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  • Problem with LINQ query

    - by Niels Bosma
    The following works fine: (from e in db.EnquiryAreas from w in db.WorkTypes where w.HumanId != null && w.SeoPriority > 0 && e.HumanId != null && e.SeoPriority > 0 && db.Enquiries.Where(f => f.WhereId == e.Id && f.WhatId == w.Id && f.EnquiryPublished != null && f.StatusId != EnquiryMethods.STATUS_INACTIVE && f.StatusId != EnquiryMethods.STATUS_REMOVED && f.StatusId != EnquiryMethods.STATUS_REJECTED && f.StatusId != EnquiryMethods.STATUS_ATTEND ).Any() select new { EnquiryArea = e, WorkType = w }); But: (from e in db.EnquiryAreas from w in db.WorkTypes where w.HumanId != null && w.SeoPriority > 0 && e.HumanId != null && e.SeoPriority > 0 && EnquiryMethods.BlockOnSite(db.Enquiries.Where(f => f.WhereId == e.Id && f.WhatId == w.Id)).Any() select new { EnquiryArea = e, WorkType = w }); + public static IQueryable<Enquiry> BlockOnSite(IQueryable<Enquiry> linq) { return linq.Where(e => e.EnquiryPublished != null && e.StatusId != STATUS_INACTIVE && e.StatusId != STATUS_REMOVED && e.StatusId != STATUS_REJECTED && e.StatusId != STATUS_ATTEND ); } I get the following error: base {System.SystemException}: {"Method 'System.Linq.IQueryable1[X.Enquiry] BlockOnSite(System.Linq.IQueryable1[X.Enquiry])' has no supported translation to SQL."}

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  • Advice on Linq to SQL mapping object design

    - by fearofawhackplanet
    I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

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  • LINQ to Entities for subtracting 2 dates

    - by Michael I
    I am trying to determine the number of days between 2 dates using LINQ with Entity Framework. It is telling me that it does not recognize Subtract on the System.TimeSpan class Here is my where portion of the LINQ query. where ((DateTime.Now.Subtract(vid.CreatedDate).TotalDays < maxAgeInDays)) Here is the error I receive in the VS.NET debugger {"LINQ to Entities does not recognize the method 'System.TimeSpan Subtract(System.DateTime)' method, and this method cannot be translated into a store expression."} Am I doing something wrong or is there a better way to get the number of days between 2 DateTimes in the entity framework? thanks Michael

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  • C# LINQ Oracle date Functions

    - by user1079925
    I am trying to generate a sql statement to be used in Oracle11g, using linq. The problem arises when using dates: The SQL generated by linq gives SELECT * FROM <table> WHERE start_date > '24/11/2012 00:00:00' and end_date < '28/11/2012 00:00:00' This causes an oracle error: ORA-01830 - date format picture ends before converting entire input string Adding TO_DATE to the query fixes the ORA-01830, as it is converting the string to a oracle date whilst now knowing the date format. SELECT * FROM <table> WHERE start_date > TO_DATE('24/11/2012 00:00:00','DD/MM/YYYY HH24:MI:SS') and end_date < TO_DATE('28/11/2012 00:00:00','DD/MM/YYYY HH24:MI:SS') So, is there a way to add TO_DATE to LINQ (for oracle)? If not, please tell me how to work around this issue. Thanks

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  • What is the leading LINQ for JavaScript library?

    - by Tom Tresansky
    I'm looking for a JavaScript library that will allow me to query complex JSON objects using a LINQ-like syntax. A quick search found a couple of promising options that look they might offer what I need: LINQ to JavaScript and jLinq Does any one have any experience using them? What are some pros and cons? Is the performance comparable? Does the function-passing syntax of LINQ to JavaScript offer any hidden benefits (I personally find the syntax of jLinq more appealing on first glance)? What have you found lacking in either project? Did you ever try contacting the authors? How responsive were they? What project is more widely used?

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  • Defaultifempty seems to work in linq to entities

    - by Rand
    I'm new to linq and linq to entities so I might have gone wrong in my assumptions, but I've been unknowingly trying to use DefaultIfEmpty in L2E. For some reason if I turn the resultset into a List, the Defaultifempty() works I don't know if I've inadvertantly crossed over into Linq area. The code below works, can anyone tell me why? And if it does work great, then it'll be of help to other people. var results = (from u in rv.tbl_user .Include("tbl_pics") .Include("tbl_area") .Include("tbl_province") .ToList() where u.tbl_province.idtbl_Province == prov select new { u.firstName, u.cellNumber, u.tbl_area.Area, u.ID,u.tbl_province.Province_desc, pic = (from p3 in u.tbl_pics where p3.tbl_user.ID == u.ID select p3.pic_path).DefaultIfEmpty("defaultpic.jpg").First() }).ToList();

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  • LLBLGEN: Linq to LLBGEN don't work

    - by StreamT
    I want to make custom select from the database table using Linq. We use LLBGEN as ORM solution. I can't do LINQ query to Entities Collection Class unless I call GetMulti(null) method of it. Is it possible to do LINQ query to LLBGEN without extracting all table first? BatchCollection batches = new BatchCollection(); BatchEntity batch = batches.AsQueryable() .Where(i => i.RegisterID == 3) .FirstOrDefault(); // Exception: Sequence don't contains any elements batches = new BatchCollection(); batches.GetMulti(null); // I don't want to extract the whole table. BatchEntity batch = batches.AsQueryable() .Where(i => i.RegisterID == 3) .FirstOrDefault(); //Works fine

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  • Teaching coworkers LINQ...

    - by cyberzed
    I have set myself upon a journey to educate my coworkers (all have accepted my mission, even the boss). Every day I seem to find a piece of code that could have been less error prone if my coworkers knew more about the framework, better-know-framework (in courtesy of DNR ;)) is part two of my teaching process. First part is teaching my coworkers about LINQ, what it can do for them and how it is written. My big question is where are all the good basic resources for LINQ education, everything if find is tightly coupled to Linq2Sql or all other sorts of material. Neither have I been able to find a tutorial for the actual linq syntax (except a specification of it all). (I hope this haven't been asked before but if it has please say so, cause then my searching skills have failed ;) )

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  • Linq to Entities and LEFT OUTER JOIN issue with MANY:1 relations

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer join instead of inner join? Because there's referential constraint on DB itself that ensures there's a record in the right table, so inner join should be used instead (and it would work much faster) If relation was many to 0..1 left outer join would be correct. Question Is it possible to write LINQ in a way so it will translate to inner join rather than left outer join. It would speed query execution a lot... I haven't used eSQL before, but would it be wise to use it in instead of LINQ? Edit I updated my tags to include technology I'm using in the background: Entity Framework V1 Devart dotConnect for Mysql MySql database If someone could test if the same is true on Microsoft SQL server it would also give me some insight if this is Devart's issue or it's a general L2EF functionality... But I suspect EF is the culprit here.

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  • Converting "is null" into a linq to sql statement

    - by Darryl Braaten
    I am having trouble replicating the following sql as a LINQ statement select TableA.* from TableA left outer join TableAinTableB on TableA.Id = TableAId where TableBId is null The following returns no lines from TableA in db.TableA join AinB in db.TableAinTableB on TableA.Id equals TableAId where AinB.TableBId == null select TableA Also tried and a few other things that didn't work. from TableA in db.TableA join AinB in db.TableAinTableB on TableA.Id equals TableAId where AinB == null select TableA TableAinTableB is a many to many table. The query I want will pull all the records from TableA that have no records in the middle table. My sql does what I want but I have no idea how to convert it to LINQ to SQL. I ended up working around it by just doing a db.ExecuteQuery("working sql"); But I would like to know if the query is possible in LINQ and how to write it, or a pointer to a document that covers this scenario. My searching did not uncover anything I found useful.

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  • Unit Testing, IDataContext and Stored Procedures via Linq

    - by Terry_Brown
    hey folks, I'm currently using Stephen Walther's approach to unit testing Linq to SQL and the datacontext (http://stephenwalther.com/blog/archive/2008/08/17/asp-net-mvc-tip-33-unit-test-linq-to-sql.aspx) which is working a treat for all things linq. My Dal layer takes in an IDataContext, I use DI (via Unity) to concrete that up as the correct DataContext object and all works well. But - we have a company policy here of writes going via Stored Procs. Has anyone come up with a solution for mocking/faking the data context and still allowing stored procs to effectively be unit tested? I've got no real experience of any of the mocking frameworks (Rhino etc.) so if these are the correct means of doing this, I'd love some pointers on guides for them. Many thanks, Terry

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  • Easiest way to retrofit retry logic on LINQ to SQL migration to SQL Azure

    - by Pat James
    I have a couple of existing ASP .NET web forms and MVC applications that currently use LINQ to SQL with a SQL Server 2008 Express database on a Windows VPS: one VPS for both IIS and SQL. I am starting to outgrow the VPS's ability to effectively host both SQL and IIS and am getting ready to split them up. I am considering migrating the database to SQL Azure and keeping IIS on the VPS. After doing initial research it sounds like implementing retry logic in the data access layer is a must-do when adopting SQL Azure. I suspect this is even more critical to implement in my situation where IIS will be on a VPS outside of the Azure infrastructure. I am looking for pointers on how to do this with the least effort and impact on my existing code base. Is there a good retry pattern that can be applied once at the LINQ to SQL data access layer, as opposed to having to wrap all of my LINQ to SQL operations in try/catch/wait/retry logic?

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  • Linq to sql Error "Data at the root level is invalid " for nullable xml column

    - by Mukesh
    I have Created a table like CREATE TABLE [dbo].[tab1]( [Id] [int] NOT NULL, [Name] [varchar](100) NOT NULL, [Meta] [xml] NULL, CONSTRAINT [PK_tab1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] When I am doing linq to sql query to fetch a data it throw an error "data at the root level is invalid linq". In further investigation I come to know that the meta column is null in that case. In real it is nullable Do I have to remove the nullable and set some blank root node as default or there is some another way to get rid of the error. My linq Query which throws error var obj1= (from obj in dbContext.tab1s where obj.id== 123 select obj).FirstOrDefault<Tab1>();

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  • Linq and Lamba Expressions - while walking a selected list perform an action

    - by Prescott
    Hey, I'm very new to linq and lamba expressions. I'm trying to walk a collection, and when I find an item that meets some criteria I'd like to add that to another separate collection. My linq to walk the collection looks like this (this works fine): From i as MyCustomItem In MyCustomItemCollection Where i.Type = "SomeType" Select i I need each of the select items to then be added to a ListItemCollection, I know I can assign that linq query to a variable, and then do a for each loop adding a new ListItem to the collection, but I'm trying o find a way to add each item to the new ListItemcollection while walking, not a second loop. Thanks ~P

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  • LINQ to SQL Web Application Best Practices

    - by derek
    In my experience building web applications, I've always used a n-tier approach. A DAL that gets data from the db and populates the objects, and BLL that gets objects from the DAL and performs any business logic required on them, and the website that gets it's display data from the BLL. I've recently started learning LINQ, and most of the examples show the queries occurring right from the Web Application code-behinds(it's possible that I've only seen overly simplified examples). In the n-tier architectures, this was always seen as a big no-no. I'm a bit unsure of how to architect a new Web Application. I've been using the Server Explorer and dbml designer in VS2008 to create the dbml and object relationships. It seems a little unclear to me if the dbml would be considered the DAL layer, if the website should call methods within a BLL, which then would do the LINQ queries, etc. What are some general architecture best practices, or approaches to creating a Web Application solution using LINQ to SQL?

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  • ASP.NET MVC 3 Linq uppercase or lowercase database search

    - by user1495557
    I need immediate help. ): and i know little english. ASP.NET MVC 3 Linq uppercase or lowercase contains search Example: string metin="baris"; var IcerikAra = (from icerik in Context.dbDokumanEditor join kategori in Context.dbDokumanKategori on icerik.KategoriID equals kategori.KategoriID where icerik.Icerik.toLower().Contains(metin) select new { KategoriID=kategori. KategoriAd=kategori.KategoriAd }).ToList(); Exception: StackTrace: at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommandentityCommand, CommandBehavior behavior) at System.Data.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues) at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator() at System.Data.Entity.Internal.Linq.InternalQuery`1.GetEnumerator() at System.Data.Entity.Infrastructure.DbQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator() at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) at Plus.Areas.DokumanEditor.Controllers.DokumanController.DokumanIcerikAramaBaslat(String metin) Error Message: An error occurred while executing the command definition. See the inner exception for details. thanks..

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  • SImplifying with LINQ - Basic selection

    - by baron
    Hello foreach (var person in peopleList.Where(person => person.FirstName == "Messi")) { selectPeople.Add(person); } I am just wondering if there is any way to simplify this using LINQ. Like rather than look at all the people I was trying to use LINQ to just fill a list with the "Messi"'s... was trying something like... var selectPeople = peopleList.Select(x=>x.FirstName=="Messi"); Then I could just add everyone in that list without a check. But it doesn't quite work as planned. Maybe there's no point simplifying that expression. But the question seemed worthwhile just to strengthen my LINQ knowledge.

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  • LINQ DataLoadOptions - Retrieval of data via Fulltext/Broken Foreign Key Relationship

    - by Alex
    I've hit a brick wall: I have an SQL Function: FUNCTION [dbo].[ContactsFTS] (@searchtext nvarchar(4000)) RETURNS TABLE AS RETURN SELECT * FROM Contacts INNER JOIN CONTAINSTABLE(Contacts, *, @searchtext) AS KEY_TBL ON Contacts.Id = KEY_TBL.[KEY] which I am calling via LINQ public IQueryable<ContactsFTSResult> SearchByFullText(String searchText) { return db.ContactsFTS(searchText); } I am projecting the ContactsFTSResult collection into a List<Contact> which is then given to my viewmodel. Here is the problem: My Contacts table (and therefore the Contact object created via LINQ to SQL) has multiple FK relationships to other information, such as Contact.BillingAddressId is an FK to an Address.Id. That information is missing after I do the fulltext search (e.g. if I try to access Contact.BillingAddress it is null). Can I add this information somehow via DataLoadOptions? I tried LoadWith<Contact>(c => c.BillingAddress) but this doesn't work, I assume because of the fact that I'm calling the function instead of doing the whole query via LINQ.

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  • Performance concern when using LINQ "everywhere"?

    - by stiank81
    After upgrading to ReSharper5 it gives me even more useful tips on code improvements. One I see everywhere now is a tip to replace foreach-statements with LINQ queries. Take this example: private Ninja FindNinjaById(int ninjaId) { foreach (var ninja in Ninjas) { if (ninja.Id == ninjaId) return ninja; } return null; } This is suggested replaced with the following using LINQ: private Ninja FindNinjaById(int ninjaId) { return Ninjas.FirstOrDefault(ninja => ninja.Id == ninjaId); } This looks all fine, and I'm sure it's no problem regarding performance to replace this one foreach. But is it something I should do in general? Or might I run into performance problems with all these LINQ queries everywhere?

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  • Databinding multiple tables linq query to gridview?

    - by Curtis White
    My question is how can I display a linq query in a gridview that has data from multiple tables AND allow the user to edit some of the fields or delete the data from a single table? I'd like to do this with either a linqdatasource or a linq query. I'm aware I can set the e.Result to the query on the selecting event. I've also been able to build a custom databound control for displaying the linq relations (parent.child). However, I'm not sure how I can make this work with delete? I'm thinking I may need to handle the delete event with custom code.

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  • Linq to NHibernate using Queryable.Where predicate

    - by Groo
    I am querying an SQLite database using LINQ to NHibernate. Person is an entity containing an Id and a Name: public class Person { public Guid Id { get; private set; } public string Name { get; private set; } } Let's say my db table contains a single person whose name is "John". This test works as expected: var query = from item in session.Linq<Person>() where (item.Name == "Mike") select item; // no such entity should exist Assert.IsFalse(query.Any()); but this one fails: var query = from item in session.Linq<Person>() select item; query.Where(item => item.Name == "Mike"); // following line actually returns the // "John" entry Assert.IsFalse(query.Any()); What am I missing?

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  • LINQ query needs either ascending or descending in the same query

    - by Sir Psycho
    Is there anyway this code can be refactored? The only difference is the order by part. Idealy I'd like to use a delegate/lamda expression so the code is reusable but I don't know how to conditionally add and remove the query operators OrderBy and OrderByDescending var linq = new NorthwindDataContext(); var query1 = linq.Customers .Where(c => c.ContactName.StartsWith("a")) .SelectMany(cus=>cus.Orders) .OrderBy(ord => ord.OrderDate) .Select(ord => ord.CustomerID); var query2 = linq.Customers .Where(c => c.ContactName.StartsWith("a")) .SelectMany(cus => cus.Orders) .OrderByDescending(ord => ord.OrderDate) .Select(ord => ord.CustomerID);

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  • Linq ChangeConflictException (ASP.NET MVC) - occurs when submitting DataContext changes

    - by Alex
    System.Data.Linq.ChangeConflictException: 2 of X updates failed. at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) at PROJECT.Controllers.HomeController.ClickProc(Int32 id, String code, String n) This is what I get very often. This action is done thousands of times a day, and I get this exception about once every 5 seconds. From what I understand it happens when something changes in the database in the period between creating DataContext and updating it. Am I right? What's the problem here and how can I fix it?

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  • Inspection of Insert Statement When Using LINQ's SubmitChanges

    - by Code Sherpa
    Hi. I want to see what my insert statement would look like as if I was wiring up an text-based ADO.NET command. How do I do this? I have been following the below link: http://damieng.com/blog/2008/07/30/linq-to-sql-log-to-debug-window-file-memory-or-multiple-writers And have added the DebugTextWriter class to my project. So, now, in my code I have the following which doesn't really do anything and I don't think its right: using(WorkbookDataContext dc = _conn.GetContext()) { if(profile.ProfileId > 0) { dc.Profiles.Attach(profile, true); } else { dc.Profiles.InsertOnSubmit(profile); } dc.Log = new DebugTextWriter(); #if DEBUG dc.Log = new System.IO.StreamWriter("linq-to-sql.log") { AutoFlush = true }; #endif dc.SubmitChanges(); } Any ideas what I am doing wrong and/or how to inspect my LINQ insert statement correctly? Thanks

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  • Possible Performance Considerations using Linq to SQL Repositories

    - by Robert Harvey
    I have an ASP.NET MVC application that uses Linq to SQL repositories for all interactions with the database. To deal with data security, I do trimming to filter data to only those items to which the user has access. This occurs in several places: Data in list views Links in a menu bar A treeview on the left hand side containing links to content Role-based security A special security attribute, inheriting from AuthorizeAttribute, that implements content-based authorization on every controller method. Each of these places instantiates a repository, which opens a Linq to Sql DataContext and accesses the database. So, by my count, each request for a page access opens at least six separate Linq to SQL DataContexts. Should I be concerned about this from a performance perspective, and if so, what can be done to mitigate it?

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