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  • Fill WinForms DataGridView From Anonymous Linq Query

    - by mdvaldosta
    // From my form BindingSource bs = new BindingSource(); private void fillStudentGrid() { bs.DataSource = Admin.GetStudents(); dgViewStudents.DataSource = bs; } // From the Admin class public static List<Student> GetStudents() { DojoDBDataContext conn = new DojoDBDataContext(); var query = (from s in conn.Students select new Student { ID = s.ID, FirstName = s.FirstName, LastName = s.LastName, Belt = s.Belt }).ToList(); return query; } I'm trying to fill a datagridview control in Winforms, and I only want a few of the values. The code compiles, but throws a runtime error: Explicit construction of entity type 'DojoManagement.Student' in query is not allowed. Is there a way to get it working in this manner?

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  • How to dynamically choose two fields from a Linq query as a result

    - by Dr. Zim
    If you have a simple Linq query like: var result = from record in db.Customer select new { Text = record.Name, Value = record.ID.ToString() }; which is returning an object that can be mapped to a Drop Down List, is it possible to dynamically specify which fields map to Text and Value? Of course, you could do a big case (switch) statement, then code each Linq query separately but this isn't very elegant. What would be nice would be something like: (pseudo code) var myTextField = db.Customer["Name"]; // Could be an enumeration?? var myValueField = db.Customer["ID"]; // Idea: choose the field outside the query var result = from record in db.Customer select new { Text = myTextField, Value = myValueField };

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  • Linq to Entity Left Outer Join

    - by radman
    Hi All, I have an Entity model with Invoices, AffiliateCommissions and AffiliateCommissionPayments. Invoice to AffiliateCommission is a one to many, AffiliateCommission to AffiliateCommissionPayment is also a one to many I am trying to make a query that will return All Invoices that HAVE a commission but not necessarily have a related commissionPayment. I want to show the invoices with commissions whether they have a commission payment or not. Query looks something like: using (var context = new MyEntitities()) { var invoices = from i in context.Invoices from ac in i.AffiliateCommissions join acp in context.AffiliateCommissionPayments on ac.affiliateCommissionID equals acp.AffiliateCommission.affiliateCommissionID where ac.Affiliate.affiliateID == affiliateID select new { companyName = i.User.companyName, userName = i.User.fullName, email = i.User.emailAddress, invoiceEndDate = i.invoicedUntilDate, invoiceNumber = i.invoiceNumber, invoiceAmount = i.netAmount, commissionAmount = ac.amount, datePaid = acp.paymentDate, checkNumber = acp.checkNumber }; return invoices.ToList(); } This query above only returns items with an AffiliateCommissionPayment.

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  • LINQ expression precedence with Skip(), Take() and OrderBy()

    - by Robert Koritnik
    I'm using LINQ to Entities and display paged results. But I'm having issues with the combination of Skip(), Take() and OrderBy() calls. Everything works fine, except that OrderBy() is assigned too late. It's executed after result set has been cut down by Skip() and Take(). So each page of results has items in order. But ordering is done on a page handful of data instead of ordering of the whole set and then limiting those records with Skip() and Take(). How do I set precedence with these statements? My example (simplified) var query = ctx.EntitySet.Where(/* filter */).OrderBy(/* expression */); int total = query.Count(); var result = query.Skip(n).Take(x).ToList();

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  • Mixing LINQ to SQL with properties of objects in a generic list

    - by BPotocki
    I am trying to accomplish something like this query: var query = from a in DatabaseTable where listOfObjects.Any(x => x.Id == a.Id) select a; Basically, I want to filter the results where a.Id equals a property of one of the objects in the generic list "listOfObjects". I'm getting the error "Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator." Any ideas on how to filter this in an easily readable way using "contains" or another method? Thanks in advance.

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  • Linq to XML - update/alter the nodes of an XML Document

    - by knox
    Hello! If got 2 Questions: 1. I've sarted working around with Linq to XML and i'm wondering if it is possible to change a XML document via Linq. I mean, is there someting like XDocument xmlDoc = XDocument.Load("sample.xml"); update item in xmlDoc.Descendants("item") where (int)item .Attribute("id") == id ... 2. I already know how to create and add a new XMLElement by simply using xmlDoc.Element("items").Add(new XElement(......); but how can i remove a single entry. XML sample data: <items> <item id="1" name="sample1" info="sample1 info" web="" /> <item id="2" name="sample2" info="sample2 info" web="" /> </itmes>

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  • Check username and password in LINQ query

    - by b0x0rz
    this linq query var users = from u in context.Users where u.UserEMailAdresses.Any(e1 => e1.EMailAddress == userEMail) && u.UserPasswords.Any(e2 => e2.PasswordSaltedHash == passwordSaltedHash) select u; return users.Count(); returns: 1 even when there is nothing in password table. how come? what i am trying to do is get the values of email and passwordHash from two separate tables (UserEMailAddresses and UserPasswords) linked via foreign keys to the third table (Users). it should be simple - checking if email and password mach from form to database. but it is not working for me. i get 1 (for count) even when there are NO entries in the UserPasswords table. is the linq query above completely wrong, or...?

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  • End user query syntax?

    - by weberc2
    I'm making a command line tool that allows end users to query a statically-schemed database; however, I want users to be able to specify boolean matchers in their query (effectively things like "get rows where (field1=abcd && field2=efgh) || field3=1234"). I did Googling a solution, but I couldn't find anything suitable for end users--still, this seems like it would be a very common problem so I suspect there is a standard solution. So: What (if any) standard query "languages" are there that might be appropriate for end users? What (if any) de facto standards are there (for example, Unix tools that solve similar problems). Failing the previous two options, can you suggest a syntax that would be simple, concise, and easy to validate?

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  • Entity LINQ on many-to-many got error "LINQ to Entities does not recognize the method 'Boolean Conta

    - by user300992
    I have 2 tables (Users and Roles) they are mapped as Many-to-Many in relational db. When I imported to Entity Data Content, they are still staying as the same relationship. Since they are mapped as Many-To-Many in Entity, I can access Users.RoleCollection or Roles.UserCollection However, when I execute this LINQ query, I got "LINQ to Entities does not recognize the method 'Boolean Contains... method, and this method cannot be translated into a store expression." var result (from a in Users from b in Roles where a.RoleCollection.Contains(b) select a); I think I must did something wrong... please help.

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  • help converting sql to linq expression with count

    - by Philip
    I am trying to convert the following SQL into a LINQ expression SELECT COUNT(ID) AS Count, MyCode FROM dbo.Archive WHERE DateSent=@DateStartMonth AND DateSent<=@DateEndMonth GROUP BY MyCode and I have been trying to follow this webpage as an example http://stackoverflow.com/questions/606124/converting-sql-containing-top-count-group-and-order-to-linq-2-entities I got this so far but I am stuck on understanding the new part var res=(from p in db.Archives where (p.DateSent>= dateStartMonth) && (p.DateSent< dateToday) group p by p.MyCode into g select new { ??????MyCode = g.something?, MonthlyCount= g.Count() }); Thanks in advance for helping greatly appreciated Philip

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  • Linq to SQL problem

    - by Ronnie Overby
    I have a local collection of recordId's (integers). I need to retrieve records that have every one of their child records' ids in that local collection. Here is my query: public List<int> OwnerIds { get; private set; } ... filteredPatches = from p in filteredPatches where OwnerIds.All(o => p.PatchesOwners.Select(x => x.OwnerId).Contains(o)) select p; I am getting this error: Local sequence cannot be used in Linq to SQL implementation of query operators except the Contains() operator. I get that .All() isn't supported by Linq to SQL, but is there a way to do what I am trying to do?

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  • How to Add Serialized LINQ to SQL Entities to a Word 2007 Document

    - by Ryan Riley
    I built a template-based document generator using the Open XML SDK (1.0), the Word 2007 Content Control Toolkit and LINQ to SQL (using the CodeSmith PLINQO templates). To do this, I serialized the LINQ to SQL entities to XML by retrieving the entity using DataLoadOptions specified in the source code. This works great, except that to initially populate the XML in my template, I currently have to copy and paste the XML from the Immediate window in VS2008 into the Content Control Toolkit, and it still has all the data from the current entity. I'm looking for two solutions: 1) Is this a good way to build a document generator with Word 2007? 1) How can I generate just the XML I need without the data? I've thought of creating an XSD and then creating an empty XML document, but wasn't sure how to do that programatically so that a business user can get the XML for the template. (That's not a requirement, just a nice-to-have.) Thanks for your feedback, Ryan

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  • LINQ query checks for null

    - by user300992
    I have a userList, some users don't have a name (null). If I run the first LINQ query, I got an error saying "object reference not set to an instance of an object" error. var temp = (from a in userList where ((a.name == "john") && (a.name != null)) select a).ToList(); However, if I switch the order by putting the checking for null in front, then it works without throwing any error: var temp = (from a in userList where ((a.name != null) && (a.name == "john")) select a).ToList(); Why is that? If that's pure C# code (not LINQ), I think both would be the same. I don't have SQL profiler, I am just curious what will be the difference when they are being translated on SQL level.

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  • Changing an extention method from linq-to-sql to entity framework

    - by Jova
    I'm changing my project from working with Linq-to-SQL to working with Entity Framework. I have some extention methods that extend the classes created by LINQ and I'm wondering how to change them to work with the entities instead Here's an example. public static int GetPublishedArticlesCount(this Table<Article> source) { return GetPublishedArticles(source.Context as DataContext, null).Count(); } This method gets the number of published articles. Instead of using this Table<Article>, what should I use instead?

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  • Linq insert statement inserts nothing, does not fail either

    - by pietjepoeier
    I am trying to insert a new account in my Acccounts table with linq. I tried using the EntityModel and Linq2Sql. I get no insert into my database nor an exception of any kind. public static Linq2SQLDataContext dataContext { get { return new Linq2SQLDataContext(); } } try { //EntityModel Accounts acc = Accounts.CreateAccounts(0, Voornaam, Straat, Huisnummer, Stad, Land, 15, EmailReg, Password1); Entities.AddToAccounts(acc); Entities.SaveChanges(); //Linq 2 SQL Account account = new Account { City = Stad, Country = Land, EmailAddress = EmailReg, Name = Voornaam, Password = Password1, Street = Straat, StreetNr = Huisnummer, StreetNrAdd = Toevoeging, Points = 25 }; dataContext.Accounts.InsertOnSubmit(account); var conf = dataContext.ChangeConflicts; // No changeConflicts ChangeSet set = dataContext.GetChangeSet(); // 0 inserts, 0 updates, 0 deletes try { dataContext.SubmitChanges(); } catch (Exception ex) { } } catch (EntityException ex) { }

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  • Help with linq to sql compiled query

    - by stackoverflowuser
    Hi I am trying to use compiled query for one of my linq to sql queries. This query contains 5 to 6 joins. I was able to create the compiled query but the issue I am facing is my query needs to check if the key is within a collection of keys passed as input. But compiled queries do not allow passing of collection (since collection can have varying number of items hence not allowed). For instance input to the function is a collection of keys. Say: List<Guid> InputKeys List<SomeClass> output = null; var compiledQuery = CompiledQueries.Compile<DataContext, IQueryable<SomeClass>>( (context) => from a in context.GetTable<A>() where InputKeys.Contains(a.Key) select a); using(var dataContext = new DataContext()) { output = compiledQuery(dataContext).ToList(); } return output; Is there any work around or better way to do the above?

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  • Linq to Sql Projection Help

    - by Micah
    I've reached the end of my Linq rope. Need your help! Heres my table structure first(all linq to sql objects): InventoryItems -ID -AmtInStock IventoryKits -ID InventoryKits_to_InventoryItems -InventoryItemID -InventoryKitID So i need to do a projection like the following var q2=from k in GetAllKits()//returns IQueryable<InventoryKit> select new VMPublication()//ViewModel Object { ID = k.ID, Name = k.Name, WebAmountInStock = ,//need to get the Min() AmtInStock from InventoryItems here ItemCode = k.ItemCode, WebAmountOrdered = k.AmtOrdered.ToString(), WebReminderAmount = "", WebAmountWarning="", Type = "Kit" }; i have no idea how to get that Min() of InventoryItem's AmtInStock in that query. Please help! Very Appreciated!

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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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  • Case insensitive string compare in LINQ-to-SQL

    - by BlueMonkMN
    I've read that it's unwise to use ToUpper and ToLower to perform case-insensitive string comparisons, but I see no alternative when it comes to LINQ-to-SQL. The ignoreCase and CompareOptions arguments of String.Compare are ignored by LINQ-to-SQL (if you're using a case-sensitive database, you get a case-sensitive comparison even if you ask for a case-insensitive comparison). Is ToLower or ToUpper the best option here? Is one better than the other? I thought I read somewhere that ToUpper was better, but I don't know if that applies here. (I'm doing a lot of code reviews and everyone is using ToLower.) Dim s = From row In context.Table Where String.Compare(row.Name, "test", StringComparison.InvariantCultureIgnoreCase) = 0 This translates to an SQL query that simply compares row.Name with "test" and will not return "Test" and "TEST" on a case-sensitive database.

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  • Using LINQ-To-Entities to Generate Information

    - by parminder
    I am working on a website where a user can add tags to their posted books, much like is currently done for questions on Stack Overflow. Classes: Books { bookId, Title } Tags { Id Tag } BooksTags { Id BookId TagId } Here are few sample records. Books BookId Title 113421 A 113422 B Tags Id Tag 1 ASP 2 C# 3 CSS 4 VB 5 VB.NET 6 PHP 7 java 8 pascal BooksTags Id BookId TagId 1 113421 1 2 113421 2 3 113421 3 4 113421 4 5 113422 1 6 113422 4 7 113422 8 Questions I need to write something in LINQ to entity queries which gives me data according to the tags: Query: bookIds where tagid = 1 Returns: bookid: 113421, 113422 Query 2: tags 1 and 2 Returns: 113421 I need tags and their count to to show in related tags, so in first case my related tags class should have following result. RelatedTags Tag Count 2 1 3 1 4 2 8 1 Second Case: RelatedTags Tag Count 3 1 4 1 How do I do this in LINQ?

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  • How to update an element with a List using LINQ and C#

    - by Addie
    I have a list of objects and I'd like to update a particular member variable within one of the objects. I understand LINQ is designed for query and not meant to update lists of immutable data. What would be the best way to accomplish this? I do not need to use LINQ for the solution if it is not most efficient. Would creating an Update extension method work? If so how would I go about doing that? EXAMPLE: (from trade in CrudeBalancedList where trade.Date.Month == monthIndex select trade).Update( trade => trade.Buy += optionQty);

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  • Can't enumerate LinQ results with left join

    - by nvtthang
    var itemSet = from item in da.GetList<Models.account>() join file in objFileStorageList on item.account_id equals file.parent_id into objFile from fileItem in objFile.DefaultIfEmpty() where item.company != null && item.company.company_id == 123 orderby item.updatedDate descending select new { Id = item.account_id, RefNo = item.refNo, StartDate = item.StartDate , EndDate = item.EndDate , Comment = item.comment, FileStorageID = fileItem != null ? fileItem.fileStorage_id : -1, Identification = fileItem != null ? fileItem.identifier : null, fileName = fileItem != null ? fileItem.file_nm : null }; It raises error message when I try to enumerate through collection result from Linq query above. LINQ to Entities does not recognize the method 'System.Collections.Generic.IEnumerable1[SCEFramework.Models.fileStorage] DefaultIfEmpty[fileStorage](System.Collections.Generic.IEnumerable1[SCEFramework.Models.fileStorage])' method, and this method cannot be translated into a store expression foreach (var item in itemSet) { string itemRef= item.RefNo; } Please suggest me any solutions. Thanks in advance.

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  • Use LINQ and C# to make a new List from an old List

    - by Addie
    This should be pretty simple, but I am new at LINQ. I have a List of FillList structs. I'd like to use LINQ to create a new List where instead of having the number of buys and sells, I would have one variable containing the sum. For example, if the FillStruct structure has buy = 4 and sell = 2 then the NewFillStruct structure will have numlong = 2. If the FillStruct structure has buy = 2 and sell = 4 then the NewFillStruct structure will have numlong = -2. Here are the structures. struct FillStruct { int buy; int sell; string date; } struct NewFillStruct { int numlong; string date; }

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