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  • How to break a list into chunks based on some property?

    - by CurlyFro
    public class InvestorMailing { public string To { get; set; } public IEnumerable<string> Attachments { get; set; } public int AttachmentCount { get; set; } public long AttachmentSize { get; set; } } i have an IList<InvestorMailing> mailingList. if the attachment size is greater than x, then i need to split my list and break it into chunks. is there an easy linq-y way to do this?

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  • ASP.MVC ModelBinding Behaviour

    - by OldBoy
    This one has me stumped, despite the numerous posts on here. The scenario is a basic MVC(2) web application with simple CRUD operations. Whenever the edit form is submitted and the UpdateModel() called, an exception is thrown: System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException was unhandled by user code This occurs against a DropDownList value which is a foreign key on the entity table. However, there is another DropDownList list on the form, representing another foreign key, which does not throw the error (unsurprisingly). Changing the property values manually inside the Edit Action: Recipe recipe = repository.GetRecipe(int.Parse(formValues["recipeid"])); recipe.CategoryId = Convert.ToInt32(formValues["CategoryId"].ToString()); recipe.Page = int.Parse(formValues["Page"].ToString()); recipe.PublicationId=Convert.ToInt32(formValues["PublicationId"].ToString()); Allows the CategoryId and Page properties to be updated, and then the error is thrown on the PublicationId. All of the referential integrity is checked an the same in the db and the dbml. Any light shed on this would be most welcome.

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  • How do I delete an object from an Entity Framework model without first loading it?

    - by Tomas Lycken
    I am quite sure I've seen the answer to this question somewhere, but as I couldn't find it with a couple of searches on SO or google, I ask it again anyway... In Entity Framework, the only way to delete a data object seems to be MyEntityModel ent = new MyEntityModel(); ent.DeleteObject(theObjectToDelete); ent.SaveChanges(); However, this approach requires the object to be loaded to, in this case, the Controller first, just to delete it. Is there a way to delete a business object referencing only for instance its ID? If there is a smarter way using Linq or Lambda expressions, that is fine too. The main objective, though, is to avoid loading data just to delete it.

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  • find users that are following other users

    - by Jakob
    Hi I'm wondering how I can go about this problem I have a DB with a Users Table, and a Followers table. The Followers table contains 2 Columns "FollowerID" and "FollowedID" I have a 1 - * relation in my datamodel between Users.ID -> Followers.FollowerID and Users.ID -> FollowedID How do I in LINQ get a set of users that are following a specific user? I'll express what I'm trying to achieve programatically I can get this far: ctx.Followers.Where(f => f.FollowedID == CurrentUser.ID) so now i have a Followers set where I have the ID of the users that follow the CurrentUser, and I could iterate through this collection and then add users after each iteration to a collection that would be a total USER collection that followed CurrentUser, but isn't there a smarter, or LINQ'er way to do this? Much appreciated Thx

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  • Unit testing with Data Access Layer

    - by chobo
    Hi, what is a good way to write unit tests with a LINQ to SQL DAL? Currently I am doing some database testing and need to create helper methods that access the database, but I don't want those methods in my main repo's. So what I have is two copies of the DAL, one in my main project and one in the Test project. Is it easier to manage these things if I create a separate project for the data layer? I'm not sure which way is a better way to approach this. If I do create a data layer project would I move all my repo's to that project as well? I'm not sure how to properly setup the layers. Thanks

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  • LinqToSql Sub Entiity Multiple And Operators

    - by halit
    Hi I have an Array of Featureset Id , My Vehicles table has got sub table as FeatureSets I wrote Sql Query Like SELECT [t0].[ID] FROM [dbo].[SearchResultView] AS [t0] Join [dbo].[VehicleFeatureSet] AS [t1] on t0.ID = t1.VehicleID where t1.FeatureSetID = 1 and t1.FeatureSetID= 2 and t1.FeatureSetID= 3 I tried. But I Couldn't var features = Request.QueryString["FeatureSets"].Split(',').ToList().ConvertAll(new Converter<string, int>(StrinToint)); IQueryable<SearchResultView> result = db.SearchResultViews.Where(m => m.Active == true); foreach (var featuree in features) { result = result.Where(m => m.VehicleFeatureSets.Any(c => c.FeatureSetID == featuree)); } How Can I write this LINQ Query

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  • Entity Framework with SQL Server 2000 (APPLY Operator) issue

    - by How Lun
    Hello, I have a simple Linq query below: var seq = (from n in GetObjects() select n.SomeKey) .Distinct() .Count(); This query works find with SQL Server 2005 and above. But, this start to give headache when I hooked the EF to SQL Server 2000. Because EF is using APPLY operator which only SQL Server 2005 and above can be supported. I do not know why the hell EF is using APPLy operator instead of sub queries. My current work around is: var seq = (from n in GetObjects() select n.SomeKey) .Distinct() .ToList() .Count(); But, I can forsee more problems to come. The above query is just a simple one. Did anyone come across such issue? And how you guys work around it? Or is there a way to force EF not to use APPLY operator? Any help will be very much appreciated. How Lun.

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  • Windows service thread not updating database until complete

    - by dfarney
    I have a windows service with a FileSystemWatcher. When a new file is dropped in my folder a new thread is created, started, and I begin processing the file. Throughout this process I am making updates to the database (Linq to SQL) to keep track of the file's processing progress. Problem is none of my database updates are reflected throughout the process, just an update after everything has been completed. Any ideas? Note: when doing dev/testing my code was in an aspx page and worked great, but when I put it in a windows service I no longer get the progress updates. Thanks!

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  • Setting a property from one collection to another collection

    - by ooo
    I have two colluections List<Application> myApps; List<Application> yourApps; These lists have overlapping overlapping data but they are coming from different sources and each source has some missing field data. Application object has a property called Description Both collections have a unique field called Key i want to see if there is a LINQ solution to: Loop through all applications in myApps and look at the key and see if that existing in yourApps. If it does, i want to take the description property from that application in yourApps and set the description property on the application on myApps to that same value i wanted to see if there was any slick way using lambda expressions (instead of having to have loops and a number of if statements.)

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  • anonymous type and multiple properties

    - by ognjenb
    I have this error: An anonymous type cannot have multiple properties with the same name. Whether this can be resolved with alias ie, whether an alias exists in LINQ var device_query = from d in DevicesEntities.device join dt in DevicesEntities.devicetype on d.DeviceTypeId equals dt.Id join l in DevicesEntities.location on d.Id equals l.DeviceId join loc in DevicesEntities.locationname on l.LocationNameId equals loc.Id where l.DeviceId == d.Id select new { d.Id, d.DeviceTypeId, d.SerialNumber, d.FirmwareRev, d.ProductionDate, d.ReparationDate, d.DateOfLastCalibration, d.DateOfLastCalibrationCheck, d.CalCertificateFile, d.Notes, d.TestReportFile, d.WarrantyFile, d.CertificateOfOriginFile, d.QCPermissionFile, d.Reserved, d.ReservedFor, d.Weight, d.Price, d.SoftwareVersion, dt.Name, dt.ArticleNumber, dt.Type, l.StartDate, //AS LastStartDate, l.LocationNameId, loc.Name //in this line I have problem };

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  • How does OfType<T>() Work?

    - by TheCloudlessSky
    How does OfType() Work? I read this link about what's going on but how exactly does the LINQ provider know how to get all objects matching the specified type. I know the IQueryable<T> "chains" up requests and then evaluates when GetEnumerator() is called (right?). Specifically I want to know how does the framework quickly do type comparison? I wrote a method in a .NET 2.0 project that went like this (since 2.0 doesn't support these kind of features): public IEnumerable<TResult> OfType<TResult>() where TResult : class { foreach (TItem item in this.InnerList) { TResult matchItem = item as TResult; if (matchItem != null) { yield return matchItem; } } } Is this the best implementation?

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  • sum of timespans

    - by frenchie
    I have a collection of objects that include a timespan variable: MyObject { TimeSpan TheDuration {get;set;} } I want to use linq to sum those times. Of course, (from r in MyCollection select r.TheDuration).Sum(); doesn't work! I'm thinking of changing the datatype of TheDuration to an int and then summing it and converting the sum to a TimeSpan. That'll be messy because each TheDuration in my collection is used in as a timespan somewhere else. Any suggestion on this summation?

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  • Using Large Arrays in VB.NET

    - by Tim
    I want to extract large amounts of data from Excel, manipulate it and put it back. I have found the best way to do this is to extract the data from an Excel Range in to a large array, change the contents on the array and write it back to the Excel Range. I am now rewriting the application using VB.NET 2008/2010 and wish to take advantage of any new features. Currently I have to loop through the contents of the array to find elements with certain values; also sorting large arrays is cumbersome. I am looking to use the new features, including LINQ to manipulate the data in my array. Does anybody have any advice on the easiest ways to filter / query, sort etc. data in a large array. Also what are the reasonable limits to the size of the array? ~Many Thanks

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  • List.clear() followed by List.add() not working.

    - by Vincent
    I have the following C# Class/Function: class Hand { private List<Card> myCards = new List<Card>(); public void sortBySuitValue() { IEnumerable<Card> query = from s in myCards orderby (int)s.suit, (int)s.value select s; myCards = new List<Card>(); myCards.AddRange(query); } } On a card Game. This works fine, however, I had trouble at first, instead of using myCards = new List(); to 'reset' myCards, I would use myCards.clear(), however, once I called the clear function, I would not be able to call myCards.add() or myCards.addRange(). The count would stay at zero. Is my current approach good? Is using LINQ to sort my cards good/bad?

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  • Any Way to Use a Join in a Lambda Where() on a Table<>?

    - by lush
    I'm in my first couple of days using Linq in C#, and I'm curious to know if there is a more concise way of writing the following. MyEntities db = new MyEntities(ConnString); var q = from a in db.TableA join b in db.TableB on a.SomeFieldID equals b.SomeFieldID where (a.UserID == CurrentUser && b.MyField == Convert.ToInt32(MyDropDownList.SelectedValue)) select new { a, b }; if(q.Any()) { //snip } I know that if I were to want to check the existence of a value in the field of a single table, I could just use the following: if(db.TableA.Where(u => u.UserID == CurrentUser).Any()) { //snip } But I'm curious to know if there is a way to do the lambda technique, but where it would satisfy the first technique's conditions across those two tables. Sorry for any mistakes or clarity, I'll edit as necessary. Thanks in advance.

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  • Check If Stored Procedure Returns Value

    - by Eric
    Hello all, I am using Linq 2 Sql in VS 2010, and I have the following stored procedure to check a username and password ALTER PROCEDURE dbo.CheckUser ( @username varchar(50), @password varchar(50) ) AS SELECT * FROM Users Where UserName=@username AND Password=@password The problem I'm having is that it throws an exception if the username and password are incorrect. I'd like to perform a check to see if there is a return value, rather than using try/catch to determine whether the procedure returned a value. Should I do this check in code (C#)? Or is there a way to do it in SQL? Thanks.

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  • Why does do this code do if(sz !=sz2) sz = sz2 !?!

    - by acidzombie24
    For the first time i created a linq to sql classes. I decided to look at the class and found this. What... why is it doing if(sz !=sz2) { sz = sz2; }. I dont understand. Why isnt the set generated as this._Property1 = value? private string _Property1; [Column(Storage="_Property1", CanBeNull=false)] public string Property1 { get { return this._Property1; } set { if ((this._Property1 != value)) { this._Property1 = value; } } }

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  • How can I support objects larger than a single tile in a 2D tile engine?

    - by Yheeky
    I´m currently working on a 2D Engine containing an isometric tile map. It´s running quite well but I'm not sure if I´ve chosen the best approach for that kind of engine. To give you an idea what I´m thinking about right now, let's have a look at a basic object for a tile map and its objects: public class TileMap { public List<MapRow> Rows = new List<MapRow>(); public int MapWidth = 50; public int MapHeight = 50; } public class MapRow { public List<MapCell> Columns = new List<MapCell>(); } public class MapCell { public int TileID { get; set; } } Having those objects it's just possible to assign a tile to a single MapCell. What I want my engine to support is like having groups of MapCells since I would like to add objects to my tile map (e.g. a house with a size of 2x2 tiles). How should I do that? Should I edit my MapCell object that it may has a reference to other related tiles and how can I find an object while clicking on single MapCells? Or should I do another approach using a global container with all objects in it?

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  • How to store a list of Objects that might change in future?

    - by Amogh Talpallikar
    I have set of Objects of the same class which have different values of their attributes. and I need to find the best match from a function under given scenarios out of these objects. In future these objects might increase as well. Quite similar to the way we have Color class in awt. we have some static color objects in the class with diff rgb values. But in my case say, I need to chose the suitable color out of these static ones based on certain criteria. So should I keep them in an arrayList or enum or keep them as static vars as in case of Colors. because I will need to parse through all of them and decide upon the best match. so I need them in some sort of collection. But in future if I need to add another type I will have to modify the class and add another list.add(object) call for this one and then it will violate the open-close principle. How should I go about it ?

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  • How would you model an objects representing different phases of an entity life cycle?

    - by Ophir Yoktan
    I believe the scenario is common mostly in business workflows - for example: loan management the process starts with a loan application, then there's the loan offer, the 'live' loan, and maybe also finished loans. all these objects are related, and share many fields all these objects have also many fields that are unique for each entity the variety of objects maybe large, and the transformation between the may not be linear (for example: a single loan application may end up as several loans of different types) How would you model this? some options: an entity for each type, each containing the relevant fields (possibly grouping related fields as sub entities) - leads to duplication of data. an entity for each object, but instead of duplicating data, each object has a reference to it's predecessor (the loan doesn't contain the loaner details, but a reference to the loan application) - this causes coupling between the object structure, and the way it was created. if we change the loan application, it shouldn't effect the structure of the loan entity. one large entity, with fields for the whole life cycle - this can create 'mega objects' with many fields. it also doesn't work well when there's a one to many or many to many relation between the phases.

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  • ReSharper 5.0s LINQ Refactoring Continues to be Amazing!

    In this post, well take a straight forward procedure based set of code and convert it to LINQ using a ReSharper from JetBrains suggestion.   Ive found that in general, when I do things with foreach syntax, there is often a better way in Linq to do this.  The better does not jump out [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Fin de LINQ to HPC : Microsoft abandonne sa plateforme de traitement de gros volumes de données pour son concurrent Hadoop

    Fin de LINQ to HPC : Microsoft abandonne sa plateforme de traitement de gros volumes de données pour se concentrer sur le support de son concurrent Hadoop Microsoft abandonne LINQ to HPC (High performance computing), nom de code Dryad, sa propre plateforme haute performance pour des calculs distribués et la gestion intensive des données, pour se concentrer sur le support de son concurrent Hadoop dans ses produits. L'éditeur avait récemment manifesté son intérêt pour la plateforme Java de stockage et de traitement par lot de très grandes quantités de données (Big Data) Hadoop, en publiant notamment deux connecteurs

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  • NHibernate: QueryOver<> help

    - by Andy Baker
    Hi, I'm just starting out with NHibernate and I'm having trouble with running more complex queries. I have entities with a list of tags attached. The user will provide two lists of tags, include and exclude. I need to find all the entities that have all of the include tags, and exclude any entites that have any tag in the exclude list. Below is my first effort- which is clearly wrong as its listing all Display objects that have any of the include tags rather than all! Any assistance is greatly appeciated. var includeTagIds = (from tag in regime.IncludeTags select tag.Id).ToList<int>(); var excludeTagIds = from tag in regime.ExcludeTags select tag.Id; var displays = session.QueryOver<Display>() .JoinQueryOver<DisplayTag>(display => display.Tags) .WhereRestrictionOn(tag => tag.Id) .IsIn(includeTagIds).List().Distinct(); return displays.ToList();

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  • Language-agnostic term for typed things that need memory

    - by FredOverflow
    Is there an accepted general term that subsumes the concepts of variables, class instances and arrays? Basically "any typed thing that needs memory". In C++, such a thing is called an object, but I'm looking for a more language-agnostic term. § 1.8 The C++ object model 1 The constructs in a C++ program create, destroy, refer to, access, and manipulate objects. An object is a region of storage. [...] An object can have a name (Clause 3). An object has a storage duration (3.7) which influences its lifetime (3.8). An object has a type (3.9).

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  • Benchmark Linq2SQL, Subsonic2, Subsonic3 - Any other ideas to make them faster ?

    - by Aristos
    I am working with Subsonic 2 more than 3 years now... After Linq appears and then Subsonic 3, I start thinking about moving to the new Linq futures that are connected to sql. I must say that I start move and port my subsonic 2 with SubSonic 3, and very soon I discover that the speed was so slow thats I didn't believe it - and starts all that tests. Then I test Linq2Sql and see also a delay - compare it with Subsonic 2. My question here is, especial for the linq2sql, and the up-coming dotnet version 4, what else can I do to speed it up ? What else on linq2sql settings, or classes, not on this code that I have used for my messures I place here the project that I make the tests, also the screen shots of the results. How I make the tests - and the accurate of my measures. I use only for my question Google chrome, because its difficult for me to show here a lot of other measures that I have done with more complex programs. This is the most simple one, I just measure the Data Read. How can I prove that. I make a simple Thread.Sleep(10 seconds) and see if I see that 10 seconds on Google Chrome Measure, and yes I see it. here are more test with this Sleep thead to see whats actually Chrome gives. 10 seconds delay 100 ms delay Zero delay There is only a small 15ms thats get on messure, is so small compare it with the rest of my tests that I do not care about. So what I measure I measure just the data read via each method - did not count the data or database delay, or any disk read or anything like that. Later on the image with the result I show that no disk activity exist on the measures See this image to see what really I measure and if this is correct Why I chose this kind of test Its simple, it's real, and it's near my real problem that I found the delay of subsonic 3 in real program with real data. Now lets tests the dals Start by see this image I have 4-5 calls on every method, the one after the other. The results are. For a loop of 100 times, ask for 5 Rows, one not exist, approximatively.. Simple adonet:81ms SubSonic 2 :210ms linq2sql :1.70sec linq2sql using CompiledQuery.Compile :239ms Subsonic 3 :15.00sec (wow - extreme slow) The project http://www.planethost.gr/DalSpeedTests.rar Can any one confirm this benchmark, or make any optimizations to help me out ? Other tests Some one publish here this link http://ormbattle.net/ (and then remove it - don not know why) In this page you can find a really useful advanced tests for all, except subsonic 2 and subsonic 3 that I have here ! Optimizing What I really ask here is if some one can now any trick how to optimize the DALs, not by changing the test code, but by changing the code and the settings on each dal. For example... Optimizing Linq2SQL I start search how to optimize Linq2sql and found this article, and maybe more exist. Finally I make the tricks from that page to run, and optimize the code using them all. The speed was near 1.50sec from 1.70.... big improvement, but still slow. Then I found a different way - same idea article, and wow ! the speed is blow up. Using this trick with CompiledQuery.Compile, the time from 1.5sec is now 239ms. Here is the code for the precompiled... Func<DataClassesDataContext, int, IQueryable<Product>> compiledQuery = CompiledQuery.Compile((DataClassesDataContext meta, int IdToFind) => (from myData in meta.Products where myData.ProductID.Equals(IdToFind) select myData)); StringBuilder Test = new StringBuilder(); int[] MiaSeira = { 5, 6, 10, 100, 7 }; using (DataClassesDataContext context = new DataClassesDataContext()) { context.ObjectTrackingEnabled = false; for (int i = 0; i < 100; i++) { foreach (int EnaID in MiaSeira) { var oFindThat2P = compiledQuery(context, EnaID); foreach (Product One in oFindThat2P) { Test.Append("<br />"); Test.Append(One.ProductName); } } } } Optimizing SubSonic 3 and problems I make many performance profiling, and start change the one after the other and the speed is better but still too slow. I post them on subsonic group but they ignore the problem, they say that everything is fast... Here is some capture of my profiling and delay points inside subsonic source code I have end up that subsonic3 make more call on the structure of the database rather than on data itself. Needs to reconsider the hole way of asking for data, and follow the subsonic2 idea if this is possible. Try to make precompile to subsonic 3 like I did in linq2Sql but fail for the moment... Optimizing SubSonic 2 After I discover that subsonic 3 is extreme slow, I start my checks on subsonic 2 - that I have never done before believing that is fast. (and it is) So its come up with some points that can be faster. For example there are many loops like this ones that actually is slow because of string manipulation and compares inside the loop. I must say to you that this code called million of times ! on a period of few minutes ! of data asking from the program. On small amount of tables and small fields maybe this is not a big think for some people, but on large amount of tables, the delay is even more. So I decide and optimize the subsonic 2 by my self, by replacing the string compares, with number compares! Simple. I do that almost on every point that profiler say that is slow. I change also all small points that can be even a little faster, and disable some not so used thinks. The results, 5% faster on NorthWind database, near 20% faster on my database with 250 tables. That is count with 500ms less in 10 seconds process on northwind, 100ms faster on my database on 500ms process time. I do not have captures to show you for that because I have made them with different code, different time, and track them down on paper. Anyway this is my story and my question on all that, what else do you know to make them even faster... For this measures I have use Subsonic 2.2 optimized by me, Subsonic 3.0.0.3 a little optimized by me, and Dot.Net 3.5

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