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• JPA One to Many using JoinTable Error

  - by user553015

  I am trying to model 1:N (Person & Address) relationship using a junction table (Person_Address). 1.Person (personId PK) 2.Address (addressId PK) 3.PersonAddress ( personId, addressId composite PK, personId FK references Person, addressid FK references Address ) @Entity public class Person { @OneToMany @JoinTable( name="PersonAddress", joinColumns = @JoinColumn( name="personId"), inverseJoinColumns = @JoinColumn( name="addressId") ) public Set<Address> getAddresses() {...} ... } I encounter following error. Not able to find any solution. Caused by: org.hibernate.MappingException: Could not determine type for: com.realestate.details.Address, at table: Person, for columns: [org.hibernate.mapping.Column(address)] at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:269) at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:253) at org.hibernate.mapping.Property.isValid(Property.java:185) at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:440) at org.hibernate.mapping.RootClass.validate(RootClass.java:192) at org.hibernate.cfg.Configuration.validate(Configuration.java:1108) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1293)

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• Immutable design with an ORM: How are sessions managed?

  - by Programmin Tool

  If I were to make a site with a mutable language like C# and use NHibernate, I would normally approach sessions with the idea of making them as create only when needed and dispose at request end. This has helped with keeping a session for multiple transactions by a user but keep it from staying open too long where the state might be corrupted. In an immutable system, like F#, I would think I shouldn't do this because it supposes that a single session could be updated constantly by any number of inserts/updates/deletes/ect... I'm not against the "using" solution since I would think that connecting pooling will help cut down on the cost of connecting every time, but I don't know if all database systems do connection pooling. It just seems like there should be a better way that doesn't compromise the immutability goal. Should I just do a simple "using" block per transaction or is there a better pattern for this?

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• Good Blog Software

  - by Darren Young

  Hi, Inspired from an earlier question regarding starting a blog, I have decided to start one myself. I only have 4 months commercial experience in C#, but I am hoping to use my blog as a tool for further learning. Maybe such things as researching and writing about a different design pattern each week, a tricky aspect of C# that I don't yet fully understand, etc, etc. My question is, can somebody recommend any good blog sites suited for writing text and code? Is there any that allow the use of code tags or similar for formatting? Thanks,

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• Is it a good idea to simplify an character -driven game engine to the point it's unnecessary to learn scripting/programming ?

  - by jokoon

  I remember, and I still think, that one cannot even make a prototyped 3D game to test just simple behaviors without using gigantic tools like unity or knowing extensive C++ programming, design pattern, a decent or basic 3D engine, etc. Now I'm wondering, since I know programming, that I'm still more lucky that the ones who need to learn programming prior to know how to make something: even scripted engines such as unity are not for kids, and to my sense they tend to dictate their ways of doing things, which is not the case with engine like ogre or irrlicht. I remember toying a little with the blender game engine, it was possible to link states or something I don't remember very well. Now I'm thinking that character driven games occupies a big part of the game market. Do you think it is a good idea to make a character-controlled oriented game engine which allows only to build AI instead of anything else ?

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• When should I consider representing the primary-key ...?

  - by JMSA

  When should I consider representing the primary-key as classes? Should we only represent primary keys as classes when a table uses composite-key? For example: public class PrimaryKey { ... ... ...} Then private PrimaryKey _parentID; public PrimaryKey ParentID { get { return _parentID; } set { _parentID = value; } } And public void Delete(PrimaryKey id) {...} When should I consider storing data as comma-separated values in a column in a DB table rather than storing them in different columns?

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• Eclipse 3.5: Implementing my own context menu for a MultipageEditorPart --> no viewer involved

  - by Patrick

  Hello! :-) In my current RCP-project i use a MultipageEditorPart. It has various pages, with simple SWT composites on it. The composites contain some Text and Combo elements. When the user right clicks onto the editor page, I want a context menu to open. This menu holds a command for creating a new editor page, with a composite on it. The command is already working, but I'm quite clueless about how to implement the context menu for the editor. Can someone help with this?

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• What is the general definition of something that can be included or excluded?

  - by gutch

  When an application presents a user with a list of items, it's pretty common that it permits the user to filter the items. Often a 'filter' feature is implemented as a set of include or exclude rules. For example: include all emails from [email protected], and exclude those emails without attachments I've seen this include/exclude pattern often; for example Maven and Google Analytics filter things this way. But now that I'm implementing something like this myself, I don't know what to call something that could be either included or excluded. In specific terms: If I have a database table of filter rules, each of which either includes or excludes matching items, what is an appropriate name of the field that stores include or exclude? When displaying a list of filters to a user, what is a good way to label the include or exclude value? (as a bonus, can anyone recommend a good implementation of this kind of filtering for inspiration?)

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• How get and set accessors work

  - by Chris Halcrow

  The standard method of implementing get and set accessors in C# and VB.NET is to use a public property to set and retrieve the value of a corresponding private variable. Am I right in saying that this has no effect of different instances of a variable? By this I mean, if there are different instantiations of an object, then those instances and their properties are completely independent right? So I think my understanding is correct that setting a private variable is just a construct to be able to implement the get and set pattern? Never been 100% sure about this.

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• What is the best way to manage application screens in SWT?

  - by parxier

  I'm creating a standalone SWT desktop application that has around 10 different screens (few wizards, help, forms, etc). Some elements on screen don't change at all (like header, background, etc) and there is a working area that changes depending on what is clicked, etc. What is the best way to manage application screens? Do I need to create all screen at startup and then show/hide them depending on what is clicked? Or do I need to create those screens dynamically? Also, I couldn't find any way to show/hide a Composite, do I need to dispose it and then create again? What is the best practice? I'm new to SWT developing outside of Eclipse so any help would be beneficial.

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• IncidentsTracker v1.2 Screenshots

  - by samkea

  he IncidentsTracker v1.2 System is a system that was developed to track Incidents happening in any particular country. It is incorporated with a maping component to enable end users search for places where an incident has happened, enter data about it and then produce reports.It's a Winforms software that was developed in a plugin style using C#  with an extensibility pattern/framework. It sits on an SQl Server backend but can also use any other databases prefered. Its Administrator just has to add the path where the database will be and it will autio create the database. This software was orignally developed to help UN Agancies and NGOs in thier work but can also be ustilised by other entities like the police, the human rights organisations, roads authority, etc etc. The development of a newer version(IncidentTracker v2) has been started in silverlight. Screenshot 01: Login. Screenshot 02: View and Search. Screenshot 03: Mapping Component

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• Introduction to JBatch

  - by reza_rahman

  It seems batch processing is moving more and more into the realm of the Java developer. In recognition of this fact, JBatch (aka Java Batch, JSR 352, Batch Applications for the Java Platform) was added to Java EE 7. In a recent article JBatch specification lead Chris Vignola of IBM provides a high level overview of the API. He discusses the core concepts/motivation, the Job Specification Language, the reader-processor-writer pattern, job operator, job repository, chunking, packaging, partitions, split/flow and the like. You can also check out the official specification yourself or try things out with the newly released Java EE 7 SDK.

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• EAV - is it really bad in all scenarios?

  - by Giedrius

  I'm thinking to use EAV for some of the stuff in one of the projects, but all questions about it in stackoverflow end up to answers calling EAV an anti pattern. But I'm wondering, if is it that wrong in all cases? Let's say shop product entity, it has common features, like name, description, image, price, etc., that take part in logic many places and has (semi)unique features, like watch and beach ball would be described by completely different aspects. So I think EAV would fit for storing those (semi)unique features? All this is assuming, that for showing product list, it is enough info in product table (that means no EAV is involved) and just when showing one product/comparing up to 5 products/etc. data saved using EAV is used. I've seen such approach in Magento commerce and it is quite popular, so may be there are cases, when EAV is reasonable?

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• How do you deal with the details when reading code?

  - by upton

  After reading some projects, I find that it is not the architecture of the software that is really hard to know. It is not hard to figure out the architecture immediately if the project is clearly designed and implemented, if it's hard and never seen before, some day later I can find out some pattern similar to the one I read in the same domain. The difficulty is that the concepts and mechanism defined by the author are really hard to guess, and these concepts may spread in the whole project which makes it hard to grasp. The situation is normal and universal and you can ask questions to your colleague when in a company. However, it gets worse if nobody around you knows these details. How do you handle these details which block your reading?

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• Function that requires many parameters

  - by user877329

  I have a problem related to this: Are there guidelines on how many parameters a function should accept? In my case, I have a function that describes a rounded rectangle. The caller specifies An integer which determines how the rectangle should be merged into previously created shapes An Anchor, which is a point that is used for alignment (right, left, top, bottom etc). (0,-1) means that position (next parameter) describes the top, middle point of the rectangle. The position of the rectangle Width and height Corner radius Should I use Parameter Object pattern in this case? It is hard to see how these parameters are related

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• How to generate "language-safe" UUIDs?

  - by HappyDeveloper

  I always wanted to use randomly generated strings for my resources' IDs, so I could have shorter URLs like this: /user/4jz0k1 But I never did, because I was worried about the random string generation creating actual words, eg: /user/f*cker. This brings two problems: it might be confusing or even offensive for users, and it could mess with the SEO too. Then I thought all I had to do was to set up a fixed pattern like adding a number every 2 letters. I was very happy with my 'generate_safe_uuid' method, but then I realized it was only better for SEO, and worse for users, because it increased the ratio of actual words being generated, eg: /user/g4yd1ck5 Now I'm thinking I could create a method 'replace_numbers_with_letters', and check that it haven't formed any words against a dictionary or something. Any other ideas? ps. As I write this, I also realized that checking for words in more than one language (eg: english and french, spanish, etc) would be a mess, and I'm starting to love numbers-only IDs again.

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• My laptop doesn't always boot to login

  - by GUI Junkie

  I have an recurring problem. Every once in a while, no pattern, the laptop freezes during boot. Sometimes at a black screen, sometimes a black screen with a not blinking cursor... The solution is to power down the laptop, cross my fingers and boot again. Sometimes it takes four or five reboots, but in the end I always get the system up and running. What bugs me is the fact that the boot is not 'stable' in a sense that apparently it doesn't always do exactly the same thing. I'm still using 10.10. The question is whether there is anything that can be done to make the system stable. (Does 11.04 have the same issue?) Edit: Today the same thing happened. First a black screen with a non blinking cursor. Second a black screen. Third login screen.

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• Boost multiindex complex struct

  - by StrifeLow

  In boost multiindex example complex_structs, it use one key in the car_manufacturer struct for car_table. If car_manufacturer have been modify to have 2 ID struct car_manufacturer { std::string name; int cm_code; car_manufacturer(const std::string& name_, const int& cm_code_):name(name_), cm_code(cm_code_){} }; What will be the key_from_key struct looks like? Have try to add another KeyExtractor or use composite index inside key_from_key, but still cannot compile. Please help on this. Thanks.

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• Is OOP becoming easier or harder?

  - by tunmise fasipe

  When the concepts of Object Oriented Programming were introduced to programmers years back it looks interesting and programming was cleaner. OOP was like this Stock stock = new Stock(); stock.addItem(item); stock.removeItem(item); That was easier to understand with self-descriptive name. But now OOP, with pattern like Data Transfer Objects (or Value Objects), Repository, Dependency Injection etc, has become more complex. To achieve the above you may have to create several classes (e.g. abstract, factory, DAO etc) and Implement several interfaces Note: I am not against best practices that makes Collaboration, Testing and Integration easier

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• Platform Framework and Middle-ware

  - by Walidix

  I really want to fix the meanings of this terms.This is what I know about them: Platform: is an environment that allows an application to run and it is usually composite by hardware and software e.g. your machine with your OS installed on it. However some software stack are also called as platform like Java Platform. Framework: is design-oriented. That is, it defines a skeleton of an application type. Also it saves time by offering, through an API, the common functionalities that a kind of applications must implement. Moreover a Framework include a software components that manage the application life-cycle. Middle-ware: is a software that offers services to an application in order to let it inter-operates with other applications or supports different platforms. Middle-ware can be a part of a framework. Is there something wrong or missing ?

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• AdventueWorks Design Patterns Project - Part 1

  - by RonGarlit

  This is the presentation I did tonight at PHILLYNJ.NET.  It is the first in a multi-part of a series on the Applied Design Patterns.   The solution files are working code with design pattern notes in the comment blocks. After the overview and higher level discussions on Enterprise Design Patterns I reviewed the low level Database Access Library of code.  With walk-throughs of the the code and unint test. After that we went through the ProductPhotoConsoleTest Application that performed intergration testing of the DBAccess Class with the AdventureWorks ProductPhoto table extracting the photos and writing them to a file folder. The Demo code and PowerPoint can be obained from this link.  https://skydrive.live.com/?wa=wsignin1.0&cid=29e34e9a8650bb9e#!/?cid=29e34e9a8650bb9e&sc=documents&id=29E34E9A8650BB9E%21151 Please note that I use Visual Studio 2010 Ultimate.  If you have a lesser version the Modeling projects likely will not work or have limited functionality and you should unload that project to prevent warning. Enjoy! --Ron

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• Why do most of us use 'i' as a loop counter variable?

  - by kprobst

  Has anyone thought about why so many of us repeat this same pattern using the same variable names? for (int i = 0; i < foo; i++) { // ... } It seems most code I've ever looked at uses i, j, k and so on as iteration variables. I suppose I picked that up from somewhere, but I wonder why this is so prevalent in software development. Is it something we all picked up from C or something like that? Just an itch I've had for a while in the back of my head.

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• Is it okay to have many Abstract classes in your application?

  - by JoseK

  We initially wanted to implement a Strategy pattern with varying implementations of the methods in a commmon interface. These will get picked up at runtime based on user inputs. As it's turned out, we're having Abstract classes implementing 3 - 5 common methods and only one method left for a varying implementation i.e. the Strategy. Update: By many abstract classes I mean there are 6 different high level functionalities i.e. 6 packages , and each has it's Interface + AbstractImpl + (series of Actual Impl). Is this a bad design in any way? Any negative views in terms of later extensibility - I'm preparing for a code/design review with seniors.

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• Store interface in array list java

  - by agazerboy

  Hi all, I am learning java. I am trying to use composite design pattern. I am trying to use following logic. ( Don't laugh I know it is very basic :) ) Item -> interface Folder -> class File -> class In folder class, can I create an arraylist of Item to store files information? ArrayList<Item> info = ArrayList<Item>(); Or should I use Folder Arraylist? ArrayList<Folder> info = ArrayList<Folder>(); I don't know if interface can store real data as there is no variable just function definitions. Thanks for helping a newbie :)

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• Fluent Nhibernate left join

  - by Ronnie

  I want to map a class that result in a left outer join and not in an innner join. My composite user entity is made by one table ("aspnet_users") and an some optional properties in a second table (like FullName in "users"). public class UserMap : ClassMap<User> { public UserMap() { Table("aspnet_Users"); Id(x => x.Id, "UserId").GeneratedBy.Guid(); Map(x => x.UserName, "UserName"); Map(x => x.LoweredUserName, "LoweredUserName"); Join("Users",mm=> { mm.Map(xx => xx.FullName); }); } } this mapping result in an inner join select so no result come out is second table as no data. I'd like to generate an left join. Is this possible only at query level?

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• How Serializable works with insert in SQL Server 2005

  - by Spence

  G'day I think I have a misunderstanding of serializable. I have two tables (data, transaction) which I insert information into in a serializable transaction (either they are both in, or both out, but not in limbo). SET TRANSACTION ISOLATION LEVEL SERIALIZABLE BEGIN TRANSACTION INSERT INTO dbo.data (ID, data) VALUES (@Id, data) INSERT INTO dbo.transactions(ID, info) VALUES (@ID, @info) COMMIT TRANSACTION I have a reconcile query which checks the data table for entries where there is no transaction at read committed isolation level. INSERT INTO reconciles (ReconcileID, DataID) SELECT Reconcile = @ReconcileID, ID FROM Data WHERE NOT EXISTS (SELECT 1 FROM TRANSACTIONS WHERE data.id = transactions.id) Note that the ID is actually a composite (2 column) key, so I can't use a NOT IN operator My understanding was that the second query would exclude any values written into data without their transaction as this insert was happening at serializable and the read was occurring at read committed. I have evidence that reconcile is picking up entries

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