.order_id as order2_3_1_, 18: orderdetai1_.product_id as product3_3_1_, 19: orderdetai1_.quantity as quantity3_1_, 20: orderdetai1_.product_id as product3_0__, 21: orderdetai1_.order_detail_id as order1_0__, 22: ROW_NUMBER() OVER( 23: ORDER BY 24: CURRENT_TIMESTAMP) as __hibernate_sort_row 25: from 26: product product0_ 27: left outer join 28: order_detail orderdetai1_ 29: on product0_.product_id=orderdetai1_.product_id 30: ) as query 31: WHERE 32: query.__hibernate_sort_row > @p1 33: ORDER BY 34: query.__hibernate_sort_row; However, because of the JOIN, what happens is that, if your products have more than one order details, you will get several records – one per order detail – per product, which means that pagination will be broken. There is an workaround, which forces you to write your LINQ query in another way: 1: session.Query<OrderDetail>().Where(x => session.Query<Product>().Select(y => y.ProductId).Take(5).Skip(5).Contains(x.Product.ProductId)).Select(x => x.Product).ToList() Or, using HQL: 1: session.CreateQuery("select od.Product from OrderDetail od where od.Product.ProductId in (select p.ProductId from Product p skip 5 take 5)").List<Product>(); The generated SQL will then be: 1: select 2: product1_.product_id as product1_4_, 3: product1_.name as name4_, 4: product1_.price as price4_ 5: from 6: order_detail orderdetai0_ 7: left outer join 8: product product1_ 9: on orderdetai0_.product_id=product1_.product_id 10: where 11: orderdetai0_.product_id in ( 12: SELECT 13: TOP (@p0) product_id 14: FROM 15: (select 16: product2_.product_id, 17: ROW_NUMBER() OVER( 18: ORDER BY 19: CURRENT_TIMESTAMP) as __hibernate_sort_row 20: from 21: product product2_) as query 22: WHERE 23: query.__hibernate_sort_row > @p1 24: ORDER BY 25: query.__hibernate_sort_row); Which will get you what you want: for 5 products, all of their order details.

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  • NHibernate Conventions

    - by Ricardo Peres
    Introduction It seems that nowadays everyone loves conventions! Not the ones that you go to, but the ones that you use, that is! It just happens that NHibernate also supports conventions, and we’ll see exactly how. Conventions in NHibernate are supported in two ways: Naming of tables and columns when not explicitly indicated in the mappings; Full domain mapping. Naming of Tables and Columns Since always NHibernate has supported the concept of a naming strategy. A naming strategy in NHibernate converts class and property names to table and column names and vice-versa, when a name is not explicitly supplied. In concrete, it must be a realization of the NHibernate.Cfg.INamingStrategy interface, of which NHibernate includes two implementations: DefaultNamingStrategy: the default implementation, where each column and table are mapped to identically named properties and classes, for example, “MyEntity” will translate to “MyEntity”; ImprovedNamingStrategy: underscores (_) are used to separate Pascal-cased fragments, for example, entity “MyEntity” will be mapped to a “my_entity” table. The naming strategy can be defined at configuration level (the Configuration instance) by calling the SetNamingStrategy method: 1: cfg.SetNamingStrategy(ImprovedNamingStrategy.Instance); Both the DefaultNamingStrategy and the ImprovedNamingStrategy classes offer singleton instances in the form of Instance static fields. DefaultNamingStrategy is the one NHibernate uses, if you don’t specify one. Domain Mapping In mapping by code, we have the choice of relying on conventions to do the mapping automatically. This means a class will inspect our classes and decide how they will relate to the database objects. The class that handles conventions is NHibernate.Mapping.ByCode.ConventionModelMapper, a specialization of the base by code mapper, NHibernate.Mapping.ByCode.ModelMapper. The ModelMapper relies on an internal SimpleModelInspector to help it decide what and how to map, but the mapper lets you override its decisions.  You apply code conventions like this: 1: //pick the types that you want to map 2: IEnumerable<Type> types = Assembly.GetExecutingAssembly().GetExportedTypes(); 3:  4: //conventions based mapper 5: ConventionModelMapper mapper = new ConventionModelMapper(); 6:  7: HbmMapping mapping = mapper.CompileMappingFor(types); 8:  9: //the one and only configuration instance 10: Configuration cfg = ...; 11: cfg.AddMapping(mapping); This is a very simple example, it lacks, at least, the id generation strategy, which you can add by adding an event handler like this: 1: mapper.BeforeMapClass += (IModelInspector modelInspector, Type type, IClassAttributesMapper classCustomizer) => 2: { 3: classCustomizer.Id(x => 4: { 5: //set the hilo generator 6: x.Generator(Generators.HighLow); 7: }); 8: }; The mapper will fire events like this whenever it needs to get information about what to do. And basically this is all it takes to automatically map your domain! It will correctly configure many-to-one and one-to-many relations, choosing bags or sets depending on your collections, will get the table and column names from the naming strategy we saw earlier and will apply the usual defaults to all properties, such as laziness and fetch mode. However, there is at least one thing missing: many-to-many relations. The conventional mapper doesn’t know how to find and configure them, which is a pity, but, alas, not difficult to overcome. To start, for my projects, I have this rule: each entity exposes a public property of type ISet<T> where T is, of course, the type of the other endpoint entity. Extensible as it is, NHibernate lets me implement this very easily: 1: mapper.IsOneToMany((MemberInfo member, Boolean isLikely) => 2: { 3: Type sourceType = member.DeclaringType; 4: Type destinationType = member.GetMemberFromDeclaringType().GetPropertyOrFieldType(); 5:  6: //check if the property is of a generic collection type 7: if ((destinationType.IsGenericCollection() == true) && (destinationType.GetGenericArguments().Length == 1)) 8: { 9: Type destinationEntityType = destinationType.GetGenericArguments().Single(); 10:  11: //check if the type of the generic collection property is an entity 12: if (mapper.ModelInspector.IsEntity(destinationEntityType) == true) 13: { 14: //check if there is an equivalent property on the target type that is also a generic collection and points to this entity 15: PropertyInfo collectionInDestinationType = destinationEntityType.GetProperties().Where(x => (x.PropertyType.IsGenericCollection() == true) && (x.PropertyType.GetGenericArguments().Length == 1) && (x.PropertyType.GetGenericArguments().Single() == sourceType)).SingleOrDefault(); 16:  17: if (collectionInDestinationType != null) 18: { 19: return (false); 20: } 21: } 22: } 23:  24: return (true); 25: }); 26:  27: mapper.IsManyToMany((MemberInfo member, Boolean isLikely) => 28: { 29: //a relation is many to many if it isn't one to many 30: Boolean isOneToMany = mapper.ModelInspector.IsOneToMany(member); 31: return (!isOneToMany); 32: }); 33:  34: mapper.BeforeMapManyToMany += (IModelInspector modelInspector, PropertyPath member, IManyToManyMapper collectionRelationManyToManyCustomizer) => 35: { 36: Type destinationEntityType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 37: //set the mapping table column names from each source entity name plus the _Id sufix 38: collectionRelationManyToManyCustomizer.Column(destinationEntityType.Name + "_Id"); 39: }; 40:  41: mapper.BeforeMapSet += (IModelInspector modelInspector, PropertyPath member, ISetPropertiesMapper propertyCustomizer) => 42: { 43: if (modelInspector.IsManyToMany(member.LocalMember) == true) 44: { 45: propertyCustomizer.Key(x => x.Column(member.LocalMember.DeclaringType.Name + "_Id")); 46:  47: Type sourceType = member.LocalMember.DeclaringType; 48: Type destinationType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 49: IEnumerable<String> names = new Type[] { sourceType, destinationType }.Select(x => x.Name).OrderBy(x => x); 50:  51: //set inverse on the relation of the alphabetically first entity name 52: propertyCustomizer.Inverse(sourceType.Name == names.First()); 53: //set mapping table name from the entity names in alphabetical order 54: propertyCustomizer.Table(String.Join("_", names)); 55: } 56: }; We have to understand how the conventions mapper thinks: For each collection of entities found, it will ask the mapper if it is a one-to-many; in our case, if the collection is a generic one that has an entity as its generic parameter, and the generic parameter type has a similar collection, then it is not a one-to-many; Next, the mapper will ask if the collection that it now knows is not a one-to-many is a many-to-many; Before a set is mapped, if it corresponds to a many-to-many, we set its mapping table. Now, this is tricky: because we have no way to maintain state, we sort the names of the two endpoint entities and we combine them with a “_”; for the first alphabetical entity, we set its relation to inverse – remember, on a many-to-many relation, only one endpoint must be marked as inverse; finally, we set the column name as the name of the entity with an “_Id” suffix; Before the many-to-many relation is processed, we set the column name as the name of the other endpoint entity with the “_Id” suffix, as we did for the set. And that’s it. With these rules, NHibernate will now happily find and configure many-to-many relations, as well as all the others. You can wrap this in a new conventions mapper class, so that it is more easily reusable: 1: public class ManyToManyConventionModelMapper : ConventionModelMapper 2: { 3: public ManyToManyConventionModelMapper() 4: { 5: base.IsOneToMany((MemberInfo member, Boolean isLikely) => 6: { 7: return (this.IsOneToMany(member, isLikely)); 8: }); 9:  10: base.IsManyToMany((MemberInfo member, Boolean isLikely) => 11: { 12: return (this.IsManyToMany(member, isLikely)); 13: }); 14:  15: base.BeforeMapManyToMany += this.BeforeMapManyToMany; 16: base.BeforeMapSet += this.BeforeMapSet; 17: } 18:  19: protected virtual Boolean IsManyToMany(MemberInfo member, Boolean isLikely) 20: { 21: //a relation is many to many if it isn't one to many 22: Boolean isOneToMany = this.ModelInspector.IsOneToMany(member); 23: return (!isOneToMany); 24: } 25:  26: protected virtual Boolean IsOneToMany(MemberInfo member, Boolean isLikely) 27: { 28: Type sourceType = member.DeclaringType; 29: Type destinationType = member.GetMemberFromDeclaringType().GetPropertyOrFieldType(); 30:  31: //check if the property is of a generic collection type 32: if ((destinationType.IsGenericCollection() == true) && (destinationType.GetGenericArguments().Length == 1)) 33: { 34: Type destinationEntityType = destinationType.GetGenericArguments().Single(); 35:  36: //check if the type of the generic collection property is an entity 37: if (this.ModelInspector.IsEntity(destinationEntityType) == true) 38: { 39: //check if there is an equivalent property on the target type that is also a generic collection and points to this entity 40: PropertyInfo collectionInDestinationType = destinationEntityType.GetProperties().Where(x => (x.PropertyType.IsGenericCollection() == true) && (x.PropertyType.GetGenericArguments().Length == 1) && (x.PropertyType.GetGenericArguments().Single() == sourceType)).SingleOrDefault(); 41:  42: if (collectionInDestinationType != null) 43: { 44: return (false); 45: } 46: } 47: } 48:  49: return (true); 50: } 51:  52: protected virtual new void BeforeMapManyToMany(IModelInspector modelInspector, PropertyPath member, IManyToManyMapper collectionRelationManyToManyCustomizer) 53: { 54: Type destinationEntityType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 55: //set the mapping table column names from each source entity name plus the _Id sufix 56: collectionRelationManyToManyCustomizer.Column(destinationEntityType.Name + "_Id"); 57: } 58:  59: protected virtual new void BeforeMapSet(IModelInspector modelInspector, PropertyPath member, ISetPropertiesMapper propertyCustomizer) 60: { 61: if (modelInspector.IsManyToMany(member.LocalMember) == true) 62: { 63: propertyCustomizer.Key(x => x.Column(member.LocalMember.DeclaringType.Name + "_Id")); 64:  65: Type sourceType = member.LocalMember.DeclaringType; 66: Type destinationType = member.LocalMember.GetPropertyOrFieldType().GetGenericArguments().First(); 67: IEnumerable<String> names = new Type[] { sourceType, destinationType }.Select(x => x.Name).OrderBy(x => x); 68:  69: //set inverse on the relation of the alphabetically first entity name 70: propertyCustomizer.Inverse(sourceType.Name == names.First()); 71: //set mapping table name from the entity names in alphabetical order 72: propertyCustomizer.Table(String.Join("_", names)); 73: } 74: } 75: } Conclusion Of course, there is much more to mapping than this, I suggest you look at all the events and functions offered by the ModelMapper to see where you can hook for making it behave the way you want. If you need any help, just let me know!

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  • Implementing an Interceptor Using NHibernate’s Built In Dynamic Proxy Generator

    - by Ricardo Peres
    NHibernate 3.2 came with an included proxy generator, which means there is no longer the need – or the possibility, for that matter – to choose Castle DynamicProxy, LinFu or Spring. This is actually a good thing, because it means one less assembly to deploy. Apparently, this generator was based, at least partially, on LinFu. As there are not many tutorials out there demonstrating it’s usage, here’s one, for demonstrating one of the most requested features: implementing INotifyPropertyChanged. This interceptor, of course, will still feature all of NHibernate’s functionalities that you are used to, such as lazy loading, and such. We will start by implementing an NHibernate interceptor, by inheriting from the base class NHibernate.EmptyInterceptor. This class does not do anything by itself, but it allows us to plug in behavior by overriding some of its methods, in this case, Instantiate: 1: public class NotifyPropertyChangedInterceptor : EmptyInterceptor 2: { 3: private ISession session = null; 4:  5: private static readonly ProxyFactory factory = new ProxyFactory(); 6:  7: public override void SetSession(ISession session) 8: { 9: this.session = session; 10: base.SetSession(session); 11: } 12:  13: public override Object Instantiate(String clazz, EntityMode entityMode, Object id) 14: { 15: Type entityType = Type.GetType(clazz); 16: IProxy proxy = factory.CreateProxy(entityType, new _NotifyPropertyChangedInterceptor(), typeof(INotifyPropertyChanged)) as IProxy; 17: 18: _NotifyPropertyChangedInterceptor interceptor = proxy.Interceptor as _NotifyPropertyChangedInterceptor; 19: interceptor.Proxy = this.session.SessionFactory.GetClassMetadata(entityType).Instantiate(id, entityMode); 20:  21: this.session.SessionFactory.GetClassMetadata(entityType).SetIdentifier(proxy, id, entityMode); 22:  23: return (proxy); 24: } 25: } Then we need a class that implements the NHibernate dynamic proxy behavior, let’s place it inside our interceptor, because it will only need to be used there: 1: class _NotifyPropertyChangedInterceptor : NHibernate.Proxy.DynamicProxy.IInterceptor 2: { 3: private PropertyChangedEventHandler changed = delegate { }; 4:  5: public Object Proxy 6: { 7: get; 8: set;} 9:  10: #region IInterceptor Members 11:  12: public Object Intercept(InvocationInfo info) 13: { 14: Boolean isSetter = info.TargetMethod.Name.StartsWith("set_") == true; 15: Object result = null; 16:  17: if (info.TargetMethod.Name == "add_PropertyChanged") 18: { 19: PropertyChangedEventHandler propertyChangedEventHandler = info.Arguments[0] as PropertyChangedEventHandler; 20: this.changed += propertyChangedEventHandler; 21: } 22: else if (info.TargetMethod.Name == "remove_PropertyChanged") 23: { 24: PropertyChangedEventHandler propertyChangedEventHandler = info.Arguments[0] as PropertyChangedEventHandler; 25: this.changed -= propertyChangedEventHandler; 26: } 27: else 28: { 29: result = info.TargetMethod.Invoke(this.Proxy, info.Arguments); 30: } 31:  32: if (isSetter == true) 33: { 34: String propertyName = info.TargetMethod.Name.Substring("set_".Length); 35: this.changed(this.Proxy, new PropertyChangedEventArgs(propertyName)); 36: } 37:  38: return (result); 39: } 40:  41: #endregion 42: } What this does for every interceptable method (those who are either virtual or from the INotifyPropertyChanged) is: For methods that came from the INotifyPropertyChanged interface, add_PropertyChanged and remove_PropertyChanged (yes, events are methods ), we add an implementation that adds or removes the event handlers to the delegate which we declared as changed; For all the others, we direct them to the place where they are actually implemented, which is the Proxy field; If the call is setting a property, it fires afterwards the PropertyChanged event. In order to use this, we need to add the interceptor to the Configuration before building the ISessionFactory: 1: using (ISessionFactory factory = cfg.SetInterceptor(new NotifyPropertyChangedInterceptor()).BuildSessionFactory()) 2: { 3: using (ISession session = factory.OpenSession()) 4: using (ITransaction tx = session.BeginTransaction()) 5: { 6: Customer customer = session.Get<Customer>(100); //some id 7: INotifyPropertyChanged inpc = customer as INotifyPropertyChanged; 8: inpc.PropertyChanged += delegate(Object sender, PropertyChangedEventArgs e) 9: { 10: //fired when a property changes 11: }; 12: customer.Address = "some other address"; //will raise PropertyChanged 13: customer.RecentOrders.ToList(); //will trigger the lazy loading 14: } 15: } Any problems, questions, do drop me a line!

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  • Entity Framework Code First: Get Entities From Local Cache or the Database

    - by Ricardo Peres
    Entity Framework Code First makes it very easy to access local (first level) cache: you just access the DbSet<T>.Local property. This way, no query is sent to the database, only performed in already loaded entities. If you want to first search local cache, then the database, if no entries are found, you can use this extension method: 1: public static class DbContextExtensions 2: { 3: public static IQueryable<T> LocalOrDatabase<T>(this DbContext context, Expression<Func<T, Boolean>> expression) where T : class 4: { 5: IEnumerable<T> localResults = context.Set<T>().Local.Where(expression.Compile()); 6:  7: if (localResults.Any() == true) 8: { 9: return (localResults.AsQueryable()); 10: } 11:  12: IQueryable<T> databaseResults = context.Set<T>().Where(expression); 13:  14: return (databaseResults); 15: } 16: }

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  • NHibernate Pitfalls: Loading Foreign Key Properties

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. When saving a new entity that has references to other entities (one to one, many to one), one has two options for setting their values: Load each of these references by calling ISession.Get and passing the foreign key; Load a proxy instead, by calling ISession.Load with the foreign key. So, what is the difference? Well, ISession.Get goes to the database and tries to retrieve the record with the given key, returning null if no record is found. ISession.Load, on the other hand, just returns a proxy to that record, without going to the database. This turns out to be a better option, because we really don’t need to retrieve the record – and all of its non-lazy properties and collections -, we just need its key. An example: 1: //going to the database 2: OrderDetail od = new OrderDetail(); 3: od.Product = session.Get<Product>(1); //a product is retrieved from the database 4: od.Order = session.Get<Order>(2); //an order is retrieved from the database 5:  6: session.Save(od); 7:  8: //creating in-memory proxies 9: OrderDetail od = new OrderDetail(); 10: od.Product = session.Load<Product>(1); //a proxy to a product is created 11: od.Order = session.Load<Order>(2); //a proxy to an order is created 12:  13: session.Save(od); So, if you just need to set a foreign key, use ISession.Load instead of ISession.Get.

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  • Vote of Disconfidence to Entity Framework

    - by Ricardo Peres
    A friend of mine has found the following problem with Entity Framework 4: Two simple classes and one association between them (one to many): One condition to filter out soft-deleted entities (WHERE Deleted = 0): 100 records in the database; A simple query: 1: var l = ctx.Person.Include("Address").Where(x => (x.Address.Name == "317 Oak Blvd." && x.Address.Number == 926) || (x.Address.Name == "891 White Milton Drive" && x.Address.Number == 497)); Will produce the following SQL: 1: SELECT 2: [Extent1].[Id] AS [Id], 3: [Extent1].[FullName] AS [FullName], 4: [Extent1].[AddressId] AS [AddressId], 5: [Extent202].[Id] AS [Id1], 6: [Extent202].[Name] AS [Name], 7: [Extent202].[Number] AS [Number] 8: FROM [dbo].[Person] AS [Extent1] 9: LEFT OUTER JOIN [dbo].[Address] AS [Extent2] ON ([Extent2].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent2].[Id]) 10: LEFT OUTER JOIN [dbo].[Address] AS [Extent3] ON ([Extent3].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent3].[Id]) 11: LEFT OUTER JOIN [dbo].[Address] AS [Extent4] ON ([Extent4].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent4].[Id]) 12: LEFT OUTER JOIN [dbo].[Address] AS [Extent5] ON ([Extent5].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent5].[Id]) 13: LEFT OUTER JOIN [dbo].[Address] AS [Extent6] ON ([Extent6].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent6].[Id]) 14: ... 15: WHERE ((N'317 Oak Blvd.' = [Extent2].[Name]) AND (926 = [Extent3].[Number])) 16: ... And will result in 680 MB of memory being taken! Now, Entity Framework has been historically known for producing less than optimal SQL, but 680 MB for 100 entities?! According to Microsoft, the problem will be addressed in the following version, there is a Connect issue open. There is even a whitepaper, Performance Considerations for Entity Framework 5, which talks about some of the changes and optimizations coming on version 5, but by reading it, I got even more concerned: “Once the cache contains a set number of entries (800), we start a timer that periodically (once-per-minute) sweeps the cache.” Say what?! The next version of Entity Framework will spawn timer threads?! When Code First came along, I thought it was a step in the right direction. Sure, it didn’t include some things that NHibernate did for quite some time – for example, different strategies for Id generation that do not rely on IDENTITY columns, which makes INSERT batching impossible, or support for enumerated types – but I thought these would come with the time. Now, enumerated types have, but so did… timer threads! I’m afraid Entity Framework is becoming a monster.

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  • Visual NHibernate Update

    - by Ricardo Peres
    I have previously talked about Visual NHibernate. It has grown since last time, now offering support for multiple databases (SQL Server, Oracle, MySQL, PostgreSQL, Firebird), generates projects from existing databases or from existing Visual Studio projects and produces XML or Fluent mappings, to name just a few. To me it is by far the most interesting tools for working with NHibernate I know of (granted, I haven't tried NHibernate Profiler). For a limited period, Slyce Software is offering a 30% discount, until the final version is released, so you may want to have a look. Please note that I am in no way related to Slyce, but made some feature requests which have been implemented (thanks, Gareth!).

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  • Pluggable Rules for Entity Framework Code First

    - by Ricardo Peres
    Suppose you want a system that lets you plug custom validation rules on your Entity Framework context. The rules would control whether an entity can be saved, updated or deleted, and would be implemented in plain .NET. Yes, I know I already talked about plugable validation in Entity Framework Code First, but this is a different approach. An example API is in order, first, a ruleset, which will hold the collection of rules: 1: public interface IRuleset : IDisposable 2: { 3: void AddRule<T>(IRule<T> rule); 4: IEnumerable<IRule<T>> GetRules<T>(); 5: } Next, a rule: 1: public interface IRule<T> 2: { 3: Boolean CanSave(T entity, DbContext ctx); 4: Boolean CanUpdate(T entity, DbContext ctx); 5: Boolean CanDelete(T entity, DbContext ctx); 6: String Name 7: { 8: get; 9: } 10: } Let’s analyze what we have, starting with the ruleset: Only has methods for adding a rule, specific to an entity type, and to list all rules of this entity type; By implementing IDisposable, we allow it to be cancelled, by disposing of it when we no longer want its rules to be applied. A rule, on the other hand: Has discrete methods for checking if a given entity can be saved, updated or deleted, which receive as parameters the entity itself and a pointer to the DbContext to which the ruleset was applied; Has a name property for helping us identifying what failed. A ruleset really doesn’t need a public implementation, all we need is its interface. The private (internal) implementation might look like this: 1: sealed class Ruleset : IRuleset 2: { 3: private readonly IDictionary<Type, HashSet<Object>> rules = new Dictionary<Type, HashSet<Object>>(); 4: private ObjectContext octx = null; 5:  6: internal Ruleset(ObjectContext octx) 7: { 8: this.octx = octx; 9: } 10:  11: public void AddRule<T>(IRule<T> rule) 12: { 13: if (this.rules.ContainsKey(typeof(T)) == false) 14: { 15: this.rules[typeof(T)] = new HashSet<Object>(); 16: } 17:  18: this.rules[typeof(T)].Add(rule); 19: } 20:  21: public IEnumerable<IRule<T>> GetRules<T>() 22: { 23: if (this.rules.ContainsKey(typeof(T)) == true) 24: { 25: foreach (IRule<T> rule in this.rules[typeof(T)]) 26: { 27: yield return (rule); 28: } 29: } 30: } 31:  32: public void Dispose() 33: { 34: this.octx.SavingChanges -= RulesExtensions.OnSaving; 35: RulesExtensions.rulesets.Remove(this.octx); 36: this.octx = null; 37:  38: this.rules.Clear(); 39: } 40: } Basically, this implementation: Stores the ObjectContext of the DbContext to which it was created for, this is so that later we can remove the association; Has a collection - a set, actually, which does not allow duplication - of rules indexed by the real Type of an entity (because of proxying, an entity may be of a type that inherits from the class that we declared); Has generic methods for adding and enumerating rules of a given type; Has a Dispose method for cancelling the enforcement of the rules. A (really dumb) rule applied to Product might look like this: 1: class ProductRule : IRule<Product> 2: { 3: #region IRule<Product> Members 4:  5: public String Name 6: { 7: get 8: { 9: return ("Rule 1"); 10: } 11: } 12:  13: public Boolean CanSave(Product entity, DbContext ctx) 14: { 15: return (entity.Price > 10000); 16: } 17:  18: public Boolean CanUpdate(Product entity, DbContext ctx) 19: { 20: return (true); 21: } 22:  23: public Boolean CanDelete(Product entity, DbContext ctx) 24: { 25: return (true); 26: } 27:  28: #endregion 29: } The DbContext is there because we may need to check something else in the database before deciding whether to allow an operation or not. And here’s how to apply this mechanism to any DbContext, without requiring the usage of a subclass, by means of an extension method: 1: public static class RulesExtensions 2: { 3: private static readonly MethodInfo getRulesMethod = typeof(IRuleset).GetMethod("GetRules"); 4: internal static readonly IDictionary<ObjectContext, Tuple<IRuleset, DbContext>> rulesets = new Dictionary<ObjectContext, Tuple<IRuleset, DbContext>>(); 5:  6: private static Type GetRealType(Object entity) 7: { 8: return (entity.GetType().Assembly.IsDynamic == true ? entity.GetType().BaseType : entity.GetType()); 9: } 10:  11: internal static void OnSaving(Object sender, EventArgs e) 12: { 13: ObjectContext octx = sender as ObjectContext; 14: IRuleset ruleset = rulesets[octx].Item1; 15: DbContext ctx = rulesets[octx].Item2; 16:  17: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Added)) 18: { 19: Object entity = entry.Entity; 20: Type realType = GetRealType(entity); 21:  22: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 23: { 24: if (rule.CanSave(entity, ctx) == false) 25: { 26: throw (new Exception(String.Format("Cannot save entity {0} due to rule {1}", entity, rule.Name))); 27: } 28: } 29: } 30:  31: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Deleted)) 32: { 33: Object entity = entry.Entity; 34: Type realType = GetRealType(entity); 35:  36: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 37: { 38: if (rule.CanDelete(entity, ctx) == false) 39: { 40: throw (new Exception(String.Format("Cannot delete entity {0} due to rule {1}", entity, rule.Name))); 41: } 42: } 43: } 44:  45: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Modified)) 46: { 47: Object entity = entry.Entity; 48: Type realType = GetRealType(entity); 49:  50: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 51: { 52: if (rule.CanUpdate(entity, ctx) == false) 53: { 54: throw (new Exception(String.Format("Cannot update entity {0} due to rule {1}", entity, rule.Name))); 55: } 56: } 57: } 58: } 59:  60: public static IRuleset CreateRuleset(this DbContext context) 61: { 62: Tuple<IRuleset, DbContext> ruleset = null; 63: ObjectContext octx = (context as IObjectContextAdapter).ObjectContext; 64:  65: if (rulesets.TryGetValue(octx, out ruleset) == false) 66: { 67: ruleset = rulesets[octx] = new Tuple<IRuleset, DbContext>(new Ruleset(octx), context); 68: 69: octx.SavingChanges += OnSaving; 70: } 71:  72: return (ruleset.Item1); 73: } 74: } It relies on the SavingChanges event of the ObjectContext to intercept the saving operations before they are actually issued. Yes, it uses a bit of dynamic magic! Very handy, by the way! So, let’s put it all together: 1: using (MyContext ctx = new MyContext()) 2: { 3: IRuleset rules = ctx.CreateRuleset(); 4: rules.AddRule(new ProductRule()); 5:  6: ctx.Products.Add(new Product() { Name = "xyz", Price = 50000 }); 7:  8: ctx.SaveChanges(); //an exception is fired here 9:  10: //when we no longer need to apply the rules 11: rules.Dispose(); 12: } Feel free to use it and extend it any way you like, and do give me your feedback! As a final note, this can be easily changed to support plain old Entity Framework (not Code First, that is), if that is what you are using.

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  • Lesser Known NHibernate Session Methods

    - by Ricardo Peres
    The NHibernate ISession, the core of NHibernate usage, has some methods which are quite misunderstood and underused, to name a few, Merge, Persist, Replicate and SaveOrUpdateCopy. Their purpose is: Merge: copies properties from a transient entity to an eventually loaded entity with the same id in the first level cache; if there is no loaded entity with the same id, one will be loaded and placed in the first level cache first; if using version, the transient entity must have the same version as in the database; Persist: similar to Save or SaveOrUpdate, attaches a maybe new entity to the session, but does not generate an INSERT or UPDATE immediately and thus the entity does not get a database-generated id, it will only get it at flush time; Replicate: copies an instance from one session to another session, perhaps from a different session factory; SaveOrUpdateCopy: attaches a transient entity to the session and tries to save it. Here are some samples of its use. ISession session = ...; AuthorDetails existingDetails = session.Get<AuthorDetails>(1); //loads an entity and places it in the first level cache AuthorDetails detachedDetails = new AuthorDetails { ID = existingDetails.ID, Name = "Changed Name" }; //a detached entity with the same ID as the existing one Object mergedDetails = session.Merge(detachedDetails); //merges the Name property from the detached entity into the existing one; the detached entity does not get attached session.Flush(); //saves the existingDetails entity, since it is now dirty, due to the change in the Name property AuthorDetails details = ...; ISession session = ...; session.Persist(details); //details.ID is still 0 session.Flush(); //saves the details entity now and fetches its id ISessionFactory factory1 = ...; ISessionFactory factory2 = ...; ISession session1 = factory1.OpenSession(); ISession session2 = factory2.OpenSession(); AuthorDetails existingDetails = session1.Get<AuthorDetails>(1); //loads an entity session2.Replicate(existingDetails, ReplicationMode.Overwrite); //saves it into another session, overwriting any possibly existing one with the same id; other options are Ignore, where any existing record with the same id is left untouched, Exception, where an exception is thrown if there is a record with the same id and LatestVersion, where the latest version wins SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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  • Local Entities with NHibernate

    - by Ricardo Peres
    You may know that Entity Framework Code First has a nice property called Local which lets you iterate through all the entities loaded by the current context (first level cache). This comes handy at times, so I decided to check if it would be difficult to have it on NHibernate. It turned out it is not, so here it is! Another nice addition to an NHibernate toolbox! public static class SessionExtensions { public static IEnumerable<T> Local<T>(this ISession session) { ISessionImplementor impl = session.GetSessionImplementation(); IPersistenceContext pc = impl.PersistenceContext; foreach (Object key in pc.EntityEntries.Keys) { if (key is T) { yield return ((T) key); } } } } //simple usage IEnumerable<Post> localPosts = session.Local<Post>(); SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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  • Checking if an Unloaded Collection Contains Elements

    - by Ricardo Peres
    If you want to know if an unloaded collection in an entity contains elements, or count them, without actually loading them, you need to use a custom query; that is because the Count property (if the collection is not mapped with lazy=”extra”) and the LINQ Count() and Any() methods force the whole collection to be loaded. You can use something like these two methods, one for checking if there are any values, the other for actually counting them: 1: public static Boolean Exists(this ISession session, IEnumerable collection) 2: { 3: if (collection is IPersistentCollection) 4: { 5: IPersistentCollection col = collection as IPersistentCollection; 6:  7: if (col.WasInitialized == false) 8: { 9: String[] roleParts = col.Role.Split('.'); 10: String ownerTypeName = String.Join(".", roleParts, 0, roleParts.Length - 1); 11: String ownerCollectionName = roleParts.Last(); 12: String hql = "select 1 from " + ownerTypeName + " it where it.id = :id and exists elements(it." + ownerCollectionName + ")"; 13: Boolean exists = session.CreateQuery(hql).SetParameter("id", col.Key).List().Count == 1; 14:  15: return (exists); 16: } 17: } 18:  19: return ((collection as IEnumerable).OfType<Object>().Any()); 20: } 21:  22: public static Int64 Count(this ISession session, IEnumerable collection) 23: { 24: if (collection is IPersistentCollection) 25: { 26: IPersistentCollection col = collection as IPersistentCollection; 27:  28: if (col.WasInitialized == false) 29: { 30: String[] roleParts = col.Role.Split('.'); 31: String ownerTypeName = String.Join(".", roleParts, 0, roleParts.Length - 1); 32: String ownerCollectionName = roleParts.Last(); 33: String hql = "select count(elements(it." + ownerCollectionName + ")) from " + ownerTypeName + " it where it.id = :id"; 34: Int64 count = session.CreateQuery(hql).SetParameter("id", col.Key).UniqueResult<Int64>(); 35:  36: return (count); 37: } 38: } 39:  40: return ((collection as IEnumerable).OfType<Object>().Count()); 41: } Here’s how: 1: MyEntity entity = session.Load(100); 2:  3: if (session.Exists(entity.SomeCollection)) 4: { 5: Int32 count = session.Count(entity.SomeCollection); 6: //... 7: }

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  • NHibernate Pitfalls: Lazy Scalar Properties Must Be Auto

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. NHibernate supports lazy properties not just for associations (many to one, one to one, one to many, many to many) but also for scalar properties. This allows, for example, only loading a potentially large BLOB or CLOB from the database if and when it is necessary, that is, when the property is actually accessed. In order for this to work, other than having to be declared virtual, the property can’t have an explicitly declared backing field, it must be an auto property: 1: public virtual String MyLongTextProperty 2: { 3: get; 4: set; 5: } 6:  7: public virtual Byte [] MyLongPictureProperty 8: { 9: get; 10: set; 11: } All lazy scalar properties are retrieved at the same time, when one of them is accessed.

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  • NHibernate Tools: Visual NHibernate

    - by Ricardo Peres
    You probably know that I’m a big fan of Slyce Software’s Visual NHibernate. To me, it is the best tool for generating your entities and mappings from an existing database (it also allows you to go the other way, but I honestly have never used it that way). What I like most about it: Great support: folks at Slyce always listen to your suggestions, give you feedback in a timely manner, and I was even lucky enough to have some of my suggestions implemented! The templating engine, which is very powerful, and more user-friendly than, for example, MyGeneration’s; one of the included templates is Sharp Architecture; Advanced model validations: it even warns you about having lazy properties declared in non-lazy entities; Integration with NHibernate Validator and generation of validation rules automatically based on the database, or on user-defined model settings; The designer: they opted for not displaying all entities in a single screen, which I think was a good decision; has support for all inheritance strategies (table per class hierarchy, table per class, table per concrete class); Generation of FluentNHibernate mappings as well as hbm.xml. I could name others, but… why don’t you see for yourself? There is a demo version available for downloading. By the way, I am in no way related to Slyce, I just happen to like their software!

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  • NHibernate Pitfalls Index

    - by Ricardo Peres
    These are the posts on NHibernate pitfalls I’ve written so far. This post will be updated whenever there are more. The SaveOrUpdate Event Collection Restrictions Specifying Event Listeners in XML Configuration Many to Many and Inverse Bags and Join Lazy Properties in Non-Lazy Entities Adding to a Bag Causes Loading Flushing Changes Private Setter on Id Property

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  • NHibernate Pitfalls: Custom Types and Detecting Changes

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. NHibernate supports the declaration of properties of user-defined types, that is, not entities, collections or primitive types. These are used for mapping a database columns, of any type, into a different type, which may not even be an entity; think, for example, of a custom user type that converts a BLOB column into an Image. User types must implement interface NHibernate.UserTypes.IUserType. This interface specifies an Equals method that is used for comparing two instances of the user type. If this method returns false, the entity is marked as dirty, and, when the session is flushed, will trigger an UPDATE. So, in your custom user type, you must implement this carefully so that it is not mistakenly considered changed. For example, you can cache the original column value inside of it, and compare it with the one in the other instance. Let’s see an example implementation of a custom user type that converts a Byte[] from a BLOB column into an Image: 1: [Serializable] 2: public sealed class ImageUserType : IUserType 3: { 4: private Byte[] data = null; 5: 6: public ImageUserType() 7: { 8: this.ImageFormat = ImageFormat.Png; 9: } 10: 11: public ImageFormat ImageFormat 12: { 13: get; 14: set; 15: } 16: 17: public Boolean IsMutable 18: { 19: get 20: { 21: return (true); 22: } 23: } 24: 25: public Object Assemble(Object cached, Object owner) 26: { 27: return (cached); 28: } 29: 30: public Object DeepCopy(Object value) 31: { 32: return (value); 33: } 34: 35: public Object Disassemble(Object value) 36: { 37: return (value); 38: } 39: 40: public new Boolean Equals(Object x, Object y) 41: { 42: return (Object.Equals(x, y)); 43: } 44: 45: public Int32 GetHashCode(Object x) 46: { 47: return ((x != null) ? x.GetHashCode() : 0); 48: } 49: 50: public override Int32 GetHashCode() 51: { 52: return ((this.data != null) ? this.data.GetHashCode() : 0); 53: } 54: 55: public override Boolean Equals(Object obj) 56: { 57: ImageUserType other = obj as ImageUserType; 58: 59: if (other == null) 60: { 61: return (false); 62: } 63: 64: if (Object.ReferenceEquals(this, other) == true) 65: { 66: return (true); 67: } 68: 69: return (this.data.SequenceEqual(other.data)); 70: } 71: 72: public Object NullSafeGet(IDataReader rs, String[] names, Object owner) 73: { 74: Int32 index = rs.GetOrdinal(names[0]); 75: Byte[] data = rs.GetValue(index) as Byte[]; 76: 77: this.data = data as Byte[]; 78: 79: if (data == null) 80: { 81: return (null); 82: } 83: 84: using (MemoryStream stream = new MemoryStream(this.data ?? new Byte[0])) 85: { 86: return (Image.FromStream(stream)); 87: } 88: } 89: 90: public void NullSafeSet(IDbCommand cmd, Object value, Int32 index) 91: { 92: if (value != null) 93: { 94: Image data = value as Image; 95: 96: using (MemoryStream stream = new MemoryStream()) 97: { 98: data.Save(stream, this.ImageFormat); 99: value = stream.ToArray(); 100: } 101: } 102: 103: (cmd.Parameters[index] as DbParameter).Value = value ?? DBNull.Value; 104: } 105: 106: public Object Replace(Object original, Object target, Object owner) 107: { 108: return (original); 109: } 110: 111: public Type ReturnedType 112: { 113: get 114: { 115: return (typeof(Image)); 116: } 117: } 118: 119: public SqlType[] SqlTypes 120: { 121: get 122: { 123: return (new SqlType[] { new SqlType(DbType.Binary) }); 124: } 125: } 126: } In this case, we need to cache the original Byte[] data because it’s not easy to compare two Image instances, unless, of course, they are the same.

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  • NHibernate Pitfalls: Cascades

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. For entities that have associations – one-to-one, one-to-many, many-to-one or many-to-many –, NHibernate needs to know what to do with their related entities, in three particular moments: when saving, updating or deleting. In particular, there are two possible behaviors: either ignore these related entities or cascade changes to them. NHibernate allows setting the cascade behavior for each association, and the default behavior is not to cascade (ignore). The possible cascade options are: None Ignore, this is the default Save-Update If the entity is being saved or updated, also save any related entities that are either not saved or have been modified and associate these related entities to the root entity. Generally safe Delete If the entity is being deleted, also delete the related entities. This is only useful for parent-child relations Delete-Orphan Identical to Delete, with the addition that if once related entity is removed from the association – orphaned –, also delete it. Also only for parent-child All Combination of Save-Update and Delete, usually that’s what we want (for parent-child relations, of course) All-Delete-Orphan Same as All plus delete any related entities who lose their relationship In summary, Save-Update is generally what you want in most cases. As for the Delete variations, they should only be used if the related entities depend on the root entity (parent-child), so that deleting the root entity and not their related entities would result in a constraint violation on the database.

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  • NHibernate Pitfalls: Private Setter on Id Property

    - by Ricardo Peres
    Having a private setter on an entity’s id property may seem tempting: in most cases, unless you are using id generators assigned or foreign, you never have to set its value directly. However, keep this in mind: If your entity is lazy and you want to prevent people from setting its value, make the setter protected instead of private, because it will need to be accessed from subclasses of your entity (generated by NHibernate); If you use stateless sessions, you can perform some operations which, on regular sessions, require you to load an entity, without doing so, for example: 1: using (IStatelessSession session = factory.OpenStatelessSession()) 2: { 3: //delete without first loading 4: session.Delete(new Customer { Id = 1 }); 5:  6: //insert without first loading 7: session.Insert(new Order { Customer = new Customer { Id = 1 }, Product = new Product { Id = 1 } }); 8:  9: //update without first loading 10: session.Update(new Order{ Id = 1, Product = new Product{ Id = 2 }}) 11: }

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  • Can I recover a rm -rf-ed Mercurial repository?

    - by WishCow
    I made the mistake of wiping out my entire project directory with a quick "rm -rf project". Of course, the .hg directory went with it. I had about 15-20 changesets, that I have not pushed to anyone, and I would really really like to get those back. The system is a Ubuntu machine, and the partiton where the delete happened is ext3, the project consist mostly of PHP files. I know about the guideline to not write to the disk in question. The first idea was to use the tool named scalpel, to get the PHP files back and diff them with the current version from the repo, and somehow carve the changes out. While it succeeded, it did not recover the file names (or there is a switch I'm missing), so I'm left with a few thousand sequentially named .php files, combing through them is not an option. Can a kind soul please save me, and suggest a way to: a) get the repo back, or b) get the files back, with filenames For those wondering how I did such a stupid thing: I was working on a file in Vim which I wanted to remove from the repository: :!hg rm % This complained that the file is in a subrepository, so I specified the following: :!hg rm % -R engine which complained that file has modifications, use -f to force. And this is when somehow, I made up the following command: :!rm -rf % -R engine Somehow, seeing "force" makes me do a rm -rf by reflex.

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  • How to make `rm` faster on ext3/linux?

    - by depesz
    I have ext3 filesystem mounted with default options. On it I have some ~ 100GB files. Removal of any of such files takes long time (8 minutes) and causes a lot of io traffic, which increases load on server. Is there any way to make the rm not as disruptive?

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  • Cron Job on Ubuntu Hardy Executing But Not Deleting Files As Expected

    - by Patrick McKenzie
    I have a bit of a pickle here and wonder if anyone can give me some pointers: I have a cron job which executes for a particular user daily and is supposed to sweep files in a particular directory. Technically, it is two jobs. I've turned on cron.log to verify they're actually executing, and they are: May 24 11:03:01 AppNameGoesHere /USR/SBIN/CRON[11257]: (mongrel_AppNameGoesHere) CMD (rm -rf /var/www/apps/AppNameGoesHere/current/public/ {popular,index,purchasing,purchasing-alternate,support,about-us,guarantee,screenshots}.htm{,l}) May 24 11:04:01 AppNameGoesHere /USR/SBIN/CRON[11260]: (mongrel_AppNameGoesHere) CMD (rm -rf /var/www/apps/AppNameGoesHere/current/public/ {stats,popular,bcf,articles,expenses}) I have removed the actual usernames and formatted it so that it is less ugly on StackOverflow. Now, my question: Despite the fact that I can see these deletions executing and apparently succeeding in the log, if I go to the specified directory, the files are still there. I initially suspected permission hijinx were going on, but I've verified that I can delete the files manually by su-ing into the mongrel_AppNameGoesHere user and issuing individual rm commands or by copy/pasting the cron job to the command line. Anything that I don't manually zap stays unzapped despite days of that cron job executing successfully. Any suggestions on to what might be happening? I was previously using Dapper Drake with these cron jobs in the /etc/crontab file directly, and when I upgraded to Hardy I moved them to user-specific crontabs (via sudo crontab -e - u mongrel_AppNameGoesHere), which was the point where they appear to have stopped working.)

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  • Effect of HOME on libreoffice to convert to pdf as non-root user

    - by user1032531
    I installed libreoffice-headless and can convert documents when logged on as root. I then tried doing so as another user, and it didn't show an error, but didn't convert the file. I then found that if I get rid of the HOME=/tmp/ayb, it works with the other user. Doesn't HOME=/tmp/ayb just allow files to default to this directory if not specified? (Sorry, I tried to search "Linux HOME", but as you probably expect, received a bunch of non-relevant results). If not, what is the purpose of specifying HOME? Why does setting HOME prevent it from converting on non-root users? Note that /tmp and /tmp/ayb or both 0777. Thank you [root@desktop ~]# yum install libreoffice-headless [root@desktop ~]# yum install libreoffice-writer [root@desktop ~]# ls -l total 48 -rwxrwxrwx. 1 NotionCommotion NotionCommotion 48128 Jul 30 02:38 document_34.doc [root@desktop ~]# HOME=/tmp/ayb; /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc convert /tmp/ayb/document_34.doc -> /tmp/ayb/document_34.pdf using writer_pdf_Export [root@desktop ~]# rm d*.pdf rm: remove regular file `document_34.pdf'? y [root@desktop ~]# /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc convert /tmp/ayb/document_34.doc -> /tmp/ayb/document_34.pdf using writer_pdf_Export [root@desktop ~]# rm d*.pdf rm: remove regular file `document_34.pdf'? y [root@desktop ~]# su NotionCommotion sh-4.1$ HOME=/tmp/ayb; /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc sh-4.1$ rm d*.pdf rm: cannot remove `d*.pdf': No such file or directory sh-4.1$ /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc sh-4.1$ rm d*.pdf rm: cannot remove `d*.pdf': No such file or directory sh-4.1$ exit exit [root@desktop ~]# su NotionCommotion sh-4.1$ /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc convert /tmp/ayb/document_34.doc -> /tmp/ayb/document_34.pdf using writer_pdf_Export sh-4.1$ rm d*.pdf sh-4.1$ HOME=/tmp/ayb; /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc sh-4.1$ rm d*.pdf rm: cannot remove `d*.pdf': No such file or directory sh-4.1$ /usr/bin/libreoffice --headless -convert-to pdf --outdir /tmp/ayb /tmp/ayb/document_34.doc sh-4.1$ rm d*.pdf rm: cannot remove `d*.pdf': No such file or directory sh-4.1$

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  • How to simply remove everything from a directory on Linux

    - by Tometzky
    How to simply remove everything from a current or specified directory on Linux? Several approaches: rm -fr * rm -fr dirname/* Does not work — it will leave hidden files — the one's that start with a dot, and files starting with a dash in current dir, and will not work with too many files rm -fr -- * rm -fr -- dirname/* Does not work — it will leave hidden files and will not work with too many files rm -fr -- * .* rm -fr -- dirname/* dirname/.* Don't try this — it will also remove a parent directory, because ".." also starts with a "." rm -fr * .??* rm -fr dirname/* dirname/.??* Does not work — it will leave files like ".a", ".b" etc., and will not work with too many files find -mindepth 1 -maxdepth 1 -print0 | xargs -0 rm -fr find dirname -mindepth 1 -maxdepth 1 -print0 | xargs -0 rm -fr As far as I know correct but not simple. find -delete find dirname -delete AFAIK correct for current directory, but used with specified directory will delete that directory also. find -mindepth 1 -delete find dirname -mindeph 1 -delete AFAIK correct, but is it the simplest way?

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