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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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• How to get address the object of an related entity with CoreData ?

  - by eemceebee

  Hi Ok, after I ran into a dead end modifieing an existing Apple example for CoreData, I started completely new creating my own project and that worked fine,..... until I tried to access a related entity. So here is what I did. I created 2 entities, where one is just the detail information of the other one, so there is a one-2-one relationship. Entity #1, Stocks: name value details -- relationship to Entity #2 Entity #2, StockDetails: bank published stock -- relationship to Entity #1 Now, I created the "Managed Object Class" for both of the Entities. Then I created a few lines to put some data into it NSManagedObjectContext *context = [self managedObjectContext]; Stocks *stockinfo= [NSEntityDescription insertNewObjectForEntityForName:@"Stocks" inManagedObjectContext:context]; stockinfo.name = @"Apple"; stockinfo.value = [NSNumber numberWithInt:200]; StockDetails *thestockdetails = [NSEntityDescription insertNewObjectForEntityForName:@"StockDetails" inManagedObjectContext:context]; thestockdetails.bank = @"Bank of America"; thestockdetails.published = [NSDate date]; thestockdetails.stock = stocks_; stockinfo.details = thestockdetails ; NSError *error; if (![context save:&error]) { NSLog(@"A Problem occured, couldn't save: %@", [error localizedDescription]); } Just want to mention here, that I do not get an error with this. Next I put everything into a UITableViewController for a preview and another for a detail view. The preview just shows infos form Entity #1 (Stocks) and when selected it shows the detail view. Now here I also display the infos form Entity #1 (Stocks) but I want to show the Entity #2 (StockDetails) aswell. This is how I try to access the data : StockDetails *details_ = [stockinfo details]; And this gives me a EXC_BAD_ACCESS. So any idea what I am doing wrong here ? Thanks

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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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• What functionality should a (basic) mock framework have?

  - by user1175327

  If i would start on writing a simple Mock framework, then what are the things that a basic mock framework MUST have? Obviously mocking any object, but what about assertions and perhaps other things? When I think of how I would write my own mock framework then I realise how much I really know (or don't know) and what I would trip up on. So this is more for educational purposes. Of course I did research and this is what i've come up with that a minimal mocking framework should be able to do. Now my question in this whole thing is, am I missing some important details in my ideas? Mocking Mocking a class: Should be able to mock any class. The Mock should preserve the properties and their original values as they were set in the original class. All method implementations are empty. Calls to methods of Mock: The Mock framework must be able to define what a mocked method must return. IE: $MockObj->CallTo('SomeMethod')->Returns('some value'); Assertions To my understanding mocking frameworks also have a set of assertions. These are the ones I think are most important (taken from SimpleTest). expect($method, $args) Arguments must match if called expectAt($timing, $method, $args) Arguments must match when called on the $timing'th time expectCallCount($method, $count) The method must be called exactly this many times expectMaximumCallCount($method, $count) Call this method no more than $count times expectMinimumCallCount($method, $count) Must be called at least $count times expectNever($method) Must never be called expectOnce($method, $args) Must be called once and with the expected arguments if supplied expectAtLeastOnce($method, $args) Must be called at least once, and always with any expected arguments And that's basically, as far as I understand, what a mock framework should be able to do. But is this really everything? Because it currently doesn't seem like a big deal to build something like this. But that's also the reason why I have the feeling that i'm missing some important details about such a framework. So is my understanding right about a mock framework? Or am i missing alot of details?

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• Entity Framework and multi-tenancy database design

  - by Junto

  I am looking at multi-tenancy database schema design for an SaaS concept. It will be ASP.NET MVC - EF, but that isn't so important. Below you can see an example database schema (the Tenant being the Company). The CompanyId is replicated throughout the schema and the primary key has been placed on both the natural key, plus the tenant Id. Plugging this schema into the Entity Framework gives the following errors when I add the tables into the Entity Model file (Model1.edmx): The relationship 'FK_Order_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderId, CompanyId}' of the table 'Order'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Order' uses the set of foreign keys '{OrderId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_Order_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderId, CompanyId}' of the table 'Order'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Order' uses the set of foreign keys '{OrderId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Product' uses the set of foreign keys '{ProductId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The question is in two parts: Is my database design incorrect? Should I refrain from these compound primary keys? I'm questioning my sanity regarding the fundamental schema design (frazzled brain syndrome). Please feel free to suggest the 'idealized' schema. Alternatively, if the database design is correct, then is EF unable to match the keys because it perceives these foreign keys as a potential mis-configured 1:1 relationships (incorrectly)? In which case, is this an EF bug and how can I work around it?

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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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• .NET Framework 4 Client Profile vs .NET Framework 3.5 Client Profile

  - by Janusz

  Currently I am targeting .NET Framework 3.5 Client profile. Under certain conditions (when .NET 1.x or 2.x is installed) the client profile is not installed and instead full version of .NET Framework 3.5. is installed. This limitation has been removed from .NET 4.0 profile - therefore its a nice improvement that significantly reduces download size on certain PCs. However, if I target application to .NET 4.0 then all the clients will have to download new framework. I think ideal scenario would be to target .NET 3.5 profile but point installer to .NET 4.0 client profile. This way PCs with 3.5 installed (65% from our tests at the moment) would be fine and the rest would install .NET 4.0. Is my thinking correct or its not feasible? Will .NET 3.5 profile application run with only .NET 4.0 profile installed? Thank you

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• Problem creating ObjectContext from different project inside solution.

  - by Levelbit

  I have two projects in my Solution. One implements my business logic and has defined entity model of entity framework. When I want to work with classes defined within this project from another project I have some problems in runtime. Actually, the most concerning thing is why I can not instantiate my, so called, TicketEntities(ObjectContext) object from other projects? when I catch following exception: The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid. I found out it's brake at: public partial class TicketEntities : global::System.Data.Objects.ObjectContext { public TicketEntities() : base("name=TicketEntities", "TicketEntities") { this.OnContextCreated(); } with exception: Unable to load the specified metadata resource. Just to remind you everthing works fine from orginal project.

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• Opening an SQL CE file at runtime with Entity Framework 4

  - by David Veeneman

  I am getting started with Entity Framework 4, and I an creating a demo app as a learning exercise. The app is a simple documentation builder, and it uses a SQL CE store. Each documentation project has its own SQL CE data file, and the user opens one of these files to work on a project. The EDM is very simple. A documentation project is comprised of a list of subjects, each of which has a title, a description, and zero or more notes. So, my entities are Subject, which contains Title and Text properties, and Note, which has Title and Text properties. There is a one-to-many association from Subject to Note. I am trying to figure out how to open an SQL CE data file. A data file must match the schema of the SQL CE database created by EF4's Create Database Wizard, and I will implement a New File use case elsewhere in the app to implement that requirement. Right now, I am just trying to get an existing data file open in the app. I have reproduced my existing 'Open File' code below. I have set it up as a static service class called File Services. The code isn't working quite yet, but there is enough to show what I am trying to do. I am trying to hold the ObjectContext open for entity object updates, disposing it when the file is closed. So, here is my question: Am I on the right track? What do I need to change to make this code work with EF4? Is there an example of how to do this properly? Thanks for your help. My existing code: public static class FileServices { #region Private Fields // Member variables private static EntityConnection m_EntityConnection; private static ObjectContext m_ObjectContext; #endregion #region Service Methods /// <summary> /// Opens an SQL CE database file. /// </summary> /// <param name="filePath">The path to the SQL CE file to open.</param> /// <param name="viewModel">The main window view model.</param> public static void OpenSqlCeFile(string filePath, MainWindowViewModel viewModel) { // Configure an SQL CE connection string var sqlCeConnectionString = string.Format("Data Source={0}", filePath); // Configure an EDM connection string var builder = new EntityConnectionStringBuilder(); builder.Metadata = "res://*/EF4Model.csdl|res://*/EF4Model.ssdl|res://*/EF4Model.msl"; builder.Provider = "System.Data.SqlServerCe"; builder.ProviderConnectionString = sqlCeConnectionString; var entityConnectionString = builder.ToString(); // Connect to the model m_EntityConnection = new EntityConnection(entityConnectionString); m_EntityConnection.Open(); // Create an object context m_ObjectContext = new Model1Container(); // Get all Subject data IQueryable<Subject> subjects = from s in Subjects orderby s.Title select s; // Set view model data property viewModel.Subjects = new ObservableCollection<Subject>(subjects); } /// <summary> /// Closes an SQL CE database file. /// </summary> public static void CloseSqlCeFile() { m_EntityConnection.Close(); m_ObjectContext.Dispose(); } #endregion }

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• 'Generic' ViewModel

  - by Ian MacPherson

  Using EF 4, I have several subtypes of a 'Business' entity (customers, suppliers, haulage companies etc). They DO need to be subtypes. I am building a general viewmodel which calls into a service from which a generic repository is accessed. As I have 4 subtypes, it would be good to have a 'generic' viewmodel used for all of these. Problem is of course is that I have to call a specific type into my generic repository, for example: BusinessToRetrieve = _repository .LoadEntity<Customer>(o => o.CustomerID == customerID); It would be good to be able to call <SomethingElse>, somethingElse being one or other of the subtypes), otherwise I shall have to create 4 near identical viemodels, which seems a waste of course! The subtype entity name is available to the viewmodel but I've been unable to figure out how to make the above call convert this into a type. An issue with achieving what I want is that presumably the lambda expression being passed in wouldn't be able to resolve on a 'generic' call ?

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• Using Entity Framework (code first) migrations in production

  - by devdigital

  I'm just looking into using EF migrations for our project, and in particular for performing schema changes in production between releases. I can see that generating SQL (delta) script files is an option, but is there no way of running the migrations programmatically on app start up? Will I instead need to add each delta script to the solution and write my own framework to apply them in order (from the current version to the latest) on bootstrap?

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• ASP.net MVC 2.0 using the same form for adding and editing.

  - by Chevex

  I would like to use the same view for editing a blog post and adding a blog post. However, I'm having an issue with the ID. When adding a blog post, I have no need for an ID value to be posted. When model binding binds the form values to the BlogPost object in the controller, it will auto-generate the ID in entity framework entity. When I am editing a blog post I DO need a hidden form field to store the ID in so that it accompanies the next form post. Here is the view I have right now. <% using (Html.BeginForm("CommitEditBlogPost", "Admin")) { %> <% if (Model != null) { %> <%: Html.HiddenFor(x => x.Id)%> <% } %> Title:<br /> <%: Html.TextBoxFor(x => x.Title, new { Style = "Width: 90%;" })%> <br /> <br /> Summary:<br /> <%: Html.TextAreaFor(x => x.Summary, new { Style = "Width: 90%; Height: 50px;" }) %> <br /> <br /> Body:<br /> <%: Html.TextAreaFor(x => x.Body, new { Style = "Height: 250px; Width: 90%;" })%> <br /> <br /> <input type="submit" value="Submit" /> <% } %> Right now checking if the model is coming in NULL is a great way to know if I'm editing a blog post or adding one, because when I'm adding one it will be null as it hasn't been created yet. The problem comes in when there is an error and the entity is invalid. When the controller renders the form after an invalid model the Model != null evaluates to false, even though we are editing a post and there is clearly a model. If I render the hidden input field for ID when adding a post, I get an error stating that the ID can't be null. Any help is appreciated. EDIT: I went with OJ's answer for this question, however I discovered something that made me feel silly and I wanted to share it just in case anyone was having a similar issue. The page the adds/edits blogs does not even need a hidden field for id, ever. The reason is because when I go to add a blog I do a GET to this relative URL BlogProject/Admin/AddBlogPost This URL does not contain an ID and the action method just renders the page. The page does a POST to the same URL when adding the blog post. The incoming BlogPost entity has a null Id and is generated by EF during save changes. The same thing happens when I edit blog posts. The URL is BlogProject/Admin/EditBlogPost/{Id} This URL contains the id of the blog post and since the page is posting back to the exact same URL the id goes with the POST to the action method that executes the edit. The only problem I encountered with this is that the action methods cannot have identical signatures. [HttpGet] public ViewResult EditBlogPost(int Id) { } [HttpPost] public ViewResult EditBlogPost(int Id) { } The compiler will yell at you if you try to use these two methods above. It is far too convenient that the Id will be posted back when doing a Html.BeginForm() with no arguments for action or controller. So rather than change the name of the POST method I just modified the arguments to include a FormCollection. Like this: [HttpPost] public ViewResult EditBlogPost(int Id, FormCollection formCollection) { // You can then use formCollection as the IValueProvider for UpdateModel() // and TryUpdateModel() if you wish. I mean, you might as well use the // argument since you're taking it. } The formCollection variable is filled via model binding with the same content that Request.Form would be by default. You don't have to use this collection for UpdateModel() or TryUpdateModel() but I did just so I didn't feel like that collection was pointless since it really was just to make the method signature different from its GET counterpart. Thanks for the help guys!

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• How do I get a right outer join in L2E?

  - by Dan

  I have two tables that I set up through the VS Entity Data Model Diagram tool. I'm trying to do a right outer join and it doesn't return results from the 2nd table. I have set up a 0..1 to MANY relationship from the diagram tool. When I run a Linq-To-Entities query, it still defaults to an INNER JOIN. From my understanding of entities, if I set up the relationship using VS, when I join the tables, it should automagically figure out the join syntax based on the relationship I supply. It doesn't seem to be doing that. I am using EF v1 (not Linq-to-Sql). Query I'm running: from s in SomeTable join t in SomeOtherTable on s.ID equals t.ID select new { s.MyFieldName, t.MyOtherFieldName }

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• Dynamic query to immediate execute?

  - by Curtis White

  I am using the MSDN Dynamic linq to sql package. It allows using strings for queries. But, the returned type is an IQueryable and not an IQueryable<T>. I do not have the ToList() method. How can I this immediate execute without manually enumerating over the IQueryable? My goal is to databind to the Selecting event on a linqtosql datasource and that throws a datacontext disposed exception. I can set the query as the Datasource on a gridview though. Any help greatly appreciated! Thanks. The dynamic linq to sql is the one from the samples that comes with visual studio.

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