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  • ruby on rails one-to-many relationship

    - by fenec
    I would like to model a betting system relationship using the power of rails. so lets start with doing something very simple modelling the relationship from a user to a bet.i would like to have a model bet with 2 primary keys. here are my migrations enter code here class CreateBets < ActiveRecord::Migration def self.up create_table :bets do |t| t.integer :user_1_id t.integer :user_2_id t.integer :amount t.timestamps end end def self.down drop_table :bets end end class CreateUsers < ActiveRecord::Migration def self.up create_table :users do |t| t.string :name t.timestamps end end def self.down drop_table :users end end the models enter code here class Bet < ActiveRecord::Base belongs_to :user_1,:class_name=:User belongs_to :user_2,:class_name=:User end class User < ActiveRecord::Base has_many :bets, :foreign_key =:user_1) has_many :bets, :foreign_key =:user_2) end when i test here in the console my relationships I got an error enter code here u1=User.create :name="aa" = # u2=User.create :name="bb" = # b=Bet.create(:user_1=u1,:user_2=u2) *****error***** QUESTIONS: 1 How do I define the relationships between these tables correctly? 2 are there any conventions to name the attributes (ex:user_1_id...) thank you for your help

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  • Why does GCC need extra declarations in templates when VS does not?

    - by Kyle
    template<typename T> class Base { protected: Base() {} T& get() { return t; } T t; }; template<typename T> class Derived : public Base<T> { public: Base<T>::get; // Line A Base<T>::t; // Line B void foo() { t = 4; get(); } }; int main() { return 0; } If I comment out lines A and B, this code compiles fine under Visual Studio 2008. Yet when I compile under GCC 4.1 with lines A and B commented, I get these errors: In member function ‘void TemplateDerived::foo()’: error: ‘t’ was not declared in this scope error: there are no arguments to ‘get’ that depend on a template parameter, so a declaration of ‘get’ must be available Why would one compiler require lines A and B while the other doesn't? Is there a way to simplify this? In other words, if derived classes use 20 things from the base class, I have to put 20 lines of declarations for every class deriving from Base! Is there a way around this that doesn't require so many declarations?

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  • MSTest/NUnit Writing BDD style "Given, When, Then" tests

    - by Charlie
    I have been using MSpec to write my unit tests and really prefer the BDD style, I think it's a lot more readable. I'm now using Silverlight which MSpec doesn't support so I'm having to use MSTest but would still like to maintain a BDD style so am trying to work out a way to do this. Just to explain what I'm trying to acheive, here's how I'd write an MSpec test [Subject(typeof(Calculator))] public class when_I_add_two_numbers : with_calculator { Establish context = () => this.Calculator = new Calculator(); Because I_add_2_and_4 = () => this.Calculator.Add(2).Add(4); It should_display_6 = () => this.Calculator.Result.ShouldEqual(6); } public class with_calculator { protected static Calculator; } So with MSTest I would try to write the test like this (although you can see it won't work because I've put in 2 TestInitialize attributes, but you get what I'm trying to do..) [TestClass] public class when_I_add_two_numbers : with_calculator { [TestInitialize] public void GivenIHaveACalculator() { this.Calculator = new Calculator(); } [TestInitialize] public void WhenIAdd2And4() { this.Calculator.Add(2).Add(4); } [TestMethod] public void ThenItShouldDisplay6() { this.Calculator.Result.ShouldEqual(6); } } public class with_calculator { protected Calculator Calculator {get;set;} } Can anyone come up with some more elegant suggestions to write tests in this way with MSTest? Thanks

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  • [F#] Parallelize code in nested loops

    - by Juliet
    You always hear that functional code is inherently easier to parallelize than non-functional code, so I decided to write a function which does the following: Given a input of strings, total up the number of unique characters for each string. So, given the input [ "aaaaa"; "bbb"; "ccccccc"; "abbbc" ], our method will returns a: 6; b: 6; c: 8. Here's what I've written: (* seq<#seq<char>> -> Map<char,int> *) let wordFrequency input = input |> Seq.fold (fun acc text -> (* This inner loop can be processed on its own thread *) text |> Seq.choose (fun char -> if Char.IsLetter char then Some(char) else None) |> Seq.fold (fun (acc : Map<_,_>) item -> match acc.TryFind(item) with | Some(count) -> acc.Add(item, count + 1) | None -> acc.Add(item, 1)) acc ) Map.empty This code is ideally parallelizable, because each string in input can be processed on its own thread. Its not as straightforward as it looks since the innerloop adds items to a Map shared between all of the inputs. I'd like the inner loop factored out into its own thread, and I don't want to use any mutable state. How would I re-write this function using an Async workflow?

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  • Remove pointer object whose reference is mantained in three different lists

    - by brainydexter
    I am not sure how to approach this problem: 'Player' class mantains a list of Bullet* objects: class Player { protected: std::list< Bullet* > m_pBullet_list; } When the player fires a Bullet, it is added to this list. Also, inside the constructor of bullet, a reference of the same object is updated in CollisionMgr, where CollisionMgr also mantains a list of Bullet*. Bullet::Bullet(GameGL*a_pGameGL, Player*a_pPlayer) : GameObject( a_pGameGL ) { m_pPlayer = a_pPlayer; m_pGameGL->GetCollisionMgr()->AddBullet(this); } class CollisionMgr { void AddBullet(Bullet* a_pBullet); protected: std::list< Bullet*> m_BulletPList; } In CollisionMgr.Update(); based on some conditions, I populate class Cell which again contain a list of Bullet*. Finally, certain conditions qualify a Bullet to be deleted. Now, these conditions are tested upon while iterating through a Cell's list. So, if I have to delete the Bullet object, from all these places, how should I do it so that there are no more dangling references to it? std::list< Bullet*>::iterator bullet_it; for( bullet_it = (a_pCell->m_BulletPList).begin(); bullet_it != (a_pCell->m_BulletPList).end(); bullet_it++) { bool l_Bullet_trash = false; Bullet* bullet1 = *bullet_it; // conditions would set this to true if ( l_Bullet_Trash ) // TrashBullet( bullet1 ); continue; } Also, I was reading about list::remove, and it mentions that it calls the destructor of the object we are trying to delete. Given this info, if I delete from one list, the object does not exist, but the list would still contain a reference to it..How do I handle all these problems ? Can someone please help me here ? Thanks PS: If you want me to post more code or provide explanation, please do let me know.

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  • extension methods with generics - when does caller need to include type parameters?

    - by Greg
    Hi, Is there a rule for knowing when one has to pass the generic type parameters in the client code when calling an extension method? So for example in the Program class why can I (a) not pass type parameters for top.AddNode(node), but where as later for the (b) top.AddRelationship line I have to pass them? class Program { static void Main(string[] args) { // Create Graph var top = new TopologyImp<string>(); // Add Node var node = new StringNode(); node.Name = "asdf"; var node2 = new StringNode(); node2.Name = "test child"; top.AddNode(node); top.AddNode(node2); top.AddRelationship<string, RelationshipsImp>(node,node2); // *** HERE *** } } public static class TopologyExtns { public static void AddNode<T>(this ITopology<T> topIf, INode<T> node) { topIf.Nodes.Add(node.Key, node); } public static INode<T> FindNode<T>(this ITopology<T> topIf, T searchKey) { return topIf.Nodes[searchKey]; } public static void AddRelationship<T,R>(this ITopology<T> topIf, INode<T> parentNode, INode<T> childNode) where R : IRelationship<T>, new() { var rel = new R(); rel.Child = childNode; rel.Parent = parentNode; } } public class TopologyImp<T> : ITopology<T> { public Dictionary<T, INode<T>> Nodes { get; set; } public TopologyImp() { Nodes = new Dictionary<T, INode<T>>(); } }

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  • C# delegate or Func for 'all methods'?

    - by Michel
    Hi, i've read something about Func's and delegates and that they can help you to pass a method as a parameter. Now i have a cachingservice, and it has this declaration: public static void AddToCache<T>(T model, double millisecs, string cacheId) where T : class public static T GetFromCache<T>(string cacheId) where T : class So in a place where i want to cache some data, i check if it exists in the cache (with GetFromCache) and if not, get the data from somewhere, and the add it to the cache (with AddToCache) Now i want to extend the AddToCache method with a parameter, which is the class+method to call to get the data Then the declaration would be like this public static void AddToCache<T>(T model, double millisecs, string cacheId, Func/Delegate methode) where T : class Then this method could check wether the cache has data or not, and if not, get the data itself via the method it got provided. Then in the calling code i could say: AddToCache<Person>(p, 10000, "Person", new PersonService().GetPersonById(1)); AddToCache<Advert>(a, 100000, "Advert", new AdvertService().GetAdverts(3)); What i want to achieve is that the 'if cache is empty get data and add to cache' logic is placed on only one place. I hope this makes sense :) Oh, by the way, the question is: is this possible?

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  • Generating a field setter and getter with ASM

    - by ng
    I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and maybe one with Javassist? Any help would be greatly appreciated.

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  • Toggle two divs and classes

    - by kuswantin
    I have two links with classes (login-form and register-form) relevant to their target forms ID, they want to toggle. I have also a predefined 'slideToggle' function to toggle better. This is what I have tried so far: $('#userbar a').click(function() { var c = $(this).attr('class'); $('#userbar a').removeClass('active'); $(this).toggleClass('active'); $('#register-form,#login-form').hide(); //bad, causing flashy $('#' + c).slideToggle('slow'); return false; }); With this I have trouble with the flashy window, and to correctly toggle the active classes when another link is clicked, the other link should not have active class anymore. Additional problem is the link is dead on serial clicks. I have another try, longer one: $('#userbar a').click(function() { var c = $(this).attr('class'); switch (c) { case 'login-form': $('#' + c).slideToggle('slow'); $(this).toggleClass('active'); $('#register-form').hide(); break; case 'register-form': $('#' + c).slideToggle('slow'); $(this).toggleClass('active'); $('#login-form').hide(); break; } return false; }); This one is worse than the first :( Any suggestion to correct the behavior? What I want is when a link with class login-form is click, so toggle the form with ID login-form, and hide the register-form if open. Any help would be very much appreciated. Thanks.

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  • ibatis throwing NullPointerException

    - by Prashant P
    i am trying to test ibatis with DB. I get NullPointerException. Below are the class and ibatis bean config, <select id="getByWorkplaceId" parameterClass="java.lang.Integer" resultMap="result"> select * from WorkDetails where workplaceCode=#workplaceCode# </select> <select id="getWorkplace" resultClass="com.ibatis.text.WorkDetails"> select * from WorkDetails </select> POJO public class WorkplaceDetail implements Serializable { private static final long serialVersionUID = -6760386803958725272L; private int code; private String plant; private String compRegNum; private String numOfEmps; private String typeIndst; private String typeProd; private String note1; private String note2; private String note3; private String note4; private String note5; } DAOimplementation public class WorkplaceDetailImpl implements WorkplaceDetailsDAO { private SqlMapClient sqlMapClient; public void setSqlMapClient(SqlMapClient sqlMapClient) { this.sqlMapClient = sqlMapClient; } @Override public WorkplaceDetail getWorkplaceDetail(int code) { WorkplaceDetail workplaceDetail=new WorkplaceDetail(); try{ **workplaceDetail= (WorkplaceDetail) this.sqlMapClient.queryForObject("workplaceDetail.getByWorkplaceId", code);** }catch (SQLException sqlex){ sqlex.printStackTrace(); } return workplaceDetail; } TestCode public class TestDAO { public static void main(String args[]) throws Exception{ WorkplaceDetail wd = new WorkplaceDetail(126, "Hoonkee", "1234", "22", "Service", "Tele", "hsgd","hsgd","hsgd","hsgd","hsgd"); WorkplaceDetailImpl impl= new WorkplaceDetailImpl(); **impl.getWorkplaceDetail(wd.getCode());** impl.saveOrUpdateWorkplaceDetails(wd); System.out.println("dhsd"+impl); } } I want to select and insert. I have marked as ** ** as a point of exception in above code Exception in thread "main" java.lang.NullPointerException at com.ibatis.text.WorkplaceDetailImpl.getWorkplaceDetail(WorkplaceDetailImpl.java:19) at com.ibatis.text.TestDAO.main(TestDAO.java:11)

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  • Using CSS to insert text

    - by abelenky
    I'm relatively new to CSS, and have used it to change the style and formatting of text. I would now like to use it to insert text as shown below: <span class="OwnerJoe">reconcile all entries</span> Which I hope I could get to show as: Joe's Task: reconcile all entries That is, simply by virtue of being of class "Owner Joe", I want the text Joe's Task: to be displayed. I could do it with code like: <span class="OwnerJoe">Joe's Task:</span> reconcile all entries. But that seems awfully redundant to both specify the class and the text. Is it possible to do what I'm looking for? EDIT One idea is to try to set it up as a ListItem <li> where the "bullet" is the text "Joe's Task". I see examples of how to set various bullet-styles and even images for bullets. Is it possible to use a small block of text for the list-bullet?

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  • IE8 claims my page has an error, firefox doesn't, and I can't find any error. Help!

    - by Bears will eat you
    This is something of a follow-up question to my question here. You can find the HTML source in a text file here. When I load that page in IE8, I get the "Done, but with errors on page." message in my status bar. The detail view shows Expected identifier sms Line: 147 Code: 0 Char: 67 and I see absolutely no problems anywhere near there. In IE8, the page is still behaving erratically w/r/t the randomly losing focus as mentioned in my other question. When I load the same exact page in Firefox (using Firebug) the console shows no errors and the page works perfectly. Any thoughts on what's going on here? This is driving me nuts and making me want to give up on even trying to write an IE friendly page. Edit: Thanks for all the comments! This page is written as a JSP, so I edit in Eclipse. I found an Eclipse warning about the onblur event for the username field. I switched it from onblur="alert(document.activeElement + ' class:' + document.activeElement.class)" to onblur="alert(document.activeElement)" and that made the bizarre IE page error vanish. I had been trying to give more info (namely, its CSS class) about specifically which element is stealing focus - to my own detriment, apparently, since Javascript was interpreting the '.class' part in the Java(script) sense. And, no, the page doesn't validate. But the errors were mostly/all ones that just didn't make sense, such as Line 14, Column 41: Attribute "LANGUAGE" is not a valid attribute. Did you mean "language"? to which I say, WTF?! But I'm still stuck trying to figure out why, as I enter text in the username & password fields, focus randomly switches to a div (working on figuring out which div currently). Edit 2: It's the div between the two "global nav" comments, at the very top of the body. Still no idea why it's happening, though.

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  • Is it possible to restrict instantiation of an object to only one other (parent) object in VB.NET?

    - by Casey
    VB 2008 .NET 3.5 Suppose we have two classes, Order and OrderItem, that represent some type of online ordering system. OrderItem represents a single line item in an Order. One Order can contain multiple OrderItems, in the form of a List(of OrderItem). Public Class Order Public Property MyOrderItems() as List(of OrderItem) End Property End Class It makes sense that an OrderItem should not exist without an Order. In other words, an OrderItem class should not be able to be instantiated on its own, it should be dependent on an Order class to contain it and instantiate it. However, the OrderItem should be public in scope so that it's properties are accessible to other objects. So, the requirements for OrderItem are: Can not be instantiated as a stand alone object; requires Order to exist. Must be public so that any other object can access it's properties/methods through the Order object. e.g. Order.OrderItem(0).ProductID. OrderItem should be able to be passed to other subs/functions that will operate on it. How can I achieve these goals? Is there a better approach?

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  • log4net - why would the same MyLog.Debug line not work at one point of startup, but work at another

    - by Greg
    Hi, During startup of my WinForms application I'm noting that there are a couple of points (before the MainForm renders) that do a "MyDataSet.GetInstance()". For the first one the MyLog.Debug line comes through in the VS2008 output window, but for a later one it does work and come through. What could explain this? What settings could I check at debug time to see why an output line for a MyLog.Debug line doesn't come out in the output window? namespace IntranetSync { public class MyDataSet { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MyDataSet)); public static MyDataSet GetInstance() { MyLog.Debug("MyDataSet GetInstance() ====================================="); if (myDataSet == null) { myDataSet = new MyDataSet(); } return myDataSet; } . . . PS. What I have been doing re log4net repository initialization is putting the following line as a private variables in the classes I use logging - is this OK? static class Program { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MainForm)); . . . public class Coordinator { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MainForm)); . . . public class MyDataSet { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MyDataSet)); . . .

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  • Which ORM to use?

    - by Paja
    I'm developing an application which will have these classes: class Shortcut { public string Name { get; } public IList<Trigger> Triggers { get; } public IList<Action> Actions { get; } } class Trigger { public string Name { get; } } class Action { public string Name { get; } } And I will have 20+ more classes, which will derive from Trigger or Action, so in the end, I will have one Shortcut class, 15 Action-derived classes and 5 Trigger-derived classes. My question is, which ORM will best suit this application? EF, NH, SubSonic, or maybe something else (Linq2SQL)? I will be periodically releasing new application versions, adding more triggers and actions (or changing current triggers/actions), so I will have to update database schema as well. I don't know if EF or NH provides any good methods to easily update the schema. Or if they do, is there any tutorial how to do that? I've already found this article about NH schema updating, quoting: Fortunately NHibernate provides us the possibility to update an existing schema, that is NHibernate creates an update script which can the be applied to the database. I've never found how to actually generate the update script, so I can't tell NH to update the schema. Maybe I've misread something, I just didn't found it. Last note: If you suggest EF, will be EF 1.0 suitable as well? I would rather use some older .NET than 4.0.

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  • Spring: Bean fails to read off values from external Properties file when using @Value annotation

    - by daydreamer
    XML Configuration <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"> <util:properties id="mongoProperties" location="file:///storage/local.properties" /> <bean id="mongoService" class="com.business.persist.MongoService"></bean> </beans> and MongoService looks like @Service public class MongoService { @Value("#{mongoProperties[host]}") private String host; @Value("#{mongoProperties[port]}") private int port; @Value("#{mongoProperties[database]}") private String database; private Mongo mongo; private static final Logger LOGGER = LoggerFactory.getLogger(MongoService.class); public MongoService() throws UnknownHostException { LOGGER.info("host=" + host + ", port=" + port + ", database=" + database); mongo = new Mongo(host, port); } public void putDocument(@Nonnull final DBObject document) { LOGGER.info("inserting document - " + document.toString()); mongo.getDB(database).getCollection(getCollectionName(document)).insert(document, WriteConcern.SAFE); } I write my MongoServiceTest as public class MongoServiceTest { @Autowired private MongoService mongoService; public MongoServiceTest() throws UnknownHostException { mongoRule = new MongoRule(); } @Test public void testMongoService() { final DBObject document = DBContract.getUniqueQuery("001"); document.put(DBContract.RVARIABLES, "values"); document.put(DBContract.PVARIABLES, "values"); mongoService.putDocument(document); } and I see failures in tests as 12:37:25.224 [main] INFO c.s.business.persist.MongoService - host=null, port=0, database=null java.lang.NullPointerException at com.business.persist.MongoServiceTest.testMongoService(MongoServiceTest.java:40) Which means bean was not able to read the values from local.properties local.properties ### === MongoDB interaction === ### host="127.0.0.1" port=27017 database=contract How do I fix this? update It doesn't seem to read off the values even after creating setters/getters for the fields. I am really clueless now. How can I even debug this issue? Thanks much!

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  • How does the CheckBox obtain it's respective drawables?

    - by alex2k8
    The CheckBox class extends the CompoundButton, but add nothing to it. But some how it obtains it's respective look. I found some declarations in Android sources, but wonder how they are mapped to CheckBox class? public class CheckBox extends CompoundButton { public CheckBox(Context context) { this(context, null); } public CheckBox(Context context, AttributeSet attrs) { this(context, attrs, com.android.internal.R.attr.checkboxStyle); } public CheckBox(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } } Styles <style name="Theme"> <item name="checkboxStyle">@android:style/Widget.CompoundButton.CheckBox</item> </style> <style name="Widget.CompoundButton.CheckBox"> <item name="android:background">@android:drawable/btn_check_label_background</item> <item name="android:button">@android:drawable/btn_check</item> </style> EDIT: Probably I was not clear... I understand how the drawable assigned to Widget.CompoundButton.CheckBox style, but how this style assigned to CheckBox class? I see the ".CheckBox" in the style name, but is this naming convention really what makes the trick? If so, what are the rules? If I derive MyCheckBox from CompoundButton, can I just define the Widget.CompoundButton.MyCheckBox style and it will work?

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  • Java Concurrency in practice sample question

    - by andy boot
    I am reading "Java Concurrency in practice" and looking at the example code on page 51. According to the book this piece of code is at risk of of failure if it has not been published properly. Because I like to code examples and break them to prove how they work. I have tried to make it throw an AssertionError but have failed. (Leading me to my previous question) Can anyone post sample code so that an AssertionError is thrown? Rule: Do not modify the Holder class. public class Holder{ private int n; public Holder(int n){ this.n = n; } public void assertSanity(){ if (n != n) { throw new AssertionError("This statement is false"); } } } I have modified the class to make it more fragile but I still can not get an AssertionError thrown. class Holder2{ private int n; private int n2; public Holder2(int n) throws InterruptedException{ this.n = n; Thread.sleep(200); this.n2 = n; } public void assertSanity(){ if (n != n2) { throw new AssertionError("This statement is false"); } } } Is it possible to make either of the above classes throw an AssertionError? Or do we have to accept that they may occasionally do so and we can't write code to prove it?

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  • java 6 web services share domain specific classes between server and client

    - by user173446
    Hi all, Context: Considering below defined Engine class being parameter of some webservice method. As we have both server and client in java we may have some benefits (???) in sharing Engine class between server and client ( i.e we may put in a common jar file to be added to both client and server classpath ) Some benefits would be : we keep specific operations like 'brushEngine' in same place build is faster as we do not need in our case to generate java code for client classes but to use them from the server build) if we later change server implementation for 'brushEngine' this is reflected automatically in client . Questions: How to share below detailed Engine class using java 6 tools ( i.e wsimport , wsgen etc )? Is there other tools for java that can achieve this sharing ? Is sharing a case that java 6 web services support is missing ? Can this case be reduced to other web service usage patterns? Thanks. Code: public class Engine { private String engineData; public String getData(){ return data; } public setData(String value){ this.data = value; } public void brushEngine(){ engineData = "BrushedEngine"+engineData; } }

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  • KODO: how set up fetch plan for bidirectional relationships?

    - by BestPractices
    Running KODO 4.2 and having an issue inefficient queries being generated by KODO. This happens when fetching an object that contains a collection where that collection has a bidrectional relationship back to the first object. Class Classroom { List<Student> _students; } Class Student { Classroom _classroom; } If we create a fetch plan to get a list of Classrooms and their corresponding Students by setting up the following fetch plan: fetchPlan.addField(Classroom.class,”_students”); This will result in two queries (get the classrooms and then get all students that are in those classrooms), which is what we would expect. However, if we include the reference back to the classroom in our fetch plan in order for the _classroom field to get populated by doing fetchPlan.addField(Student.class, “_classroom”), this will result in X number of additional queries where X is the number of students in each classroom. Can anyone explain how to fix this? KODO already has the original Classroom objects at the point that it's executing the queries to retrieve the Classroom objects and set them in each Student object's _classroom field. So I would expect KODO to simply set those objects in the _classroom field on each Student object accordingly and not go back to the database. Once again, the documentation is sorely lacking with Kodo/JDO/OpenJPA but from what I've read it should be able to do this more efficiently. Note-- EAGER_FETCH.PARALLEL is turned on and I have tried this with caching (query and data caches) turned on and off and there is no difference in the resultant queries.

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  • Pass Linq Expression to a function

    - by Kushan Hasithe Fernando
    I want to pass a property list of a class to a function. with in the function based on property list I'm going to generate a query. As exactly same functionality in Linq Select method. Here I'm gonna implement this for Ingress Database. As an example, in front end I wanna run a select as this, My Entity Class is like this public class Customer { [System.Data.Linq.Mapping.ColumnAttribute(Name="Id",IsPrimaryKey=true)] public string Id { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Name")] public string Name { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Address")] public string Address { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Email")] public string Email { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Mobile")] public string Mobile { get; set; } } I wanna call a Select function like this, var result = dataAccessService.Select<Customer>(C=>C.Name,C.Address); then,using result I can get the Name and Address properties' values. I think my Select function should looks like this, ( *I think this should done using Linq Expression. But im not sure what are the input parameter and return type. * ) Class DataAccessService { // I'm not sure about this return type and input types, generic types. public TResult Select<TSource,TResult>(Expression<Func<TSource,TResult>> selector) { // Here using the property list, // I can get the ColumnAttribute name value and I can generate a select query. } } This is a attempt to create a functionality like in Linq. But im not an expert in Linq Expressions. There is a project call DbLinq from MIT, but its a big project and still i couldn't grab anything helpful from that. Can someone please help me to start this, or can someone link me some useful resources to read about this.

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  • Rails - Why is HAML showing the full hash?

    - by Mr. Demetrius Michael
    View: !!! %html %head %title= full_title(yield(:title)) =stylesheet_link_tag "application", media: "all" =javascript_include_tag "application" =csrf_meta_tags =render 'layouts/shim' %body =render 'layouts/header' .container =flash.each do |key, value| %div{class: "alert alert-#{key}"} #{value} Controller def create @user = User.new(params[:user]) if @user.save flash[:success] = "This is Correct" redirect_to @user else flash[:wrong] = "no" render 'new' end end Regardless of the flash (:success or :wrong or otherwise) it always compiles the entire hash as html (below) Output: <!DOCTYPE html> .... <div class='container'> <div class='alert alert-wrong'>no</div> {:wrong=&gt;&quot;no&quot;} </div> </body> </html> I have no idea why {:wrong=&gt;&quot;no&quot;} is being displayed. I've been staring at this terminal for hours. What's interesting is that the hash is being outputted with the container id, but not in the alert class. It feels like an indentation problem, but I went through several permutations with no success.

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  • OO - inheritance vs. decoration problem

    - by Karel J
    Hi all, I have an OOP-related question. I have an interface, say: class MyInterface { public int getValue(); } In my project, this interface is implemented by 7 implementations: class MyImplementation1 implements MyInterface { ... } ... class MyImplementation7 implements MyInterface { ... } These implementations are used by several different modules. For some modules, the behaviour of the MyInterface must be adjusted slightly. Let's that it must return the value of the implementator + 1 (for the sake of example). I solved this by creating a little decorator: class MyDifferentInterface implements MyInterface { private MyInterface i; public MyDifferentInterface(MyInterface i) { this.i = i; } public int getValue() { return i.getValue() + 1; } } This does the job. Here is my problem: one of the modules doesn't accept an MyInterface parameter, but MyImplementation4 directly. The reason for this is that this module needs specific behaviour of MyImplementation4, which are not covered by the interface MyInterface on itself. But, and here comes the difficulty, this module must also work on the modified version of MyImplementation4. That is, getValue() must return +1; What is the best way to solve this? I fail to come up with a solution which does not include lots of code duplicates. Please note that although the example above is pretty small and simple, the interface and the decorator is quite large and complicated. Thanks a lot all.

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  • Java: creating objects of arrays with different names at runtime and accessing/updating them

    - by scriptingalias
    Hello, I'm trying to create a class that can instantiate arrays at runtime by giving each array a "name" created by the createtempobjectname() method. I'm having trouble making this program run. I would also like to see how I could access specific objects that were created during runtime and accessing those arrays by either changing value or accessing them. This is my mess so far, which compiles but gets a runtime exception. import java.lang.reflect.Array; public class arrays { private static String temp; public static int name = 0; public static Object o; public static Class c; public static void main(String... args) { assignobjectname(); //getclassname();//this is supposed to get the name of the object and somehow //allow the arrays to become updated using more code? } public static void getclassname() { String s = c.getName(); System.out.println(s); } public static void assignobjectname()//this creates the object by the name returned { //createtempobjectname() try { String object = createtempobjectname(); c = Class.forName(object); o = Array.newInstance(c, 20); } catch (ClassNotFoundException exception) { exception.printStackTrace(); } } public static String createtempobjectname() { name++; temp = Integer.toString(name); return temp; } }

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  • jQuery Swapping Elements

    - by zuk1
    Ok let me make an example: <head> <script type="text/javascript"> $(document).ready(function(){ $("#options_2").hide(); $("#options_3").hide(); }); </script> </head> <body> <div id="options_1">option 1</div> <div id="options_2">option 2</div> <div id="options_3">option 3</div> <a href="" class="selected">choose option 1</a> <a href="">choose option 2</a> <a href="">choose option 3</a> </body> As you can see only option 1 is visible by default, and the link you click to show option 1 has the class="selected" by default, showing the user that that option is currently selected. I basically want it so that when they click "choose option 2" the options 1 div hides itself and the options 2 div shows itself, and then gives the second link the selected class and removes the class from the image link. It basically just tabs using links and divs but due to the format I have to display it in I cannot use any of the tabs plugins I have found online.

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