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  • How to perform a Linq2Sql query on the following dataset

    - by Bas
    I have the following tables: Person(Id, FirstName, LastName) { (1, "John", "Doe"), (2, "Peter", "Svendson") (3, "Ola", "Hansen") (4, "Mary", "Pettersen") } Sports(Id, Name) { (1, "Tennis") (2, "Soccer") (3, "Hockey") } SportsPerPerson(Id, PersonId, SportsId) { (1, 1, 1) (2, 1, 3) (3, 2, 2) (4, 2, 3) (5, 3, 2) (6, 4, 1) (7, 4, 2) (8, 4, 3) } Looking at the tables, we can conclude the following facts: John plays Tennis John plays Hockey Peter plays Soccer Peter plays Hockey Ola plays Soccer Mary plays Tennis Mary plays Soccer Mary plays Hockey Now I would like to create a Linq2Sql query which retrieves the following: Get all Persons who play Hockey and Soccer Executing the query should return: Peter and Mary Anyone has any idea's on how to approach this in Linq2Sql?

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  • MVC ASP.NET, ObjectContext and Ajax. Weird Behaviour

    - by fabianadipolo
    Hi, i've been creating a web application in mvc asp.net. I have three different project/solutions. One solution contains the model in EF (DAL) and all the methods to add, update, delete and query the objects in the model, the objectcontext is managed here in a per request basis. Other solution contains a content management system in wich authorized users insert, delete, update and access objects through the DAL mentioned before. And the last solution contains the web page that is accessed by all users and where the only operations executed are selects, no update, inserts or deletes here. All the selects are executed against the DAL mentioned before (the first solution). The problem here is that i'm not sure whether an HttpContext lifespan ObjectContext is the best solution. I have a lot of ajax calls in my web app and i'm not sure if an httpcontext could interfere with the performance of the application. I've been noticed that in some cases, specially when someone is working in the content manager inserting, updating or deleting, when you try to click on any link of the user web application (the web app that is accessed by any user - the third one that i mentioned before) the web page freezes and it remains stucked transferring data. In order to stop that behaviour you have to stop and refresh or click several times on the link. Excuse me for my bad english. I hope you could understand and could help me to solve this issue. Thanx in advance.

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  • Is there a way to create a SyndicationFeed from a String?

    - by Roberto Bonini
    Hi, I'm trying to recreate a SyndicationFeed object (System.ServiceModel.Syndication) from XML data that has been stored locally. If I were working with XMLDocument, this would be easy.I'd call LoadXml(string). The SyndicationFeed will only load from an XMLReader. The XMLReader will only take a Stream or another XMLReader or a TextReader. Since XMLDocument will load a string, I've tried to do this as follows (in the form of a Extension Method): public static SyndicationFeed ToSyndicationFeed(this XmlDocument document) { Stream thestream = Stream.Null; XmlWriter thewriter = XmlWriter.Create(thestream); document.WriteTo(thewriter); thewriter.Flush(); XmlReader thereader = XmlReader.Create(thestream); SyndicationFeed thefeed = SyndicationFeed.Load(thereader); return thefeed; } I can't get this to work. The Stream is always empty even though the XMLDocument is populated with the Feed to be loaded into the SyndicationFeed. Any help or pointers you can give would be most helpful. Thanks, Roberto

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  • Why can't I see the 'dataset project' property in Visual Studio DataSet designer?

    - by Ryan
    Hi, I am trying to follow 'n tier app design' tutorials and they tell me to set the DataSet Project property from the Data Set Designer in VS, to split table adaptors and entities into seprate projects. I can't see that property! (I'm looking in the same place shown on the videos... all other properties match) Does anybody know why? The video is here http://windowsclient.net/learn/video.aspx?v=14625 (4:36 is where the property is set) I'm using VS c# 2008 Express, with SQL Server Express 2008. Thanks a lot for any help Ryan

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  • EF OrderBy method doesn't work with joins

    - by dudeNumber4
    Following works (ordered by name): from t in context.Table1.OrderBy( "it.Name" ) select t This doesn't work (no ordering): from t in context.Table1.OrderBy( "it.Name" ) join t2 in context.Table2 on t.SomeId equals t2.SomeId select t Nor does this (trying to reference the parent table to order): from t in context.Table1 join t2 in context.Table2.OrderBy( "it.Table1.Name" ) on t.SomeId equals t2.SomeId select t Nor does this (trying to order on the child table): from t in context.Table1 join t2 in context.Table2.OrderBy( "it.ChildName" ) on t.SomeId equals t2.SomeId select t How do I cause OrderBy not to be ignored while joining?

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  • How does TransactionScope guarantee data integrity across multiple databases?

    - by Bas Smit
    Hey guys, Can someone tell me the principle of how TransactionScope guarantees data integrity across multiple databases? I imagine it first sends the commands to the databases and then waits for the databases to respond before sending them a message to apply the command sent earlier. However when execution is stopped abruptly when sending those apply messages we could still end up with a database that has applied the command and one that has not. Can anyone shed some light on this? Edit: I guess what Im asking is can I rely on TransactionScope to guarantee data integrity when writing to multiple databases in case of a power outage or a sudden shutdown. Thanks, Bas Example: using(var scope=new TransactionScope()) { using (var context = new FirstEntities()) { context.AddToSomethingSet(new Something()); context.SaveChanges(); } using (var context = new SecondEntities()) { context.AddToSomethingElseSet(new SomethingElse()); context.SaveChanges(); } scope.Complete(); }

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  • Custom model in ASP.NET MVC controller: Custom display message for Date DataType

    - by Rita
    Hi I have an ASP.NET MVC Page that i have to display the fields in customized Text. For that I have built a CustomModel RequestViewModel with the following fields. Description, Event, UsageDate Corresponding to these my custom Model has the below code. So that, the DisplayName is displayed on the ASP.NET MVC View page. Now being the Description and Event string Datatype, both these fields are displaying Custom DisplayMessage. But I have problem with Date Datatype. Instead of "Date of Use of Slides", it is still displaying UsageDate from the actualModel. Anybody faced this issue with DateDatatype? Appreciate your responses. Custom Model: [Required(ErrorMessage="Please provide a description")] [DisplayName("Detail Description")] [StringLength(250, ErrorMessage = "Description cannot exceed 250 chars")] // also need min length 30 public string Description { get; set; } [Required(ErrorMessage="Please specify the name or location")] [DisplayName("Name/Location of the Event")] [StringLength(250, ErrorMessage = "Name/Location cannot exceed 250 chars")] public string Event { get; set; } [Required(ErrorMessage="Please specify a date", ErrorMessageResourceType = typeof(DateTime))] [DisplayName("Date of Use of Slides")] [DataType(DataType.Date)] public string UsageDate { get; set; } ViewCode: <p> <%= Html.LabelFor(model => model.Description) %> <%= Html.TextBoxFor(model => model.Description) %> <%= Html.ValidationMessageFor(model => model.Description) %> </p> <p> <%= Html.LabelFor(model => model.Event) %> <%= Html.TextBoxFor(model => model.Event) %> <%= Html.ValidationMessageFor(model => model.Event) %> </p> <p> <%= Html.LabelFor(model => model.UsageDate) %> <%= Html.TextBoxFor(model => model.UsageDate) %> <%= Html.ValidationMessageFor(model => model.UsageDate) %> </p>

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  • retrieve newly inserted record ID with Linq2SQL

    - by devmania
    hi, i am using the following private BlogDataContext db = new BlogDataContext (); article.Created = DateTime.UtcNow; article.Modified = DateTime.UtcNow; db.Articles.InsertOnSubmit(article); db.SubmitChanges( ); int id = article.Id; i am wondering is this save, i mean will it give me the Id of the article user inserted or will there be case of concurrences if another user update the article in fraction of second after this user ? thanks in advanced.

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  • .Except<T> is throwing an Exception

    - by Jason
    I have the following code: Public Shared Function GetAvailableManufacturers() As List(Of Manufacturer) 'first get all the live orders and extract their mfrs' Dim sos As List(Of OrderForm) = GetFormsByStatus(StockStatus.Building) Dim unavailableMfrs As New List(Of Manufacturer) For Each so As StockingOrder In sos unavailableMfrs.Add(so.Source) Next 'then remove all mfrs with an open SO from a list of all mfrs' Dim allMfrs As List(Of Manufacturer) = Manufacturer.GetManufacturers Return allMfrs.Except(unavailableMfrs) <----- error here End Function Explanation of what the above does: GetFormsByStatus() self-explanatory GetManufacturers() returns a list of all manufacturers in the database My idea to get available manufacturers was to get a list of all the manufacturers in my open forms, then get a list of all manufacturers and exclude all the manufacturers in the first list, illustrated like so (pseudo): List A: {1,2,3,4,5,6,7,8,9,10} List B: {5,7,10} Result: {1,2,3,4,6,8,9} I have set up my Manufacturer class according to this article so that it can be compared, but I'm still getting this error: Unable to cast object of type '<ExceptIterator>d__92'1[csCore.Manufacturer]' to type 'System.Collections.Generic.List'1[csCore.Manufacturer]'. I thought at first that because during testing GetFormsByStatus() returns 0 results maybe that was causing problems, but it doesn't make sense that Except() wouldn't work if the provided list had 0 items. Can anyone spot what I'm doing wrong? Thanks so much!

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  • Complex sorting of XML subnodes in .Net3.5 onwards

    - by MicMit
    XML structure expressed in Xpath kind of Records/Record/Actions/Action/ActionDate the other node on the same level Records/Record/Actions/Action/CTCDate Is there easy or not easy way to sort it on "order by ActionDate,CTCDate" ( in SQL notation ), but per Actions for each selected Record when we iterate somehow ( not per XML file ). File around 50M

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  • MVC and repository pattern data effeciency

    - by Shawn Mclean
    My project is structured as follows: DAL public IQueryable<Post> GetPosts() { var posts = from p in context.Post select p; return posts; } Service public IList<Post> GetPosts() { var posts = repository.GetPosts().ToList(); return posts; } //Returns a list of the latest feeds, restricted by the count. public IList<PostFeed> GetPostFeeds(int latestCount) { List<Post> post - GetPosts(); //CODE TO CREATE FEEDS HERE return feeds; } Lets say the GetPostFeeds(5) is supposed to return the 5 latest feeds. By going up the list, doesn't it pull down every single post from the database from GetPosts(), just to extract 5 from it? If each post is say 5kb from the database, and there is 1 million records. Wont that be 5GB of ram being used per call to GetPostFeeds()? Is this the way it happens? Should I go back to my DAL and write queries that return only what I need?

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  • ADO.NET Known Issues?

    - by Israel Rodriguez
    So, I'm starting a new Project in my company, and it's kinda big. We are going to use .NET 3.5, and I wish to known if there are any know bugs or perfomance issues that could give weird behaviour for my project? I'm reading some things about EFv4 and all they say is that EFv3.5 have too many problems. After all, what's the best and fastest way, ADO.NET Entities or extract the data from my DB directly to a DataReader? The EF Oracle provider is stable? The project will be .NET 3.5 and Oracle.

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  • MVC and repository pattern data efficiency

    - by Shawn Mclean
    My project is structured as follows: DAL public IQueryable<Post> GetPosts() { var posts = from p in context.Post select p; return posts; } Service public IList<Post> GetPosts() { var posts = repository.GetPosts().ToList(); return posts; } //Returns a list of the latest feeds, restricted by the count. public IList<PostFeed> GetPostFeeds(int latestCount) { List<Post> post - GetPosts(); //CODE TO CREATE FEEDS HERE return feeds; } Lets say the GetPostFeeds(5) is supposed to return the 5 latest feeds. By going up the list, doesn't it pull down every single post from the database from GetPosts(), just to extract 5 from it? If each post is say 5kb from the database, and there is 1 million records. Wont that be 5GB of ram being used per call to GetPostFeeds()? Is this the way it happens? Should I go back to my DAL and write queries that return only what I need?

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  • Most efficient algorithm for merging sorted IEnumerable<T>

    - by franck
    Hello, I have several huge sorted enumerable sequences that I want to merge. Theses lists are manipulated as IEnumerable but are already sorted. Since input lists are sorted, it should be possible to merge them in one trip, without re-sorting anything. I would like to keep the defered execution behavior. I tried to write a naive algorithm which do that (see below). However, it looks pretty ugly and I'm sure it can be optimized. It may exist a more academical algorithm... IEnumerable<T> MergeOrderedLists<T, TOrder>(IEnumerable<IEnumerable<T>> orderedlists, Func<T, TOrder> orderBy) { var enumerators = orderedlists.ToDictionary(l => l.GetEnumerator(), l => default(T)); IEnumerator<T> tag = null; var firstRun = true; while (true) { var toRemove = new List<IEnumerator<T>>(); var toAdd = new List<KeyValuePair<IEnumerator<T>, T>>(); foreach (var pair in enumerators.Where(pair => firstRun || tag == pair.Key)) { if (pair.Key.MoveNext()) toAdd.Add(pair); else toRemove.Add(pair.Key); } foreach (var enumerator in toRemove) enumerators.Remove(enumerator); foreach (var pair in toAdd) enumerators[pair.Key] = pair.Key.Current; if (enumerators.Count == 0) yield break; var min = enumerators.OrderBy(t => orderBy(t.Value)).FirstOrDefault(); tag = min.Key; yield return min.Value; firstRun = false; } } The method can be used like that: // Person lists are already sorted by age MergeOrderedLists(orderedList, p => p.Age); assuming the following Person class exists somewhere: public class Person { public int Age { get; set; } } Duplicates should be conserved, we don't care about their order in the new sequence. Do you see any obvious optimization I could use?

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  • How can I handle UTF-8 while posting to a vBulletin board with WWW::Mechanize?

    - by MrMirror
    I have a problem with some automating posting to bulletin board... If I send the posting form to the vBulletin board, I get corrupted entities. Feel free to copy-paste the script and try it... It looks like the board's expecting some decoded utf8, but if I send the message decoded the entities are still wrong. #!/usr/bin/perl use strict; use warnings; use WWW::Mechanize; use Digest::MD5 qw(md5_hex); my $mech = WWW::Mechanize->new(); my $base_url = 'http://www.boerse.bz/'; my $username = 'MrMirror'; my $password = 'test'; $mech->get($base_url); print "Login\n"; $mech->form_number(1); $mech->field('vb_login_username' => $username); $mech->field('vb_login_password' => $password); $mech->field('vb_login_md5password' => md5_hex($password)); $mech->field('vb_login_md5password_utf' => md5_hex($password)); $mech->submit(); unless ($mech->content() =~ m!Weiterleitung!gi) { print "No Rediction!\n"; exit; } print "Redict\n"; $mech->get($base_url); unless ($mech->content() =~ m!Logout!gi) { print "Login Failed!\n"; exit; } $mech->get($base_url .'/newthread.php?do=newthread&f=173'); $mech->form_number(3); $mech->field('subject' => 'MrMirror makes some testing ä ö ü ß'); $mech->field('message' => "ä ö ü ß"); ### everything allright here $mech->dump_forms(); ### preview submit, don't wanna spam around ;) $mech->click('preview'); print "\n\n\n---------------------------------------------------------------------\n\n\n"; ### same form, wrong entities :( $mech->dump_forms();

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  • How can I tell datacontext I've updated a record via StoreProcedure

    - by Ldsenow
    Hi Geeks, I've a stroe procedure to update a record and after running it I use LinqToSql to delete the record. I know it is weird but I just want to test how smart the datacontext it is and understand how it works. Since the datacontext caches the results so any change via it can be recorded but now I use a store procedure to update something, it would not know. So when I try to delete it, an exception comes out "Row not found or changed". How I can tell the datacontext what I have updated? If I can do so the problem will sovle.

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  • MVC 2.0 - JqGrid Sorting with Mulitple Tables

    - by Billy Logan
    I am in the process of implementing the jqGrid and would like to be able to use the sorting functionality. I have run into some issues with sorting columns that are related to the base table. Here is the script to load the grid: public JsonResult GetData(GridSettings grid) { try { using (IWE dataContext = new IWE()) { var query = dataContext.LKTYPE.Include("VWEPICORCATEGORY").AsQueryable(); ////sorting query = query.OrderBy<LKTYPE>(grid.SortColumn, grid.SortOrder); //count var count = query.Count(); //paging var data = query.Skip((grid.PageIndex - 1) * grid.PageSize).Take(grid.PageSize).ToArray(); //converting in grid format var result = new { total = (int)Math.Ceiling((double)count / grid.PageSize), page = grid.PageIndex, records = count, rows = (from host in data select new { TYPE_ID = host.TYPE_ID, TYPE = host.TYPE, CR_ACTIVE = host.CR_ACTIVE, description = host.VWEPICORCATEGORY.description }).ToArray() }; return Json(result, JsonRequestBehavior.AllowGet); } } catch (Exception ex) { //send the error email ExceptionPolicy.HandleException(ex, "Exception Policy"); } //have to return something if there is an issue return Json(""); } As you can see the description field is a part of the related table("VWEPICORCATEGORY") and the order by is targeted at LKTYPE. I am trying to figure out how exactly one goes about sorting that particular field or maybe even a better way to implement this grid using multiple tables and it's sorting functionality. Thanks in advance, Billy

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  • LinqToSql - ChangeConflictException. when submiting child and parent

    - by ari
    This problem drives me crazy. Here's the code using (BizNetDB db = new BizNetDB()) { var dbServiceCall = db.ServiceCalls.SingleOrDefault(x => x.ServiceCallID == serviceCallDetail.ServiceCallID); var dbServiceCallDetail = dbServiceCall.ServiceCallDetaills.SingleOrDefault(x=> x.ServiceCallDetailID == serviceCallDetail.ServiceCallDetailID); if (dbServiceCallDetail == null) { dbServiceCallDetail = new Data.ServiceCallDetaill(); dbServiceCall.ServiceCallDetaills.Add(dbServiceCallDetail); } dbServiceCallDetail.EndSession = serviceCallDetail.EndSession; dbServiceCallDetail.ExitTime = serviceCallDetail.ExitTime; dbServiceCallDetail.Solution = serviceCallDetail.Solution; dbServiceCallDetail.StartSession = serviceCallDetail.StartSession; serviceCallDetail.SessionMinutes = (serviceCallDetail.EndSession - serviceCallDetail.StartSession).Minutes; serviceCallDetail.DriveMinutes = serviceCallDetail.ExitTime.HasValue ? (serviceCallDetail.StartSession - serviceCallDetail.ExitTime.Value).Minutes : 0; var totalMinutes = (from d in db.ServiceCallDetaills .Where(x => x.ServiceCallID == serviceCallDetail.ServiceCallID && x.ServiceCallDetailID != dbServiceCallDetail.ServiceCallDetailID) group d by d.ServiceCallID into g select new { SessionMinutes = g.Sum(x => x.SessionMinutes), DriveMinutes = g.Sum(x => x.DriveMinutes) }).First(); dbServiceCall.SessionMinutes = totalMinutes.SessionMinutes + serviceCallDetail.SessionMinutes; dbServiceCall.DriveMinutes = totalMinutes.DriveMinutes + serviceCallDetail.DriveMinutes; try { db.SubmitChanges(); } catch (ChangeConflictException ex) { db.ChangeConflicts.ResolveAll(RefreshMode.OverwriteCurrentValues); db.SubmitChanges(); } The second Submit did solve the problem.. but I want to solve it from the root! when I disabled this lines (The parent changes): dbServiceCall.SessionMinutes = totalMinutes.SessionMinutes + serviceCallDetail.SessionMinutes; dbServiceCall.DriveMinutes = totalMinutes.DriveMinutes + serviceCallDetail.DriveMinutes; everithing is Ok. please help...

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  • How to write Sql or LinqToSql for this scenario?

    - by Mike108
    How to write Sql or LinqToSql for this scenario? A table has the following data: Id UserName Price Date Status 1 Mike 2 2010-4-25 0:00:00 Success 2 Mike 3 2010-4-25 0:00:00 Fail 3 Mike 2 2010-4-25 0:00:00 Success 4 Lily 5 2010-4-25 0:00:00 Success 5 Mike 1 2010-4-25 0:00:00 Fail 6 Lily 5 2010-4-25 0:00:00 Success 7 Mike 2 2010-4-26 0:00:00 Success 8 Lily 5 2010-4-26 0:00:00 Fail 9 Lily 2 2010-4-26 0:00:00 Success 10 Lily 1 2010-4-26 0:00:00 Fail I want to get the summary result from the data, the result should be: UserName Date TotalPrice TotalRecord SuccessRecord FailRecord Mike 2010-04-25 8 4 2 2 Lily 2010-04-25 10 2 2 0 Mike 2010-04-26 2 1 1 0 Lily 2010-04-26 8 3 1 2 The TotalPrice is the sum(Price) groupby UserName and Date The TotalRecord is the count(*) groupby UserName and Date The SuccessRecord is the count(*) groupby UserName and Date where Status='Success' The FailRecord is the count(*) groupby UserName and Date where Status='Fail' The TotalRecord = SuccessRecord + FailRecord The sql server 2005 database script is: /****** Object: Table [dbo].[Pay] Script Date: 04/28/2010 22:23:42 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Pay]') AND type in (N'U')) BEGIN CREATE TABLE [dbo].[Pay]( [Id] [int] IDENTITY(1,1) NOT NULL, [UserName] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NULL, [Price] [int] NULL, [Date] [datetime] NULL, [Status] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NULL, CONSTRAINT [PK_Pay] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) END GO SET IDENTITY_INSERT [dbo].[Pay] ON INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (1, N'Mike', 2, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (2, N'Mike', 3, CAST(0x00009D6300000000 AS DateTime), N'Fail') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (3, N'Mike', 2, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (4, N'Lily', 5, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (5, N'Mike', 1, CAST(0x00009D6300000000 AS DateTime), N'Fail') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (6, N'Lily', 5, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (7, N'Mike', 2, CAST(0x00009D6400000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (8, N'Lily', 5, CAST(0x00009D6400000000 AS DateTime), N'Fail') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (9, N'Lily', 2, CAST(0x00009D6400000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (10, N'Lily', 1, CAST(0x00009D6400000000 AS DateTime), N'Fail') SET IDENTITY_INSERT [dbo].[Pay] OFF

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  • InsertOnSubmit - NullReferenceException

    - by Jackie Chou
    I have 2 Model AccountEntity [Table(Name = "Account")] public class AccountEntity { [Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] public int id { get; set; } [Column(CanBeNull = false, Name = "email")] public string email { get; set; } [Column(CanBeNull = false, Name = "pwd")] public string pwd { get; set; } [Column(CanBeNull = false, Name = "row_guid")] public Guid guid { get; set; } private EntitySet<DetailsEntity> details_id { get; set; } [Association(Storage = "details_id", OtherKey = "id", ThisKey = "id")] public ICollection<DetailsEntity> detailsCollection { get; set; } } DetailsEntity [Table(Name = "Details")] public class DetailsEntity { public DetailsEntity(AccountEntity a) { this.Account = a; } [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "int")] public int id { get; set; } private EntityRef<AccountEntity> _account = new EntityRef<AccountEntity>(); [Association(IsForeignKey = true, Storage = "_account", ThisKey = "id")] public AccountEntity Account { get; set; } } Main using (Database db = new Database()) { AccountEntity a = new AccountEntity(); a.email = "hahaha"; a.pwd = "13212312"; a.guid = Guid.NewGuid(); db.Account.InsertOnSubmit(a); db.SubmitChanges(); } that has relationhip AccountEntity <- DetailsEntity (1-n) when i'm trying to insert a record exception throws NullReferenceException cause: by EntitySet null please help me make it insert

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