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  • Problem persisting inheritance tree

    - by alaiseca
    I have a problem trying to map an inheritance tree. A simplified version of my model is like this: @MappedSuperclass @Embeddable public class BaseEmbedded implements Serializable { @Column(name="BE_FIELD") private String beField; // Getters and setters follow } @MappedSuperclass @Embeddable public class DerivedEmbedded extends BaseEmbedded { @Column(name="DE_FIELD") private String deField; // Getters and setters follow } @MappedSuperclass public abstract class BaseClass implements Serializable { @Embedded protected BaseEmbedded embedded; public BaseClass() { this.embedded = new BaseEmbedded(); } // Getters and setters follow } @Entity @Table(name="MYTABLE") @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name="TYPE", discriminatorType=DiscriminatorType.STRING) public class DerivedClass extends BaseClass { @Id @Column(name="ID", nullable=false) private Long id; @Column(name="TYPE", nullable=false, insertable=false, updatable=false) private String type; public DerivedClass() { this.embedded = new DerivedClass(); } // Getters and setters follow } @Entity @DiscriminatorValue("A") public class DerivedClassA extends DerivedClass { @Embeddable public static NestedClassA extends DerivedEmbedded { @Column(name="FIELD_CLASS_A") private String fieldClassA; } public DerivedClassA() { this.embedded = new NestedClassA(); } // Getters and setters follow } @Entity @DiscriminatorValue("B") public class DerivedClassB extends DerivedClass { @Embeddable public static NestedClassB extends DerivedEmbedded { @Column(name="FIELD_CLASS_B") private String fieldClassB; } public DerivedClassB() { this.embedded = new NestedClassB(); } // Getters and setters follow } At Java level, this model is working fine, and I believe is the appropriate one. My problem comes up when it's time to persist an object. At runtime, I can create an object which could be an instance of DerivedClass, DerivedClassA or DerivedClassB. As you can see, each one of the derived classes introduces a new field which only makes sense for that specific derived class. All the classes share the same physical table in the database. If I persist an object of type DerivedClass, I expect fields BE_FIELD, DE_FIELD, ID and TYPE to be persisted with their values and the remaining fields to be null. If I persist an object of type DerivedClass A, I expect those same fields plus the FIELD_CLASS_A field to be persisted with their values and field FIELD_CLASS_B to be null. Something equivalent for an object of type DerivedClassB. Since the @Embedded annotation is at the BaseClass only, Hibernate is only persisting the fields up to that level in the tree. I don't know how to tell Hibernate that I want to persist up to the appropriate level in the tree, depending on the actual type of the embedded property. I cannot have another @Embedded property in the subclasses since this would duplicate data that is already present in the superclass and would also break the Java model. I cannot declare the embedded property to be of a more specific type either, since it's only at runtime when the actual object is created and I don't have a single branch in the hierarchy. Is it possible to solve my problem? Or should I resignate myself to accept that there is no way to persist the Java model as it is? Any help will be greatly appreciated.

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  • How can i implement the NULL Object Design Pattern in a generic form?

    - by Colour Blend
    Is there a way to implement the null object design pattern in a generic form so that i don't need to implement it for every buisness object. For me, there are two high level classes you'll need for every business class. One for a single record and another for a list. So i think there should be a way to implement the NULL Object design pattern at a high level and not have to implement it for every class. Is there a way and how please?

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  • SQL not yielding expected results

    - by AnonJr
    I have three tables related to this particular query: Lawson_Employees: LawsonID (pk), LastName, FirstName, AccCode (numeric) Lawson_DeptInfo: AccCode (pk), AccCode2 (don't ask, HR set up), DisplayName tblExpirationDates: EmpID (pk), ACLS (date), EP (date), CPR (date), CPR_Imported (date), PALS (date), Note The goal is to get the data I need to report on all those who have already expired in one or more certification, or are going to expire in the next 90 days. Some important notes: This is being run as part of a vbScript, so the 90-day date is being calculated when the script is run. I'm using 2010-08-31 as a placeholder since its the result at the time this question is being posted. All cards expire at the end of the month. (which is why the above date is for the end of August and not 90 days on the dot) A valid EP card supersedes ACLS certification, but only the latter is required of some employees. (wasn't going to worry about it until I got this question answered, but if I can get the help I'll take it) The CPR column contains the expiration date for the last class they took with us. (NULL if they didn't take any classes with us) The CPR_Imported column contains the expiration date for the last class they took somewhere else. (NULL if they didn't take it elsewhere, and bravo for following policy) The distinction between CPR classes is important for other reports. For purposes of this report, all we really care about is which one is the most current - or at least is currently current. If I have to, I'll ignore ACLS and PALS for the time being as it is non-compliance with CPR training that is the big issue at the moment. (not that the others won't be, but they weren't mentioned in the last meeting...) Here's the query I have so far, which is giving me good data: SELECT iEmp.LawsonID, iEmp.LastName, iEmp.FirstName, dept.AccCode2, dept.DisplayName, Exp.ACLS, Exp.EP, Exp.CPR, Exp.CPR_Imported, Exp.PALS, Exp.Note FROM (Lawson_Employees AS iEmp LEFT JOIN Lawson_DeptInfo AS dept ON dept.AccCode = iEmp.AccCode) LEFT JOIN tblExpirationDates AS Exp ON iEmp.LawsonID = Exp.EmpID WHERE iEmp.CurrentEmp = 1 AND ((Exp.ACLS <= #2010-08-31# AND Exp.ACLS IS NOT NULL) OR (Exp.CPR <= #2010-08-31# AND Exp.CPR_Imported <= #2010-08-31#) OR (Exp.PALS <= #2010-08-31# AND Exp.PALS IS NOT NULL)) ORDER BY dept.AccCode2, iEmp.LastName, iEmp.FirstName; After perusing the result set, I think I'm missing some expiration dates that should be in the result set. Am I missing something? This is the sucky part of being the only developer in the department... no one to ask for a little help.

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  • C++: How to count all instantiated objects at runtime?

    - by nina
    I have a large framework consisting of many C++ classes. Is there a way using any tools at runtime, to trace all the C++ objects that are being constructed and currently exist? For example, at a certain time t1, perhaps the application has objects A1, A2 and B3, but at time t2, it has A1, A4, C2 and so on? This is a cross platform framework but I'm familiar with working in Linux, Solaris and (possibly) Mac OS X.

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  • Why would it be necessary to subclass from object in Python?

    - by rmh
    I've been using Python for quite a while now, and I'm still unsure as to why you would subclass from object. What is the difference between this: class MyClass(): pass And this: class MyClass(object): pass As far as I understand, object is the base class for all classes and the subclassing is implied. Do you get anything from explicitly subclassing from it? What is the most "Pythonic" thing to do?

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  • ZF Autoloader to load ancestor and requested class

    - by Pekka
    I am integrating Zend Framework into an existing application. I want to switch the application over to Zend's autoloading mechanism to replace dozens of include() statements. I have a specific requirement for the autoloading mechanism, though. Allow me to elaborate. The existing application uses a core library (independent from ZF), for example: /Core/Library/authentication.php /Core/Library/translation.php /Core/Library/messages.php this core library is to remain untouched at all times and serves a number of applications. The library contains classes like class ancestor_authentication { ... } class ancestor_translation { ... } class ancestor_messages { ... } in the application, there is also a Library directory: /App/Library/authentication.php /App/Library/translation.php /App/Library/messages.php these includes extend the ancestor classes and are the ones that actually get instantiated in the application. class authentication extends ancestor_authentication { } class translation extends ancestor_translation { } class messages extends ancestor_messages { } usually, these class definitions are empty. They simply extend their ancestors and provide the class name to instantiate. $authentication = new authentication(); The purpose of this solution is to be able to easily customize aspects of the application without having to patch the core libraries. Now, the autoloader I need would have to be aware of this structure. When an object of the class authentication is requested, the autoloader would have to: 1. load /Core/Library/authentication.php 2. load /App/Library/authentication.php My current approach would be creating a custom function, and binding that to Zend_Loader_Autoloader for a specific namespace prefix. Is there already a way to do this in Zend that I am overlooking? The accepted answer in this question kind of implies there is, but that may be just a bad choice of wording. Are there extensions to the Zend Autoloader that do this? Can you - I am new to ZF - think of an elegant way, conforming with the spirit of the framework, of extending the Autoloader with this functionality? I'm not necessary looking for a ready-made implementation, some pointers (This should be an extension to the xyz method that you would call like this...) would already be enough.

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  • boost::asio and socket ownership

    - by vedro so snegom
    Hello I've two classes (Negotiator, Client), both has their own boost::asio::ip::tcp::socket. Is there a way to transfer socket object to Client after negotiation is finished. I'm looking forward to do something like that: boost::asio::ip::tcp::socket sock1(io); //... boost::asio::ip::tcp::socket sock2; sock2.assign(sock1); This operation must guarantee that the connection won't be closed when sock1 is destroyed.

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  • Kohana 3 Auto loading Models

    - by pigfox
    I'm attempting to use a Model but I get a fatal error so I assume it doesn't autoload properly. ErrorException [ Fatal Error ]: Class 'Properties_Model' not found The offending controller line: $properties = new Properties_Model; The model: class Properties_Model extends Model { public function _construct() { parent::_construct(); } } I also put the class in three different locations hoping one would work, all there failed. They are: application/classes/model application/model application/models What am I missing?

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  • Primary language - QtC++, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Idiomatic scheme and generic programming, why only on numbers ?

    - by Skeptic
    Hi, In Scheme, procedures like +, -, *, / works on different types of numbers, but we don't much see any other generic procedures. For example, length works only on list so that vector-length and string-length are needed. I guess it comes from the fact that the language doesn't really offer any mechanism for defining generic procedure (except cond of course) like "type classes" in Haskell or a standardized object system. Is there an idiomatic scheme way to handle generic procedures that I'm not aware of ?

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  • Compare class objects

    - by reto
    I have to compare a class object against a list of pre defined classes. Is it safe to use == or should I use equals()? if (klass == KlassA.class) { } else if (klass == KlassB.class) { } else if (klass == KlassC.class) { } else { } Note: I cannot use instanceof, I don't have an object, I just have the class object. I (mis)use it like an enum in this situation! Thanks!

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  • Foreign Keys Duplicated in DataGridView

    - by John Doe
    I created a Windows Forms Application to which I added a DataGridView and LINQ to SQL Classes from one of my databases. I can successfully bind one of my database's tables to my DataGridView: var dataSource = from c in _db.NetworkedEquipments select c; dataGridView1.DataSource = dataSource; However, the foreign keys get duplicated, that is, the columns appear twice. How can I prevent this?

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  • Java compilation with two versions of Eclipse

    - by lepnio
    I've got an old project in Eclipse 2.1 and compiled with a JDK 1.4.2_12. I want to upgrade the version of Eclipse to Eclipse Galileo. I've imported my project and set the compilation level to 1.4 and I've also updated my build path to use the correct JDK. The problem is that when I compare the compiled files in the classes folder in the two versions of Eclipse, the MD5 checksum are different. Should I be worried about that fact or this is normal?

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  • Prepopulate jQuery Data in html

    - by Mikael
    jQuery has the very cool feature/method ".data", i wonder if there is a way to have the data in the code so that jQuery can use it when the rendering of html is done. Suppose i have a repeater and looping out children, and i want to add some data to those children without using classes etc. Will i have to add javascript to that repeater just to add stuff to the "data of jquery" or is there some better way?

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  • STL class for reference-counted pointers?

    - by hasen j
    This should be trivial but I can't seem to find it (unless no such class exists!) What's the STL class (or set of classes) for smart pointers? UPDATE Thanks for the responses, I must say I'm surprised there's no standard implementation. I ended up using this one: http://www.gamedev.net/reference/articles/article1060.asp

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  • Unit Test Organization

    - by cam
    I'm using Nunit for unit testing, and added another project called "Unit Testing" to my current solution. I referenced Nunit, and changed the Namespace to the same namespace used in the main project. I can't seem to figure out how to get access to all the classes, files, etc in the main project. Is there something I have to do to link two projects?

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  • Finding an unnamed union in a struct::Haiku

    - by Freeman Lou
    So I have this assignment, and I have to find an unnamed union in struct _pthread_rwlock in pthread.h in the Haiku open source project. I began this assignment with some knowledge of c++ (past inheritance, polymorphism, and classes), but I find that what I learned do not help at all in my situation. I've opened the header file, and a source file named pthread_rwlock.cpp, and tried to look for the unnamed union, but there seems to be no unions in either file. What would be the correct way to find the problem?

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  • Binding of JText fields value to Info Class

    - by Faizan Ahmed
    Is there any way to automatic binding of Swing JTextFields to Info Class. e.g private JTextField receiptId; private JTextField Id; public class Info { private string receiptId; private String id; // Getters and Setters } Is there any way when I entered values from Swing page then automatically values bind with my Info class? After that I can pass my Info object to other classes instead of sending all Text Fields.

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  • XMLEncoder in java for serialization

    - by tom
    Im just wondering how i use xmlencoder to serialize ArrayList where foo is my own made class. Do i have to do anything in particular, ie define my own xml structure first and then call toString on each value in my list and write it out? Can anyone point me to a good tutorial? http://java.sun.com/products/jfc/tsc/articles/persistence4/ Thats what i have been looking at but it doesnt seem to mention what to do with non library classes. Thanks

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  • Excel VBA File not Found

    - by Brett
    During development of some Excel vba code about every other iteration where I go in and add some code then save the file, the next time I open the thing (it is automatically set to run the code on open) I get a spurious "File not Found" error. To fix it I copy all the code- modules and classes plus the startup code, to a fresh blank excel file save it and it runs fine. This happens in both Excel 2003 and 2007. What is happening here?

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