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• LINQ to XML contents of child records.

  - by Fossaw

  I have this LINQ to XML enquiry... var Records = from Item in XDoc.Root.Elements("Item") where (string)Item.Element("ItemNumber") == item.ID.ToString select Item; ... where ItemNumber is a reference number used in the XML, (originally written by this program but manually edited by "others"), and item.ID is the database version of the same thing. The query executes, and I can test for the number of entries in the result fine... if (Records.Count() < 1) ... you get the idea. I have established that there is only one record. Each Item has several child fields. I want to test the values of the child fields are reasonable before passing them on to the database update sub-system. The XML is produced by the program, but edited by users, so I need to really check what is coming back. So I tried... if (DB_English.ToString() != Records.Elements("English").ToString()) ... DB_English is from the database, but the XML in Records, does not contain the contents of that field, it contains... System.Xml.Linq.Extensions+<GetElements>d__29`1[System.Xml.Linq.XElement] ... so, how do I get the value of this element in the XML file? I need to check the field in the XML has not been altered, (the manual editors of this data file are not potentially 100% reliable).

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• Update mapping table in Linq

  - by Gary McGill

  I have a table Customers with a CustomerId field, and a table of Publications with a PublicationId field. Finally, I have a mapping table CustomersPublications that records which publications a customer can access - it has two fields: CustomerId field PublicationId. For a given customer, I want to update the CustomersPublications table based on a list of publication ids. I want to remove records in CustomersPublications where the PublicationId is not in the list, and add new records where the PublicationId is in the list but not already in the table. This would be easy in SQL, but I can't figure out how to do it in Linq. For the delete part, I tried: var recordsToDelete = dataContext.CustomersPublications.Where ( cp => (cp.CustomerId == customerId) && ! publicationIds.Contains(cp.PublicationId) ); dataContext.CustomersPublications.DeleteAllOnSubmit(recordsToDelete); ... but that didn't work. I got an error: System.NotSupportedException: Method 'Boolean Contains(Int32)' has no supported translation to SQL So, I tried using Any(), as follows: var recordsToDelete = dataContext.CustomersPublications.Where ( cp => (cp.CustomerId == customerId) && ! publicationIds.Any(p => p == cp.PublicationId) ); ... and this just gives me another error: System.NotSupportedException: Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator Any pointers? [I have to say, I find Linq baffling (and frustrating) for all but the simplest queries. Better error messages would help!]

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• Need advice on comparing the performance of 2 equivalent linq to sql queries

  - by uvita

  I am working on tool to optimize linq to sql queries. Basically it intercepts the linq execution pipeline and makes some optimizations like for example removing a redundant join from a query. Of course, there is an overhead in the execution time before the query gets executed in the dbms, but then, the query should be processed faster. I don't want to use a sql profiler because I know that the generated query will be perform better in the dbms than the original one, I am looking for a correct way of measuring the global time between the creation of the query in linq and the end of its execution. Currently, I am using the Stopwatch class and my code looks something like this: var sw = new Stopwatch(); sw.Start(); const int amount = 100; for (var i = 0; i < amount; i++) { ExecuteNonOptimizedQuery(); } sw.Stop(); Console.Writeline("Executing the query {2} times took: {0}ms. On average, each query took: {1}ms", sw.ElapsedMilliseconds, sw.ElapsedMilliseconds / amount, amount); Basically the ExecutenNonOptimizedQuery() method creates a new DataContext, creates a query and then iterates over the results. I did this for both versions of the query, the normal one and the optimized one. I took the idea from this post from Frans Bouma. Is there any other approach/considerations I should take? Thanks in advance!

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• oData/ADO.NET Data Services using LINQ-to-SQL with a decryption layer

  - by Program.X

  I have written an application using LINQ-to-SQL that submits a web form into a database. I absact the LINQ-to-SQL away using a Repository pattern. This repository has the basic methods: Get(), Save(), etc. As a development of the project, I needed to encrypt certain fields in the form. This was trivial, as I just added the encryption calls to the Get(), Save() methods in the Repository. Now, I want to put an oData layer over it, to allow RESTful extraction from MS Excel 2010 (when it comes out). I have this working, after a few stumbles on useless error messages, etc. However, obviously, those encrypted fields are still encrypted. My repository pattern would have decrypted these for me. As far as I know, I have to directly bind my oData service to the LINQ-to-SQL context for the schema, etc. to work - unless I enter a whole world of pain (any URLs appreciated). Is there a way I can insert my encryption/decryption layer into the request so decryption is done "on the fly"? I looked at the OnStartProcessingRequest() overload of DataService but this doesn't seem that useful.

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• "Order By" in LINQ-to-SQL Causes performance issues

  - by panamack

  I've set out to write a method in my C# application which can return an ordered subset of names from a table containing about 2000 names starting at the 100th name and returning the next 20 names. I'm doing this so I can populate a WPF DataGrid in my UI and do some custom paging. I've been using LINQ to SQL but hit a snag with this long executing query so I'm examining the SQL the LINQ query is using (Query B below). Query A runs well: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) Query B takes 40 seconds: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) ORDER BY [t0].[name] When I add the ORDER BY [t0].[name] to the outer query it slows down the query. How can I improve the second query? This was my LINQ stuff Nick int sessionId = 1; int start = 100; int count = 20; // Query subjects with the shoot's session id var subjects = cldb.Subjects.Where<Subject>(s => s.Session_id == sessionId); // Filter as per params var orderedSubjects = subjects .OrderBy<Subject, string>( s => s.Col_zero ); var filteredSubjects = orderedSubjects .Skip<Subject>(start) .Take<Subject>(count);

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• Acceessing some aggregate functions in a linq datasource in a GridView

  - by Stephen Pellicer

  I am working on a traditional WebForms project. In the project I am trying out some Linq datasources with plans to eventually migrate to an MVC architecture. I am still very new to Linq. I have a GridView using a Linq datasource. The entities I am showing has a to many relationship and I would like to get the maximum value of a column in the many side of the relationship. I can show properties of the base entity in the gridview: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.JobNumber"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.JobNumber") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> I can also show the count of the many related property: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.tHourlies.Count"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.tHourlies.Count") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> Is there a way to get the max value of a column called WeekEnding in the tHourlies collection to show in the GridView?

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• Call method immediately after object construction in LINQ query

  - by Steffen

  I've got some objects which implement this interface: public interface IRow { void Fill(DataRow dr); } Usually when I select something out of db, I go: public IEnumerable<IRow> SelectSomeRows { DataTable table = GetTableFromDatabase(); foreach (DataRow dr in table.Rows) { IRow row = new MySQLRow(); // Disregard the MySQLRow type, it's not important row.Fill(dr); yield return row; } } Now with .Net 4, I'd like to use AsParallel, and thus LINQ. I've done some testing on it, and it speeds up things alot (IRow.Fill uses Reflection, so it's hard on the CPU) Anyway my problem is, how do I go about creating a LINQ query, which calls Fills as part of the query, so it's properly parallelized? For testing performance I created a constructor which took the DataRow as argument, however I'd really love to avoid this if somehow possible. With the constructor in place, it's obviously simple enough: public IEnumerable<IRow> SelectSomeRowsParallel { DataTable table = GetTableFromDatabase(); return from DataRow dr in table.Rows.AsParallel() select new MySQLRow(dr); } However like I said, I'd really love to be able to just stuff my Fill method into the LINQ query, and thus not need the constructor overload.

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• Linq to SQL code generator features

  - by Anders Abel

  I'm very fond of Linq to SQL and the programming model it encourages. I think that in many cases when you are in control of both the database schema and the code it is not worth the effort to have different relational and object models for the data. Working with Linq to SQL makes it simple to have type safe data access from .NET, using the partial extension methods to implement business rules. Unfortunately I do not like the dbml designer due to the lack of a schema refresh function. So far I have used SqlMetal, but that lacks the customization options of the dbml designer. Because of that I've started working on a tool which regenerates the whole code file like SqlMetal, but has the ability to do the customizations that are available in the dbml designer (and maybe more in the future). The customizations will be described in an xml file which only contains those parts that shouldn't have default values. This should keep the xml file size down as well as the maintenance burden of it. To help me focus on the right features, I would like to know: What would be your favourite feature in a linq to sql code generator?

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• using linq to sql

  - by mazhar

  Well I am new to this orm stuff. We have to create a large project . I read about linq to sql . will it be appropiate to use it in the project of high risk . i found no problem with it personally but the thing is that there will be no going back once started.So i need some feedback from the orm gurus here at the msdn.Will entity framework will be better?( I am in doubt about link to sql because I have read and heard negative feedback here and there) I will be using mvc2 as the framework. So please give the feedback about linq to sql in this regard. q2) Also I am a fan of stored procedure as they are precomputed and fasten up the thing and I have never worked without them.I know that linq to sql support stored procedures but will it be feasible to give up stored procedure seeing the beautiful data access layer generated with little effort as we are also in a need of rapid development. q3) If some changes to some fields required in the database in Link to Sql how will the changes be accommodated in the data access layer.

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• using linq to sql

  - by user324831

  Well I am new to this orm stuff. We have to create a large project . I read about linq to sql . will it be appropiate to use it in the project of high risk . i found no problem with it personally but the thing is that there will be no going back once started.So i need some feedback from the orm gurus here at the msdn.Will entity framework will be better?( I am in doubt about link to sql because I have read and heard negative feedback here and there) I will be using mvc2 as the framework. So please give the feedback about linq to sql in this regard. q2) Also I am a fan of stored procedure as they are precomputed and fasten up the thing and I have never worked without them.I know that linq to sql support stored procedures but will it be feasible to give up stored procedure seeing the beautiful data access layer generated with little effort as we are also in a need of rapid development. q3) If some changes to some fields required in the database in Link to Sql how will the changes be accommodated in the data access layer.

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• Convert SQL to LINQ in MVC3 with Ninject

  - by Jeff

  I'm using MVC3 and still learning LINQ. I'm having some trouble trying to convert a query to LINQ to Entities. I want to return an employee object. SELECT E.EmployeeID, E.FirstName, E.LastName, MAX(EO.EmployeeOperationDate) AS "Last Operation" FROM Employees E INNER JOIN EmployeeStatus ES ON E.EmployeeID = ES.EmployeeID INNER JOIN EmployeeOperations EO ON ES.EmployeeStatusID = EO.EmployeeStatusID INNER JOIN Teams T ON T.TeamID = ES.TeamID WHERE T.TeamName = 'MyTeam' GROUP BY E.EmployeeID, E.FirstName, E.LastName ORDER BY E.FirstName, E.LastName What I have is a few tables, but I need to get only the newest status based on the EmployeeOpertionDate. This seems to work fine in SQL. I'm also using Ninject and set my query to return Ienumerable. I played around with the group by option but it then returns IGroupable. Any guidance on converting and returning the property object type would be appreciated. Edit: I started writing this out in LINQ but I'm not sure how to properly return the correct type or cast this. public IQueryable<Employee> GetEmployeesByTeam(int teamID) { var q = from E in context.Employees join ES in context.EmployeeStatuses on E.EmployeeID equals ES.EmployeeID join EO in context.EmployeeOperations on ES.EmployeeStatusID equals EO.EmployeeStatusID join T in context.Teams on ES.TeamID equals T.TeamID where T.TeamName == "MyTeam" group E by E.EmployeeID into G select G; return q; } Edit2: This seems to work for me public IQueryable<Employee> GetEmployeesByTeam(int teamID) { var q = from E in context.Employees join ES in context.EmployeeStatuses on E.EmployeeID equals ES.EmployeeID join EO in context.EmployeeOperations.OrderByDescending(eo => eo.EmployeeOperationDate) on ES.EmployeeStatusID equals EO.EmployeeStatusID join T in context.Teams on ES.TeamID equals T.TeamID where T.TeamID == teamID group E by E.EmployeeID into G select G.FirstOrDefault(); return q; }

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• Creating a Linq->HQL provider

  - by Mike Q

  Hi all, I have a client application that connects to a server. The server uses hibernate for persistence and querying so it has a set of annotated hibernate objects for persistence. The client sends HQL queries to the server and gets responses back. The client has an auto-generated set of objects that match the server hibernate objects for query results and basic persistence. I would like to support using Linq to query as well as Hql as it makes the queries typesafe and quicker to build (no more typos in HQL string queries). I've looked around at the following but I can't see how to get them to fit with what I have. NHibernate's Linq provider - requires using NHibernate ISession and ISessionFactory, which I don't have LinqExtender - requires a lot of annotations on the objects and extending a base type, too invasive What I really want is something that will generate give me a nice easy to process structure to build the HQL queries from. I've read most of a 15 page article written by one of the C# developers on how to create custom providers and it's pretty fraught, mainly because of the complexity of the expression tree. Can anyone suggest an approach for implementing Linq - HQL translation? Perhaps a library that will the cleanup of the expression tree into something more SQL/HQLish. I would like to support select/from/where/group by/order by/joins. Not too worried about subqueries.

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• "Most popular" GROUP BY in LINQ?

  - by tags2k

  Assuming a table of tags like the stackoverflow question tags: TagID (bigint), QuestionID (bigint), Tag (varchar) What is the most efficient way to get the 25 most used tags using LINQ? In SQL, a simple GROUP BY will do: SELECT Tag, COUNT(Tag) FROM Tags GROUP BY Tag I've written some LINQ that works: var groups = from t in DataContext.Tags group t by t.Tag into g select new { Tag = g.Key, Frequency = g.Count() }; return groups.OrderByDescending(g => g.Frequency).Take(25); Like, really? Isn't this mega-verbose? The sad thing is that I'm doing this to save a massive number of queries, as my Tag objects already contain a Frequency property that would otherwise need to check back with the database for every Tag if I actually used the property. So I then parse these anonymous types back into Tag objects: groups.OrderByDescending(g => g.Frequency).Take(25).ToList().ForEach(t => tags.Add(new Tag() { Tag = t.Tag, Frequency = t.Frequency })); I'm a LINQ newbie, and this doesn't seem right. Please show me how it's really done.

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• LINQ query to find if items in a list are contained in another list

  - by cjohns

  I have the following code: List<string> test1 = new List<string> { "@bob.com", "@tom.com" }; List<string> test2 = new List<string> { "[email protected]", "[email protected]" }; I need to remove anyone in test2 that has @bob.com or @tom.com. What I have tried is this: bool bContained1 = test1.Contains(test2); bool bContained2 = test2.Contains(test1); bContained1 = false but bContained2 = true. I would prefer not to loop through each list but instead use a Linq query to retrieve the data. bContained1 is the same condition for the Linq query that I have created below: List<string> test3 = test1.Where(w => !test2.Contains(w)).ToList(); The query above works on an exact match but not partial matches. I have looked at other queries but I can find a close comparison to this with Linq. Any ideas or anywhere you can point me to would be a great help.

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• WPF & Linq To SQL binding ComboBox to foreign key

  - by ZeroDelta

  I'm having trouble binding a ComboBox to a foreign key in WPF using Linq To SQL. It works fine when displaying records, but if I change the selection on the ComboBox, that change does not seem to affect the property to which it is bound. My SQL Server Compact file has three tables: Players (PK is PlayerID), Events (PK is EventID), and Matches (PK is MatchID). Matches has FKs for the the other two, so that a match is associated with a player and an event. My window for editing a match uses a ComboBox to select the Event, and the ItemsSource is set to the result of a LINQ query to pull all of the Events. And of course the user should be able to select the Event based on EventName, not EventID. Here's the XAML: <ComboBox x:Name="cboEvent" DisplayMemberPath="EventName" SelectedValuePath="EventID" SelectedValue="{Binding Path=EventID, UpdateSourceTrigger=PropertyChanged}" /> And some code-behind from the Loaded event handler: var evt = from ev in db.Events orderby ev.EventName select ev; cboEvent.ItemsSource = evt.ToList(); var mtch = from m in db.Matches where m.PlayerID == ((Player)playerView.CurrentItem).PlayerID select m; matchView = (CollectionView)CollectionViewSource.GetDefaultView(mtch); this.DataContext = matchView; When displaying matches, this works fine--I can navigate from one match to the next and the EventName is shown correctly. However, if I select a new Event via this ComboBox, the CurrentItem of the CollectionView doesn't seem to change. I feel like I'm missing something stupid! Note: the Player is selected via a ListBox, and that selection filters the matches displayed--this seems to be working fine, so I didn't include that code. That is the reason for the "PlayerID" reference in the LINQ query

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• Slow T-SQL query, convert to LINQ to Object

  - by yimbot

  I have a T-SQL query which populates a DataSet from an MSSQL database. string qry = "SELECT * FROM EvnLog AS E WHERE TimeDate = (SELECT MAX(TimeDate) From EvnLog WHERE Code = E.Code) AND (Event = 8) AND (TimeDate BETWEEN '" + Start + "' AND '" + Finish + "')" The database is quite large and being the type of nested query it is, the Data Adapter can take a number of minutes to fill the DataSet. I have extended the DataAdapter's timeout value to 480 seconds to combat it, but the client still complains about slow performance and occassional timeouts. To combat this, I was considering executing a simpler query (ie. just taking the date range) and then populating a Generic List which I could then execute a Linq query against. The simple query executes very quickly which is great. However, I cannot seem to build a Linq query which generates the same results as the T-SQL query above. Is this the best solution to this problem? Can anyone provide tips on rewriting the above T-SQL into Linq? I have also considered using a DataView, but cannot seem to get the results from that either.

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• LINQ to SQL Converter

  - by user609511

  How can I convert My LINQ to SQL ? i have this LINQ statement: int LimCol = Convert.ToInt32(LimitColis); result = oListTUP .GroupBy(x => new { x.Item1, x.Item2, x.Item3, x.Item4, x.Item5 }) .Select(g => new { Key = g.Key, Sum = g.Sum(x => x.Item6), Poids = g.Sum(x => x.Item7), }) .Select(p => new { Key = p.Key, Items = Enumerable.Repeat(LimCol, p.Sum / LimCol).Concat(Enumerable.Repeat(p.Sum % LimCol, p.Sum % LimCol > 0 ? 1 : 0)), CalculPoids = p.Poids / Enumerable.Repeat(LimCol, p.Sum / LimCol).Concat(Enumerable.Repeat(p.Sum % LimCol, p.Sum % LimCol > 0 ? 1 : 0)).Count() }) .SelectMany(p => p.Items.Select(i => Tuple.Create(p.Key.Item1, p.Key.Item2, p.Key.Item3, p.Key.Item4, p.Key.Item5, i, p.CalculPoids))) .ToList(); } It works well, but somehow want to push it and it become too complicated, so I want to convert it into Pure SQL. I have tried SQL Profiler and LinqPad, but neither shows me the SQL. How can I see the SQL code from My LINQ ? Thank you in advance.

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• Map inheritance from generic class in Linq To SQL

  - by Ksenia Mukhortova

  Hi everyone, I'm trying to map my inheritance hierarchy to DB using Linq to SQL: Inheritance is like this, classes are POCO, without any LINQ to SQL attributes: public interface IStage { ... } public abstract class SimpleStage<T> : IStage where T : Process { ... } public class ConcreteStage : SimpleStage<ConcreteProcess> { ... } Here is the mapping: <Database Name="NNN" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007"> <Table Name="dbo.Stage" Member="Stage"> <Type Name="BusinessLogic.Domain.IStage"> <Column Name="ID" Member="ID" DbType="Int NOT NULL IDENTITY" IsPrimaryKey="true" IsDbGenerated="true" AutoSync="OnInsert" /> <Column Name="StageType" Member="StageType" IsDiscriminator="true" /> <Type Name="BusinessLogic.Domain.SimpleStage" IsInheritanceDefault="true"> <Type Name="BusinessLogic.Domain.ConcreteStage" IsInheritanceDefault="true" InheritanceCode="1"/> </Type> </Type> </Table> </Database> In the runtime I get error: System.InvalidOperationException was unhandled Message="Mapping Problem: Cannot find runtime type for type mapping 'BusinessLogic.Domain.SimpleStage'." Neither specifying SimpleStage, nor SimpleStage<T> in mapping file helps - runtime keeps producing different types of errors. DC is created like this: StreamReader sr = new StreamReader(@"MappingFile.map"); XmlMappingSource mapping = XmlMappingSource.FromStream(sr.BaseStream); DataContext dc = new DataContext(@"connection string", mapping); If Linq to SQL doesn't support this, could you, please, advise some other ORM, which does. Thanks in advance, Regards! Ksenia

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• fastest way to check to see if a certain index in a linq statement is null

  - by tehdoommarine

  Basic Details I have a linq statement that grabs some records from a database and puts them in a System.Linq.Enumerable: var someRecords = someRepoAttachedToDatabase.Where(p=>true); Suppose this grabs tons (25k+) of records, and i need to perform operations on all of them. to speed things up, I have to decided to use paging and perform the operations needed in blocks of 100 instead of all of the records at the same time. The Question The line in question is the line where I count the number of records in the subset to see if we are on the last page; if the number of records in subset is less than the size of paging - then that means there are no more records left. What I would like to know is what is the fastest way to do this? Code in Question int pageSize = 100; bool moreData = true; int currentPage = 1; while (moreData) { var subsetOfRecords = someRecords.Skip((currentPage - 1) * pageSize).Take(pageSize); //this is also a System.Linq.Enumerable if (subsetOfRecords.Count() < pageSize){ moreData = false;} //line in question //do stuff to records in subset currentPage++; } Things I Have Considered subsetOfRecords.Count() < pageSize subsetOfRecords.ElementAt(pageSize - 1) == null (causes out of bounds exception - can catch exception and set moreData to false there) Converting subsetOfRecords to an array (converting someRecords to an array will not work due to the way subsetOfRecords is declared - but I am open to changing it) I'm sure there are plenty of other ideas that I have missed.

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• C# Linq Select Problem in Method Chain.

  - by Gnought

  Note that the _src inherit IQueryable<U> and V inherit new(); I wrote the following statement, there is no syntax error. IQueryable<V> a = from s in _src where (s.Right - 1 == s.Left) select new V(); But if i re-wrote it as follows, the Visual Studio editor complains an error in the "Select" IQueryable<V> d = _src.Where(s => s.Right - 1 == s.Left).Select(s=> new V()); The Error is: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly. Candidates are: System.Collections.Generic.IEnumerable<V> Select<U,V>(this System.Collections.Generic.IEnumerable<U>, System.Func<U,V>) (in class Enumerable) System.Linq.IQueryable<V> Select<U,V>(this System.Linq.IQueryable<U>, System.Linq.Expressions.Expression<System.Func<U,V>>) (in class Queryable) Could anyone explain this phenomenon, and what the solution is to fix the error?

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• child objects in linq

  - by gangt

  I checked before I posted but couldn't find a solution. I'm new to linq and it is draining my brain to understand it. I have an xml and want to use linq to fill object that has a child object. the xml and my linq is below. My issue is on this line TaskItems = t.Elements("taskdetail").ToList<TaskItem>() //this line doesn't work how do I fill this child object? var task1 = from t in xd.Descendants("taskheader") select new { Id = t.Element("id").Value, Name = t.Element("name").Value, IsActive = Convert.ToBoolean(Convert.ToInt16(t.Element("isactive").Value)) TaskItems = t.Elements("taskdetail").ToList<TaskItem>() }; <tasks> <taskheader> <id>1</id> <name>some task</name> <isactive>1</isactive> <taskdetail> <taskid>1</taskid> <name>action1</name> <value>some action</value> </taskdetail> <taskdetail> <taskid>1</taskid> <name>action2</name> <value>some other action</value> </taskdetail> </taskheader> </tasks> public class Task { public int Id; public string Name; public bool IsActive; public List<TaskItem> TaskItems = new List<TaskItem>(); } public class TaskItem { public int TaskId; public string Name; public string Value; }

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• sql to linq translated code

  - by ognjenb

  SQL: SELECT o.Id, o.OrderNumber, o.Date, d.Name AS 'Distributor', d.Notes AS 'DistrNotes', -- distributer c.Name AS 'Custoer', c.Notes AS 'CustmNotes', -- customer t.Name AS 'Transporter', -- transporter o.InvoiceFile, o.Notes, o.AwbFile, o.TrackingFile, o.Status, o.DeliveryNotification, o.ServiceType, o.ValidityDate, o.DeliveryTime, o.Weight, o.CustomerId, o.CustomerOrderNumber, o.CustomerDate, o.Shipment, o.Payment, o.TransporterId, o.TotalPrice, o.Discount, o.AlreadyPaid, o.Delivered, o.Received, o.OrderEnteredBy, CONCAT(e.Name, ' ', e.Surname) AS 'IBEKO Engineer', o.Confirmed FROM `order` o LEFT JOIN person d ON o.`DistributorId` = d.`Id` LEFT JOIN person c ON o.`CustomerId` = c.Id LEFT JOIN Transporter t ON o.`TransporterId` = t.Id LEFT JOIN IbekoEngineer e ON o.OrderEnteredBy = e.Id LINQ: testEntities6 ordersEntities = new testEntities6(); var orders_query = (from o in ordersEntities.order join pd in ordersEntities.person on o.DistributorId equals pd.Id join pc in ordersEntities.person on o.CustomerId equals pc.Id join t in ordersEntities.transporter on o.TransporterId equals t.Id select new OrdersModel { Id = o.Id, OrderNumber = o.OrderNumber, Date = o.Date, Distributor_Name = pdk.Name, Distributor_Notes = pdk.Notes, Customer_Name = pc.Name, Customer_Notes = pc.Notes, Transporter_Name = t.Name, InvoiceFile = o.InvoiceFile, Notes = o.Notes, AwbFile = o.AwbFile, TrackingFile = o.TrackingFile, Status = o.Status, DeliveryNotification = o.DeliveryNotification, ServiceType = o.ServiceType, ValidityDate = o.ValidityDate, DeliveryTime = o.DeliveryTime, Weight = o.Weight, CustomerId = o.CustomerId, CustomerOrderNumber = o.CustomerOrderNumber, CustomerDate = o.CustomerDate, Shipment = o.Shipment, Payment = o.Payment, TransporterId = o.TransporterId, TotalPrice = o.TotalPrice, Discount = o.Discount, AlreadyPaid = o.AlreadyPaid, Delivered = o.Delivered, Received = o.Received, OrderEnteredBy = o.OrderEnteredBy, Confirmed = o.Confirmed }); I translated the above SQL code into linq. SQL code return data from database but LINQ not return data. Why?

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• Logic for capturing unique characteristics in an object array. C# LINQ [closed]

  - by Shawn H.

  Given the following "response" or array of objects, what would be the most efficient way to get the desired results. There must be an easier way than the exhaustive and tedious way I'm doing it now. A LINQ solution would be fantastic. Situation #1 <things> <thing id="1"> <feature>Tall</feature> </thing> <thing id="2"> <feature>Tall</feature> </thing> <thing id="3"> <feature>Tall</feature> <feature>Wide</feature> </thing> <thing id="4"> <feature>Tall</feature> </thing> </things> Result: Wide Situation #2 <things> <thing id="1"> <feature>Short</feature> </thing> <thing id="2"> <feature>Tall</feature> </thing> <thing id="3"> <feature>Tall</feature> <feature>Wide</feature> </thing> <thing id="4"> <feature>Tall</feature> </thing> </things> Result: Wide, Short, Tall Situation #3 <things> <thing id="1"> <feature>Tall</feature> <feature>Thin</feature> </thing> <thing id="2"> <feature>Tall</feature> </thing> <thing id="3"> <feature>Tall</feature> <feature>Wide</feature> </thing> <thing id="4"> <feature>Tall</feature> </thing> </things> Result: Wide, Thin Thanks.

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• NHibernate LINQ query throws error "Could not resolve property"

  - by Xorandor

  I'm testing out using LINQ with NHibernate but have run into some problems with resolving string.length. I have the following public class DC_Control { public virtual int ID { get; private set; } public virtual string Name { get; set; } public virtual bool IsEnabled { get; set; } public virtual string Url { get; set; } public virtual string Category { get; set; } public virtual string Description { get; set; } public virtual bool RequireScriptManager { get; set; } public virtual string TriggerQueryString { get; set; } public virtual DateTime? DateAdded { get; set; } public virtual DateTime? DateUpdated { get; set; } } public class DC_ControlMap : ClassMap<DC_Control> { public DC_ControlMap() { Id(x => x.ID); Map(x => x.Name).Length(128); Map(x => x.IsEnabled); Map(x => x.Url); Map(x => x.Category); Map(x => x.Description); Map(x => x.RequireScriptManager); Map(x => x.TriggerQueryString); Map(x => x.DateAdded); Map(x => x.DateUpdated); } } private static ISessionFactory CreateSessionFactory() { return Fluently.Configure() .Database(FluentNHibernate.Cfg.Db.MsSqlConfiguration.MsSql2008) .Mappings(m => m.FluentMappings.AddFromAssembly(Assembly.GetExecutingAssembly())) .ExposeConfiguration(c => c.SetProperty("connection.connection_string", "CONNSTRING")) .ExposeConfiguration(c => c.SetProperty("proxyfactory.factory_class", "NHibernate.ByteCode.Castle.ProxyFactoryFactory,NHibernate.ByteCode.Castle")) .BuildSessionFactory(); } public static void test() { using (ISession session = sessionFactory.OpenSession()) { var sqlQuery = session.CreateSQLQuery("select * from DC_Control where LEN(url) > 80").AddEntity(typeof(DC_Control)).List<DC_Control>(); var linqQuery= session.Linq<DC_Control>().Where(c => c.Url.Length > 80).ToList(); } } In my test method I first try and perform the query using SQL, this works just fine. Then I want to do the same thing in LINQ, and it throws the following error: NHibernate.QueryException: could not resolve property: Url.Length of: DC_Control I've searched alot for this "could not resolve property" error, but I can't quite figure out, what this means. Is this because the LINQ implementation is not complete? If so it's a bit disappointing coming from Linq2Sql where this would just work. I also tried it setting up the mapping with a hbm.xml instead of using FluentNHibernate but it produced teh same error.

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• C# where does the dbml file come from?

  - by 5YrsLaterDBA

  Learning C# and learing Linq now. have lots of qestions about it. Basically I need a step by step tutorial. I suppose the dbml file is the configuration file of the database. I double click it and VS will open it with kind of design diagram. I can create/delete/modify table here? I can use add new item to add the Linq to SQL Classes to get a dbml file? what's next? generate tables in database? generate sql script? generate cs files? when? how?

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