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• Update Related Entity Of Detached Entity

  - by Hemslingo

  I'm having an issue updating an entity with multiple related entities. I've got a very simple model which consists of an article entity and a list of categories the article can be related to. You can choose from a check box list which of these categories are associated to it...which works fine. The problem crops up when I actually come to update an existing entity using the dbContext. As I am updating this entity, I have already detached it from the context ready to re-attach it later so the update can execute properly. I can see that after I posting the model, the category(s) are being added to the article entity just fine and it looks like it updates in the repository with no errors occurring. When I look in the database the article has updated as normal but the category(s) have not. Here is my (simplified) update code... public virtual bool Attach(T entity) { _dbContext.Entry(entity).State = EntityState.Modified; _dbSet.Attach(entity); return this.Commit(); } Any help will be much appreciated.

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• Why does the Combo.SelectedValue get lost after some time

  - by tzup

  So I have this asp:DropDownList on a page. It renders like this (in IE7): <select name="ctl00$cphFilter$cbLista" onchange="javascript:setTimeout('__doPostBack(\'ctl00$cphFilter$cbLista\',\'\')', 0)" id="ctl00_cphFilter_cbLista" class="agsSelect"> <option selected="selected" value="4350">A</option> <option value="4352">B</option> <option value="4349">C</option> <option value="4348">D</option> And then I have a grid and a button on the same page. When the user clicks the button the selected item of the dropdown is read (well a datasource object reads it) and the grid does a databind after a trip to a DB where it gets some data based on that selected value. This works fine most of the time. However sometimes, the selection in the dropdownlist seems to get lost even though the rendered page says the A is the selected item. The datasource object is defined like this: <asp:ObjectDataSource ID="dsVM" runat="server" EnablePaging="False" SelectMethod="Select" SortParameterName="sort" TypeName="X.Business.Entities.LPVM.BE"> <SelectParameters> <asp:ControlParameter Name="listaId" Type="Int32" ControlID="cphFilter$cbLista" PropertyName="SelectedValue" /> </SelectParameters> </asp:ObjectDataSource> Any ideas why the grid would reload its data with a select parameter that is 0 instead of the selected value of the dropdownlist? EDIT Suppose the dropdownlist is bound, the user selected B and the grid is bound as well and shows the right data. Now, I wait 2 minutes and I click the Refresh button. Surprisingly, at this particular moment the dropdownlist.SelectedValue (which I already know it was 4352 before I clicked because that's how it looks in the rendered page) is actually an empty string. Where did the value go?

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• Core data setReturnsDistinctResult not working

  - by Moze

  So i'm building a small application, it uses core data database of ~25mb size with 4 entities. It's for bus timetables. In one table named "Stop" there are have ~1300 entries of bus stops with atributes "name", "id", "longitude", "latitude" and couple relationships. Now there are many stops with same name but different coordinates and id. Search is implemented using NSPredicate. So I want to show all distinct stop names in table view, i'm using setReturnsDistinctResults with NSDictionaryResultType and setPropertiesToFetch. But setReturnsDistinctResult is not working and I'm still getting all entries. Heres code: - (NSFetchRequest *)fetchRequest { if (fetchRequest == nil) { fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Stop" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; NSArray *sortDescriptors = [NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES] autorelease]]; [fetchRequest setSortDescriptors:sortDescriptors]; [fetchRequest setResultType:NSDictionaryResultType]; [fetchRequest setPropertiesToFetch:[NSArray arrayWithObject:[[entity propertiesByName] objectForKey:@"name"]]]; [fetchRequest setReturnsDistinctResults:YES]; DebugLog(@"fetchRequest initialized"); } return fetchRequest; } ///////////////////// - (NSFetchedResultsController *)fetchedResultsController { if (self.predicateString != nil) { self.predicate = [NSPredicate predicateWithFormat:@"name CONTAINS[cd] %@", self.predicateString]; [self.fetchRequest setPredicate:predicate]; } else { self.predicate = nil; [self.fetchRequest setPredicate:predicate]; } fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:self.fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:sectionNameKeyPath cacheName:nil]; return fetchedResultsController; } ////////////// - (UITableViewCell *)tableView:(UITableView *)table cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } cell.textLabel.text = [[fetchedResultsController objectAtIndexPath:indexPath] valueForKey:@"name"]; return cell; }

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• How to create database records for a financial year

  - by David A Gibson

  Hello, I need to create entities (specifically contracts) in a database table that are associated with a financial year. These contracts will be applied to projects. Any contract variation will be recorded by creating a new contract record for the same financial year but the original will remain associated with the project as a history. The projects can last several years and so at any one time a project will have a live contract record for each year as well as any number of historic contracts for that year. All of which is incidental but I'm trying to provide some context. If the contracts where for the year - it would be easy and I'd just store the Year either as a date field with the 1st of January or just an Integer. However the contracts run for financial years and I don't know how to approach this. I don't want a separate table containing the financial years as I don't want the users to have to maintain this. I don't want to store the financial year as a string "2009/2010" as this is not ideal for sorting/extracting the data. Any ideas will be helpful, my best so far is to have starting and ending year in 2 columns and just "KNOW" that starting is April of the year etc Thanks

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• Magento Set Grid to Filter Automatically by Current Day using Existing Datetime Column in Grid

  - by Tegan Snyder

  In Magento I'm creating a custom module and would love to be able to filter automatically by the datetime column so that the intial grid listing shows only entities related to "todays" date. Here is my datetime column: $this->addColumn('ts', array( 'header' => $hlp->__('Activated'), 'align' => 'left', 'index' => 'ts', 'type' => 'datetime', 'width' => '160px', )); I'm think there should be a way for me to just add a filter to the collection like so: $now = Mage::getModel('core/date')->timestamp(time()); $dateTime = date('m/d/y h:i:s', $now); $collection = Mage::getModel('mymodule/items')->getCollection() ->addFieldToFilter('ts', $dateTime); But this doesn't work? Am I using the wrong filter? My "ts" field in the database is a "datetime" field, but the default magento "From: " - "To:" date range selectors don't use hours, minutes, seconds. Any ideas? Thanks, Tegan

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• partial entity loading and management in silverlight / wcf ria

  - by Dan Wray

  I have a Silverlight 4 app which pulls entities down from a database using WCF RIA services. These data objects are fairly simple, just a few fields but one of those fields contains binary data of an arbitrarily size. The application needs access to this data basically asap after a user has logged in, to display in a list, enable selection etc. My problem is because of the size of this data, the load times are not acceptable and can approach the default timeout of the RIA service. I'd like to somehow partially load the objects into my local data context so that I have the IDs, names etc but not the binary data. I could then at a later point (ie when it's actually needed) populate the binary fields of those objects I need to display. Any suggestions on how to accomplish this would be welcome. Another approach which has occurred to me whilst writing this question (how often does that happen?!) is that I could move the binary data into a seperate database table joined to the original record 1:1 which would allow me to make use of RIA's lazy loading on that binary data. again.. comments welcome! Thanks.

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• Hibernate and parent/child relations

  - by Marco

  Hi to all, I'm using Hibernate in a Java application, and i feel that something could be done better for the management of parent/child relationships. I've a complex set of entities, that have some kind of relationships between them (one-to-many, many-to-many, one-to-one, both unidirectional and bidirectional). Every time an entity is saved and it has a parent, to estabilish the relationship the parent has to add the child to its collection (considering a one-to-may relationship). For example: Parent p = (Parent) session.load(Parent.class, pid); Child c = new Child(); c.setParent(p); p.getChildren().add(c); session.save(c); session.flush(); In the same way, if i remove a child then i have to explicitly remove it from the parent collection too. Child c = (Child) session.load(Child.class, cid); session.delete(c); Parent p = (Parent) session.load(Parent.class, pid); p.getChildren().remove(c); session.flush(); I was wondering if there are some best practices out there to do this jobs in a different way: when i save a child entity, automatically add it to the parent collection. If i remove a child, automatically update the parent collection by removing the child, etc. For example, Child c = new Child(); c.setParent(p); session.save(c); // Automatically update the parent collection session.flush(); or Child c = (Child) session.load(Child.class, cid); session.delete(c); // Automatically updates its parents (could be more than one) session.flush(); Anyway, it would not be difficult to implement this behaviour, but i was wondering if exist some standard tools or well known libraries that deals with this issue. And, if not, what are the reasons? Thanks

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• Maintaining a pool of DAO Class instances vs doing new operator

  - by Fazal

  we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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• XML: what processing rules apply for values intertwined with tags?

  - by iCE-9

  I've started working on a simple XML pull-parser, and as I've just defuzzed my mind on what's correct syntax in XML with regards to certain characters/sequences, ignorable whitespace and such (thank you, http://www.w3schools.com/xml/xml_elements.asp), I realized that I still don't know squat about what can be sketched up as the following case (which Validome finds well-formed very much; note that I only want to use xml files for data storage, no entities, DTD or Schemas needed): <bookstore> <book id="1"> <author>Kurt Vonnegut Jr.</author> <title>Slapstick</title> </book> We drop a pie here. <book id="2">Who cares anyway? <author>Stephen King</author> <title>The Green Mile</title> </book> And another one here. <book id="3"> <author>Next one</author> <title>This time with its own title</title> </book> </bookstore> "We drop a pie here." and "And another one here." are values of the 'bookstore' element. "Who cares anyway?" is a value related to the second 'book' element. How are these processed, if at all? Will "We drop a pie here." and "Another one here." be concatenated to form one value for the 'bookstore' element, or are they treated separately, stored somewhere, affecting the outcome of the parsing of the element they belong to, or...?

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• Idiomatic default sort using WCF RIA, Entity Framework 4, Silverlight 4?

  - by Duncan Bayne

  I've got two Silverlight 4.0 ComboBoxes; the second displays the children of the entity selected in the first: <ComboBox Name="cmbThings" ItemsSource="{Binding Path=Things,Mode=TwoWay}" DisplayMemberPath="Name" SelectionChanged="CmbThingsSelectionChanged" /> <ComboBox Name="cmbChildThings" ItemsSource="{Binding Path=SelectedThing.ChildThings,Mode=TwoWay}" DisplayMemberPath="Name" /> The code behind the view provides a (simple, hacky) way to databind those ComboBoxes, by loading Entity Framework 4.0 entities through a WCF RIA service: public EntitySet<Thing> Things { get; private set; } public Thing SelectedThing { get; private set; } protected override void OnNavigatedTo(NavigationEventArgs e) { var context = new SortingDomainContext(); context.Load(context.GetThingsQuery()); context.Load(context.GetChildThingsQuery()); Things = context.Things; DataContext = this; } private void CmbThingsSelectionChanged(object sender, SelectionChangedEventArgs e) { SelectedThing = (Thing) cmbThings.SelectedItem; if (PropertyChanged != null) { PropertyChanged.Invoke(this, new PropertyChangedEventArgs("SelectedThing")); } } public event PropertyChangedEventHandler PropertyChanged; What I'd like to do is have both combo boxes sort their contents alphabetically, and I'd like to specify that behaviour in the XAML if at all possible. Could someone please tell me what is the idiomatic way of doing this with the SL4 / EF4 / WCF RIA technology stack?

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• Saving multiple objects in a single call in rails

  - by CaptnCraig

  I have a method in rails that is doing something like this: a = Foo.new("bar") a.save b = Foo.new("baz") b.save ... x = Foo.new("123", :parent_id => a.id) x.save ... z = Foo.new("zxy", :parent_id => b.id) z.save The problem is this takes longer and longer the more entities I add. I suspect this is because it has to hit the database for every record. Since they are nested, I know I can't save the children before the parents are saved, but I would like to save all of the parents at once, and then all of the children. It would be nice to do something like: a = Foo.new("bar") b = Foo.new("baz") ... saveall(a,b,...) x = Foo.new("123", :parent_id => a.id) ... z = Foo.new("zxy", :parent_id => b.id) saveall(x,...,z) That would do it all in only two database hits. Is there an easy way to do this in rails, or am I stuck doing it one at a time?

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• How to associate static entity instances in a Session without database retrieval

  - by Michael Hedgpeth

  I have a simple Result class that used to be an Enum but has evolved into being its own class with its own table. public class Result { public static readonly Result Passed = new Result(StatusType.Passed) { Id = [Predefined] }; public static readonly Result NotRun = new Result(StatusType.NotRun) { Id = [Predefined] }; public static readonly Result Running = new Result(StatusType.Running) { Id = [Predefined] }; } Each of these predefined values has a row in the database at their predefined Guid Id. There is then a failed result that has an instance per failure: public class FailedResult : Result { public FailedResult(string description) : base(StatusType.Failed) { . . . } } I then have an entity that has a Result: public class Task { public Result Result { get; set; } } When I save a Task, if the Result is a predefined one, I want NHibernate to know that it doesn't need to save that to the database, nor does it need to fetch it from the database; I just want it to save by Id. The way I get around this is when I am setting up the session, I call a method to load the static entities: protected override void OnSessionOpened(ISession session) { LockStaticResults(session, Result.Passed, Result.NotRun, Result.Running); } private static void LockStaticResults(ISession session, params Result[] results) { foreach (var result in results) { session.Load(result, result.Id); } } The problem with the session.Load method call is it appears to be fetching to the database (something I don't want to do). How could I make this so it does not fetch the database, but trusts that my static (immutable) Result instances are both up to date and a part of the session?

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• Should I remove all inheritance from my model in order to work with ria services?

  - by TimothyP

  I've posted some questions on this before, but it's different. So consider a small portion of our model: Person Customer Employee Spouse Person is the base class which has 3 classes that inherit from it. These 4 are very central in our design and link to many other entities. I could solve all the problems I'm experiencing with ria-services by removing the inheritance but that would really increase the complexety of the model. The first problem I experienced was that I couldn't query for Customers, Employees or Spouses, but someone gave me a solution, which was to add something like this to the DomainService: public IQueryable<Employee> GetEmployees() { return this.ObjectContext.People.OfType<Employee>(); } public IQueryable<Customer> GetCustomers() { return this.ObjectContext.People.OfType<Customer>(); } public IQueryable<Spouse> GetSpouses() { return this.ObjectContext.People.OfType<Spouse>(); } Next I tried something that seemed very normal to me: var employee = new Employee() { //.... left out to reduce the length of this question }; var spouse = new Spouse() { //.... left out to reduce the length of this questions }; employee.Spouse = spouse; context.People.Add(spouse); context.People.Add(employee); context.SubmitChanges(); Then I get the following exception: Cannot retrieve an entity set for the derived entity type 'Spouse'. Use EntityContainer.GetEntitySet(Type) to get the entity set for the base entity type 'Person'. Even when the spouse is already in the database, and I retreive it first I get similar exceptions. Also note that for some reason in some places "Persons" is used instead of "People"... So how do I solve this problem, what am I doing wrong and will I keep running into walls when using ria services with inheritance? I found some references on the web, all saying it works and then some DomainService code in which they suposedly changed something but no details... I'm using VS2010 RC1 + Silveright 4

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• Can't Compile Correct Mapping File

  - by NoOne

  Hello, Im now developping one application in C# with Remoting objects and NHibernate. So here is a image explaining how my projects are divided. Views Layer This layer will be responsible for the users interface. This layer will always use the Controls Layer to create and edit objects; Control Layer This is my persistence layer, here Ill have all the NHibernate configuration. This is my critic point, because ListSingleton Project will have only my RemoteObject. (Here I have the App.config file) Models Layer Entity layer. Here I only have the entities classes and their respective mapping. I’ve done a test solution with no remoting and only with the projects of the Control and Model Layers. It was all working ok. Now that I added the Views Layer and set the solution to start with projects Client and Server (Client calls the Control Layer and this would do a try to persist a object) I’m getting a error at : Configuration cfg = new Configuration(); cfg.AddXmlFile("mapping/User.hbm.xml"); InnerException: {"Could not compile the mapping document: mapping/User.hbm.xml"} InnerException.InnerException: {"Could not find the dialect in the configuration"} StackTrace in the InnerException.InnerException " em NHibernate.Dialect.Dialect.GetDialect(IDictionary`2 props)\r\n em NHibernate.Cfg.Configuration.AddValidatedDocument(NamedXmlDocument doc)" But I know that there is no error in the mapping file because I used in my test application.

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• Can't wrap my head around appengine data store persistence

  - by aloo

  Hi, I've run into the "can't operate on multiple entity groups in a single transaction." problem when using APPENGINE FOR JAVA w/ JDO with the following code: PersistenceManager pm = PMF.get().getPersistenceManager(); Query q = pm.newQuery("SELECT this FROM " + TypeA.class.getName() + " WHERE userId == userIdParam "); q.declareParameters("String userIdParam"); List<TypeA> poos = (List<TypeA>) q.execute(userIdParam); for (TypeA a : allTypeAs) { a.setSomeField(someValue); } pm.close(); } The problem it seems is that I can't operate on a multiple entities at the same time b/c they arent in the same entity group while in a transaction. Even though it doesn't seem like I'm in a transaction, appengine generates one because I have the following set in my jdoconfig.xml: <property name="datanucleus.appengine.autoCreateDatastoreTxns" value="true"/> Fine. So far I think I understand. BUT - if I replace TypeA in the above code, with TypeB - I don't get the error. I don't believe there is anything different between type a and type b - they both have the same key structure. They do have different fields but that shouldn't matter, right? My question is - what could possible be different between TypeA and TypeB that they give this different behavior? And consequently what do you I fundamentally misunderstand that this behavior could even exist.... Thanks.

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• Eager loading OneToMany in Hibernate with JPA2

  - by pihentagy

  I have a simple @OneToMany between Person and Pet entities: @OneToMany(mappedBy="owner", cascade=CascadeType.ALL, fetch=FetchType.EAGER) public Set<Pet> getPets() { return pets; } I would like to load all Persons with associated Pets. So I came up with this (inside a test class): @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration public class AppTest { @Test @Rollback(false) @Transactional(readOnly = false) public void testApp() { CriteriaBuilder qb = em.getCriteriaBuilder(); CriteriaQuery<Person> c = qb.createQuery(Person.class); Root<Person> p1 = c.from(Person.class); SetJoin<Person, Pet> join = p1.join(Person_.pets); TypedQuery<Person> q = em.createQuery(c); List<Person> persons = q.getResultList(); for (Person p : persons) { System.out.println(p.getName()); for (Pet pet : p.getPets()) { System.out.println("\t" + pet.getNick()); } } However, turning the SQL logging on shows, that it executes 3 queries (having 2 Persons in the DB). Hibernate: select person0_.id as id0_, person0_.name as name0_, person0_.sex as sex0_ from Person person0_ inner join Pet pets1_ on person0_.id=pets1_.owner_id Hibernate: select pets0_.owner_id as owner3_0_1_, pets0_.id as id1_, pets0_.id as id1_0_, pets0_.nick as nick1_0_, pets0_.owner_id as owner3_1_0_ from Pet pets0_ where pets0_.owner_id=? Hibernate: select pets0_.owner_id as owner3_0_1_, pets0_.id as id1_, pets0_.id as id1_0_, pets0_.nick as nick1_0_, pets0_.owner_id as owner3_1_0_ from Pet pets0_ where pets0_.owner_id=? Any tips? Thanks Gergo

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• How to output KML by GAE

  - by Niklas R

  Hi I use KML for a google map where entities have a geopt.db coordinate and soft memory limit was exceeded with 213.465 MB after servicing 1 requests total. The log says /list.kml 200 13130ms 10211cpu_ms 4238api_cpu_ms The file list.kml which outputs about 455,7 KB is a template as follows <?xml version="1.0" encoding="UTF-8"?><kml xmlns="http:// www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http:// www.w3.org/2005/Atom"> <Document>{% for a in list %} <Placemark> <name> </name> <description> <![CDATA[<a href="http://{{host}}/{{a.key.id}}"> {{ a.title }} </a> <br/>{{a.text}}]]> </description> <Style> <IconStyle> <Icon> <href> http://www.google.com/intl/en_us/mapfiles/ms/icons/green-dot.png </href> </Icon> </IconStyle> </Style> <Point> <coordinates> {{a.geopt.lon|floatformat:2}},{{a.geopt.lat|floatformat:2}} </coordinates> </Point> </Placemark> {% endfor %} </Document> </kml> Is there a memory leak in the template or the python that passes the list variable? Can I improve using other template engine or other framework than default? Is kmz compression a good idea in this case? Thanks in advance for any suggestion where or how to change the code.

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• In a bidirectional JPA OneToMany/ManyToOne association, what is meant by "the inverse side of the as

  - by Bytecode Ninja

  In these examples on TopLink JPA Annotation Reference: Example 1-59 @OneToMany - Customer Class With Generics @Entity public class Customer implements Serializable { ... @OneToMany(cascade=ALL, mappedBy="customer") public Set<Order> getOrders() { return orders; } ... } Example 1-60 @ManyToOne - Order Class With Generics @Entity public class Order implements Serializable { ... @ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return customer; } ... } It seams to me that the Customer entity is the owner of the association. However, in the explanation for the mappedBy attribute in the same document, it is written that: if the relationship is bidirectional, then set the mappedBy element on the inverse (non-owning) side of the association to the name of the field or property that owns the relationship as Example 1-60 shows. However, if I am not wrong, looks like in the example the mappedBy is actually specified on the owning side of the association, rather than the non-owning side. So my question is basically: In a bidirectional (one-to-many/many-to-one) association, which of the entities is the owner? How can we designate the One side as the owner? How can we designate the Many side as the owner? What is meant by "the inverse side of the association"? How can we designate the One side as the inverse? How can we designate the Many side as the inverse? Thanks in advance.

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• Using game of life or other virtual environment for artificial (intelligence) life simulation? [clos

  - by Berlin Brown

  One of my interests in AI focuses not so much on data but more on biologic computing. This includes neural networks, mapping the brain, cellular-automata, virtual life and environments. Described below is an exciting project that includes develop a virtual environment for bots to evolve in. "Polyworld is a cross-platform (Linux, Mac OS X) program written by Larry Yaeger to evolve Artificial Intelligence through natural selection and evolutionary algorithms." http://en.wikipedia.org/wiki/Polyworld " Polyworld is a promising project for studying virtual life but it still is far from creating an "intelligent autonomous" agent. Here is my question, in theory, what parameters would you use create an AI environment? Possibly a brain environment? Possibly multiple self contained life organisms that have their own "brain" or life structures. I would like a create a spin on the game of life simulation. What if you have a 64x64 game of life grid. But instead of one grid, you might have N number of grids. The N number of grids are your "life force" If all of the game of life entities die in a particular grid then that entire grid dies. A group of "grids" makes up a life form. I don't have an immediate goal. First, I want to simulate an environment and visualize what is going on in the environment with OpenGL and see if there are any interesting properties to the environment. I then want to add "scarce resources" and see if the AI environment can manage resources adequately.

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• Is ADO.NET Entity framework database schema update possible ?

  - by fyasar

  Hi All I'm working on proof of concept application like crm and i need your some advice. My application's data layer completely dynamic and run onto EF 3.5. When the user update the entity, change relation or add new column to the database, first i'm planning make for these with custom classes. After I rebuild my database model layer with new changes during the application runtime. And my model layer tie with tightly coupled to my project for easy reflecting model layer changes (It connected to my project via interfaces and loading onto to application domain in the runtime). I need to create dynamic entities, create entity relations and modify them during the runtime after that i need to create change database script for updating database schema. I know ADO.NET team says "we will be able to provide this property in EF 4.0", but i don't need to wait for them. How can i update database changes during the runtime via EF 3.5 ? For example, i need to create new entity or need to change some entity schema, add new properties or change property types after than how can apply these changes on the physical database schema ? Any ideas ?

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• questions about name mangling in C++

  - by Tim

  I am trying to learn and understand name mangling in C++. Here are some questions: (1) From devx When a global function is overloaded, the generated mangled name for each overloaded version is unique. Name mangling is also applied to variables. Thus, a local variable and a global variable with the same user-given name still get distinct mangled names. Are there other examples that are using name mangling, besides overloading functions and same-name global and local variables ? (2) From Wiki The need arises where the language allows different entities to be named with the same identifier as long as they occupy a different namespace (where a namespace is typically defined by a module, class, or explicit namespace directive). I don't quite understand why name mangling is only applied to the cases when the identifiers belong to different namespaces, since overloading functions can be in the same namespace and same-name global and local variables can also be in the same space. How to understand this? Do variables with same name but in different scopes also use name mangling? (3) Does C have name mangling? If it does not, how can it deal with the case when some global and local variables have the same name? C does not have overloading functions, right? Thanks and regards!

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• Why are my Fluent NHibernate SubClass Mappings generating redundant columns?

  - by Brook

  I'm using Fluent NHibernate 1.x build 694, built against NH 3.0 I have the following entities public abstract class Card { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } public virtual Product Product { get; set; } public virtual Sprint Sprint { get; set; } } public class Story:Card { public virtual double Points { get; set; } public virtual int Priority { get; set; } public virtual IList<Task> Tasks { get; set; } } And the following mappings public class CardMap:ClassMap<Card> { public CardMap() { Id(c => c.Id) .Index("Card_Id"); Map(c => c.Name) .Length(50) .Not.Nullable(); Map(c => c.Description) .Length(1024) .Not.Nullable(); References(c=>c.Product) .Not.Nullable(); References(c=>c.Sprint) .Nullable(); } } public class StoryMap : SubclassMap<Story> { public StoryMap() { Map(s => s.Points); Map(s => s.Priority); HasMany(s => s.Tasks); } } When I generate my Schema, the tables are created as follows Card --------- Id Name Description Product_id Sprint_id Story ------------ Card_id Points Priority Product_id Sprint_id What I would have expected would have been to see the columns Product_id and Sprint_id ONLY in the Card table, not the Story table. What am I doing wrong or misunderstanding?

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• Understanding Domain Driven Design

  - by Nihilist

  Hi I have been trying to understand DDD for few weeks now. Its very confusing. I dont understand how I organise my projects. I have lot of questions on UnitOfWork, Repository, Associations and the list goes on... Lets take a simple example. Album and Tracks. Album: AlbumId, Name, ListOf Tracks Tracks: TrackId, Name Question1: Should i expose Tracks as a IList/IEnumerabe property on Album ? If that how do i add an album ? OR should i expose a ReadOnlyCollection of Tracks and expose a AddTrack method? Question2: How do i load Tracks for Album [assuming lazy loading]? should the getter check for null and then use a repository to load the tracks if need be? Question3: How do we organise the assemblies. Like what does each assembly have? Model.dll - does it only have the domain entities? Where do the repositories go? Interfaces and implementations both. Can i define IAlbumRepository in Model.dll? Infrastructure.dll : what shold this have? Question4: Where is unit of work defined? How do repository and unit of work communicate? [ or should they ] for example. if i need to add multiple tracks to album, again should this be defined as AddTrack on Album OR should there a method in the repository? Regardless of where the method is, how do I implement unit of work here? Question5: Should the UI use Infrastructure..dll or should there be ServiceLayer? Do my quesitons make sense? Regards

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• Bind button visibility to the expresion (C#)

  - by drasto

  I have a delete button in each row of GridView (component ASP.NET). I want some of the delete buttons to be invisible. The visibility of the delete button should depend on the data that are back the row. GridView is backed by EntityDataSource. GridView displays entities called Category, one instance in each row. Entity Category has (besides others) also a field of type EntityCollection. Name of that field is Items. Basically I want to allow user to delete a row only if the Items field of backing Category entity is an empty collection. I cannot make up the binding of Visible property. I have no experience with bindings and Google does not really help. This is how the button looks right now: <asp:Button ID="DeleteButton" runat="server" CommandName="Delete" Text="Delete" Visible=??? ></asp:Button> I don't know what should replace ???. The button schold be visible only when this expression evaluates to true: ((SimpleEShop.Model.Category) dataItem).Items.LongCount() <= 0 where dataItem variable contains data of current row in the table. What is the binding that I need ?

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• How do tools like Hiphop for PHP deal with heterogenous arrays?

  - by Derek Thurn

  I think HipHop for PHP is an interesting tool. It essentially converts PHP code into C++ code. Cross compiling in this manner seems like a great idea, but I have to wonder, how do they overcome the fundamental differences between the two type systems? One specific example of my general question is heterogeneous data structures. Statically typed languages don't tend to let you put arbitrary types into an array or other container because they need to be able to figure out the types on the other end. If I have a PHP array like this: $mixedBag = array("cat", 42, 8.5, false); How can this be represented in C++ code? One option would be to use void pointers (or the superior version, boost::any), but then you need to cast when you take stuff back out of the array... and I'm not at all convinced that the type inferencer can always figure out what to cast to at the other end. A better option, perhaps, would be something more like a union (or boost::variant), but then you need to enumerate all possible types at compile time... maybe possible, but certainly messy since arrays can contain arbitrarily complex entities. Does anyone know how HipHop and similar tools which go from a dynamic typing discipline to a static discipline handle these types of problems?

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