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• Exemplars of large document-centric applications with COM/XPCOM/.NET interfaces.

  - by Warren P

  I am looking for exemplars (design examples) showing the use of interfaces (aka 'protocols' for you smalltalkers) to design a document management architecture in a large Word Processor, Spreadsheet, vector graphic or publishing package, or office-productivity (non-database) application with support for as many of the following as possible: any open source project, will be ideal, and language of implementation is unimportant since I am looking for design examples, however an object oriented language with support for "interfaces" is a must. I know at least a dozen languages, and I'm willing to study any application's source. use of "interface" could loosely be applied to either XPCOM or COM interfaces, or .NET interfaces, or even the use of pure-virtual (virtual+abstract) base-classes for OOP languages that lack the ability to declare an interface distinct from a class. I am mostly looking for a robust, thorough and flexible implementation for a document, IDocument, various document views (IDocumentView), and whatever operations make sense in that case. I am particular interested in cases where the product in question is a real-world product. For example, if anybody familiar with OpenOffice can tell me if the code contains a good sample design. I am looking for design documentation that outlines the design of the interfaces for such an application. So for example, if the openoffice spreadsheet has such an interface design, then that might be the best case, because it is a widely used real-world design, with millions of users, rather than a textbook example, which is minimal, and contrived. I know that the Mozilla platform uses XPCOM, and its design is heavily "interface" oriented, but I am looking more for a "word processor" or "spreadsheet" type of document design, rather than a web-browser. I am particularly interested in the interfaces used to access to data and meta-data such as markup (attributes like bold, and italics, and font size), and the ability to search and look up named entities within a document.

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• Entity framework 4.0 compiled query with Where() clause issue

  - by Andrey Salnikov

  Hello, I encountered with some strange behavior of System.Data.Objects.CompiledQuery.Compile function - here is my code for compile simple query: private static readonly Func<DataContext, long, Product> productQuery = CompiledQuery.Compile((DataContext ctx, long id) => ctx.Entities.OfType<Data.Product>().Where(p => p.Id == id) .Select(p=>new Product{Id = p.Id}).SingleOrDefault()); where DataContext inherited from ObjectContext and Product is a projection of POCO Data.Product class. My data context in first run contains Data.Product {Id == 1L} and in second Data.Product {Id == 2L}. First using of compilled query productQuery(dataContext, 1L) works perfect - in result I have Product {Id == 1L} but second run productQuery(dataContext, 2L) always returns null, instead of context in second run contains single product with id == 2L. If I remove Where clause I will get correct product (with id == 2L). It seems that first id value caching while first run of productQuery, and therefore all further calls valid only when dataContext contains Data.Product {id==1L}. This issue can't be reproduced if I've used direct query instead of its precompiled version. Also, all tests I've performed on test mdf base using SQL Server 2008 express and Visual studio 2010 final from my ASP.net application.

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• Entity Framework EntityKey / Foreign Key problem.

  - by Ronny176

  Hi, I keep getting the same error: Entities in 'VlaamseOverheidMeterEntities.ObjectMeter' participate in the 'FK_ObjectMeter_Meter' relationship. 0 related 'Meter' were found. 1 'Meter' is expected. I have the following table structure: Meter 1 <- * ObjectMeter * - 1 VO_Object It is always the same scenario: The first meter is added to the database, the second meter gives the error above. I have the following code in my manager: public List<string> addTemporary(string username, string meterNaam, string readingType, string parentID) { Meter meter = new Meter(); VO_Object voObject = objectManager.getObjectByID(parentID); ObjectMeter objMeter = new ObjectMeter(); meter.readingType = (int)Enum.Parse(typeof(ReadingType), readingType); meter.isActive = true; meter.name = meterNaam; meter.startDate = DateTime.Now; meter.endDate = DateTime.Now.AddYears(6000); meter.uniqueIdentifier = "N/A"; meter.meterType = (int)Enum.Parse(typeof(MeterType), "NA"); meter.meterCategory = (int)Enum.Parse(typeof(MeterCategory), "NA"); meter.energyType = (int)Enum.Parse(typeof(EnergyType), "NA"); meter.utilityType = (int)Enum.Parse(typeof(UtilityType), "NA"); meter.unitOfMeasure = (int)Enum.Parse(typeof(UnitOfMeasure), "NA"); objMeter.valid_from = meter.startDate; objMeter.valid_until = meter.endDate; objMeter.Meter = meter; objMeter.VO_Object = voObject; createMeter(meter); List<String> str = new List<string>(); str.Add("" + meter.meterID); str.Add(meter.name); return str; } and this in my Dao Class which links to the database: internal void CreateMeter(Meter _meter) { _entities.AddToMeter(_meter); _entities.SaveChanges(); } Can someone please explain this error? Ronald

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• Unable to delete inherited entity class in EF4

  - by Coding Gorilla

  I have two entities in an EF4 model (using Model First), let's call them EntityA and EntityB. EntityA is marked as abstract, and EntityB inherits from EntityA. They are similar to the following: public class EntityA { public Guid Id; public string Name; public string Uri; } public class EntityB : EntityA { public string AnotherProperty; } The generated database tables look as I would expect them, with EntityA as on table, and then another table like: EntityA_EntityB Id (PK, FK, uniqueidentifier) AnotherProperty (varchar) There is a foreign key constraint on EntityA_EntityB that references EntityA's Id property, no cascades are configured (although I did try changing these myself). The problem is that when I attempt to do something like: Context.DeleteObject(EntityA_EntityB); EF attempts to delete the EntityA_EntityB table record before deleting the EntityA table record, which of course violates the foreign key constraint on EntityA_EntityB table. Using EFProfiler I see the following commands being sent to the database: delete [dbo].[EntityA_EntityB] where (([Id] = '5c02899f-09ea-2ed9-d44b-01aef80f6b64' /* @0 */) followed by delete [dbo].[EntityA] where ([Id] = '5c02899f-09ea-2ed9-d44b-01aef80f6b64' /* @0 */) I'm completely stumped as to how to get around this problem. I would think the EF should know that it needs to delete the base class first, before deleting the inherited class. I know I could do some triggers or other database type solutions, but I'd rather avoid doing that if I can. All my classes are POCO built using some customized T4 templates. I don't want to paste in a lot of extraneous code, but if you need more information I'll provide what I can.

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• LINQ: display results from empty lists

  - by Douglas H. M.

  I've created two entities (simplified) in C#: class Log { entries = new List<Entry>(); DateTime Date { get; set; } IList<Entry> entries { get; set; } } class Entry { DateTime ClockIn { get; set; } DateTime ClockOut { get; set; } } I am using the following code to initialize the objects: Log log1 = new Log() { Date = new DateTime(2010, 1, 1), }; log1.Entries.Add(new Entry() { ClockIn = new DateTime(0001, 1, 1, 9, 0, 0), ClockOut = new DateTime(0001, 1, 1, 12, 0, 0) }); Log log2 = new Log() { Date = new DateTime(2010, 2, 1), }; The method below is used to get the date logs: var query = from l in DB.GetLogs() from e in l.Entries orderby l.Date ascending select new { Date = l.Date, ClockIn = e.ClockIn, ClockOut = e.ClockOut, }; The result of the above LINQ query is: /* Date | Clock In | Clock Out 01/01/2010 | 09:00 | 12:00 */ My question is, what is the best way to rewrite the LINQ query above to include the results from the second object I created (Log2), since it has an empty list. In the other words, I would like to display all dates even if they don't have time values. The expected result would be: /* Date | Clock In | Clock Out 01/01/2010 | 09:00 | 12:00 02/01/2010 | | */

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• Create a model that switches between two different states using Temporal Logic?

  - by NLed

  Im trying to design a model that can manage different requests for different water sources. Platform : MAC OSX, using latest Python with TuLip module installed. For example, Definitions : Two water sources : w1 and w2 3 different requests : r1,r2,and r3 - Specifications : Water 1 (w1) is preferred, but w2 will be used if w1 unavailable. Water 2 is only used if w1 is depleted. r1 has the maximum priority. If all entities request simultaneously, r1's supply must not fall below 50%. - The water sources are not discrete but rather continuous, this will increase the difficulty of creating the model. I can do a crude discretization for the water levels but I prefer finding a model for the continuous state first. So how do I start doing that ? Some of my thoughts : Create a matrix W where w1,w2 ? W Create a matrix R where r1,r2,r3 ? R or leave all variables singular without putting them in a matrix I'm not an expert in coding so that's why I need help. Not sure what is the best way to start tackling this problem. I am only interested in the model, or a code sample of how can this be put together. edit Now imagine I do a crude discretization of the water sources to have w1=[0...4] and w2=[0...4] for 0, 25, 50, 75,100 percent respectively. == means implies Usage of water sources : if w1[0]==w2[4] -- meaning if water source 1 has 0%, then use 100% of water source 2 etc if w1[1]==w2[3] if w1[2]==w2[2] if w1[3]==w2[1] if w1[4]==w2[0] r1=r2=r3=[0,1] -- 0 means request OFF and 1 means request ON Now what model can be designed that will give each request 100% water depending on the values of w1 and w2 (w1 and w2 values are uncontrollable so cannot define specific value, but 0...4 is used for simplicity )

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• How difficult is it to write our own Robots API, similar to G Wave Robots API ? Please read the deta

  - by user169650

  Consider the following entities : a) My own Wave-server b) My own Robots API c) Tomcat d) Google wave server/any other wave server Let us consider that a and d interact with one another via Google wave federation protocol. Now, I want to write my own Robots API in Java (similar to that of G Wave Robots API) using which I want to create Robots; which I want to host in entity c), which may in-turn connect to a) for listening to events and responding with operations. Let us consider that a) is already in place, i.e. implemented. Let us also consider that the Robot running on tomcat and entity a) are co-located, so that we do not need to use JSON-RPC for receiving events/sending operations; instead we can use Java interfaces. Now, my questions are : 1.How much of an effort is it to write my own Robots API to run on a tomcat container ? 2.What are the salient points to be taken care of ? Am I missing some important point here ? 3.How can I reuse some of the classes/packages/interfaces (e.g. com.google.wave.api.AbstractRobot, com.google.wave.api.event) with little/no changes at all ?

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• Core Data combined Query

  - by Chris Summer

  Hey, i have question related to CoreData. My iphone project has 2 Entities, Organisation and Brand with a 1 to many "BrandsToOrg" relationship and inverse. So my project has a Mapview, where you can see all the Organisations and a little subview when you click on those Organisations.At the subview there is a "show Brands" Button, which should init a new TableView who only shows the brands belong to the seleceted organisation. Any ideas how i can code that? thx NSPredicate *predicate = [NSPredicate predicateWithFormat: @"(TitleMedium == %@)",@"Rock Antenne"];???? NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:self.entityName inManagedObjectContext:managedObjectContext]; [request setEntity:entity]; // If a predicate was passed, pass it to the query if(predicate != nil) { [request setPredicate:predicate]; } // If a sort key was passed, use it for sorting. NSString *sortKey=@"TitleMedium"; BOOL sortAscending=YES; if(sortKey != nil) { NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:sortKey ascending:sortAscending]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; } NSError *error; NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; [request release]; [self setEntityArray:mutableFetchResults];

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• hibernate annotation bi-directional mapping

  - by smithystar

  I'm building a web application using Spring framework and Hibernate with annotation and get stuck with a simple mapping between two entities. I'm trying to create a many-to-many relationship between User and Course. I followed one of the Hibernate tutorials and my implementation is as follows: User class: @Entity @Table(name="USER") public class User { private Long id; private String email; private String password; private Set<Course> courses = new HashSet<Course>(0); @Id @GeneratedValue @Column(name="USER_ID") public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Column(name="USER_EMAIL") public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Column(name="USER_PASSWORD") public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_COURSE", joinColumns = { @JoinColumn(name = "USER_ID") }, inverseJoinColumns = { @JoinColumn(name = "COURSE_ID") }) public Set<Course> getCourses() { return courses; } public void setCourses(Set<Course> courses) { this.courses = courses; } } Course class: @Entity @Table(name="COURSE") public class Course { private Long id; private String name; @Id @GeneratedValue @Column(name="COURSE_ID") public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Column(name="NAME") public String getName() { return name; } public void setName(String name) { this.name = name; } } The problem is that this implementation only allows me to go one way user.getCourses() What do I need to change, so I can go in both directions? user.getCourses() course.getUsers() Any help would be appreciated.

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• Does implementing a Java class under an open-source library's package name constitutes a modificatio

  - by Minyu

  Greetings, I understand that this is not the best forum for getting legal advices. But I am still wondering if anybody has some experience around this topic, or can point me to relevant resources that explain it. I have tried to search it online but could not find clear answers. Assuming I am using a Java open-source library from "somecompany", specifically its entities in the "org.somecompany.somepackage". During development, I found that I need to access some of the internals of that package that are not exposed through its public interface. So I thought maybe creating my own classes under the same "org.somecompany.somepackage" name would make that easier. My question is: does this constitutes a modification of the open-source library? The fully qualified name of my classes look like "org.somecompany.somepackage.myclass". It does seem an "extension" of the original library, even though I am not modifying the original library source or binary. I am also not adding my classes to the open-source jar files. Any advice or pointer to resources will be appreciated!

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• Spring MVC: Where to place validation and how to validation entity references.

  - by arrages

  Let's say I have the following command bean for creating a user: public class CreateUserCommand { private String userName; private String email; private Integer occupationId; pirvate Integer countryId; } occupationId and countryId are drop down selected values on the form. They map to an entity in the database (Occupation, Country). This command object is going to be fed to a service facade like so: userServiceFacade.createUser(CreateUserCommand command); This facade will construct a user entity to be sent to the actual service. So I suppose that in the facade layer I will have to make several dao calls to map all the lookup properties of the User entity. Based on this what is the best strategy to validate that occupationId and countryId map to real entities? Where is the best place to perform this validation? There is the spring validator but I am not sure this is the best place for this, for one I am wary of this method as validation is tied to the web tier, but also that means I would need to make the dao calls in the validator for validation but I would need to call the dao's in the facade layer again when the command - entity translation occurs. Is there anything I can do better? Thanks.

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• How can I determine whether or not to add project items using IWizard?

  - by taarskog

  Hi, I am generating entity wrappers in VS2010 based on dynamic objects in a CRM system. In addition to the entity code, I want to add an EntityBase of which all entities inherit from. If the file exists in the project from before, it should not be added. I am using an IWizard implementation to give the generator the object names etc. Is it possible in the IWizard implementation to determine whether or not to add an item if it exists in the project from before? How do I get a hold of the project handle and its items in or before the ShouldAddProjectItem method? My code so far (not completed): public class EntityWizardImplementation : IWizard { public void BeforeOpeningFile(ProjectItem projectItem) { //Note: Nothing here. } public void ProjectFinishedGenerating(Project project) { //Note: Nothing here. } public void ProjectItemFinishedGenerating(ProjectItem projectItem) { //Note: Nothing here. } public void RunFinished() { //Note: Nothing here. } public void RunStarted(object automationObject, Dictionary<string, string> replacementsDictionary, WizardRunKind runKind, object[] customParams) { try { var window = new WizardWindow(); // Replace parameters gathered from the wizard replacementsDictionary.Add("$crmEntity$", window.CrmEntity); replacementsDictionary.Add("$crmOrganization$", window.CrmOrganization); replacementsDictionary.Add("$crmMetadataServiceUrl$", window.CrmMetadataUrl); window.Close(); } catch (SoapException se) { MessageBox.Show(se.ToString()); } catch (Exception e) { MessageBox.Show(e.ToString()); } } public bool ShouldAddProjectItem(string filePath) { // This is where I assume it is correct to handle the preexisting file. return true; } }

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• Best practices for "search data class" in ASP.NET MVC

  - by Tim Ridgely

  Hi everybody, I'm hoping this isn't too subjective, but I'm new to ASP.NET MVC and I'm trying to figure out how others may have solved similar problems. Basically, I have two entities, Customers and Orders. A customer has many orders; an order belongs to exactly one customer. I'm making an Order Search feature that should allow a user to search for orders based on order or customer information. Pretty straightforward, I think. I've read in other posts that the search controller should use GET, but I think it makes more sense to use POST because of the large number of search params. I'm using Entity Framework to create my models, and that's in a separate class library project and namespace. This article talks about using binding instead of Request.Form to get at the POST data. Would it make decent sense to make a class to hold all the search data that could be materialized by the magic model binding? Otherwise I'd just be poking through the FormCollection to pull out particular values, which might be fine. Where would you recommend making such a class?

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• NHibernate Performance Optimization | Suggestions invited!!!

  - by user336749

  Hi, I’m facing an issue with NHibernate performance and can you please suggest me some optimizations? Below mentioned is a small summary of my application architecture I have a windows service which is listening to a messaging bus. On receiving a message the service creates an object out of which a property is the received xml snippet and saves the message to the DB (uses NH). There is a WPF UI with a readonly connection to the DB, and on refresh of the UI it displays the objects on the screen. While the UI does a refresh, it retrieves the xml and deserializes it , from which the object’s properties are derived and binded to the screen. For example assume an xml XXX is received by the service, it deserializes the xml , creates the book object and save it to the DB and a property/column is SCHEMA which contains the xml snippet. The UI while refreshed searches all book objects by ID and creates the book objects out of the xml which is being saved (yes, the xml is the constructor param). Now my issue is that the refresh takes more than 2 minutes to display say 50 book objects. I analyzed it using the NHibernate profiler, and found that the time spend within the DB is negligible, however time spent to create the entities is proportionally huge(10ms:1990 ms).I guess it’s due to the fairly huge size of xml snippet and it’s deserialization. My question is, how can I improve the performance. I dispose sessions after every refresh and is not lazy loading (please note that the time spend in DB is negligible). On every refresh it’s possible that all objects are updated by some downstream systems or maybe one of them are updated.Can I implement some sort of caching mechanism in this case? Thanks in advance for any suggestions. Regards, -Mike

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• how to find by date from timestamp column in JPA criteria

  - by Kre Toni

  I want to find a record by date. In entity and database table datatype is timestamp. I used Oracle database. @Entity public class Request implements Serializable { @Id private String id; @Version private long version; @Temporal(TemporalType.TIMESTAMP) @Column(name = "CREATION_DATE") private Date creationDate; public Request() { } public Request(String id, Date creationDate) { setId(id); setCreationDate(creationDate); } public String getId() { return id; } public void setId(String id) { this.id = id; } public long getVersion() { return version; } public void setVersion(long version) { this.version = version; } public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } } in mian method public static void main(String[] args) { RequestTestCase requestTestCase = new RequestTestCase(); EntityManager em = Persistence.createEntityManagerFactory("Criteria").createEntityManager(); em.getTransaction().begin(); em.persist(new Request("005",new Date())); em.getTransaction().commit(); Query q = em.createQuery("SELECT r FROM Request r WHERE r.creationDate = :creationDate",Request.class); q.setParameter("creationDate",new GregorianCalendar(2012,12,5).getTime()); Request r = (Request)q.getSingleResult(); System.out.println(r.getCreationDate()); } in oracle database record is ID CREATION_DATE VERSION 006 05-DEC-12 05.34.39.200000 PM 1 Exception is Exception in thread "main" javax.persistence.NoResultException: getSingleResult() did not retrieve any entities. at org.eclipse.persistence.internal.jpa.EJBQueryImpl.throwNoResultException(EJBQueryImpl.java:1246) at org.eclipse.persistence.internal.jpa.EJBQueryImpl.getSingleResult(EJBQueryImpl.java:750) at com.ktrsn.RequestTestCase.main(RequestTestCase.java:29)

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• data ownership and performance

  - by Ami

  We're designing a new application and we ran into some architectural question when thinking about data ownership. we broke down the system into components, for example Customer and Order. each of this component/module is responsible for a specific business domain, i.e. Customer deals with CRUD of customers and business process centered around customers (Register a n new customer, block customer account, etc.). each module is the owner of a set of database tables, and only that module may access them. if another module needs data that is owned by another module, it retrieves it by requesting it from that module. so far so good, the question is how to deal with scenarios such as a report that needs to show all the customers and for each customer all his orders? in such a case we need to get all the customers from the Customer module, iterate over them and for each one get all the data from the Order module. performance won't be good...obviously it would be much better to have a stored proc join customers table and orders table, but that would also mean direct access to the data that is owned by another module, creating coupling and dependencies that we wish to avoid. this is a simplified example, we're dealing with an enterprise application with a lot of business entities and relationships, and my goal is to keep it clean and as loosely coupled as possible. I foresee in the future many changes to the data scheme, and possibly splitting the system into several completely separate systems. I wish to have a design that would allow this to be done in a relatively easy way. Thanks!

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• Why newly created entity object with navigation property is automaticly added to ObjectContext?

  - by Levelbit

  I have to entities: Company and Location (one to many). When I create new Location entity object and assign navigation property(Company) with the navigation property of already existing Location object (Location _new = new Location(); _new.Company = _old.Company). It seems that at that point newly created object is added to Object Context automatically, because when I call SaveChanges method that object is insert to database although I didn't call ObjectContext.AddObject(_new). I'm new in EF so there is probably reason why I have result like this? Is there need to assign also CompanyReference filed too and how to do it? IDaoFactory daoFactory = new DaoFactory(); ILocationDao locaitonDao = daoFactory.GetLocationDao(); IEnumerable<Location> locations = locaitonDao.GetLocations(); Location _old = locations.First(); Location _new = new Location(); _new.LocationName = _old.LocationName; _new.Company = _old.Company;// 1 _new.Address = _old.Address; //... ContactEntities.SaveChanges();//2 If I execute line (1) instantly _new object is added to object context and I can see additional datarow in my datagrid after line (2) is executed.

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• NHibernate Entity code conversion from #C to VB.Net

  - by CoderRoller

  Hello and thanks for your help in advance. I am starting on the NHibernate world and i am experimenting with the NHibernate CookBook recipes, i am trying to set a base entity class for my entities and this is the C# code for this. I would like to know whats the VB.NET version so i can implement it in my sample project. This is the C# code: public abstract class Entity<TId> { public virtual TId Id { get; protected set; } public override bool Equals(object obj) { return Equals(obj as Entity<TId>); } private static bool IsTransient(Entity<TId> obj) { return obj != null && Equals(obj.Id, default(TId)); } private Type GetUnproxiedType() { return GetType(); } public virtual bool Equals(Entity<TId> other) { if (other == null) return false; if (ReferenceEquals(this, other)) return true; if (!IsTransient(this) && !IsTransient(other) && Equals(Id, other.Id)) { var otherType = other.GetUnproxiedType(); var thisType = GetUnproxiedType(); return thisType.IsAssignableFrom(otherType) || otherType.IsAssignableFrom(thisType); } return false; } public override int GetHashCode() { if (Equals(Id, default(TId))) return base.GetHashCode(); return Id.GetHashCode(); } } I tried using an online converter but puts a Nothing reference in place of default(TId) that doesn't seem right to me that's why I request for help: Private Shared Function IsTransient(obj As Entity(Of TId)) As Boolean Return obj IsNot Nothing AndAlso Equals(obj.Id, Nothing) End Function I Would appreciate the insight you may give me on the subject.

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• How to persist in order

  - by parhs

  I have two entities: EXAM and EXAM_NORMAL. EXAM @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; private String name; private String codeName; @Enumerated(EnumType.STRING) private ExamType examType; @ManyToOne private Category category; @OneToMany(mappedBy="id",cascade=CascadeType.PERSIST) @OrderBy("id") private List<Exam_Normal> exam_Normal; EXAM_NORMAL @Id private Long item; @Id @ManyToOne private Exam id; @Enumerated(EnumType.STRING) private Gender gender; private Integer age_month_from; private Integer age_month_to; The problem is that if I put a list of EXAM_NORMAL at an EXAM class if I try to persist(EXAM) I get an error because it tries to persist EXAM_NORMAL first but it cant because the primary key of EXAM is missing because it isn't persisted... Is there any way to define the order? Or should I set null the list, persist and then set the list again? thanks:)

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• Problem with inherited classes in C#

  - by Unniloct

  I have a class called "Entity," with two child classes: "Creature" and "Item." (I'm making a game.) Creature has two functions called "Attack," one for attacking Creatures, and one for attacking Items. So far, everything works well. Now I'm working on the shooting bit, so I have a function called SelectTarget(). It takes all of the Entities (both Creatures and Items) in the player's view that the player can shoot and lets the player choose one. So here lies the problem: SelectTarget() returns an Entity, but I need some code to figure out whether that Entity is a Creature or an Item, and process it appropriately. Since this question looks kind of empty without any code, and I'm not 100% sure my explanation is good enough, here's where I'm at: if (Input.Check(Key.Fire)) { Entity target = Game.State.SelectTarget.Run(); this.Draw(); if (target != null) { //Player.Attack(target); // This won't work, because I have: // Player.Attack((Creature)Target) // Player.Attack((Item)Target) // but nothing for Entity, the parent class to Creature and Item. return true; } } (If the way the game is laid out seems weird, it's a roguelike.)

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• Why Is Java Missing Access Specifiers?

  - by Tom Tresansky

  Does anyone understand why Java is missing: An access specifier which allows access by the class and all subclasses, but NOT by other classes in the same package? (Protected-minus) An access specifier which allows access by the class, all classes in the same package, AND all classes in any sub-package? (Default-plus) An access specifier which adds classes in sub-packages to the entities currently allowed access by protected? (Protected-plus) I wish I had more choices than protected and default. In particular, I'm interested in the Protected-plus option. Say I want to use a Builder/Factory patterned class to produce an object with many links to other objects. The constructors on the objects are all default, because I want to force you to use the factory class to produce instances, in order to make sure the linking is done correctly. I want to group the factories in a sub-package to keep them all together and distinct from the objects they are instantiating---this just seems like a cleaner package structure to me. No can do, currently. I have to put the builders in the same package as the objects they are constructing, in order to gain the access to defaults. But separating project.area.objects from project.area.objects.builders would be so nice. So why is Java lacking these options? And, is there anyway to fake it?

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• Mapping many-to-many association table with extra column(s)

  - by user635524

  My database contains 3 tables: User and Service entities have many-to-many relationship and are joined with the SERVICE_USER table as follows: USERS - SERVICE_USER - SERVICES SERVICE_USER table contains additional BLOCKED column. What is the best way to perform such a mapping? These are my Entity classes @Entity @Table(name = "USERS") public class User implements java.io.Serializable { private String userid; private String email; @Id @Column(name = "USERID", unique = true, nullable = false,) public String getUserid() { return this.userid; } .... some get/set methods } @Entity @Table(name = "SERVICES") public class CmsService implements java.io.Serializable { private String serviceCode; @Id @Column(name = "SERVICE_CODE", unique = true, nullable = false, length = 100) public String getServiceCode() { return this.serviceCode; } .... some additional fields and get/set methods } I followed this example http://giannigar.wordpress.com/2009/09/04/m ... using-jpa/ Here is some test code: User user = new User(); user.setEmail("e2"); user.setUserid("ui2"); user.setPassword("p2"); CmsService service= new CmsService("cd2","name2"); List<UserService> userServiceList = new ArrayList<UserService>(); UserService userService = new UserService(); userService.setService(service); userService.setUser(user); userService.setBlocked(true); service.getUserServices().add(userService); userDAO.save(user); The problem is that hibernate persists User object and UserService one. No success with the CmsService object I tried to use EAGER fetch - no progress Is it possible to achieve the behaviour I'm expecting with the mapping provided above? Maybe there is some more elegant way of mapping many to many join table with additional column?

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• NHibernate: Using value tables for optimization AND dynamic join

  - by Kostya

  Hi all, My situation is next: there are to entities with many-to-many relation, f.e. Products and Categories. Also, categories has hierachial structure, like a tree. There is need to select all products that depends to some concrete category with all its childs (branch). So, I use following sql statement to do that: SELECT * FROM Products p WHERE p.ID IN ( SELECT DISTINCT pc.ProductID FROM ProductsCategories pc INNER JOIN Categories c ON c.ID = pc.CategoryID WHERE c.TLeft >= 1 AND c.TRight <= 33378 ) But with big set of data this query executes very long and I found some solution to optimize it, look at here: DECLARE @CatProducts TABLE ( ProductID int NOT NULL ) INSERT INTO @CatProducts SELECT DISTINCT pc.ProductID FROM ProductsCategories pc INNER JOIN Categories c ON c.ID = pc.CategoryID WHERE c.TLeft >= 1 AND c.TRight <= 33378 SELECT * FROM Products p INNER JOIN @CatProducts cp ON cp.ProductID = p.ID This query executes very fast but I don't know how to do that with NHIbernate. Note, that I need use only ICriteria because of dynamic filtering\ordering. If some one knows a solution for that, it will be fantastic. But I'll pleasure to any suggestions of course. Thank you ahead, Kostya

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• Best way to store data in database when you don't know the type

  - by stiank81

  I have a table in my database that represents datafields in a custom form. The DataField gives some representation of what kind of control it should be represented with, and what value type it should take. Simplified you can say that I have 2 entities in this table - Textbox taking any string and Textbox only taking numbers. Now I have the different values stored in a separate table, referencing the datafield definition. What is the best way to store the data value here, when the type differs? One possible solution is to have the FieldValue table hold one field per possible value type. Now this would certainly be redundant, but at least I would get the value stored in its correct form - simplifying queries later. FieldValue ---------- Id DataFieldId IntValue DoubleValue BoolValue DataValue .. Another possibility is just storing everything as String, and casting this in the queries. I am using .Net with NHibernate, and I see that at least here there is a Projections.Cast that can be used to cast e.g. string to int in the query. Either way in these two solutions I need to know which type to use when doing the query, but I will know that from the DataField, so that won't be a problem. Anyway; I don't think any of these solutions sounds good. Are they? Or is there a better way?

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• Abstract away a compound identity value for use in business logic?

  - by John K

  While separating business logic and data access logic into two different assemblies, I want to abstract away the concept of identity so that the business logic deals with one consistent identity without having to understand its actual representation in the data source. I've been calling this a compound identity abstraction. Data sources in this project are swappable and various and the business logic shouldn't care which data source is currently in use. The identity is the toughest part because its implementation can change per kind of data source, whereas other fields like name, address, etc are consistently scalar values. What I'm searching for is a good way to abstract the concept of identity, whether it be an existing library, a software pattern or just a solid good idea of some kind is provided. The proposed compound identity value would have to be comparable and usable in the business logic and passed back to the data source to specify records, entities and/or documents to affect, so the data source must be able to parse back out the details of its own compound ids. Data Source Examples: This serves to provide an idea of what I mean by various data sources having different identity implementations. A relational data source might express a piece of content with an integer identifier plus a language specific code. For example. content_id language Other Columns expressing details of content 1 en_us 1 fr_ca The identity of the first record in the above example is: 1 + en_us However when a NoSQL data source is substituted, it might somehow represent each piece of content with a GUID string 936DA01F-9ABD-4d9d-80C7-02AF85C822A8 plus language code of a different standardization, And a third kind of data source might use just a simple scalar value. So on and so forth, you get the idea.

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