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Search found 905 results on 37 pages for 'association'.

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• Adding existing entity to navigation property of a different entity

  - by Shay Friedman

  I'm using EF4 and I'm running into a problem when I try to do something that looks quite trivial to me. I have two entities, let's call them A and B. These entities have a many-to-many association between them with a navigation property on A that contains a list of related B entities. What I want to do is to add existing B entities to a new A entity. When I try to do that, I get an exception: AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges. Has anyone run into such a problem?

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• Entity Relationship Diagramming

  - by Ben Aston

  I'd like to improve my understanding of cardinality constraints in ER diagrams. I have two entities: User Location But, I want the relationship between these two entities to be many-to-many (a user can be in many locations and a location can have many users). To do this I need to introduce an association class UserLocation. Is it correct to say I now have 3 entities? If I were to draw an ER diagam of the above, would I draw in the UserLocation entity, and would the cardinality look like this? User 1 ------ * User Location * ------ 1 Location

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• Windows Vista, Default Programs API, file format associations, and (un)installers - explosive mix!

  - by Alex T.

  My application is a rather well behaved Windows citizen, so when I ported it to Windows Vista/7 I replaced my custom file format association code with support for the Default Programs API. However I ran into a problem when trying to make uninstaller for my application - there seems to be no way to remove file format associations via Default Programs API. I tried to call IApplicationAssociationRegistration::ClearUserAssociations but it actually removes all associations, including the ones for other applications - completely restoring default state of the OS (which is of course unacceptable). I tried to call IApplicationAssociationRegistration::SetAppAsDefault to return file format associations to the previous "owner" - but it does not help, because my application handles many unique file formats which the OS does not support and there is no previous "owners". And Windows does not allow to pass empty strings to SetAppAsDefault... So what do I do? Any good solutions?

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• Datamapper has n relationship with multiple keys

  - by jing

  I am working on a simple relationship with DataMapper, a ruby webapp to track games. A game belongs_to 4 players, and each player can have many games. When I call player.games.size, I seem to be getting back a result of 0, for players that I know have games associated with them. I am currently able to pull the player associations off of game, but can't figure out why player.games is empty. Do I need to define a parent_key on the has n association, or is there something else I'm missing? class Game belongs_to :t1_p1, :class_name => 'Player', :child_key => [:player1_id] belongs_to :t1_p2, :class_name => 'Player', :child_key => [:player2_id] belongs_to :t2_p1, :class_name => 'Player', :child_key => [:player3_id] belongs_to :t2_p2, :class_name => 'Player', :child_key => [:player4_id] ... end class Player has n, :games ... end

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• Accessing Active Directory Role Membership through LDAP using SQL Server 2005

  - by David Neale

  I would like to get a list of Active Directory users along with the security groups they are members of using SQL Server 2005 linked servers. I have the query working to retrieve records but I'm not sure how to access the memberOf attribute (it is a multi-value LDAP attribute). I have this temporary to store the information: DROP TABLE #ADUSERGROUPS CREATE TABLE #ADUSERGROUPS ( sAMAccountName varchar(30), UserGroup varchar(50) ) Each group/user association should be one row. This is my SELECT statement: SELECT sAMAccountName,memberOf FROM OpenQuery(ADSI, '<LDAP://hqdc04/DC=nt,DC=avs>; (&(objectClass=User)(sAMAccountName=9695)(sn=*)(mail=*)(userAccountControl=512)); sAMAccountName,memberOf;subtree') I get this error msg: OLE DB error trace [OLE/DB Provider 'ADSDSOObject' IRowset::GetData returned 0x40eda: Data status returned from the provider: [COLUMN_NAME=memberOf STATUS=DBSTATUS_E_CANTCONVERTVALUE], [COLUMN_NAME=sAMAccountName STATUS=DBSTATUS_S_OK]]. Msg 7346, Level 16, State 2, Line 2 Could not get the data of the row from the OLE DB provider 'ADSDSOObject'. Could not convert the data value due to reasons other than sign mismatch or overflow.

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• Representing Objective C Protocols on UML class diagrams

  - by joec

  How should i correctly reference protocols on a UML class diagram? For example my ListViewController conforms to the UITableViewDataSource and UITableViewDelegate protocols... where do i put the cellForRowAtIndexPath or numberOfRowsInSection methods? ... in ListViewController where they are implemented or in something like this: <<Protocol>> UITableViewDataSource --------------------- --------------------- -numberOfRowsInSection If i did the latter what would be the association between the ListViewController class and the protocol box be? All i have to show is how i hook into Cocoa Touch some how. Thanks.

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• Implementing Domain Driven Design

  - by Steve Dunn

  Is anyone using the techniques from Domain Driven Design? I've recently read the Eric Evans book of the same name (well, most of it!) and would be interested to hear from anyone who's implemented all/some of it in a project (particularly in C#/C++) I've kept this question open ended as I'd like to see as many comments as possible, but I have a few questions in particular: 1 - Should value types be real 'value types' if the language supports it? e.g. a struct in C# 2- Is there any feature in C# that makes clearer the association between the language and the model (for instance, this is an entity, this is an aggregate etc.)

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• Rails polymorphic associations, two assoc types in one class

  - by snitko

  Consider a class: class Link < ActiveRecord::Base has_many :link_votes, :as => :vote_subject, :class_name => 'Vote' has_many :spam_votes, :as => :vote_subject, :class_name => 'Vote' end The problem is, when I'm adding a new vote with @link.link_votes << Vote.new the vote_subject_type is 'Link', while I wish it could be 'link_votes' or something like that. Is this an AR limitation or is there a way to workaround this thing? I've actually found one related answer, but I'm not quite sure about what it says: http://stackoverflow.com/questions/1168047/polymorphic-association-with-multiple-associations-on-the-same-model/1764117#1764117

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• Sunspot / Solr full text search - how to index Rails associations

  - by Sam

  Is it possible to index through an association with Sunspot? For example, if a Customer has_many Contacts, I want a 'searchable' block on my Customer model that indexes the Contact#first_name and Contact#last_name columns for use in searches on Customer. acts_as_solr has an :include option for this. I've simply been combining the associated column names into a text field on Customer like shown below, but this doesn't seem very flexible. searchable do text :organization_name, :default_boost => 2 text :billing_address1, :default_boost => 2 text :contact_names do contacts.map { |contact| contact.to_s } end Any suggestions?

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• Inserting Rows in Relationship using a Strongly Typed DataSet

  - by Manuel Faux

  I'm using ADO.NET with a strongly typed dataset in C# (.NET 3.5). I want to insert a new row to two tables which are related in an 1:n relation. The table Attachments holds the primary key part of the relation and the table LicenseAttachments holds the foreign key part. AttachmentsDataSet.InvoiceRow invoice; // Set to a valid row, also referenced in InvoiceAttachments AttachmentsDataSet.AttachmentsRow attachment; attachment = attachmentsDataSet.Attachments.AddAttachmentsRow("Name", "Description"); attachmentsDataSet.InvoiceAttachments.AddInvoiceAttachmentsRow(invoice, attachment); Of course when I first update the InvoicesAttachments table, I'll get a foreign key violation from the SQL server, so I tried updating the Attachments table first, which will create the rows, but will remove the attachment association in the InvoiceAttachments table. Why? How do I solve this problem?

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• myth about factory pattern

  - by leiz

  This has bothered me for awhile, and I have no clues if this is a myth. It seems that a factory pattern can ease the pain of adding a dependency for a class. For example, in a book, it has something like this Suppose that you have a class named Order. Initially it did not depend on anything. Therefore you didn't bother using a factory to create Order objects and you just used plain new to instantiate the objects. However, you now have a requirement that Order has to be created in association with a Customer. There are million places you need to change to add this extra parameter. If only you had de?ned a factory for the Order class, you would have met the new requirement without the same pain. How is this not same pain as adding an extra parameter to the constructor? I mean you would still need to provide an extra argument for the factory and that is also used by million places, right?

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• Show different sub-sets in edit view

  - by Martin R-L

  In the context of C# 4, ASP.NET MVC 2, and NHibernate; I've got the following scenario: Let's assume an entity Product that have an association to ProductType. In a product edit view; how do I implement that only a sub-set of the product's properties are shown in an elegant and DRY way? Use a product view model builder, and from different view models automagically generate the view with my own Html.EditorForModel() (including drop-downs and other stuff not out-of-the-box)? Attribute the properties of one view model and use the Html.EditorForModel() way aforementioned? Use one model, but implement different web controls (view strategies) (can it be done DRY?)? Something else entirely?

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• RoR associations through or not through?

  - by showFocus

  I have four models that are related to one another, the way I have it setup at the moment is I have to select a county, region and country when entering a new city. class Country < ActiveRecord::Base has_many :regions has_many :counties has_many :cities end class Region < ActiveRecord::Base has_one :country has_many :counties has_many :cities end class County < ActiveRecord::Base has_one :country has_one :region has_many :cities end class City < ActiveRecord::Base has_one :country has_one :region has_one :county end Would it be better to use the :through symbol in the association? So I could say the city: has_one :country, :through => :region Not sure if this is correct, I have read how :through works but I'm not sure if this is the best solution. I am a newbie and while I'm not struggling with the syntax and how things work, it would be good to get opinions on best practices and the way things should be done from some rails wizards! Thanks in advance.

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• Django model manager didn't work with related object when I do aggregated query

  - by Satoru.Logic

  Hi, all. I'm having trouble doing an aggregation query on a many-to-many related field. Let's begin with my models: class SortedTagManager(models.Manager): use_for_related_fields = True def get_query_set(self): orig_query_set = super(SortedTagManager, self).get_query_set() # FIXME `used` is wrongly counted return orig_query_set.distinct().annotate( used=models.Count('users')).order_by('-used') class Tag(models.Model): content = models.CharField(max_length=32, unique=True) creator = models.ForeignKey(User, related_name='tags_i_created') users = models.ManyToManyField(User, through='TaggedNote', related_name='tags_i_used') objects_sorted_by_used = SortedTagManager() class TaggedNote(models.Model): """Association table of both (Tag , Note) and (Tag, User)""" note = models.ForeignKey(Note) # Note is what's tagged in my app tag = models.ForeignKey(Tag) tagged_by = models.ForeignKey(User) class Meta: unique_together = (('note', 'tag'),) However, the value of the aggregated field used is only correct when the model is queried directly: for t in Tag.objects.all(): print t.used # this works correctly for t in user.tags_i_used.all(): print t.used #prints n^2 when it should give n Would you please tell me what's wrong with it? Thanks in advance.

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• Image selector/picker

  - by MrThomas

  Using Ruby on Rails what steps can I take to create a image picker. This is a image object which I can use all over my app: Using paperclip and a polymathic association making images available to all other models. I wish to list the images in each model and chose which of them is associated to a individual new or old record. for example: I could use the image as a sidebar image or a banner or advert image etc. I would be great full for any help. Thanks Dan

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• ASP.net MVC - OneToOne relationship with pluralized nomenclature

  - by ludicco

  Hi, I have an OneToOne relationship between my models Account and Company the table names are Accounts and Companies respectively. Here is a brief screenshot of the structure: http://cl.ly/1AEU Everything works well, but mysteriously when I use the OneToOne associations I have accessors like: var db = new DB(); var account = db.Accounts.First(); var company = account.Companies; // note the plural not the singular accessor So, what's happing is that even if using OneToOne association, I still get the plural accessor with "companies" and not "company", if it this is a pure object representation and not an EntitySet generated in case when it s an oneToMany relationship. Is there a way to get this nomenclature to be applied properly? Thanks a lot

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• Rails: Polymorphic User Table a good idea with AuthLogic?

  - by sscirrus

  Hi everyone, I have a system where I need to login three user types: customers, companies, and vendors from one login form on the home page. I have created one User table that works according to AuthLogic's example app at http://github.com/binarylogic/authlogic_example. I have added a field called "User Type" that currently contains either 'Customer', 'Company', or 'Vendor'. Note: each user type contains many disparate fields so I'm not sure if Single Table Inheritance is the best way to go (would welcome corrections if this conclusion is invalid). Is this a polymorphic association where each of the three types is 'tagged' with a User record? How should my models look so I have the right relationships between my User table and my user types Customer, Company, Vendor? Thanks very much!

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• Bidirectional one-to-many associations with indexed collections in NHibernate

  - by Jørn Schou-Rode

  Last summer, I asked a question regarding how to add new object to an IList mapped as a one-to-many with NHibernate. One of the answers let me to this paragraph in the documentation: Please note that NHibernate does not support bidirectional one-to-many associations with an indexed collection (list, map or array) as the "many" end, you have to use a set or bag mapping. While I am pretty sure I understand what this paragraph says, I have no idea why or how to work around this limitation. As I am now again working with a model that seems to require a "bidirectional one-to-many association with an index collection", I figured the time was right for follow-up questions: Why does NHibernate have this limitation on associations? It is my impression that the guys behind NHibernate are quite clever, so I assume there is a pretty good reason. What are the common workarounds for this shortcoming? Making the collection a non-indexed bag and adding an explicit Position property to the child class? Any better solutions?

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• UML Class Relationships

  - by 01010011

  Hi, I would like to confirm whether I am on the right track when identifying common UML class relationships. For example, is the relationship between: 1 a stackoverflow member and his/her stackoverflow user account categorized as a composition relationship or an aggregation relationship? At first I thought it was an association because this member "has a" account. However on second thought, I am thinking its composition because each "part" (user account) belongs to only one whole (user) at a time, meaning for as long as I am logged into stackoverflow, I have to use this one and only account until I log off. If I log back onto stackoverflow with a different account then its composition again. Do you agree? 2 a database and a person's user account an aggregation relationship? I think so because 1 database (the whole) can store 0...* number of user accounts (the parts) but another database can store the same user accounts. Finally, can anyone recommend a website that specializes in designing code using UML? Thanks in advance

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• Rails - Associations - Automatically setting an association_id for a model which has 2 belongs_to

  - by adam

  I have 3 models class User < ... belongs_to :language has_many :posts end class Post < ... belongs_to :user belongs_to :language end class Language < ... has_many :users has_many :posts end Im going to be creating lots of posts via users and at the same time I have to also specify the language the post was written in, which is always the language associatd with the user i.e. @user.posts.create(:text => "blah", :language_id => @user.language_id) That's fine but the way I set the language doesn't sit well with me. The language will always be that of the users so is there a 'best-practice' way of doing this? I know a little about callbacks and association extensions but not sure of any pitfalls.

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• What is the proper way to create a recursive entity in the Entity Framework?

  - by Orion Adrian

  I'm currently using VS 2010 RC, and I'm trying to create a model that contains a recursive self-referencing entity. Currently when I import the entity from the model I get an error indicating that the parent property cannot be part of the association because it's set to 'Computed' or 'Identity', though I'm not sure why it does it that way. I've been hand-editing the file to get around that error, but then the model simply doesn't work. What is the proper way to get recursive entities to work in the Entity Framework. CREATE TABLE [dbo].[Appointments]( [AppointmentId] [int] IDENTITY(1,1) NOT NULL, [Description] [nvarchar](1024) NULL, [Start] [datetime] NOT NULL, [End] [datetime] NOT NULL, [Username] [varchar](50) NOT NULL, [RecurrenceRule] [nvarchar](1024) NULL, [RecurrenceState] [varchar](20) NULL, [RecurrenceParentId] [int] NULL, [Annotations] [nvarchar](50) NULL, [Application] [nvarchar](100) NOT NULL, CONSTRAINT [PK_Appointments] PRIMARY KEY CLUSTERED ( [AppointmentId] ASC ) ) GO ALTER TABLE [dbo].[Appointments] WITH CHECK ADD CONSTRAINT [FK_Appointments_ParentAppointments] FOREIGN KEY([RecurrenceParentId]) REFERENCES [dbo].[Appointments] ([AppointmentId]) GO ALTER TABLE [dbo].[Appointments] CHECK CONSTRAINT [FK_Appointments_ParentAppointments] GO

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• Need Help on entity framework

  - by Sarathi1904

  I have 3 tables(Roles,Actions and RoleActionLinks). Roles table has few columns(RoleID,RoleName,Desc). Actions table has few colums(ActionID,ActionName,Desc). In RoleActionLink is created for store the association between Roles and Actions and this table has the columns such as RoleID,ActionID When I created the data model(edmx). it shows only Role and Action as entity. i did not find RoleActionLink table. but even there is no direct relation between Roles and Actions table, both tables are automatically related using RoleActionLink table. When i create the new Action, a action record should be populated in Action table(this is works fine). At the same time, i need to populate record in RoleActionLinks table. But i dont have the entity to populate. Please tell me how to accomplish my needs.

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• Rails can't render polymorphic associations to XML?

  - by ambertch

  When I render XML with an :include clause for a polymorphic association I have, it doesn't work. I end up with the XML returning the object pointers instead of the actual objects, like: <posts> #<Comment:0x102ed1540>#<Comment:0x102ecaa38>#<Comment:0x102ec7fe0>#<Comment:0x102ec3cd8> </posts> Yet as_json works! When I render JSON with :include clause, the associations are rendered correctly and I get something like: posts":[ {"type":"Comment","created_at":"2010-04-20T23:02:30-07:00","id":7,"content":"fourth comment"}, {"type":"Comment","created_at":"2010-04-20T23:02:26-07:00","id":6,"content":"third comment"}] My current workaround is using XML builder, but I'm not too comfortable with that in the long run. Does anyone happen to know about this issue? I'm kind of in a catch-22 because while XML doesn't render the associations, as_json doesn't render in a kosher json format (returns an array rather than a list of hashes as proper json should) and the deserializer I'm using on the client side would require modification to parse the json correctly.

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• How can I make an "abstract" enum in a .NET class library?

  - by Lazlo

  I'm making a server library in which the packet association is done by enum. public enum ServerOperationCode : byte { LoginResponse = 0x00, SelectionResponse = 0x01, BlahBlahResponse = 0x02 } public enum ClientOperationCode : byte { LoginRequest = 0x00, SelectionRequest = 0x01, BlahBlahRequest = 0x02 } That works fine when you're working in your own project - you can compare which enum member is returned (i.e. if (packet.OperationCode == ClientOperationCode.LoginRequest)). However, since this is a class library, the user will have to define its own enum. Therefore, I have two enums to add as "abstract" - ServerOperationCode and ClientOperationCode. I know it's not possible to implement abstract enums in C#. How would I go doing this?

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• Problem with nested lambda expressions.

  - by Lehto

  Hey I'm trying to do a nested lambda expression like to following: textLocalizationTable.Where( z => z.SpokenLanguage.Any( x => x.FromCulture == "en-GB") ).ToList(); but i get the error: Member access 'System.String FromCulture' of 'DomainModel.Entities.SpokenLanguage' not legal on type 'System.Data.Linq.EntitySet`1[DomainModel.Entities.SpokenLanguage]. TextLocalization has this relation to spokenlanguage: [Association(OtherKey = "LocalizationID", ThisKey = "LocalizationID", Storage = "_SpokenLanguage")] private EntitySet<SpokenLanguage> _SpokenLanguage = new EntitySet<SpokenLanguage>(); public EntitySet<SpokenLanguage> SpokenLanguage { set { _SpokenLanguage = value; } get { return _SpokenLanguage; } } Any idea what is wrong?

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