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• How do I query through a many-to-many relationship using NHibernate Criteria and Lambda Extensions?

  - by Brian Kendig

  In my database I have a Person table and an Event table (parties, meetings, &c.). This many-to-many relationship is represented through an Invitation table. Each Person can have many Invitations. Each Event can also have many Invitations. If I want a list of Events to which a Person is invited, I can use this HQL query: IQuery query = Session.CreateQuery("SELECT i.Event from Invitation i where i.Person = :p"); query.SetParameter("p", person); return query.List<Person>(); How would I write this query with NHibernate criteria and Lambda Extensions?

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• NHibernate: Can I access a generated primary key after saving a model?

  - by littlecharva

  Howdy, So I've got a simple table with an ID field that's incrementally generated on INSERT. I've set the mapping up in NHibernate to reflect this: <id name="ID"> <generator class="identity" /> </id> And it all works fine. Trouble is, I need to get the generated ID after I've saved a new model to use elsewhere: var model = new MyModel(); session.SaveOrUpdate(model); But at this stage model.ID == null, not the ID. Any ideas? Anthony

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• What is the "Entity" reffering to in fluent Nhibernate Mapping Configuration?

  - by percent20

  I am trying to learn fluent nhibernate better so am doing a basic sample application from scratch, instead of using someone elses framework. However, I am finding I really don't understand what is going on in assigning mapping files. I have seen a lot of code examples which are all showing the same code, but nothing that spells it out. No description of how it works just that it works. Here is a code example that I see often. return Fluently.Configure() .Database(config) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<Entity>()) .BuildSessionFactory(); So in the code example what is Entity? and how does that piece of code work? Part of me thinks it is the name of the assembly, but seeing as how the namespace I am using is usually the name of the assembly the compiler complains that I am using a namespace as a type. I feel this is important and am rather flustered by the fact I can't figure it out. Thanks

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• Can Fluent NHibernate be configured to use an arbitrary prefix on a property backing field?

  - by dommer

  I'm currently using a convention to (auto)map collection properties to backing fields in Fluent NHibernate. So, I map a property "Orders" to a field "_orders". The convention I'm using to do this is: public class HasManyAccessConvention : IHasManyConvention { public void Apply(IOneToManyCollectionInstance instance) { instance.Access.CamelCaseField(CamelCasePrefix.Underscore); } } Can I write a convention that maps a (collection) property to a field with a non-standard prefix (ignoring whether this is good coding practice for the present)? So, the property "Orders" would be mapped to "xyz_orders", for example. If so, how would I go about this?

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• Improving the performance of an nHibernate Data Access Layer.

  - by Amitabh

  I am working on improving the performance of DataAccess Layer of an existing Asp.Net Web Application. The scenerios are. Its a web based application in Asp.Net. DataAccess layer is built using NHibernate 1.2 and exposed as WCF Service. The Entity class is marked with DataContract. Lazy loading is not used and because of the eager-fetching of the relations there is huge no of database objects are loaded in the memory. No of hits to the database is also high. For example I profiled the application using NHProfiler and there were about 50+ sql calls to load one of the Entity object using the primary key. I also can not change code much as its an existing live application with no NUnit test cases at all. Please can I get some suggestions here?

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• how to force nhibernate to set the foreign key of the child item?

  - by npeBeg

  i have a collection in the mapping: <bag name="Values" cascade="all-delete-orphan" lazy="false" inverse="true"> <key column="[TemplateId]"/> <one-to-many class="MyNamespace.Value, MyLib"/> </bag> the Value object has a foreign key [TemplateId]. both entities has their generator set to "identity". when i call session.Save() for the parent Template object, the Value objects has their [TemplateId] (the foreign key) set to zero, so an SQL exception appears. how do i forse nhibernate to set the FK value for the child items to the value of the inserted parent object?

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• NHibernate will insert but not update after move to host with shared server running mysql.

  - by Andy LifeBrixx

  Hi, I have a site running MVC and Nhibernate (not fluent) using standard session per request in an http module, runs fine locally (also with mysql) but after a move to a hosting provider no update statements are being issued. I can insert but not update, no exceptions are raised, I have the 'show_sql' option switched on which locally shows the update statements being issued but on the server no update statements are logged. I don't think NHProf is an option for me as I can only run asp.net apps on my shared server, are there any other methods of diagnosing NH issues like this ? Anyone had a similar issue ? Cheers, A

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• Mapping Object Relationships - QuickStart with NHibernate (Part 3)

  - by BobPalmer

  For this third tutorial, we'll be introducing users new to NHibernat to basic object relationships, starting with a simple many-to-one relationship.  I decided that it would make sense to at least get the readers through some basic relationship mapping (including varieties of parent/child and many to many relationships) before diverging into UI, since most folks are looking for enough to bootstrap themsevles into using NHibernate, and this almost always means some kind of relation between their objects. You can find a link to the article at: http://docs.google.com/Doc?docid=0AUP-rKyyUMKhZGczejdxeHZfMjJmM3c3M3Bnbg&hl=en As always, comments, corrections, and suggestions are appreciated! -Bob

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• Registration to NHibernate Day opens at 3:15pm CET

  Today the registration to the first European NHibernate Day opens, at 3:15pm CET (2:15pm in London). We setup a countdown on the NHDay.eu website that will redirect you to the registration page at the precise moment the registration opens. But remember that there are only 220 seats available, and last time we finished them all in less than one day. If you are not decided yet, here are some facts that can help you decide: the event is donation based, so no fixed entry fee. Ayende and Steve...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• DDD/NHibernate Use of Aggregate root and impact on web design - ex. Editing children of aggregate ro

  - by pbrophy

  Hopefully, this fictitious example will illustrate my problem: Suppose you are writing a system which tracks complaints for a software product, as well as many other attributes about the product. In this case the SoftwareProduct is our aggregate root and Complaints are entities that only can exist as a child of the product. In other words, if the software product is removed from the system, so shall the complaints. In the system, there is a dashboard like web page which displays many different aspects of a single SoftwareProduct. One section in the dashboard, displays a list of Complaints in a grid like fashion, showing only some very high level information for each complaint. When an admin type user chooses one of these complaints, they are directed to an edit screen which allows them to edit the detail of a single Complaint. The question is: what is the best way for the edit screen to retrieve the single Complaint, so that it can be displayed for editing purposes? Keep in mind we have already established the SoftwareProduct as an aggregate root, therefore direct access to a Complaint should not be allowed. Also, the system is using NHibernate, so eager loading is an option, but my understanding is that even if a single Complaint is eager loaded via the SoftwareProduct, as soon as the Complaints collection is accessed the rest of the collection is loaded. So, how do you get the single Complaint through the SoftwareProduct without incurring the overhead of loading the entire Complaints collection?

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• Automatic .NET code, nhibernate session, and LINQ datacontext clean-up?

  - by AverageJoe719

  Hi all, in my goal to adopt better coding practices I have a few questions in general about automatic handling of code. I have heard different answers both from online and talking with other developers/programmers at my work. I am not sure if I should have split them into 3 questions, but they all seem sort of related: 1) How does .NET handle instances of classes and other code things that take up memory? I recently found out about using the factory pattern for certain things like service classes so that they are only instantiated once in the entire application, but then I was told that '.NET handles a lot of that stuff automatically when mentioning it.' 2) How does Nhibernate's session handle automatic clean-up of un-used things? I've seen some say that it is great at handling things automatically and you should just use a session factory and that's it, no need to close it. But I have also read and seem many examples where people close the hibernate session. 3) How does LINQ's datacontext handle this? Most of the time I never .disposed my datacontext's and the app didn't see to take a performance hit (though I am not running anything super intensively), but it seems like most people recommend disposing of your datacontext after you are done with it. However, I have seen many many code examples where the dispose method is never called. Also in general I found it kind of annoying that you couldn't access even one-deep child related objects after disposing of the datacontext unless you explicity also grabbed them in the query. Thanks all. I am loving this site so far, I kind of get lost and spend hours just reading things on here. =)

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• How to migrate primary key generation from "increment" to "hi-lo"?

  - by Bevan

  I'm working with a moderate sized SQL Server 2008 database (around 120 tables, backups are around 4GB compressed) where all the table primary keys are declared as simple int columns. At present, primary key values are generated by NHibernate with the increment identity generator, which has worked well thus far, but precludes moving to a multiprocessing environment. Load on the system is growing, so I'm evaluating the work required to allow the use of multiple servers accessing a common database backend. Transitioning to the hi-lo generator seems to be the best way forward, but I can't find a lot of detail about how such a migration would work. Will NHibernate automatically create rows in the hi-lo table for me, or do I need to script these manually? If NHibernate does insert rows automatically, does it properly take account of existing key values? If NHibernate does take care of thing automatically, that's great. If not, are there any tools to help? Update NHibernate's increment identifier generator works entirely in-memory. It's seeded by selecting the maximum value of used identifiers from the table, but from that point on allocates new values by a simple increment, without reference back to the underlying database table. If any other process adds rows to the table, you end up with primary key collisions. You can run multiple threads within the one process just fine, but you can't run multiple processes. For comparison, the NHibernate identity generator works by configuring the database tables with identity columns, putting control over primary key generation in the hands of the database. This works well, but compromises the unit of work pattern. The hi-lo algorithm sits inbetween these - generation of primary keys is coordinated through the database, allowing for multiprocessing, but actual allocation can occur entirely in memory, avoiding problems with the unit of work pattern.

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• In Fluent NHibernate, how would I map the following domain models?

  - by Brandon

  I have a user class that looks something like this public class User { public virtual int Id { get; set; } public virtual long ValueA { get; set; } public virtual int? ValueB { get; set; } } ValueA is automatically assigned by the system. It is used in a lookup that would map to UserClass. However, if a value for ValueB exists, then it would do the lookup for UserClass in a different way. Right now the way I handle it is to get the User and then perform a separate lookup each time. return user.ValueB.HasValue ? Find(user.ValueB.Value) : Find(user.ValueA); Is there any way to make Fluent NHibernate do this for me so I can have UserClass as a property on the User class instead of having to do the lookup separately? I was thinking of the ComponentMap but I'm not sure how to make it account for the two possible lookup values.

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• Get Nhibernate entity and complete it from a web service.

  - by Nour Sabouny

  Hi every one. let's say that i have an order system. each "Order" references a "Customer" Object. when i fill the orders list in Data Access Layer, the customer object should be brought from a Customer Web Service "WCF". so i didn't map the Customer property in the Order mapping class, Id(o => o.OrderID).GeneratedBy.Identity(); //References(o => o.Customer).Not.Nullable().Column("CustomerID"); HasMany(o => o.Details).KeyColumn("OrderID").Cascade.AllDeleteOrphan(); Map(c => c.CustomerID).Not.Nullable(); and asked the nhibernate session to get me the orders list. and tried to loop on every order in the list to fill it's customer property, doe's any body have a good idea for this ???? IList<Order> lst = Session.CreateCriteria<Order>().List<Order>(); foreach (Order order in lst) order.Customer = serviceProxy.GetCustomerByID(order.CustomerID);

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• How do I serialize/deserialize a NHibernate entity that has references to other objects?

  - by Daniel T.

  I have two NHibernate-managed entities that have a bi-directional one-to-many relationship: public class Storage { public virtual string Name { get; set; } public virtual IList<Box> Boxes { get; set; } } public class Box { public virtual string Box { get; set; } [DoNotSerialize] public virtual Storage ParentStorage { get; set; } } A Storage can contain many Boxes, and a Box always belongs in a Storage. I want to edit a Box's name, so I send it to the client using JSON. Note that I don't serialize ParentStorage because I'm not changing which storage it's in. The client edits the name and sends the Box back as JSON. The server deserializes it back into a Box entity. Problem is, the ParentStorage property is null. When I try to save the Box to the database, it updates the name, but also removes the relationship to the Storage. How do I properly serialize and deserialize an entity like a Box, while keeping the JSON data size to a minimum?

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• Can I set NHibernate's default "OrderBy" to be "CreatedDate" not "Id"?

  - by Chris F

  This is an oddball question I figure. Can I get NHibernate to ask SQL to sort data by CreatedDate by default unless I set an OrderBy in my HQL or Criteria? I'm interested in knowing whether this sort can be accomplished at the DB level to avoid bringing in LINQ. The reason is that I use GUIDs for Ids and when I do something like this: Sheet sheet = sheetRepository.Get(_someGUID); IList<SheetLineItems> lineItems = sheet.LineItems; to fetch all of the lineItems, they come back in whatever arbitrary way that SQL sorts that fetch, which I figure is GUID. At some point I'll add ordinals to my line items, but for now, I just want to use CreatedDate as the sort criteria. I don't want to be forced to do: IList<SheetLineItem> lineItems = sheetLineItemRepository.GetAll(_sheetGUID); and then writing that method to sort by CreatedDate. I figure if everything is just sorted on CreatedDate by default, that would be fine, unless specifically requested otherwise.

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• How can I provide values for non-grouped columns in NHibernate?

  - by ddc0660

  I have a criteria query: Session.CreateCriteria<Sell043Report>() .SetProjection(.ProjectionList() .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.location)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.agent)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.cusip)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.SettlementDate)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.salePrice)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.foreignFx)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.batchNumber)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.origSaleDate)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.planName)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.dateTimeAdded)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.shares)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.netMoney)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.grossMoney)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.taxWithheld)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.fees))) .List<Sell043Report>(); that generates the following SQL: SELECT this_.location as y0_, this_.agent as y1_, this_.cusip as y2_, this_.SettlementDate as y3_, this_.salePrice as y4_, this_.foreignFx as y5_, this_.batchNumber as y6_, this_.origSaleDate as y7_, this_.planName as y8_, this_.dateTimeAdded as y9_, sum(this_.shares) as y10_, sum(this_.netMoney) as y11_, sum(this_.grossMoney) as y12_, sum(this_.taxWithheld) as y13_, sum(this_.fees) as y14_ FROM MIS_IPS_Sell043Report this_ GROUP BY this_.location, this_.agent, this_.cusip, this_.SettlementDate, this_.salePrice, this_.foreignFx, this_.batchNumber, this_.origSaleDate, this_.planName, this_.dateTimeAdded however the Sell043Report table has additional columns than those listed in the SELECT statement so I'm receiving this error when attempting to get a list of Sell043Reports: System.ArgumentException: The value "System.Object[]" is not of type "xyz.Sell043Report" and cannot be used in this generic collection. I suspect the problem is that I'm not selecting all of the columns for a Sell043Report and so it doesn't know how to map the dataset to the object. I'm trying to achieve something like this: SELECT this_.location as y0_, this_.agent as y1_, this_.cusip as y2_, this_.SettlementDate as y3_, this_.salePrice as y4_, this_.foreignFx as y5_, this_.batchNumber as y6_, this_.origSaleDate as y7_, this_.planName as y8_, this_.dateTimeAdded as y9_, sum(this_.shares) as y10_, sum(this_.netMoney) as y11_, sum(this_.grossMoney) as y12_, sum(this_.taxWithheld) as y13_, sum(this_.fees) as y14_, '' as Address1, '' as Address2 // etc FROM MIS_IPS_Sell043Report this_ GROUP BY this_.location, this_.agent, this_.cusip, this_.SettlementDate, this_.salePrice, this_.foreignFx, this_.batchNumber, this_.origSaleDate, this_.planName, this_.dateTimeAdded How can I do this using NHibernate?

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• Multiple collections tied to one base collection with filters and eventing

  - by damienc88

  I have a complex model served from my back end, which has a bunch of regular attributes, some nested models, and a couple of collections. My page has two tables, one for invalid items, and one for valid items. The items in question are from one of the nested collections. Let's call it baseModel.documentCollection, implementing DocumentsCollection. I don't want any filtration code in my Marionette.CompositeViews, so what I've done is the following (note, duplicated for the 'valid' case): var invalidDocsCollection = new DocumentsCollection( baseModel.documentCollection.filter(function(item) { return !item.isValidItem(); }) ); var invalidTableView = new BookIn.PendingBookInRequestItemsCollectionView({ collection: app.collections.invalidDocsCollection }); layout.invalidDocsRegion.show(invalidTableView); This is fine for actually populating two tables independently, from one base collection. But I'm not getting the whole event pipeline down to the base collection, obviously. This means when a document's validity is changed, there's no neat way of it shifting to the other collection, therefore the other view. What I'm after is a nice way of having a base collection that I can have filter collections sit on top of. Any suggestions?

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• how to add a Client in SCCM system collections

  - by user29845

  Hi, I am building a new sccm client VM. My only doubt is how to add the system name of the client to all systems collections before building the OS. Many Thanks in advance. :) Kind Regards, Yuvi

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• Shallow Copy vs DeepCopy in C#.NET

  Hope below example helps to understand the difference. Please drop a comment if any doubts. using System; using System.IO; using System.Runtime.Serialization.Formatters.Binary; namespace ShallowCopyVsDeepCopy {     class Program     {         static void Main(string[] args)         {             var e1 = new Emp { EmpNo = 10, EmpName = "Smith", Department = new Dep { DeptNo = 100, DeptName = "Finance" } };             var e2 = e1.ShallowClone();             e1.Department.DeptName = "Accounts";             Console.WriteLine(e2.Department.DeptName);             var e3 = new Emp { EmpNo = 10, EmpName = "Smith", Department = new Dep { DeptNo = 100, DeptName = "Finance" } };             var e4 = e3.DeepClone();             e3.Department.DeptName = "Accounts";             Console.WriteLine(e4.Department.DeptName);         }     }     [Serializable]     class Dep     {         public int DeptNo { get; set; }         public String DeptName { get; set; }     }     [Serializable]     class Emp     {         public int EmpNo { get; set; }         public String EmpName { get; set; }         public Dep Department { get; set; }         public Emp ShallowClone()         {             return (Emp)this.MemberwiseClone();         }         public Emp DeepClone()         {             MemoryStream ms = new MemoryStream();             BinaryFormatter bf = new BinaryFormatter();             bf.Serialize(ms, this);             ms.Seek(0, SeekOrigin.Begin);             object copy = bf.Deserialize(ms);             ms.Close();             return copy as Emp;         }     } } span.fullpost {display:none;}

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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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• Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

  - by Motti Strom

  Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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• Shallow Copy vs DeepCopy in C#.NET

  Hope below example helps to understand the difference. Please drop a comment if any doubts. using System; using System.IO; using System.Runtime.Serialization.Formatters.Binary; namespace ShallowCopyVsDeepCopy {     class Program     {         static void Main(string[] args)         {             var e1 = new Emp { EmpNo = 10, EmpName = "Smith", Department = new Dep { DeptNo = 100, DeptName = "Finance" } };             var e2 = e1.ShallowClone();             e1.Department.DeptName = "Accounts";             Console.WriteLine(e2.Department.DeptName);             var e3 = new Emp { EmpNo = 10, EmpName = "Smith", Department = new Dep { DeptNo = 100, DeptName = "Finance" } };             var e4 = e3.DeepClone();             e3.Department.DeptName = "Accounts";             Console.WriteLine(e4.Department.DeptName);         }     }     [Serializable]     class Dep     {         public int DeptNo { get; set; }         public String DeptName { get; set; }     }     [Serializable]     class Emp     {         public int EmpNo { get; set; }         public String EmpName { get; set; }         public Dep Department { get; set; }         public Emp ShallowClone()         {             return (Emp)this.MemberwiseClone();         }         public Emp DeepClone()         {             MemoryStream ms = new MemoryStream();             BinaryFormatter bf = new BinaryFormatter();             bf.Serialize(ms, this);             ms.Seek(0, SeekOrigin.Begin);             object copy = bf.Deserialize(ms);             ms.Close();             return copy as Emp;         }     } } span.fullpost {display:none;}

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• How can a collection class instantiate many objects with one database call?

  - by Buttle Butkus

  I have a baseClass where I do not want public setters. I have a load($id) method that will retrieve the data for that object from the db. I have been using static class methods like getBy($property,$values) to return multiple class objects using a single database call. But some people say that static methods are not OOP. So now I'm trying to create a baseClassCollection that can do the same thing. But it can't, because it cannot access protected setters. I don't want everyone to be able to set the object's data. But it seems that it is an all-or-nothing proposition. I cannot give just the collection class access to the setters. I've seen a solution using debug_backtrace() but that seems inelegant. I'm moving toward just making the setters public. Are there any other solutions? Or should I even be looking for other solutions?

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• ArrayList in Java [on hold]

  - by JNL

  I was implementing a program to remove the duplicates from the 2 character array. I implemented these 2 solutions, Solution 1 worked fine, but Solution 2 given me UnSupportedoperationException. I am wonderring why i sthat so? The two solutions are given below; public void getDiffernce(Character[] inp1, Character[] inp2){ // Solution 1: // ********************************************************************************** List<Character> list1 = new ArrayList<Character>(Arrays.asList(inp1)); List<Character> list2 = new ArrayList<Character>(Arrays.asList(inp2)); list1.removeAll(list2); System.out.println(list1); System.out.println("*********************************************************************************"); // Solution 2: Character a[] = {'f', 'x', 'l', 'b', 'y'}; Character b[] = {'x', 'b','d'}; List<Character> al1 = new ArrayList<Character>(); List<Character> al2 = new ArrayList<Character>(); al1 = (Arrays.asList(a)); System.out.println(al1); al2 = (Arrays.asList(b)); System.out.println(al2); al1.removeAll(al2); // retainAll(al2); System.out.println(al1); }

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