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• edmx - The operation could not be completed - After adding Inheritance

  - by vdh_ant

  Hey guys I have an edmx model which I have draged 2 tables onto - One called 'File' and the other 'ApplicaitonFile'. These two tables have a 1 to 1 relationship in the database. If I stop here everything works fine. But in my model, I want 'ApplicaitonFile' to inherit from 'File'. So I delete the 1 to 1 relationship then configure 'ApplicaitonFile' from 'File' and then remove the FileId from 'ApplicaitonFile' which was the primary key. (Note I am following the instructions from here). If I leave the model open at this point everything is fine, but as soon as I close it, if I try and reopen it again I get the following error "The operation could not be completed". I have been searching for a solution and found this - http://stackoverflow.com/questions/944050/entity-model-does-not-load but as far as I can tell I don't have a duplicate InheritanceConnectors (although I don't know exactly what I'm looking for but I can't see anything out of the ordinary - like 2 connectors with the same name) and the relationship I originally have is a 1 to 1 not a 1 to 0..1 Any ideas???

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• Typecasting EnityObject

  - by AJ

  Hello, I'm new to C# and am stuck on the following. I have a Silverlight web service that uses LINQ to query a ADO.NET entity object. e.g.: [OperationContract] public List<Customer> GetData() { using (TestEntities ctx = new TestEntities()) { var data = from rec in ctx.Customer select rec; return data.ToList(); } } This works fine, but what I want to do is to make this more abstract. The first step would be to return a List<EntityObject> but this gives a compiler error, e.g.: [OperationContract] public List<EntityObject> GetData() { using (TestEntities ctx = new TestEntities()) { var data = from rec in ctx.Customer select rec; return data.ToList(); } } The error is: Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<SilverlightTest.Web.Customer>' to 'System.Collections.Generic.IEnumerable<System.Data.Objects.DataClasses.EntityObject>'. An explicit conversion exists (are you missing a cast?) What am i doing wrong? Thanks, AJ

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• Generic list typecasting problem

  - by AJ

  Hello, I'm new to C# and am stuck on the following. I have a Silverlight web service that uses LINQ to query a ADO.NET entity object. e.g.: [OperationContract] public List<Customer> GetData() { using (TestEntities ctx = new TestEntities()) { var data = from rec in ctx.Customer select rec; return data.ToList(); } } This works fine, but what I want to do is to make this more abstract. The first step would be to return a List<EntityObject> but this gives a compiler error, e.g.: [OperationContract] public List<EntityObject> GetData() { using (TestEntities ctx = new TestEntities()) { var data = from rec in ctx.Customer select rec; return data.ToList(); } } The error is: Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<SilverlightTest.Web.Customer>' to 'System.Collections.Generic.IEnumerable<System.Data.Objects.DataClasses.EntityObject>'. An explicit conversion exists (are you missing a cast?) What am i doing wrong? Thanks, AJ

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• Disable chaching in JPA (eclipselink)

  - by James

  Hi, I want to use JPA (eclipselink) to get data from my database. The database is changed by a number of other sources and I therefore want to go back to the database for every find I execute. I have read a number of posts on disabling the cache but this does not seem to be working. Any ideas? I am trying to execute the following code: EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("default"); EntityManager em = entityManagerFactory.createEntityManager(); MyLocation one = em.createNamedQuery("MyLocation.findMyLoc").getResultList().get(0); MyLocation two = em.createNamedQuery("MyLocation.findMyLoc").getResultList().get(0); System.out.println(one==two); one==two is true while I want it to be false. I have tried adding each/all the following to my persistence.xml <property name="eclipselink.cache.shared.default" value="false"/> <property name="eclipselink.cache.size.default" value="0"/> <property name="eclipselink.cache.type.default" value="None"/> I have also tried adding the @Cache annotation to the Entity itself: @Cache( type=CacheType.NONE, // Cache nothing expiry=0, alwaysRefresh=true ) Am I misunderstanding something? Thank you, James

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• Getting the first result from a LINQ query - why does ElementAt<T>(0) fails when First<T>() succeeds

  - by Mr Roys

  I have a method AddStudent() which looks for a student with the same name and returns an existing student from the database if there is a student with the same name, otherwise it creates a new student and adds it to the database. I'm curious why se = students.First<StudentEntity>(); succeeds when se = students.ElementAt<StudentEntity>(0); fails when I try to get the first result from the LINQ query. Aren't the two methods the same? The full code for the method is shown below. public Student AddStudent(string name) { using (SchoolEntities db = new SchoolEntities()) { // find student with same name via LINQ var students = from s in db.StudentEntitySet where s.name == name select s; StudentEntity se = default(StudentEntity); // if student with the same name is already present, return // that student if (students.Count<StudentEntity>() > 0) { // if i use ElementAt, if fails with a "LINQ to Entities does not // recognize the method 'StudentEntity ElementAt[StudentEntity] // (System.Linq.IQueryable`1[StudentEntity], Int32)' method, // and this method cannot be translated into a store expression.", // but not when I use First. Why? // se = students.ElementAt<StudentEntity>(0); se = students.First<StudentEntity>(); } else { // passing 0 for first parameter (id) since it's represented by // a BigInt IDENTITY field in the database so any value // doesn't matter. se = StudentEntity.CreateStudentEntity(0, name); db.AddToStudentEntitySet(se); db.SaveChanges(); } // create a Student object from the Entity object return new Student(se); } } Thanks!

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• WCF Service invalid with Silverlight

  - by Echilon

  I'm trying to get WCF working with Silverlight. I'm a total beginner to WCF but have written asmx services in the past. For some reason when I uncomment more than one method in my service Silverlight refuses to let me use it, saying it is invalid. My code is below if anyone could help. I'm using the Entity Framework if that makes a difference. [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class MessageService {//: IMessageService { /// <summary> /// Sends a new message. /// </summary> /// <param name="recipientUsername">The recipient username.</param> /// <param name="subject">The subject.</param> /// <param name="messageBody">The message body.</param> [OperationContract] public void SendMessageByDetails(string recipientUsername, string subject, string messageBody) { MessageDAL.SendMessage(recipientUsername, subject, messageBody); } /// <summary> /// Sends a new message. /// </summary> /// <param name="msg">The message to send.</param> [OperationContract] public void SendMessage(Message msg) { MessageDAL.SendMessage(msg); } }

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• Dynamic Linq Library Guid exceptions

  - by Adan

  I am having a problem with the Dynamic Linq Library. I get a the following error "ParserException was unhandled by user code ')" or ','". I have a Dicitionary and I want to create a query based on this dictionary. So I loop through my dictionary and append to a string builder "PersonId = (GUID FROM DICTIONARY). I think the problem is were I append to PersonId for some reason I can't seem to convert my string guid to a Guid so the dynamic library don't crash. I have tried this to convert my string guid to a guid, but no luck. query.Append("(PersonId = Guid(" + person.Key + ")"); query.Append("(PersonId = " + person.Key + ")"); I am using VS 2010 RTM and RIA Services as well as the Entity Framework 4. //This is the loop I use foreach (KeyValuePair<Guid, PersonDetails> person in personsDetails) { if ((person.Value as PersonDetails).IsExchangeChecked) { query.Append("(PersonId = Guid.Parse(" + person.Key + ")"); } } //Domain service call var query = this.ObjectContext.Persons.Where(DynamicExpression.ParseLambda<Person, bool>(persons)); Please help, and if you know of a better way of doing this I am open to suggestions.

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• Deep copy objects from different namespaces

  - by Wasim

  Hi all, I have the following situation: I have class User with the follwing properies : public class User { string user name ; List <Contact> contacts ; List <BookMark> book marks; . . . } I have the same class in a different namespace , with some different properties . BWT , it's the same situation of it's classes (Contact) and (BookMark). I need to make a deep copy of the same properties from the two classes . Actually , I arrive to this situation by having an Entity Framework edmx file . I created the first database (SQL server 2008) from this model . And copied he same edmx file to another project and created the database with SQL CE db. Now I get the first data model objects by WCF service and need to persist them in the local database in my application . The objects are the same but there are some changs because of the modeling issue with a different databse. Do you have any workarround about this assue. Thanks in advance ...

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• What is the best method for updating all changed data in EF 4?

  - by Soul_Master

  I try to create some method that can update any changed data from changed Data object (this object is generated by ASP.NET MVC) to old Data object (this object is retrieved from current data in DBMS) like the following code. public static bool UpdateSomeData(SomeEntities context, SomeModelType changedData) { var oldData = GetSomeModelTypeById(context, changedData.ID); UpdateModel(oldData, changedData); return context.SaveChanges() > 0; } I try to create method for saving any changed data without affects other unchanged data like the following source code. public static void UpdateModel<TModel>(TModel oldData, TModel changedData) { foreach (var pi in typeof(TModel).GetProperties() .Where ( // Ignore Change ID property for security reason x => x.Name.ToUpper() != "ID" && x.CanRead && x.CanWrite && ( // It must be primitive type or Guid x.PropertyType.FullName.StartsWith("System") && !x.PropertyType.FullName.StartsWith("System.Collection") && !x.PropertyType.FullName.StartsWith("System.Data.Entity.DynamicProxies") ) ) { var oldValue = pi.GetValue(oldData, null); var newValue = pi.GetValue(changedData, null); if (!oldValue.Equals(newValue)) { pi.SetValue(oldData, newValue, null); } } } I am not sure about the above method because it is so ugly method for updating data. From recent bug, it realizes me that if you update some property like Navigation Properties (related data from other table), it will remove current record from database. I don't understand why it happened. But it is very dangerous for me. So, do you have any idea for this question to ensure me about updating data from ASP.NET MVC? Thanks,

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• How to return all records and whether a related record exists?

  - by David Glenn

  Using Entity Framework 4 CTP5 I have a basic model and a basic DbContext that works public class Customer { public int CustomerId { get; set; } public int Name { get; set; } //... public ICollection<Address> Addresses { get; set; } public bool HasAddress { get { return Addresses.Count > 0; } } } public class Address { public int AddressId { get; set; } public string StreetLine1 { get; set; } //.... public Customer Customer { get; set; } } How can I query my DbContext to return all customers and whether they have an address? A customer can have multiple addresses and I don't want to return all the addresses for each customer when I am only interested in whether they have an address or not. I use context.Customers.Include(c => c.Addresses) but that returns all addresses for each customer

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• EF 6 Code First Many to many With Payload and self referencing many to many

  - by lesley86

  I Have the problem where i have a many to many relationship and on one of the tables there will be a self referencing many to many. So basically a school have zero or many groups and many groups can have 0 or many schools. The groups table will contain a parent child many to many with itself because a group can be a child of another group or it can have no children and that child can have a child, one child can also have many parents or a entity can have no parents. I created a mapping table with Payload to solvethe first many to many problem. code snippet public class School { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps } public class SchoolGroup { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps } public class SchoolGroupMap { public virtual School School public virtual SchoolGroup SchoolGroup } i Then tried modifying the code the following way for the the self referencing many to many public class SchoolGroup { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps public virtual ICollection<SchoolGroup> Parents public virtual ICollection<SchoolGroup> Children } I changed the context with has many and an auto mapping table (forgive me i have been trying so many things today i do not have the exact code). I received an error the properties on the classes must match. Can anyone help please. I want to do create navigation properties on the self referencing many to many. Also a seed example would be appreciated regards

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• Modelling deterministic and nondeterministic data separately

  - by Superstringcheese

  I'm working with the Microsoft ADO.NET Entity Framework for a game project. Following the advice of other posters on SO, I'm considering modelling deterministic and nondeterministic data separately. The idea for this came from a discussion on multiplayer games, but it seemed to make sense in a single-player scenario as well. Deterministic (things that aren't going to change during gameplay) Attributes (Strength, Agility, etc.) and their descriptions Skills and their descriptions and requirements Races, Factions, Equipment, etc. Base Attribute/Skill/Equipment loadouts for monsters Nondeterministic (things that will change a lot during gameplay) Beings' current AttributeModifers (Potion of Might = +10 Strength), current health and mana, etc. Player inventory, cash, experience, level Player quests states Player FactionRelationships ...and so on. My deterministic model would serve as a set of constants. My nondeterministic model would provide my on-the-fly operable data and would be serialized to a savegame file to maintain game state between play sessions. The data store will be an embedded SQL Compact database. So I might want to create relations between my Attributes table (deterministic model) and my BeingAttributeModifiers table (nondeterministic model), but how do I set that up across models? Det model/db Nondet model/db ____________ ________________________ |Attributes | |PlayerAttributeModifiers| |------------| |------------------------| |Id | |Id | |Name | |AttributeId | |Description | |SourceId | ------------ |Value | ------------------------ Should I use two separate models (edmx) that transact with a single database containing both deterministic-type and nondeterministic-type tables? Or should/can I use two separate databases in one model? Or two models each with their own database? With distinct models/dbs it seems like this will get really complicated and I'll end up fighting EF a lot, rolling my own transaction code, and generally losing out on a lot of the advantages of the framework. I know these are vague questions, I'm just looking for a sanity check before I forge ahead any further.

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• EF 4 Self Tracking Entities does not work as expected.

  - by ashraf

  I am using EF4 Self Tracking Entities (VS2010 Beta 2 CTP 2 plus new T4 generator). But when I try to update entity information it does not update to database as expected. I setup 2 service calls. one for GetResource(int id) which return a resource object. the second call is SaveResource(Resource res); here is the code. public Resource GetResource(int id) { using (var dc = new MyEntities()) { return dc.Resources.Where(d => d.ResourceId == id).SingleOrDefault(); } } public void SaveResource(Resource res) { using (var dc = new MyEntities()) { dc.Resources.ApplyChanges(res); dc.SaveChanges(); // Nothing save to database. } } //Windows Console Client Calls var res = service.GetResource(1); res.Description = "New Change"; // Not updating... service.SaveResource(res); // does not change anything. It seems to me that ChangeTracker.State is always show as "Unchanged". anything wrong in this code?

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• Multi threading in WCF RIA Services

  - by synergetic

  I use WCF RIA Services to update customer database. In domain service: public void UpdateCustomer(Customer customer) { this.ObjectContext.Customers.AttachAsModified(customer); syncCustomer(customer); } After update, a database trigger launches and depending on the columns updated it may insert a new record in CustomerChange table. syncCustomer(customer) method is executed to check for a new record in the CustomerChange table and if found it will create a text file which contains customer information and forwards that file to external system for import. Now this synchronization may take a time so I wanted to execute it in different thread. So: private void syncCustomer(Customer customer) { this.ObjectContext.SaveChanges(); new Thread(() => syncCustomerInfo(customer.CustomerID)) { IsBackground = true }.Start(); } private void syncCustomerInfo(int customerID) { //Thread.Sleep(2000); //does real job here ... ... } The problem is in most cases syncCustomerInfo method cannot find any new CustomerChange record even if it was definitely there. If I force thread sleep then it finds a new record. I also looked Entity Framework events but the only event provided by object context is SavingChanges which occur before changes are saved. Please suggest me what else to try.

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• Linq to Entities custom ordering via position mapping table

  - by Bigfellahull

  Hi, I have a news table and I would like to implement custom ordering. I have done this before via a positional mapping table which has newsIds and a position. I then LEFT OUTER JOIN the position table ON news.newsId = position.itemId with a select case statement CASE WHEN [position] IS NULL THEN 9999 ELSE [position] END and order by position asc, articleDate desc. Now I am trying to do the same with Linq to Entities. I have set up my tables with a PK, FK relationship so that my News object has an Entity Collection of positions. Now comes the bit I can't work out. How to implement the LEFT OUTER JOIN. I have so far: var query = SelectMany (n => n.Positions, (n, s) => new { n, s }) .OrderBy(x => x.s.position) .ThenByDescending(x => x.n.articleDate) .Select(x => x.n); This kinda works. However this uses a INNER JOIN so not what I am after. I had another idea: ret = ret.OrderBy(n => n.ShufflePositions.Select(s => s.position)); However I get the error DbSortClause expressions must have a type that is order comparable. I also tried ret = ret.GroupJoin(tse.ShufflePositions, n => n.id, s => s.itemId, (n, s) => new { n, s }) .OrderBy(x => x.s.Select(z => z.position)) .ThenByDescending(x => x.n.articleDate) .Select(x => x.n); but I get the same error! If anyone can help me out, it would be much appreciated!

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• Using ADO.NET Entities LINQ Provider to model complex SQL Queries?

  - by Ivan Zlatanov

  What I find really powerful in ADO.NET Entities or LINQ to SQL, is the ability to model complex queries. I really don't need the mappings that Entities or LINQ to SQL are doing for me - I just need the ability to model complex expressions that can be translated into T-SQL. My question is - am I abusing too much? Can I use the Entity Framework for modeling queries and just that? Should I? I know I can write my own custom LINQ to SQL provider, but that is just not possible to handle in the time spans I have. What is the best approach to model complex T-SQL queries? How do you handle conditional group byes, orders, joins, unions etc in the OOP world? Using StringBuilders for this kind of job feels too ugly and harder to maintain given the possibilities we have with Expression Trees. When I use StringBuilder to model a complex SQL Query I feel kind of guilty! I feel the same way as when I have to hard code any number into my code that is different than 0 or 1. Feeling that makes you ask yourself if there is a better and cleaner way of doing it... I must mention that I am using C# 4.0, but I am not specifically looking for an answer in this language, but rather in the domain of CLR 4.

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• EF/LINQ: Where() against a property of a subtype

  - by ladenedge

  I have a set of POCOs, all of which implement the following simple interface: interface IIdObject { int Id { get; set; } } A subset of these POCOs implement this additional interface: interface IDeletableObject : IIdObject { bool IsDeleted { get; set; } } I have a repository hierarchy that looks something like this: IRepository<T <: BasicRepository<T <: ValidatingRepository<T (where T is IIdObject) I'm trying to add a FilteringRepository to the hierarchy such that all of the POCOs that implement IDeletableObject have a Where(p => p.IsDeleted == false) filter applied before any other queries take place. My goal is to avoid duplicating the hierarchy solely for IDeletableObjects. My first attempt looked like this: public override IQueryable<T> Query() { return base.Query().Where(t => ((IDeletableObject)t).IsDeleted == false); } This works well with LINQ to Objects, but when I switch to an EF backend I get: "LINQ to Entities only supports casting Entity Data Model primitive types." I went on to try some fancier parameterized solutions, but they ultimately failed because I couldn't make T covariant in the following case for some reason I don't quite understand: interface IQueryFilter<out T> // error { Expression<Func<T, bool>> GetFilter(); } I'd be happy to go into more detail on my more complicated solutions if it would help, but I think I'll stop here for now in hope that someone might have an idea for me to try. Thanks very much in advance!

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• edmx - The operation could not be completed - When adding Inheritance

  - by vdh_ant

  Hey guys I have an edmx model which I have draged 2 tables onto - One called 'File' and the other 'ApplicaitonFile'. These two tables have a 1 to 1 relationship in the database. If I stop here everything works fine. But in my model, I want 'ApplicaitonFile' to inherit from 'File'. So I delete the 1 to 1 relationship then configure 'ApplicaitonFile' from 'File' and then remove the FileId from 'ApplicaitonFile' which was the primary key. (Note I am following the instructions from here). If I leave the model open at this point everything is fine, but as soon as I close it, if I try and reopen it again I get the following error "The operation could not be completed". I have been searching for a solution and found this - http://stackoverflow.com/questions/944050/entity-model-does-not-load but as far as I can tell I don't have a duplicate InheritanceConnectors (although I don't know exactly what I'm looking for but I can't see anything out of the ordinary - like 2 connectors with the same name) and the relationship I originally have is a 1 to 1 not a 1 to 0..1 Any ideas??? this is driving me crazy...

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• Parallel.Foreach loop creating multiple db connections throws connection errors?

  - by shawn.mek

  Login failed. The login is from an untrusted domain and cannot be used with Windows authentication I wanted to get my code running in parallel, so I changed my foreach loop to a parallel foreach loop. It seemed simple enough. Each loop connects to the database, looks up some stuff, performs some logic, adds some stuff, closes the connection. But I get the above error? I'm using my local sql server and entity framework (each loop uses it's own context). Is there some problem with connecting multiple times using the same local login or something? How did I get around this? I have (before trying to covert to a parallel.foreach loop) split my list of objects that I am foreach looping through into four groups (separate csv files) and run four concurrent instances of my program (which ran faster overall than just one, thus the idea for parallel). So it seems connecting to the db shouldn't be a problem? Any ideas? EDIT: Here's before var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); ForEach(cloneIdAndAccessions in allAccessionsFromObs) DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); after var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); Parallel.ForEach(allAccessionsFromObs, cloneIdAndAccessions => DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); Inside the DoWork I use the BioEntities using (var bioEntities = new BioEntities(connectionString)) {...}

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• Is there any way to provide custom factory for .Net Framework creation Entities from EF4 ?

  - by ILICH

  There are a lot of posts about how cool POCO objects are and how Entity Framework 4 supports them. I decided to try it out with domain driven development oriented architecture and finished with domain entities that has dependencies from services. So far so good. Imagine my Products are POCO objects. When i query for objects like this: NorthwindContext db = new NorthwindContext(); var products = db.Products.ToList(); EF creates instances of products for me. Now I want to inject dependencies in my POCO objects (products) The only way I see is make some method within NorthwindContext that makes something like pseudo-code below: public List<Product> GetProducts(){ var products = database.Products.ToList(); container.BuildUp(products); //inject dependencies return products; } But what if i want to make my repository to be more flexible like this: public ObjectSet<Product> GetProducts() { ... } So, I really need a factory to make it more lazy and linq friendly. Please help !

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• Effective books for learning the intricacies of business application development?

  - by OffApps Cory

  I am a self taught "developer". I use the term loosely because I only know enough to make myself dangerous. I have no theory background, and I only pick up things to get this little tool to work or make that control do what I want. That said, I am looking for some reading material that explains some of the theory behind application development especially from a business standpoint. Really I need to understand what all of these terms that float around really talk about. Business Logic Layer, UI abstraction level and all that. Anyone got a reading list that they feel helped them understand this stuff? I know how to code stuff up so that it works. It is not pretty mostly because I don't know the elegant way of doing it, and it is not planned out very well (I also don't know how to plan an application). Any help would be appreciated. I have read a number of books on what I thought was the subject, but they all seem to rehash basic coding and what-not. This doesn't have to be specific to VB.NET or WPF (or Entity Framework) but anything with those items would be quite helpful.

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• Detaching all entities of T to get fresh data

  - by Goran

  Lets take an example where there are two type of entites loaded: Product and Category, Product.CategoryId - Category.Id. We have available CRUD operations on products (not Categories). If on another screen Categories are updated (or from another user in the network), we would like to be able to reload the Categories, while preserving the context we currently use, since we could be in the middle of editing data, and we do not want changes to be lost (and we cannot depend on saving, since we have incomplete data). Since there is no easy way to tell EF to get fresh data (added, removed and modified), we thought of twp possible ways: 1) Getting products attached to context, and categories detached from context. This would mean that we loose the ability to access Product.Category.Name, which we do sometimes require, so we would need to manually resolve it (example when printing data). 2) detaching / attaching all Categories from current context. Context.ChangeTracker.Entries().Where(x => x.Entity.GetType() == typeof(T)).ForEach(x => x.State = EntityState.Detached); And then reload the categories, which will get fresh data. Do you find any problem with this second approach? We understand that this will require all constraints to be put on foreign keys, and not navigation properties, since when detaching all Categories, Product.Category navigation properties would be reset to null also. Also, there could be a potential performance problem, which we did not test, since there could be couple of thousand products loaded, and all would need to resolve navigation property when reloading. Which of the two do you prefer, and is there a better way (EF6 + .NET 4.0)?

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• Circular Reference exception with JSON Serialisation with MVC3 and EF4 CTP5w

  - by nakchak

  Hi I'm having problems with a circular reference when i try and serialise an object returned via EF4 CTP5. Im using the code first approach and simple poco's for my model. I have added [ScriptIgnore] attributes to any properties that provide a back references to an object and annoyingly every seems to work fine if i manually instantiate the poco's, i.e. they serialise to JSON fine, and the scriptignore attribute is acknowledged. However when i try and serialise an object returned from the DAL i get the circular reference exception "A circular reference was detected while serializing an object of type 'System.Data.Entity.DynamicProxies.xxxx'" I have tried several ways of retreiving the data but they all get stuck with this error: public JsonResult GetTimeSlot(int id) { TimeSlotDao tsDao = new TimeSlotDao(); TimeSlot ts = tsDao.GetById(id); return Json(ts); } The method below works slightly better as rather than the timeslot dynamic proxied object causing the circular refference its the appointment object. public JsonResult GetTimeSlot(int id) { TimeSlotDao tsDao = new TimeSlotDao(); var ts = from t in tsDao.GetQueryable() where t.Id == id select new {t.Id, t.StartTime, t.Available, t.Appointment}; return Json(ts); } Any ideas or solutions to this problem? Update I would prefer to use the out of the box serialiser if possible although Json.Net via nuget is ok as an alternative i would hope its possible to use it as I intended as well...

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• Is .NET 4.0 just a show?

  - by Will Marcouiller

  I went to a presentation about the .NET Framework and Visual Studio 2010, last night. The topis were: ASP.NET 4 - Some of the new features of ASP.NET 4 More control over ClientID's in WebForms; Output Caching; ... // Some other stuff I don't really remember being more in framework and WinForms world. Entity Framework 2.0 (.NET 4.0) T4 Templates; Domain driven development; Data driven development; Contexts (edmx files); Some of real-world limitations of EF4 (projects with over 70 to 75 tables); Better POCO support, despite there are still these hidden EntityObject and StructuralObject, but used differently in comparison to EF 1.0 so that it doesn't take off your inheritance; Allows to easily choose how to persist the hierarchy into the underlying database; Code only (start working with EF4 directly from your code!); Design by Contract (DbC). The most interesting feature is, and only, as far as I'm concerned, all related to parallelism made easier. Which really works! No additional assembly references to add. In conclusion, I'm far from impressed about .NET Framework 4.0, apart that it makes some things easier to do. But when you're used to make it a way, it doesn't really change much, in my opinion. Is it me who cannot foresee what .NET 4.0 has to offer? What would you guys base your decision on to migrate to .NET 4.0, in a practical way?

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• Handling duplicate insertion

  - by Francis

  So I've got this piece of code which, logically should work but Entity Framework is behaving unexpectedly. Here: foreach (SomeClass someobject in allObjects) { Supplier supplier = new Supplier(); supplier.primary_key = someobject.id; supplier.name = someobject.displayname; try { sm.Add(supplier); ro.Created++; } catch (Exception ex) { ro.Error++; } } Here's what I have in sm.Add() public Supplier Add(Supplier supplier) { try { _ctx.AddToSupplier(supplier); _ctx.SaveChanges(); return supplier; } catch (Exception ex) { throw; } } I can have records in allObjects that have the same id. My piece of code needs to support this and just move on to the next and try to insert it, which I think should work. If this happens, an exception is throw, saying that records with dupe PKs cannot be inserted (of course). The exception mentions the value of the PK, for example 1000. All is well, a new supplier is passed to sm.Add() containing a PK that's never been used before. (1001) Weirdly though, when doing SaveChanges(), EF will whine about not being able to insert records with dupe PKs. The exception still mentions 1000 even though supplier contains 10001 in primary_key. I feel this is me not using _ctx properly. Do I need to call something else to sync it ?

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