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  • Hibernate 1:M relationship ,row order, constant values table and concurrency

    - by EugeneP
    table A and B need to have 1:M relationship a and b are added during application runtime, so A created, then say 4 B's created. Each B instance has to come in order, so that I could later extract them in the same order as I added them. The app will be a web-app running on Tomcat, so 10 instances may work simultaneously. So my question are: 1) How to preserve inserting order, so that I could extract B instances that A references in the same order as I persisted them. That's tricky, because we add to a Collection and then it gets saved (am I right?). So, it depends on how Hibernate saves it, what if it changes the order in what we added instances? I've seen something like LIST instead of SET when describing relationships, is that what I need? 2) How to add a 3-rd column to B so that I could differentiate the instances, something like SEX(M,F,U) in B table. Do I need a special table, or there's and easy way to describe constants in Hibernate. What do you recommend? 3) Talking about concurrency, what methods do you recommend to use? There should be no collisions in the db and as you see, there might easily be some if rows are not inserted (PK added) right where it is invoked without delays ?

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  • NSInvalidArgumentException: Illegal attempt to establish a relationship between objects in different

    - by iPhoneDollaraire
    I have an app based on the CoreDataBooks example that uses an addingManagedObjectContext to add an Ingredient to a Cocktail in order to undo the entire add. The CocktailsDetailViewController in turn calls a BrandPickerViewController to (optionally) set a brand name for a given ingredient. Cocktail, Ingredient and Brand are all NSManagedObjects. Cocktail requires at least one Ingredient (baseLiquor) to be set, so I create it when the Cocktail is created. If I add the Cocktail in CocktailsAddViewController : CocktailsDetailViewController (merging into the Cocktail managed object context on save) without setting baseLiquor.brand, then it works to set the Brand from a picker (also stored in the Cocktails managed context) later from the CocktailsDetailViewController. However, if I try to set baseLiquor.brand in CocktailsAddViewController, I get: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Illegal attempt to establish a relationship 'brand' between objects in different contexts' From this question I understand that the issue is that Brand is stored in the app's managedObjectContext and the newly added Ingredient and Cocktail are stored in addingManagedObjectContext, and that passing the ObjectID instead would avoid the crash. What I don't get is how to implement the picker generically so that all of the Ingredients (baseLiquor, mixer, garnish, etc.) can be set during the add, as well as one-by-one from the CocktailsDetailViewController after the Cocktail has been created. In other words, following the CoreDataBooks example, where and when would the ObjectID be turned into the NSManagedObject from the parent MOC in both add and edit cases? -IPD UPDATE - Here's the code: - (IBAction)addCocktail:(id)sender { CocktailsAddViewController *addViewController = [[CocktailsAddViewController alloc] init]; addViewController.title = @"Add Cocktail"; addViewController.delegate = self; // Create a new managed object context for the new book -- set its persistent store coordinator to the same as that from the fetched results controller's context. NSManagedObjectContext *addingContext = [[NSManagedObjectContext alloc] init]; self.addingManagedObjectContext = addingContext; [addingContext release]; [addingManagedObjectContext setPersistentStoreCoordinator:[[fetchedResultsController managedObjectContext] persistentStoreCoordinator]]; Cocktail *newCocktail = (Cocktail *)[NSEntityDescription insertNewObjectForEntityForName:@"Cocktail" inManagedObjectContext:self.addingManagedObjectContext]; newCocktail.baseLiquor = (Ingredient *)[NSEntityDescription insertNewObjectForEntityForName:@"Ingredient" inManagedObjectContext:self.addingManagedObjectContext]; newCocktail.mixer = (Ingredient *)[NSEntityDescription insertNewObjectForEntityForName:@"Ingredient" inManagedObjectContext:self.addingManagedObjectContext]; newCocktail.volume = [NSNumber numberWithInt:0]; addViewController.cocktail = newCocktail; UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:addViewController]; [self.navigationController presentModalViewController:navController animated:YES]; [addViewController release]; [navController release]; }

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  • Complex relationship between tables in NHibernate

    - by Ilya Kogan
    Hi all, I'm writing a Fluent NHibernate mapping for a legacy Oracle database. The challenge is that the tables have composite primary keys. If I were at total freedom, I would redesign the relationships and auto-generate primary keys, but other applications must write to the same database and read from it, so I cannot do it. These are the two tables I'll focus on: Example data Trips table: 1, 10:00, 11:00 ... 1, 12:00, 15:00 ... 1, 16:00, 19:00 ... 2, 12:00, 13:00 ... 3, 9:00, 18:00 ... Faults table: 1, 13:00 ... 1, 23:00 ... 2, 12:30 ... In this case, vehicle 1 made three trips and has two faults. The first fault happened during the second trip, and the second fault happened while the vehicle was resting. Vehicle 2 had one trip, during which a fault happened. Constraints Trips of the same vehicle never overlap. So the tables have an optional one-to-many relationship, because every fault either happens during a trip or it doesn't. If I wanted to join them in SQL, I would write: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime and then I'd get a dataset where every fault appears exactly once (one-to-many as I said). Note that there is no Vehicles table, and I don't need one. But I did create a view that contains all VehicleIds from both tables, so I can use it as a junction table. What am I actually looking for? The tables are huge because they cover years of data, and every time I only need to fetch a range of a few hours. So I need a mapping and a criteria that will run something like the following SQL underneath: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime where Faults.FaultTime between :p0 and :p1 Do you have any ideas how to achieve it? Note 1: Currently the application shouldn't write to the database, so persistence is not a must, although if the mapping supports persistence, it may help at some point in the future. Note 2: I know it's a tough one, so if you give me a great answer, you will be properly rewarded :) Thank you for reading this long question, and now I only hope for the best :)

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  • One-to-many relationship with JDO in Google App Engine

    - by Marvin
    I've followed the GAE docs on setting up one-to-many relationship in JDO but I'm still having trouble in retrieving the collection data back. I have no problem getting the other non-collection fields back. Here are my classes: @PersistenceCapable public class User{ @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; @Persistent private String uniqueId; @Persistent private String email; @Persistent private List<Address> addresses = new ArrayList<Address>() ; ... } @PersistenceCapable public class Phone{ @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; @Persistent private String number; ... } public class UserDaoImpl implements UserDao { public void insertUser(User user) { if(user.getKey() == null) { com.google.appengine.api.datastore.Key key = KeyFactory.createKey(User.class.getSimpleName(), user.getEmail()); user.setKey(key); } PersistenceManager pm = PersistenceManagerWrapper.getPersistenceManager(); notNull(user); try { pm.makePersistent(user); } finally { pm.close(); } } @SuppressWarnings("unchecked") public User getUser(String uniqueId) { PersistenceManager pm = PersistenceManagerWrapper.getPersistenceManager(); Query query = pm.newQuery(User.class); query.setFilter("uniqueId == uniqueIdParam"); query.declareParameters("String uniqueIdParam"); User user = null; try { List<User> users = (List<User>)(query.execute(uniqueId)); //TODO abstract this if(users.size() > 0) user = users.get(0); } finally { pm.close(); } return user; } } public class UserDaoImplTest { @Test public void getUserTest() { User user = createTestUser(); assertNotNull("The user object should not be null", user); userDao.insertUser(user); User returnedUser = userDao.getUser(TEST_USER_ID); assertNotNull("The returnedUser object should not be null", returnedUser); Assert.assertPropertyEqualsExcludeProperties("User Object", user, returnedUser, ""); } } When I run the test, all the properties for User is populated but the list of Phone if I get is empty.

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  • Django Multi-Table Inheritance VS Specifying Explicit OneToOne Relationship in Models

    - by chefsmart
    Hope all this makes sense :) I'll clarify via comments if necessary. Also, I am experimenting using bold text in this question, and will edit it out if I (or you) find it distracting. With that out of the way... Using django.contrib.auth gives us User and Group, among other useful things that I can't do without (like basic messaging). In my app I have several different types of users. A user can be of only one type. That would easily be handled by groups, with a little extra care. However, these different users are related to each other in hierarchies / relationships. Let's take a look at these users: - Principals - "top level" users Administrators - each administrator reports to a Principal Coordinators - each coordinator reports to an Administrator Apart from these there are other user types that are not directly related, but may get related later on. For example, "Company" is another type of user, and can have various "Products", and products may be supervised by a "Coordinator". "Buyer" is another kind of user that may buy products. Now all these users have various other attributes, some of which are common to all types of users and some of which are distinct only to one user type. For example, all types of users have to have an address. On the other hand, only the Principal user belongs to a "BranchOffice". Another point, which was stated above, is that a User can only ever be of one type. The app also needs to keep track of who created and/or modified Principals, Administrators, Coordinators, Companies, Products etc. (So that's two more links to the User model.) In this scenario, is it a good idea to use Django's multi-table inheritance as follows: - from django.contrib.auth.models import User class Principal(User): # # # branchoffice = models.ForeignKey(BranchOffice) landline = models.CharField(blank=True, max_length=20) mobile = models.CharField(blank=True, max_length=20) created_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalcreator") modified_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalmodifier") # # # Or should I go about doing it like this: - class Principal(models.Model): # # # user = models.OneToOneField(User, blank=True) branchoffice = models.ForeignKey(BranchOffice) landline = models.CharField(blank=True, max_length=20) mobile = models.CharField(blank=True, max_length=20) created_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalcreator") modified_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalmodifier") # # # Please keep in mind that there are other user types that are related via foreign keys, for example: - class Administrator(models.Model): # # # principal = models.ForeignKey(Principal, help_text="The supervising principal for this Administrator") user = models.OneToOneField(User, blank=True) province = models.ForeignKey( Province) landline = models.CharField(blank=True, max_length=20) mobile = models.CharField(blank=True, max_length=20) created_by = models.ForeignKey(User, editable=False, blank=True, related_name="administratorcreator") modified_by = models.ForeignKey(User, editable=False, blank=True, related_name="administratormodifier") I am aware that Django does use a one-to-one relationship for multi-table inheritance behind the scenes. I am just not qualified enough to decide which is a more sound approach.

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  • ASP.NET MVC 2: Linq to SQL entity w/ ForeignKey relationship and Default ModelBinder strangeness

    - by Simon
    Once again I'm having trouble with Linq to Sql and the MVC Model Binder. I have Linq to Sql generated classes, to illustrate them they look similar to this: public class Client { public int ClientID { get; set; } public string Name { get; set; } } public class Site { public int SiteID { get; set; } public string Name { get; set; } } public class User { public int UserID { get; set; } public string Name { get; set; } public int? ClientID { get; set; } public EntityRef<Client> Client { get; set; } public int? SiteID { get; set; } public EntityRef<Site> Site { get; set; } } The 'User' has a relationship with the 'Client' and 'Site . The User class has nullable ClientIDs and SiteIDs because the admin users are not bound to a Client or Site. Now I have a view where a user can edit a 'User' object, the view has fields for all the 'User' properties. When the form is submitted, the appropiate 'Save' action is called in my UserController: public ActionResult Save(User user, FormCollection form) { //form['SiteID'] == 1 //user.SiteID == 1 //form['ClientID'] == 1 //user.ClientID == null } The problem here is that the ClientID is never set, it is always null, even though the value is in the FormCollection. To figure out whats going wrong I set breakpoints for the ClientID and SiteID getters and setters in the Linq to Sql designer generated classes. I noticed the following: SiteID is being set, then ClientID is being set, but then the Client EntityRef property is being set with a null value which in turn is setting the ClientID to null too! I don't know why and what is trying to set the Client property, because the Site property setter is never beeing called, only the Client setter is being called. Manually setting the ClientID from the FormCollection like this: user.ClientID = int.Parse(form["ClientID"].ToString()); throws a 'ForeignKeyReferenceAlreadyHasValueException', because it was already set to null before. The only workaround I have found is to extend the generated partial User class with a custom method: Client = default(EntityRef<Client>) but this is not a satisfying solution. I don't think it should work like this? Please enlighten me someone. So far Linq to Sql is driving me crazy! Best regards

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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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  • JPA - Entity design problem

    - by Yatendra Goel
    I am developing a Java Desktop Application and using JPA for persistence. I have a problem mentioned below: I have two entities: Country City Country has the following attribute: CountryName (PK) City has the following attribute: CityName Now as there can be two cities with same name in two different countries, the primaryKey for City table in the datbase is a composite primary key composed of CityName and CountryName. Now my question is How to implement the primary key of the City as an Entity in Java @Entity public class Country implements Serializable { private String countryName; @Id public String getCountryName() { return this.countryName; } } @Entity public class City implements Serializable { private CityPK cityPK; private Country country; @EmbeddedId public CityPK getCityPK() { return this.cityPK; } } @Embeddable public class CityPK implements Serializable { public String cityName; public String countryName; } Now as we know that the relationship from Country to City is OneToMany and to show this relationship in the above code, I have added a country variable in City class. But then we have duplicate data(countryName) stored in two places in the City class: one in the country object and other in the cityPK object. But on the other hand, both are necessary: countryName in cityPK object is necessary because we implement composite primary keys in this way. countryName in country object is necessary because it is the standard way of showing relashionship between objects. How to get around this problem?

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  • How do I serialize/deserialize a NHibernate entity that has references to other objects?

    - by Daniel T.
    I have two NHibernate-managed entities that have a bi-directional one-to-many relationship: public class Storage { public virtual string Name { get; set; } public virtual IList<Box> Boxes { get; set; } } public class Box { public virtual string Box { get; set; } [DoNotSerialize] public virtual Storage ParentStorage { get; set; } } A Storage can contain many Boxes, and a Box always belongs in a Storage. I want to edit a Box's name, so I send it to the client using JSON. Note that I don't serialize ParentStorage because I'm not changing which storage it's in. The client edits the name and sends the Box back as JSON. The server deserializes it back into a Box entity. Problem is, the ParentStorage property is null. When I try to save the Box to the database, it updates the name, but also removes the relationship to the Storage. How do I properly serialize and deserialize an entity like a Box, while keeping the JSON data size to a minimum?

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  • LINQ2SQL: How to let a column accept null values as zero (0) in Self-Relation table

    - by Remon
    As described in the img, I got a parent-Children relation and since the ParentID not accepting null values (and I can't change to nullabel due to some restriction in the UI I have), how can I remove an existence relation between ReportDataSources in order to change the parent for them (here i want to set the parentId for one of them = 0) how could i do that since i cant change the ParentID directly and setting Parent = null is not valid public void SetReportDataSourceAsMaster(ReportDataSource reportDataSource) { //Some logic - not necessarily for this scenario //Reset Master this.ReportDataSources.ToList().ForEach(rds => rds.IsMaster = false); //Set Master reportDataSource.IsMaster = true; //Set Parent ID for the rest of the Reports data sources this.ReportDataSources.Where(rds => rds.ID != reportDataSource.ID).ToList().ForEach(rds => { //Change Parent ID rds.Parent = reportDataSource; //Remove filttering data rds.FilteringDataMembers.Clear(); //Remove Grouping Data rds.GroupingDataMembers.Clear(); }); //Delete parent HERE THE EXCEPTION THROWN AFTER CALLING SUBMITCHANGES() reportDataSource.Parent = null; //Other logic } Exception thrown after calling submitChanges An attempt was made to remove a relationship between a ReportDataSource and a ReportDataSource. However, one of the relationship's foreign keys (ReportDataSource.ParentID) cannot be set to null.

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  • Hibernate: update on parent-child relationship causes duplicate children

    - by TimmyJ
    I have a parent child relationship in which the parent has a collection of children (a set to be specific). The child collection is setup with cascade="all-delete-orphan". When I initially save the parent element everything works as expected. However, when I update the parent and save again, all the children are re-saved. This behavior leads me to believe that the parent is losing its reference to the collection of children, and therefore when persisting all the children are re-saved. It seems the only way to fix this is to not use the setter method of this child collection, but unfortunately this setter is called implicitly in my application (Spring MVC is used to bind a multi-select form element to this collection, and the setter is called by spring on the form submission). Overwriting this setter to not lose the reference (ie, do a colleciton.clear() and collection.addAll(newCollection) rather than collection = newCollection) is apparently a hibernate no-no, as is pointed out here: https://forum.hibernate.org/viewtopic.php?t=956859 Does anyone know how to circumvent this problem? I've posted some of my code below. The parent hibernate configuration: <hibernate-mapping package="org.fstrf.masterpk.domain"> <class name="ReportCriteriaBean" table="masterPkReportCriteria"> <id name="id" column="id"> <generator class="org.hibernate.id.IncrementGenerator" /> </id> <set name="treatmentArms" table="masterPkTreatmentArms" sort="org.fstrf.masterpk.domain.RxCodeComparator" lazy="false" cascade="all-delete-orphan" inverse="true"> <key column="runid"/> <one-to-many class="TreatmentArm"/> </set> </class> </hibernate-mapping> The parent object: public class ReportCriteriaBean{ private Integer id; private Set<TreatmentArm> treatmentArms; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public Set<TreatmentArm> getTreatmentArms() { return treatmentArms; } public void setTreatmentArms(Set<TreatmentArm> treatmentArms) { this.treatmentArms = treatmentArms; if(this.treatmentArms != null){ for(TreatmentArm treatmentArm : this.treatmentArms){ treatmentArm.setReportCriteriaBean(this); } } } The child hibernate configuration: <hibernate-mapping package="org.fstrf.masterpk.domain"> <class name="TreatmentArm" table="masterPkTreatmentArms"> <id name="id" column="id"> <generator class="org.hibernate.id.IncrementGenerator" /> </id> <many-to-one name="reportCriteriaBean" class="ReportCriteriaBean" column="runId" not-null="true" /> <property name="rxCode" column="rxCode" not-null="true"/> </class> </hibernate-mapping> The child object: public class TreatmentArm { private Integer id; private ReportCriteriaBean reportCriteriaBean; private String rxCode; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public ReportCriteriaBean getReportCriteriaBean() { return reportCriteriaBean; } public void setReportCriteriaBean(ReportCriteriaBean reportCriteriaBean) { this.reportCriteriaBean = reportCriteriaBean; } public String getRxCode() { return rxCode; } public void setRxCode(String rxCode) { this.rxCode = rxCode; } }

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  • When should one use the Abstract, Implements, or extends keywords?

    - by kdavis8
    I'm just now moving from a beginner to intermediate level android programmer in the java language. i can successfully write a game framework of classes that work together to accomplish a task beyond basic things, like hello world. but i'm having issues with some pretty basic OOP concepts; When should i derive from an abstract class? When is it more efficient to use an Interface instead of simply sub classing a parent? Basically, between extends, implements, and the abstract keywords, which keywords should be used instead of the others? i'm not looking for a basic definition, as i know them. i need to no when and why i should apply them to my code? what advantages does one have over the other? which is best for game development?

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  • How to define an n-m relation in doctrine?

    - by murze
    If got a table "Article" and a table "Tags". Articles can have multiple tags and tags can hang to multiple articles. The class BaseArticle looks like this: abstract class BaseArticle extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('article'); $this->hasColumn('article_id', 'integer', 8, array( 'type' => 'integer', 'length' => 8, 'fixed' => false, 'unsigned' => false, 'primary' => true, 'autoincrement' => true, )); $this->hasColumn('title', 'string', null, array( 'type' => 'string', 'fixed' => false, 'unsigned' => false, 'primary' => false, 'notnull' => false, 'autoincrement' => false, )); $this->hasColumn('text', 'string', null, array( 'type' => 'string', 'fixed' => false, 'unsigned' => false, 'primary' => false, 'notnull' => false, 'autoincrement' => false, $this->hasColumn('url', 'string', 255, array( 'type' => 'string', 'length' => 255, 'fixed' => false, 'unsigned' => false, 'primary' => false, 'notnull' => false, 'autoincrement' => false, )); } public function setUp() { parent::setUp(); $this->hasMany('Tag as Tags', array( 'local' => 'article_id', 'foreign'=>'tag_id', 'refClass'=>'Articletag') ); } } The BaseTag-class like this: abstract class BaseTag extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('tag'); $this->hasColumn('tag_id', 'integer', 4, array( 'type' => 'integer', 'length' => 4, 'fixed' => false, 'unsigned' => false, 'primary' => true, 'autoincrement' => true, )); $this->hasColumn('name', 'string', null, array( 'type' => 'string', 'fixed' => false, 'unsigned' => false, 'primary' => false, 'notnull' => false, 'autoincrement' => false, )); } public function setUp() { parent::setUp(); $this->hasMany('Article as Articles', array( 'local' => 'tag_id', 'foreign'=>'article_id', 'refClass'=>'Articletag') ); } } And the relationship class like this: abstract class BaseArticletag extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('articletag'); $this->hasColumn('article_id', 'integer', 8, array( 'type' => 'integer', 'length' => 8, 'fixed' => false, 'unsigned' => false, 'primary' => true, 'autoincrement' => false, )); $this->hasColumn('tag_id', 'integer', 4, array( 'type' => 'integer', 'length' => 4, 'fixed' => false, 'unsigned' => false, 'primary' => true, 'autoincrement' => false, )); } public function setUp() { parent::setUp(); } } When I try to get a property from the article all goes well by using: $article = Doctrine_Query::create()->from('Article a') ->where('id = ?' , 1) ->fetchOne(); echo $article->title; //gives me the title But when I try this: foreach($article->Tags as $tag) { echo($tag->name) } I get an error: Unknown record property / related component "Tags" on "Article"

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  • How to model a relationship that NHibernate (or Hibernate) doesn’t easily support

    - by MylesRip
    I have a situation in which the ideal relationship, I believe, would involve Value Object Inheritance. This is unfortunately not supported in NHibernate so any solution I come up with will be less than perfect. Let’s say that: “Item” entities have a “Location” that can be in one of multiple different formats. These formats are completely different with no overlapping fields. We will deal with each Location in the format that is provided in the data with no attempt to convert from one format to another. Each Item has exactly one Location. “SpecialItem” is a subtype of Item, however, that is unique in that it has exactly two Locations. “Group” entities aggregate Items. “LocationGroup” is as subtype of Group. LocationGroup also has a single Location that can be in any of the formats as described above. Although I’m interested in Items by Group, I’m also interested in being able to find all items with the same Location, regardless of which group they are in. I apologize for the number of stipulations listed above, but I’m afraid that simplifying it any further wouldn’t really reflect the difficulties of the situation. Here is how the above could be diagrammed: Mapping Dilemma Diagram: (http://www.freeimagehosting.net/uploads/592ad48b1a.jpg) (I tried placing the diagram inline, but Stack Overflow won't allow that until I have accumulated more points. I understand the reasoning behind it, but it is a bit inconvenient for now.) Hmmm... Apparently I can't have multiple links either. :-( Analyzing the above, I make the following observations: I treat Locations polymorphically, referring to the supertype rather than the subtype. Logically, Locations should be “Value Objects” rather than entities since it is meaningless to differentiate between two Location objects that have all the same values. Thus equality between Locations should be based on field comparisons, not identifiers. Also, value objects should be immutable and shared references should not be allowed. Using NHibernate (or Hibernate) one would typically map value objects using the “component” keyword which would cause the fields of the class to be mapped directly into the database table that represents the containing class. Put another way, there would not be a separate “Locations” table in the database (and Locations would therefore have no identifiers). NHibernate (or Hibernate) do not currently support inheritance for value objects. My choices as I see them are: Ignore the fact that Locations should be value objects and map them as entities. This would take care of the inheritance mapping issues since NHibernate supports entity inheritance. The downside is that I then have to deal with aliasing issues. (Meaning that if multiple objects share a reference to the same Location, then changing values for one object’s Location would cause the location to change for other objects that share the reference the same Location record.) I want to avoid this if possible. Another downside is that entities are typically compared by their IDs. This would mean that two Location objects would be considered not equal even if the values of all their fields are the same. This would be invalid and unacceptable from the business perspective. Flatten Locations into a single class so that there are no longer inheritance relationships for Locations. This would allow Locations to be treated as value objects which could easily be handled by using “component” mapping in NHibernate. The downside in this case would be that the domain model becomes weaker, more fragile and less maintainable. Do some “creative” mapping in the hbm files in order to force Location fields to be mapped into the containing entities’ tables without using the “component” keyword. This approach is described by Colin Jack here. My situation is more complicated than the one he describes due to the fact that SpecialItem has a second Location and the fact that a different entity, LocatedGroup, also has Locations. I could probably get it to work, but the mappings would be non-intuitive and therefore hard to understand and maintain by other developers in the future. Also, I suspect that these tricky mappings would likely not be possible using Fluent NHibernate so I would use the advantages of using that tool, at least in that situation. Surely others out there have run into similar situations. I’m hoping someone who has “been there, done that” can share some wisdom. :-) So here’s the question… Which approach should be preferred in this situation? Why?

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  • Java sockets: multiple client threads on same port on same machine?

    - by espcorrupt
    I am new to Socket programming in Java and was trying to understand if the below code is not a wrong thing to do. My question is: Can I have multiple clients on each thread trying to connect to a server instance in the same program and expect the server to read and write data with isolation between clients" public class Client extends Thread { ... void run() { Socket socket = new Socket("localhost", 1234); doIO(socket); } } public class Server extends Thread { ... void run() { // serverSocket on "localhost", 1234 Socket clientSock = serverSocket.accept(); executor.execute(new ClientWorker(clientSock)); } } Now can I have multiple Client instances on different threads trying to connect on the same port of the current machine? For example, Server s = new Server("localhost", 1234); s.start(); Client[] c = new Client[10]; for (int i = 0; i < c.length; ++i) { c.start(); }

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  • Cannot truncate table because it is being referenced by a FOREIGN KEY constraint?

    - by ctrlShiftBryan
    Using MSSQL2005, Can I truncate a table with a foreign key constraint if I first truncate the child table(the table with the primary key of the FK relationship)? I know I can use a DELETE without a where clause and then RESEED the identity OR Remove the FK, truncate and recreate but I thought as long as you truncate the child table you'll be OK however I'm getting a "Cannot truncate table 'TableName' because it is being referenced by a FOREIGN KEY constraint." error.

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  • How do I update with a newly-created detached entity using NHibernate?

    - by Daniel T.
    Explanation: Let's say I have an object graph that's nested several levels deep and each entity has a bi-directional relationship with each other. A -> B -> C -> D -> E Or in other words, A has a collection of B and B has a reference back to A, and B has a collection of C and C has a reference back to B, etc... Now let's say I want to edit some data for an instance ofC. In Winforms, I would use something like this: var instanceOfC; using (var session = SessionFactory.OpenSession()) { // get the instance of C with Id = 3 instanceOfC = session.Linq<C>().Where(x => x.Id == 3); } SendToUIAndLetUserUpdateData(instanceOfC); using (var session = SessionFactory.OpenSession()) { // re-attach the detached entity and update it session.Update(instanceOfC); } In plain English, we grab a persistent instance out of the database, detach it, give it to the UI layer for editing, then re-attach it and save it back to the database. Problem: This works fine for Winform applications because we're using the same entity all throughout, the only difference being that it goes from persistent to detached to persistent again. The problem occurs when I'm using a web service and a browser, sending over JSON data. In this case, the data that comes back is no longer a detached entity, but rather a transient one that just happens to have the same ID as the persistent one. If I use this entity to update, it will wipe out the relationship to B and D unless I sent the entire object graph over to the UI and got it back in one piece. Question: My question is, how do I serialize detached entities over the web, receive them back, and save them, while preserving any relationships that I didn't explicitly change? I know about ISession.SaveOrUpdateCopy and ISession.Merge() (they seem to do the same thing?), but this will still wipe out the relationships if I don't explicitly set them. I could copy the fields from the transient entity to the persistent entity one by one, but this doesn't work too well when it comes to relationships and I'd have to handle version comparisons manually.

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  • Symfony2 same form, different entities NOT related

    - by user1381537
    I'm trying to write one form for submitting against MySQL DB, but I can't get it working, I've tried a lot of things (separate forms, create an ->add('foo', new foo()) to a field, and trying to parse plain SQL with a normal HTML form is my only solution, which is obviously not the best. This is my DB structure: As you can see I need to insert the comments textarea to ticketcomments among the user who wrote it, etc. On crmentity the description field. Then on ticketcf the fields that I need to submit from form, are this (because you wont know if I don't tell you because of the field names): tcf.cf594 AS Type, tcf.cf675 AS Suscription, tcf.cf770 AS ID_PRODUCT, tcf.cf746 AS NotificationDate, tcf.cf747 AS ResponseDate, tcf.cf748 AS ResolutionDate, And, of course, every table needs to have the same ticketid id for the submitted form, so we can retrieve it with one simple query. It will be easy to do with plain SQL instead of using DQL and Symfony2 forms, but is not a good way to do it. Also, here's my "Ticket list" query, if you need it to have it more clear... SELECT t.ticketNo AS Ticket, t.title AS Asunto, t.status AS Estado, t.updateLog AS LOG, t.hours AS Horas, t.solution AS Solucion, t.priority AS Prioridad, tcf.cf594 AS Tipo, tcf.cf675 AS Suscripcion, tcf.cf770 AS IDPROD, tcf.cf746 AS F_Noti, tcf.cf747 AS F_Resp, tcf.cf748 AS F_Reso, CONCAT (cd.firstname, cd.lastname) AS Contacto, crm.description AS Descripcion, crm.crmid AS id FROM WbsGoclientsBundle:VtigerTroubletickets t INNER JOIN WbsGoclientsBundle:VtigerTicketcf tcf WITH t.ticketid = tcf.ticketid INNER JOIN WbsGoclientsBundle:VtigerContactdetails cd WITH t.parentId = cd.contactid INNER JOIN WbsGoclientsBundle:VtigerCrmentity crm WITH t.ticketid = crm.crmid WHERE t.parentId IN ( SELECT cd1.contactid FROM WbsGoclientsBundle:VtigerContactdetails cd1 WHERE cd1.accountid = ( SELECT cd2.accountid FROM WbsGoclientsBundle:VtigerContactdetails cd2 WHERE cd2.contactid = :contactid)) AND t.status <> \'Closed\' And also "Ticket details" query (which is not in DQL format yet, only SQL) is so simple, it only retrieve the comments field and createdtime from ticketcomments appended to this query so we have all the fields... Thank you. This is a test form, using troubletickets and ticketcomments, it's returning errores because I can't set a comments field because troubletickets doesn't has it, but I need that field to be submitted to ticketcomments ... VtigerTicketcommentsType <?php namespace WbsGo\clientsBundle\Form\Type; use Symfony\Component\Form\AbstractType, Symfony\Component\Form\FormBuilderInterface; use Symfony\Component\OptionsResolver\OptionsResolverInterface; class VtigerTicketcommentsType extends AbstractType { public function buildForm(FormBuilderInterface $builder, array $options) { $builder ->add('ticketid') ->add('comments') ->add('ownerid') ->add('ownertype') ->add('createdtype') ; } public function setDefaultOptions(OptionsResolverInterface $resolver) { $resolver->setDefaults(array( 'data_class' => 'WbsGo\clientsBundle\Entity\VtigerTicketcomments' )); } public function getName() { return 'comments'; } } OpenTicketType.php <?php namespace WbsGo\clientsBundle\Form; use Symfony\Component\Form\AbstractType, Symfony\Component\Form\FormBuilderInterface ; use WbsGo\clientsBundle\Form\Type\VtigerTicketcommentsType; use Symfony\Component\OptionsResolver\OptionsResolverInterface; class OpenTicketType extends AbstractType { public function buildForm(FormBuilderInterface $builder, array $options) { $builder ->add('title') ->add('priority') ->add('solution') ->add('comments', 'collection', array( 'type' => new VtigerTicketcommentsType() )) ; } public function setDefaultOptions(OptionsResolverInterface $resolver) { $resolver->setDefaults(array( 'data_class' => 'WbsGo\clientsBundle\Entity\VtigerTroubletickets' )); } public function getName() { return 'ticket'; } } TicketController.php <?php namespace WbsGo\clientsBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; use WbsGo\clientsBundle\Entity\VtigerTroubletickets; use WbsGo\clientsBundle\Entity\VtigerTicketcomments; use WbsGo\clientsBundle\Form\OpenTicketType; use Symfony\Component\HttpFoundation\Request; class TicketController extends Controller { public function indexAction() { $em = $this->getDoctrine()->getManager(); $tickets = $em ->getRepository('WbsGoclientsBundle:VtigerTroubletickets') ->findAllOpenByCustomerId($this->getUser()->getId()); $userdata = $this->getDoctrine()->getManager() ->getRepository('WbsGoclientsBundle:VtigerContactdetails') ->findContact($this->getUser()->getId()); return $this ->render('WbsGoclientsBundle:Ticket:index.html.twig', array('tickets' => $tickets, 'userdata' => $userdata)); } public function addAction() { $assets = $this->getDoctrine()->getManager() ->getRepository('WbsGoclientsBundle:VtigerAssets') ->findAssetByAccountId($this->getUser()->getId()); $assetlist = array(); foreach ($assets as $key => $v) { $assetlist[$key] = $key; } $form = $this->createForm(new OpenTicketType(), new VtigerTroubletickets()); return $this ->render('WbsGoclientsBundle:Ticket:add.html.twig', array('form' => $form->createView(), 'assets' => $assets,)); } } This is the error Symfony2 is returning Neither the property "comments" nor one of the methods "getComments()", "isComments()", "hasComments()", "_get()" or "_call()" exist and have public access in class "WbsGo\clientsBundle\Entity\VtigerTroubletickets". EDIT 2 This code is actually rendering my forms, but I need help in order to submit each XXXType form to its corresponding table. public function buildForm(FormBuilderInterface $builder, array $options) { $builder ->add('descripcion') ->add('prioridad') ->add('solucion') ->add('comment', new VtigerTicketcommentsType() ) ->add('contacto') ->add('suscripcion') ->add('producto', 'entity', array( 'class' => 'WbsGo\clientsBundle\Entity\VtigerAssets', 'property' => 'assetname', 'empty_value' => '--SELECT--', 'query_builder' => function(\WbsGo\clientsBundle\Entity\VtigerAssetsRepository $repository) { //return $repository->findAssetByAccountId($this->customerId); return $repository->createQueryBuilder('a') ->select('a') ->where('a.account = (SELECT cd.accountid FROM WbsGoclientsBundle:VtigerContactdetails cd WHERE cd.contactid = ?1)') ->setParameter(1, $this->customerId); } ) ) ->add('hardware') ->add('backup') ->add('web') ->add('restore') ->add('customerId') ; } I also removed ->add('ticketid') from VtigerTicketcommentsType.php because it has relationship and is not needed. it's auto_incremental and must be generated once everything is submitted.

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  • Entity Framework 4 ste delete foreign key relationship

    - by user169867
    I'm using EF4 and STE w/ Silverlight. I'm having trouble deleting child records from my primary entity. For some reason I can remove child entities if their foreign key to my primary entity is part of their Primary Key. But if it's not, they don't get removed. I believe these posts explains it: http://mocella.blogspot.com/2010/01/entity-framework-v4-object-graph.html http://blogs.msdn.com/dsimmons/archive/2010/01/31/deleting-foreign-key-relationships-in-ef4.aspx My question is how how do I remove a child record who's foreign key is not part of its primary key in Silverlight where I don't have access to a DeleteObject() function?

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  • Proper way to add record to many to many relationship in Django

    - by blcArmadillo
    First off, I'm planning on running my project on google app engine so I'm using djangoappengine which as far as I know doesn't support django's ManyToManyField type. Because of this I've setup my models like this: from django.db import models from django.contrib.auth.models import User class Group(models.Model): name = models.CharField(max_length=200) class UserGroup(models.Model): user = models.ForeignKey(User) group = models.ForeignKey(Group) On a page I have a form field where people can enter a group name. I want the results from this form field to create a UserGroup object for the user - group combination and if the group doesn't yet exist create a new Group object. At first I started putting this logic in the UserGroup class with a add_group method but quickly realized that it doesn't really make sense to put this in the UserGroup class. What would the proper way of doing this be? I saw some stuff about model managers. Is this what those are for?

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  • Oracle & Active Directory : A love/hate relationship

    - by Frank
    Hi SO'ers, I'm currently trying to access Active Directory via the dbms_ldap API in Pl/Sql (Oracle). The trouble is that I'm not able to connect with my own username and password or anynoymously. However, in C# I can connect anonymously with this code : DirectoryEntry ldap = new DirectoryEntry("LDAP://Hostname"); DirectorySearcher searcher = new DirectorySearcher(ldap); searcher.Filter = "(SAMAccountName=username)"; SearchResult result = searcher.FindOne(); If I try to connect anonymously in Oracle, I only get the error(ORA-31202 : LDAP client/server error) when I try to search (and the result code for the bind is SUCCESS)... my_session := dbms_ldap.init('HOST','389'); retval := dbms_ldap.simple_bind_s(my_session, '', ''); retval := dbms_ldap.search_s(my_session, ldap_base, dbms_ldap.scope_subtree, 'objectclass=*', my_attrs, 0, my_message); Why is the anonymous connection is C# works but doesn't work in Pl/Sql? Do you have any other idea to connect to Active Directory via Oracle? Help me reunite them together. Thanks. Edit When I bind with anonymous credentials I get : ORA-31202: DBMS_LDAP: LDAP client/server error 00000000: LdapErr: DSID-0C090627, comment: In order to perform this operation a successful bind must be completed on the connection And if I try to connect with my credentials, which are supposed to be valid since I'm connected to the domain with it... I get : ORA-31202: DBMS_LDAP: LDAP client/server error Invalid credentials 80090308: LdapErr: DSID-0C090334, comment: AcceptSecurityContext error

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  • C# WPF XAML DataTable binding to relationship

    - by LnDCobra
    I have the following tables: Company {CompanyID, CompanyName} Deal {CompanyID, Value} And I have a listbox: <ListBox Name="Deals" Height="100" Width="420" Margin="0,20,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" Visibility="Visible" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding}" SelectionChanged="Deals_SelectionChanged"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBlock Text="{Binding companyRowByBuyFromCompanyFK.CompanyName}" FontWeight="Bold" /> <TextBlock Text=" -> TGS -> " /> <TextBlock Text="{Binding BuyFrom}" FontWeight="Bold" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> As you can see, I want to display the CompanyName rather then the ID which is a foreign Key. The relation "companyRowByBuyFromCompanyFK" exists, as in Deals_SelectionChanged I can access companyRowByBuyFromCompanyFK property of the Deals row, and I also can access the CompanyName propert of that row. Is the reason why this is not working because XAML binding uses the [] indexer? Rather than properties on the CompanyRows in my DataTable? At the moment im getting values such as - TGS - 3 - TGS - 4 What would be the best way to accomplish this? Make a converter to convert foreign keys using Table being referenced as custom parameter. Create Table View for each table? This would be long winded as I have quite a large number of tables that have foreign keys.

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  • Creating a second form page for a has_many relationship

    - by Victor Martins
    I have an Organization model that has_many users through affiliations. And, in the form of the organization ( the standard edit ) I use semanting_form_for and semantic_fields_for to display the organization fields and affiliations fields. But I wish to create a separete form just to handle the affiliations of a specific organization. I was trying to go to the Organization controller and create a an edit_team and update_team methods then on the routes create those pages, but it's getting a mess and not working. am I on the right track?

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  • The relationship between OPC and DCOM

    - by typoknig
    Hi all, I am trying to grasp the link between OPC and DCOM. I have watched all four of the tutorials here and I think I have a good feeling for what OPC is, but in one of the tutorials (the third one 35 seconds in) the narrator states that OPC is based on DCOM, but I do not understand how the two are really linked. My confusion comes from a question my professor posed in which he asked "How and where would you deploy OPC instead of DCOM and vice-versa." His question makes it seem like the two are not as linked as my research suggests. I'm not looking for anyone to answer the question, I just want to know the relation between OPC and DCOM, then I can figure the rest out. Specifically I would like to know if: 1.) One is always based on the other 2.) One can always be deployed without the other.

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  • Django User M2M relationship

    - by Antonio
    When trying to syncdb with the following models: class Contact(models.Model): user_from = models.ForeignKey(User,related_name='from_user') user_to = models.ForeignKey(User, related_name='to_user') class Meta: unique_together = (('user_from', 'user_to'),) User.add_to_class('following', models.ManyToManyField('self', through=Contact, related_name='followers', symmetrical=False)) I get the following error: Error: One or more models did not validate: auth.user: Accessor for m2m field 'following' clashes with related m2m field 'User.followers'. Add a related_name argument to the definition for 'following'. auth.user: Reverse query name for m2m field 'following' clashes with related m2m field 'User.followers'. Add a related_name argument to the definition for 'following'. auth.user: The model User has two manually-defined m2m relations through the model Contact, which is not permitted. Please consider using an extra field on your intermediary model instead. auth.user: Accessor for m2m field 'following' clashes with related m2m field 'User.followers'. Add a related_name argument to the definition for 'following'. auth.user: Reverse query name for m2m field 'following' clashes with related m2m field 'User.followers'. Add a related_name argument to the definition for 'following'.

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