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  • linq-to-sql combine child expressions

    - by VictorS
    I need to create and combine several expressions for child entity into one to use it on "Any" operator of a parent. Code now looks like this: Expresion<Child, bool> startDateExpression = t => t.start_date >= startDate; Expression<Child, bool> endDateExpression = t => t.end_date <= endDate; .... ParameterExpression param = startDateExpression.Parameters[0]; Expression<Func<T, bool>> Combined = Expression.Lambda<Func<Child, bool>>( Expression.AndAlso(startDateExpression.Body, startDateExpression.Body), param); //but now I am trying to use combined expression on parent //this line fails just to give an idea on what I am trying to do: //filter type is IQueryable<Parent>; var filter = filter.Where(p =>p.Children.Any(Combined)); How can I do that? Is there better(more elegant way way of doing it?

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  • Problem with LINQ Where Clause

    - by Krishma
    var results = from formNumber in context.DetailTM join c in context.ClaimPeriodTM on formNumber.ClaimPeriod equals c.Cid where formNumber.FormNumber.StartsWith(fNumber) && formNumber.RegistrationNumber != registrationNumber select new { RegNo = formNumber.RegistrationNumber, CP = c.ClaimPeriod, FormNo = formNumber.FormNumber }; The AND CLAUSE with .STARTSWITH Doesn't work. If I use == operator the query works fine. I tried adding brackets to the where clause but it didn't help. Any idea what is missing. Thank you in Advance.

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  • LINQ to Objects .Distinct() not pulling distinct objects

    - by Anthony Potts
    I have two ways that I am doing a fuzzy search for a customer. One is by an abbreviated name and the other is by the customers full name. When I take these two and then union them together (which I have read several places should remove distinct values) I get duplicates. Thinking that all I need to do is then call the .Distinct() method on this I also still get Duplicates. Do I need to implement some compare functionality in my customer object? My code: Dim shortNameMatch As List(Of ICustomer) = CustomerLibrary.GetCustomersByShortName(term) Dim custNameMatch As List(Of ICustomer) = CustomerLibrary.GetCustomersByCustName(term) Dim allMatch = (From a In (From s In shortNameMatch Select s).Union(From c In custNameMatch Select c) Select a).Distinct()

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  • LINQ If .Any matches .Any

    - by molgan
    Hello I have 2 string arrays, and I would like to return if any of them exists in _authRole array. How is that done? string[] _userRoles = userdata.Split(','); string[] _authRoles = AuthRoles.Split(','); bool isAuthorized = _authRoles.Any(_userRoles ??); /M

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  • Linq to xml not able to add new elements

    - by Fore
    We save our xml in a "text" field in the database. So first I check if it exist any xml, if not I create a new xdocument, fill it with the necessary xml. else i just add the new element. Code looks like this: XDocument doc = null; if (item.xmlString == null || item.xmlString == "") { doc = new XDocument(new XDeclaration("1.0", "utf-8", "yes"), new XElement("DataTalk", new XAttribute(XNamespace.Xmlns + "xsi", "http://www.w3.org/2001/XMLSchema-instance"), new XAttribute(XNamespace.Xmlns + "xsd", "http://www.w3.org/2001/XMLSchema"), new XElement("Posts", new XElement("TalkPost")))); } else { doc = XDocument.Parse(item.xmlString); } This is working alright to create a structure, but then the problem appears, when I want to add new TalkPost. I get an error saying incorrectly structured document. The following code when adding new elements: doc.Add(new XElement("TalkPost", new XElement("PostType", newDialog.PostType), new XElement("User", newDialog.User), new XElement("Customer", newDialog.Customer), new XElement("PostedDate", newDialog.PostDate), new XElement("Message", newDialog.Message)));

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  • How to use Linq group a order list by Date

    - by Daoming Yang
    I have a order list and want to group them by the created date. Each order's created datetime will be like "2010-03-13 11:17:16.000" How can I make them only group by date like "2010-03-13"? var items = orderList.GroupBy(t => t.DateCreated) .Select(g => new Order() { DateCreated = g.Key }) .OrderByDescending(x => x.OrderID).ToList();

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  • Linq-to-sql Add item and a one-to-many record at once

    - by Oskar Kjellin
    I have a function where I can add articles and users can comment on them. This is done with a one to many relationship like= "commentId=>ArticleId". However when I try to add the comment to the database at the same time as I add the one to many record, the commentId is not known. Like this code: Comment comment = new Comment(); comment.Date = DateTime.UtcNow; comment.Text = text; comment.UserId = userId; db.Comments.InsertOnSubmit(comment); comment.Articles.Add(new CommentsForArticle() { ArticleId = articleId, CommentId = comment.CommentId }); The commentId will be 0 before i press submit. Is there any way arround not having to submit in between or do I simply have to cut out the part where I have a one-to-many relationship and just use a CommentTable with a column like "ArticleId". What is best in a performance perspective? I understand the underlying issue, I just want to know which solution works best.

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  • C# LINQ: Join and Group

    - by Soo
    I have two tables TableA aId aValue TableB bId aId bValue I want to join these two tables via aId, and from there, group them by bValue var result = from a in db.TableA join b in db.TableB on a.aId equals b.aId group b by b.bValue into x select new {x}; My code doesn't recognize the join after the group. In other words, the grouping works, but the join doesn't (or at least I can't figure out how to access all of the data after the join). Any help would be appreciated. I'm a n00b.

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  • VB.NET LINQ to SQL Delete All Records

    - by Daniel
    I am having problems with deleting all records in a table with VB.NET. I am using this code to delete all records in the Contacts table For Each contact In database.Contacts database.Contacts.DeleteOnSubmit(contact) Next But I get this error Can't perform Create, Update or Delete operations on 'Table(Contact)' because it has no primary key. Anyone have any suggestions? Thanks

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  • linq null refactoring code

    - by user276640
    i have code public List<Files> List(int? menuId) { if (menuId == null) { return _dataContext.Files.ToList(); } else { return _dataContext.Files.Where(f => f.Menu.MenuId == menuId).ToList(); } } is it possible to make it only one line like return _dataContext.Files.Where(f = f.Menu.MenuId == menuId).ToList();?

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  • Linq SqlMethods.Like fails

    - by Russell Steen
    I'm following the tips here, trying to leverage the statement that the sql doesn't get created until the enumerator is tripped. However I get the following error on the code below. I'm using Linq2Entities, not linq2sql. Is there a way to do this in Linq2entities? Method 'Boolean Like(System.String, System.String)' cannot be used on the client; it is only for translation to SQL. query = db.MyTables.Where(x => astringvar.Contains(x.Field1)); if (!String.IsNullOrEmpty(typeFilter)) { if (typeFilter.Contains('*')) { typeFilter = typeFilter.Replace('*', '%'); query = query.Where(x=> SqlMethods.Like(x.Type, typeFilter)); } else { query = query.Where(x => x.Type == typeFilter); } }

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  • No output from Linq to XML

    - by Gogster
    Hi all, I have the following code: protected void Page_Load(object sender, EventArgs e) { XElement xml = XElement.Load(Server.MapPath("ArenasMembers.xml")); var query = from p in xml.Descendants("members") select new { Name = p.Element("name").Value, Email = p.Attribute("email").Value }; foreach (var member in query) { Response.Write("Employee: " + member.Name + " " + member.Email + "<br />"); } } Which, using the hover information in Visual Studio, is reading the XNL file in correctly, however the foreach is not outputting any of the records. XML: <?xml version="1.0" encoding="utf-8" ?> <members> <member> <arena>EAA Office</arena> <memberid>1</memberid> <name>Jane Doe</name> <email>[email protected]</email> </member> <member> <arena>EAA Office</arena> <memberid>2</memberid> <name>John Bull</name> <email>[email protected]</email> </member> <member> <arena>O2 Arena</arena> <memberid>3</memberid> <name>John Doe</name> <email>[email protected]</email> </member> <member> <arena>O2 Arena</arena> <memberid>4</memberid> <name>Bernard Cribbins</name> <email>[email protected]</email> </member> <member> <arena>Colourline Arena</arena> <memberid>5</memberid> <name>John Bon Jovi</name> <email>[email protected]</email> </member> <member> <arena>NIA</arena> <memberid>6</memberid> <name>Rhianna</name> <email>[email protected]</email> </member> </members> Can you see what is wrong?

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  • Linq to Sql Data class in dbml

    - by Simon
    I am abit curious about dbml.... Should I create one dbml file for one database or separated into different parts e.g. User dbml (only tables relate to users) etc? When I do this I will have abit of problems. Assume the User dbml has a User table and if the Order dbml has a User table as well, this won't be allowed if the entity namespace are the same. If I have set a different entity namespace for each of the dbml, it works but this will gives me a different entity of User table. When a single data returns to Business Logic layer, there is a difficulty of knowing which entity namespace of the user table to be used. If I built one dbml file instead of having separate dbml, will single dbml appear slower than the separated dbml version when fetching the data from the database.

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  • Odd Linq behavior with IList / IEnumerable

    - by Aren B
    I've got the following code: public IList<IProductViewModel> ChildProducts { get; set; } public IList<IProductViewModel> GiftItems { get; set; } public IList<IProductViewModel> PromoItems { get; set; } public IList<IProductViewModel> NonGiftItems { get { return NonPromoItems.Except(GiftItems, new ProductViewModelComparer()).ToList(); } } public IList<IProductViewModel> NonPromoItems { get { return ChildProducts.Where(p => !p.IsPromotion).ToList(); } } So basically, NonPromoItems is (ChildProducts - PromoItems) and NonGiftItems is (NonPromoItems - GiftItems) However When: ChildProducts = IEnumerable<IProductViewModel>[6] PromoItems = IEnumerable<IProductViewModel>[1] where item matches 1 item in ChildProducts GiftItems = IEnumerable<IProductViewModel>[0] My Result is NonPromoItems = IEnumerable<IProductViewModel>[5] This is Correct NonGiftItems = IEnumerable<IProductViewModel>[4] This is Incorrect Somehow an Except(...) is removing an item when given an empty list to subtract. Any ideas anyone?

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  • How to use Linq to group DateTime by month and days calculation

    - by Daoming Yang
    Hi all, I have two questions: First one: I have a order list and want to group them by the created month for the reports. Each order's created datetime will be like "2010-03-13 11:17:16.000" How can I make them only group by date like "2010-03"? Note: the DateCreated is the DateTime tpye The following code is not correct. var items = orderList.GroupBy(t => t.DateCreated.Month) .Select(g => new Order() { DateCreated = g.Key }) .OrderByDescending(x => x.OrderID).ToList(); Second one: Output the full months between two dates in C# If an user choose 2010-04-08 and 2010-06-04, I want to output the 2010-04-01 and 2010-06-30. I can always get the first day and last day of the months, but I want to find out some other options Many thanks. Many thanks.

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  • 'And' operator in Linq

    - by Ani
    I have a query that prints userid in label1 when username is entered.Works fine; but i want to write query for username and password that prints userid. so how can i write it? i tried writing using 'and' operator but dont seems to work. int id = (from auser in lq.logins where auser.username == userNameString //&& auser.Password =pwdString select auser.userid).SingleOrDefault(); label1.Text = id.ToString(); Thanks Ani

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  • Compiled Linq Queries with Built-in SQL functions

    - by Brandi
    I have a query that I am executing in C# that is taking way too much time: string Query = "SELECT COUNT(HISTORYID) FROM HISTORY WHERE YEAR(CREATEDATE) = YEAR(GETDATE()) "; Query += "AND MONTH(CREATEDATE) = MONTH(GETDATE()) AND DAY(CREATEDATE) = DAY(GETDATE()) AND USERID = '" + EmployeeID + "' "; Query += "AND TYPE = '5'"; I then use SqlCommand Command = new SqlCommand(Query, Connection) and SqlDataReader Reader = Command.ExecuteReader() to read in the data. This is taking over a minute to execute from C#, but is much quicker in SSMS. I see from google searching you can do something with CompiledQuery, but I'm confused whether I can still use the built in SQL functions YEAR, MONTH, DAY, and GETDATE. If anyone can show me an example of how to create and call a compiled query using the built in functions, I will be very grateful! Thanks in advance.

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  • LINQ "table" variable

    - by Cat
    I'm trying to turn a method I have right now into a more "generic" method that returns a string. Right now, the method uses a statement like this: var app = (from d in testContext.DAPPs where d.sserID == (Guid)user.ProviderUserKey select d).ToList(); I process the results of "app", add extra text etc. The piece that changes (that I need to make more "generic") is the table name (DAPPs). Is there a way I can do that, or, a better way to go around this all together?

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  • DBnull in Linq query causing problems

    - by nat
    hi there i am doing a query thus: int numberInInterval = (from dsStatistics.J2RespondentRow item in jStats.J2Respondent where item.EndTime > dtIntervalLower && item.EndTime <= dtIntervalUpper select item).count(); there appear to be some dbnulls in the endtime column.. any way i can avoid these? tried adding && where item.endtime != null.. and even != dbnull.value do i have to do a second (first) query to grab all that arent null then run the above one? im sure its super simple fix, but im still missing it.. as per thanks nat

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  • Why LINQ will work this way?

    - by Benny
    public static ArrayList GetStudentAsArrayList() { ArrayList students = new ArrayList { new Student() { RollNumber = 1,Name ="Alex " , Section = 1 ,HostelNumber=1 }, new Student() { RollNumber = 2,Name ="Jonty " , Section = 2 ,HostelNumber=2 }, }; return students; } this doesn't compile: ArrayList is not IEnumerable ArrayList lstStudents = GetStudentAsArrayList(); var res = from r in lstStudents select r; but this will compile: ArrayList lstStudents = GetStudentAsArrayList(); var res = from Student r in lstStudents select r; Can anybody explain? what's the magic here?

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  • Linq To Sql: Compiled Queries and Extension Methods

    - by Beni
    Hi community, I'm interessted, how does Linq2Sql handles a compiled query, that returns IQueryable. If I call an extension method based on a compiled query like "GetEntitiesCompiled().Count()" or "GetEntitiesCompiled().Take(x)". What does Linq2Sql do in the background? This would be very bad, so in this situation I should write a compiled query like "CountEntitiesCompiled". Does he load the result (in this case "GetEntitiesCompiled()") into the memory (mapped to the entity class like "ToList()")? So what situations make sense, when the compiled queries return IQueryable, that query is not able to modify, before request to the Sql-Server. So in my opinion I can just as good return List. Thanks for answers!

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  • Using Multiple Foreign Keys to the same table in LINQ

    - by Graeme
    I have a table Users and a table Items In the Items table, I have fields such as ModifiedBy CreatedBy AssignedTo which all have a userId integer. The database is set up to have these as foreign keys back to the Users table. When using LINQToSQL, the relationships which are automatically built from the dbml end up giving me names like User, User1 and User2 e.g. myItem.User1.Name or myItem.User2.Name Obviously this isn't very readable and I'd like it be along the lines of myItem.CreatedByUser.Name or myItem.ModifiedByUser.Name etc I could change the names of the relationships but that means I have to redo that every time I change the db schema and refresh the dbml. Is there any way round this?

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  • Which LINQ query is more effective?

    - by Danny Chen
    I have a huge IEnumerable(suppose the name is myItems), which way is more effective? Solution 1: Filter it first then ForEach. Array.ForEach(myItems.Where(FILTER-IT-HERE).ToArray(),MY-ACTION); Solution 2: Do RETURN in MY-ACTION if the item is not up to the mustard. Array.ForEach(myItems.ToArray(),MY-ACTION-WITH-FILTER); Is one of them always better than another? Or any other good suggestions? Thanks in advance.

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  • Linq 2 SQL Store inherited classes - not mapped to tables in the database

    - by user348672
    Hi. I'm trying to introduce the Linq2SQL technique into the project and have encountered the following issue: I've created ORM classes based on the Northwind database. In some other application I create several classes derived from the Linq2SQL classes. I'm able to add such a class to EntitySet but the application fails to submit changes. Is there any way around this? Sample code(MyClass is derived from the Order): DataClasses1DataContext northwind = new DataClasses1DataContext(); Product chai = northwind.Products.Single(p => p.ProductName == "Chai"); Product tofu = northwind.Products.Single(p => p.ProductName == "Tofu"); Order myOrder = new Order(); myOrder.OrderDate = DateTime.Now; myOrder.RequiredDate = DateTime.Now.AddDays(1); myOrder.Freight = 34; Order_Detail myItem1 = new Order_Detail(); myItem1.Product = chai; myItem1.Quantity = 12345; Order_Detail myItem2 = new Order_Detail(); myItem2.Product = tofu; myItem2.Quantity = 3; myOrder.Order_Details.Add(myItem1); myOrder.Order_Details.Add(myItem2); Customer myCustomer = northwind.Customers.Single(c => c.CompanyName == "B's Beverages"); MyClass newOrder = new MyClass(); newOrder.OrderDate = DateTime.Now; newOrder.RequiredDate = DateTime.Now.AddDays(31); newOrder.Freight = 35; Order_Detail myItem3 = new Order_Detail(); myItem3.Product = tofu; myItem3.Quantity = 3; newOrder.Order_Details.Add(myItem3); myCustomer.Orders.Add(myOrder); myCustomer.Orders.Add(newOrder); As I said I'm able to add the newOrder object but unable to submit into the database.

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  • linq null parameter

    - by kusanagi
    how can i do the code static string BuildMenu(List<Menu> menu, int? parentId) { foreach (var item in menu.Where(i => i.ParentMenu == parentId || i.ParentMenu.MenuId == parentId).ToList()) { } } return BuildMenu(menuList,null); so if parentId==null then return only records i = i.ParentMenu == null but when parentId is 0 then return records with i.ParentMenu.MenuId == parentId

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