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• EF Forced Concurrency Checks

  - by Imran

  Hi, I have an issue with EF 4.0 that I hope someone can help with. I currently have an entity that I want to update in a last in wins fashion (i.e. ignore concurrency checks and just overwrite whats in the db with what is submitted). It seems Entity Framework not only includes the primary key of the entity in the where clause of the generated sql, but also any foreign key fields. This is annoying as it means that I don't get true last in wins semantics and need to know what value the fk field had before the update or I get a concurrency exception. I am aware that this can be short circuited by including a foreign key field as well as the navigation property on the entity. I would like to avoid this if possible as it's not a very clean solution. I was just wondering if there was any other way to override this behaviour? It seems like more of a bug than a feature. I have no problem with ef doing concurrency checks if I instruct it to do so but not being able to bypass concurrency completely is a bit of a hindrance as there are many valid scenarios where this is not needed

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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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• MVC 2 - Name Attributes on HTML Input Field when using Parent/Child Entities

  - by Click Ahead

  Hi All, I'm pretty new to MVC 2 using the Entity Framework. I have two tables Company {ID int identity PK,Name nvarchar} and User {ID int identity PK,UserName nvarchar,CompanyID int FK}. A Foreign Key exists between User and Company. I generated my ADO.NET Entity Data Model, a Controller and a view to insert a record. My HTML form has the fields Company and UserName and the idea is when I click save a Company and User is inserted into the database. Sounds straight forward right! My question is as follows: I created a strongly-typed view derived from my 'User' entity. I'm using the the html helper Html.TextBoxFor(model = model.Organisation.Name) but the html name attribute for this input field is 'Organisation.Name'. My problem with this is that the dot throws up all sorts of issues in JQuery, which sees this as a property. If I want to change the name I read that I can use DataAnnotations but because I used the Entity Designer this involves using Buddy Classes. Seems like a bit of overkill just to change the html name attribute on this input field. Am I approaching this the right way or am I missing something here? Thanks for the help !

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• Saving Abstract and Sub classes to database

  - by bretddog

  Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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• EF4 + STE: Reattaching via a WCF Service? Using a new objectcontext each and every time?

  - by Martin

  Hi there, I am planning to use WCF (not ria) in conjunction with Entity Framework 4 and STE (Self tracking entitites). If i understnad this correctly my WCF should return an entity or collection of entities (using LIST for example and not IQueryable) to the client (in my case silverlight) The client then can change the entity or update it. At this point i believe it is self tracking???? This is where i sort of get a bit confused as there are a lot of reported problems with STEs not tracking.. Anyway... Then to update i just need to send back the entity to my WCF service on another method to do the update. I should be creating a new OBJECTCONTEXT everytime? In every method? If i am creaitng a new objectcontext everytime in everymethod on my WCF then don't i need to re-attach the STE to the objectcontext? So basically this alone wouldn't work?? using(var ctx = new MyContext()) { ctx.Orders.ApplyChanges(order); ctx.SaveChanges(); } Or should i be creating the object context once in the constructor of the WCF service so that 1 call and every additional call using the same wcf instance uses the same objectcontext? I could create and destroy the wcf service in each method call from the client - hence creating in effect a new objectcontext each time. I understand that it isn't a good idea to keep the objectcontext alive for very long. Any insight or information would be gratefully appreciated thanks

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• How to change Fluent NHibernate reference column name on a HasMany relationship using IHasManyConven

  - by snicker

  Currently I'm using Fluent NHibernate to generate my database schema, but I want the entities in a HasMany relationship to point to a different column for the reference. IE, this is what NHibernate will generate in the creation DDL: alter table `Pony` add index (Stable_ID), add constraint Ponies_Stable foreign key (Stable_Id) references `Stable` (Id); This is what I want to have: alter table `Pony` add index (Stable_ID), add constraint Ponies_Stable foreign key (Stable_Id) references `Stable` (EntityId); Where Stable.ID would be the primary key and Stable.EntityId is just another column that I set. I have a class already that looks like this: public class ForeignKeyReferenceConvention : IHasManyConvention { public void Apply(IOneToManyCollectionInstance instance) { instance.Cascade.All(); //What goes here so that I can change the reference column? } } What do I have to do to get the reference column to change?

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• DataMapper and Codeigniter - how to fully manage a many-to-many relationship

  - by user252160

  I have the following relationship CType has many Field Field has many Ctype and of course the tables used are fields, ctypes, and ctypes_fields. Normally, the ctypes_fields table should contain only ids referencing the other two tables. However, i'd like to put there a "options" field that will contain some content for the concrete instance only. I walked through all DataMapper tuts but I could'n find relevant info on how I could extract these specific values (the ones in the relation table) Should I create a separate model for this relation table or there is a clever way to do this ?

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• Database theory - relationship between two tables

  - by iansinke

  I have a database with two tables - let's call them Foo and Bar. Each foo may be related to any number of bars, and each bar may be related to any number of foos. I want to be able to retrieve, with one query, the foos that are associated with a certain bar, and the bars that are associated with a certain foo. My question is, what is the best way of recording these relationships? Should I have a separate table with records of each relationship (e.g. two columns, foo and bar)? Should the foo table have a column for a list of bars, and vice versa? Is there another option that I'm overlooking? I'm using SQL Server, if that makes a difference.

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• Drupal Views Duplicate values being returned when using a relationship

  - by Linda

  I am having a problem with views. I have a view and am passing it a taxonomy term by name to it. I then have a relationship to a related node. For my output fields I am returning the related Title and related Body. I however have duplicates in my results. I have turned distinct to yes but believe this is working on the nodes being return and not the related node. Any ideas how I can remove the duplicates? Update Below is the query being run when I only get the title SELECT DISTINCT(node.nid) AS nid, node_node_data_field_wine_company.title AS node_node_data_field_wine_company_title, node_node_data_field_wine_company.nid AS node_node_data_field_wine_company_nid FROM node node LEFT JOIN content_type_wine node_data_field_wine_company ON node.vid = node_data_field_wine_company.vid INNER JOIN node node_node_data_field_wine_company ON node_data_field_wine_company.field_wine_company_nid = node_node_data_field_wine_company.nid LEFT JOIN term_node term_node ON node.vid = term_node.vid INNER JOIN term_data term_data ON term_node.tid = term_data.tid WHERE term_data.name = 'test' GROUP BY nid It looks like I should be grouping by node_node_data_field_wine_company_nid or selecting distinct values from there. Any ideas?

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• VB FFT - stuck understanding relationship of results to frequency

  - by WaveyDavey

  Trying to understand an fft (Fast Fourier Transform) routine I'm using (stealing)(recycling) Input is an array of 512 data points which are a sample waveform. Test data is generated into this array. fft transforms this array into frequency domain. Trying to understand relationship between freq, period, sample rate and position in fft array. I'll illustrate with examples: ======================================== Sample rate is 1000 samples/s. Generate a set of samples at 10Hz. Input array has peak values at arr(28), arr(128), arr(228) ... period = 100 sample points peak value in fft array is at index 6 (excluding a huge value at 0) ======================================== Sample rate is 8000 samples/s Generate set of samples at 440Hz Input array peak values include arr(7), arr(25), arr(43), arr(61) ... period = 18 sample points peak value in fft array is at index 29 (excluding a huge value at 0) ======================================== How do I relate the index of the peak in the fft array to frequency ?

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• Maintaining both sides of self-referential many-to-many relationship in Grails domain object

  - by Ali G

  I'm having some problems getting a many-to-many relationship working in grails. Is there anything obviously wrong with the following: class Person { static hasMany = [friends: Person] static mappedBy = [friends: 'friends'] String name List friends = [] String toString() { return this.name } } class BootStrap { def init = { servletContext -> Person bob = new Person(name: 'bob').save() Person jaq = new Person(name: 'jaq').save() jaq.friends << bob println "Bob's friends: ${bob.friends}" println "Jaq's friends: ${jaq.friends}" } } I'd expect Bob to be friends with Jaq and vice-versa, but I get the following output at startup: Running Grails application.. Bob's friends: [] Jaq's friends: [Bob] (I'm using Grails 1.2.0)

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• With windows authentication, The trust relationship between the primary domain and the trusted domai

  - by yamspog

  I have my asp.net web server setup to use windows authentication. It is authenticating just fine with my current logged in user. I can verify this by viewing ... HttpContext.Current.User.Identity.Name And I can verify that I am authenticated by viewing... HttpContext.Current.User.Identity.IsAuthenticated However, when I call the .IsInRole function I get the trust relationship error... HttpContext.Current.User.IsInRole("accounting") I have found online references to problems with supplying domain name with the role name (domain\accounting), but I still get the same error. Any suggestions on where to look or troubleshoot the problem?

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• Drupal Views Multiple values being returned when using a relationship

  - by Linda

  I am having a problem with views. I have a view and am passing it a taxonomy term by name to it. I then have a relationship to a related node. For my output fields I am returning the related Title and related Body. I however have duplicates in my results. I have turned distinct to yes but believe this is working on the nodes being return and not the related node. Any ideas how I can remove the duplicates?

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• Combining a one-to-one relationship into one object in Fluent NHibernate

  - by Mike C.

  I have a one-to-one relationship in my database, and I'd like to just combine that into one object in Fluent NHibernate. The specific tables I am talking about are the aspnet_Users and aspnet_Membership tables from the default ASP.NET Membership implementation. I'd like to combine those into one simple User object and only get the fields I want. I would also like to make this read-only, as I want to use the built-in ASP.NET Membership API to modify. I simply want to take advantage of lazy-loading. Any help would be appreciated. Thanks!

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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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• Ordered many-to-many relationship in NHibernate

  - by Kristoffer

  Let's say I have two classes: Item and ItemCollection, where ItemCollection contains an ordered list of Item objects with an index, i.e. the list is ordered in a way specified by the user. Let's also say that they have a many-to-many relationship, an ItemCollection can contain many items and an Item can belong to several ItemCollections. That would, in my head, require three tables in the database. One for Item, one for ItemCollection and one for the ordered mapping. The mapping table would contain three columns: int ItemID int ItemCollectionID int ListIndex QUESTION: How would you design the ItemCollection class? Should the list of Item objects be a list, dictionary or other? What would the NHibernate mapping look like to get the ListIndex into the picture?

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• What is Silverlight's relationship -- if any -- to WPF?

  - by xarzu

  I was working with a WPF application and I decided that the controls and graphics I wanted to display on the grid might look better if it was a silverlight component. I thought this way because of all the cool silverlight controls that look very flash-like. But now that I have gottem my Visual Studio 2010 set up with SIlverlight, it seems that every silverlight app I can make are ASP.NET in nature. It seems that instead of a cool GUI control to make, Silverlight is telling me that it is primarely a dataflow sort of application for the web. What is the relationship, if any, between WPF and Silverlight. Can I or can I not put a silverlight control into my existing WPF application?

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• Relationship between .NET ClassLoader and Assembly

  - by smwikipedia

  I am wondering about the relationship between .NET ClassLoader and Assembly I use the "!dumpdomain xxxx" command and got the following output: Domain 1: 00522108 LowFrequencyHeap: 0052212c HighFrequencyHeap: 00522178 StubHeap: 005221c4 Stage: OPEN SecurityDescriptor: 00523430 Name: BoxUnbox.exe **Assembly**: 0056eb88 [C:\Windows\assembly\GAC_32\mscorlib\2.0.0.0__b77a5c561934e089\mscorlib.dll] **ClassLoader**: 0056ec08 SecurityDescriptor: 0056c078 Module Name 56d71000 C:\Windows\assembly\GAC_32\mscorlib\2.0.0.0__b77a5c561934e089\mscorlib.dll **Assembly**: 005794f0 [] **ClassLoader**: 00579570 SecurityDescriptor: 0057a018 Module Name 00152c5c I noticed that the "ClassLoader" and "Assembly" appear in pair. It seems each Assembly is accompanied with its own "ClassLoader". Why like this? Is this a litte noisy? Why not just assign one "ClassLoader" to a AppDomain and use it to load all the used Assembly into the AppDomain? Isnt't this design more elegant? Many thanks.

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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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• Hibernate Tools / mysql 5

  - by cc96ai

  hibernate tools eclipse plugin cannot generate the mysql 5 relationship mysql driver: com.mysql.jdbc.Driver any idea why ?

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• Synonym for "Many-to-Many" relationship (relational databases)

  - by Byron

  What's a synonym for a "many-to-many" relationship? I've finished writing an object-relational mapper but I'm still stumped as to what to name the function that adds that relation. addParent() and addChild() seemed quite logical for the many-to-one/one-to-many and addSuperclass() for one-to-one inheritance, but addManyToMany() would sound quite unintuitive to an object-oriented programmer. addSibling() or addCousin() doesn't really make sense either. Any suggestions? And before you dismiss this as a non-programming question, please remember that consistent naming schemes and encapsulation are pretty integral to programming :)

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• rails override default getter for a relationship (belongs_to)

  - by brad

  So I know how to override the default getters for attributes of an ActiveRecord object using def custom_getter return self[:custom_getter] || some_default_value end I'm trying to achieve the same thing however for a belongs to association. For instance. class Foo < AR belongs_to :bar def bar return self[:bar] || Bar.last end end class Bar < AR has_one :foo end When I say: f = Foo.last I'd like to have the method f.bar return the last Bar, rather than nil if that association doesn't exist yet. This doesn't work however. The reason is that self[:bar] is always undefined. It's actually self[:bar_id]. I can do something naive like: def bar if self[:bar_id] return Bar.find(self[:bar_id]) else return Bar.last end end However this will always make a db call, even if Bar has already been fetched, which is certainly not ideal. Does anyone have an insight as to how I might have a relationship such that the belongs_to attribute is only loaded once and has a default value if not set.

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• Using a UIPickerView to make a CoreData Relationship

  - by DVG

  Okay, so I have a fairly simple application set up. I have two different CoreData Entities, Games and Platforms, each have one attribute: name, and they have a one-to-many relationship between them. Platforms are populated on the first launch of the application, and will never change as a result of user input. I'm working on my Add view to let the user add new games to their personal database, and each game should select from a platform. The add view itself is a grouped table view with static custom cells. Tapping the platform cell should advance the user to another view to select the platform. My thought is that UIPickerView seems like a logical choice for the control, since the Platform list is static, but I'm not sure how to use it with CoreData. Even if I construct a fetch request to get the Platform objects and extract the strings out, how do I go about linking the new Game object to the original Platform object?

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• Rails AR validates_uniqueness_of against polymorphic relationship

  - by aaronrussell

  Is it posible to validate the uniqueness of a child model's attribute scoped against a polymorphic relationship? For example I have a model called field that belongs to fieldable: class Field < ActiveRecord::Base belongs_to :fieldable, :polymorphic => :true validates_uniqueness_of :name, :scope => :fieldable_id end I have several other models (Pages, Items) which have many Fields. So what I want is to validate the uniqueness of the field name against the parent model, but the problem is that occasionally a Page and an Item share the same ID number, causing the validations to fail when they shouldn't. Am I just doing this wrong or is there a better way to do this?

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• Silverlight error-handling conventions: There is no relationship between onSilverlightError and Repo

  - by rasx

  When I see the call System.Windows.Browser.HtmlPage.Window.Eval (which is evil) in ReportErrorToDOM (in App.xaml.cs) this shows me that it has no relationship to onSilverlightError. So what kind of JavaScript-based scenario calls onSilverlightError? When will onSilverlightError definitely be needed? What are Silverlight error-handling conventions in general? This is a very important comment by Erik Monk but needs more detail: There are 2 kinds of terminal errors in Silverlight. 1) Managed errors (hit the managed Application_UnhandledException method). Note that some errors may not even get to this point. If the managed infrastructure can't be loaded for some reason (out of memory error maybe...), you won't get this kind of error. Still, if you can get it, you can use a web service (or the CLOG project) to communicate it back to the server. 2) Javascript errors.

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