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  • Linq-to-Entities Left JOIN

    - by shivesh
    This is my query: from forum in Forums join post in Posts on forum equals post.Forum into postGroup from p in postGroup where p.ParentPostID==0 select new { forum.Title, forum.ForumID, LastPostTitle = p.Title, LastPostAddedDate = p.AddedDate }).OrderBy(o=>o.ForumID) Currently the Join is not left join, meaning if some forum doesn't have a post that belongs to it, it will not be returned. The forum without posts must be returned with null (or default) values for the post properties.

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  • Linq DateTime expressions wont compare if only one is nullable

    - by tigermain
    I have been getting the following exception: The binary operator GreaterThanOrEqual is not defined for the types 'System.Nullable`1[System.DateTime]' and 'System.DateTime'. I am getting the left hand expression from a class property which is a nullable datetime variable and my right hand side is using Expression.Constant(new Nullable<DateTime>(DateTime.Now)) However I still get the above exception despite explicitly setting the right hand expression to a nullable type

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  • Select more then one node from XML using LINQ

    - by podeig
    I have such XML <root> <content> .... </content> <index> .... </index> <keywords> .... </keywords> </root> But I need to select just and nodes. <content> .... </content> <index> .... </index> I found out how to select just one node. XElement Content = new XElement("content", from el in xml.Elements() select el.Element("content").Elements()); How can I get both nodes?

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  • linq selecting into custom object

    - by user276640
    what is wrong with such code public List<SearchItem> Search(string find) { return (from i in _dataContext.News where i.Text.Contains(find) select new SearchItem { ControllerAction = "test", id = i.Id.ToString(), LinkText = "test" }).ToList(); } public struct SearchItem { public string ControllerAction; public string LinkText; public string id; }

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  • linq merge elements with orderby

    - by Sanja Melnichuk
    Hi all. I need to select all terminals sorted by Attributes[2] // get all query IQueryable<ITerminal> itt = repository.Terminals.GetQuery(); // get all with Attributes[2] IQueryable<ITerminal> itt2 = itt .Select(item => new { attrs = item.Attributes[2], term = item }) .OrderBy(x => x.attrs) .Select(x => x.term); Now how to select from itt all terminals but ordered by itt2 results? How to order them by itt2? Example: itt = c,d,r,a,w,b itt2 = a,b,c // after select and after merge: a,b,c d,r,w Thanks all

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  • How to use linq to find the minimum

    - by Danvil
    I have a class A { public float Score; ... } and a List<A> items and would like to find the A which has minimal score. Using items.Min(x => x.Score) gives the minimal score and not the instance with minimal score. How can I get the instance with only iterating once through my Collection?

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  • Searching with Linq

    - by Phil
    I have a collection of objects, each with an int Frame property. Given an int, I want to find the object in the collection that has the closest Frame. Here is what I'm doing so far: public static void Search(int frameNumber) { var differences = (from rec in _records select new { FrameDiff = Math.Abs(rec.Frame - frameNumber), Record = rec }).OrderBy(x => x.FrameDiff); var closestRecord = differences.FirstOrDefault().Record; //continue work... } This is great and everything, except there are 200,000 items in my collection and I call this method very frequently. Is there a relatively easy, more efficient way to do this?

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  • Hos to group the complex list objects by using Linq

    - by Daoming Yang
    I want to select and group the products, and rank them by the number of times they occur. For example, I have an OrderList each of order object has a OrderProductVariantList(OrderLineList), and each of OrderProductVariant object has ProductVariant, and then the ProductVariant object will have a Product object which contains product information. A friend helped me with the following code. It could be compiled, but it did not return any value/result. I used the watch window for the query and it gave me "The name 'query' does not exist in the current context". Can anyone help me? Many thanks. var query = orderList.SelectMany( o => o.OrderLineList ) // results in IEnumerable<OrderProductVariant> .Select( opv => opv.ProductVariant ) .Select( pv => p.Product ) .GroupBy( p => p ) .Select( g => new { Product = g.Key, Count = g.Count() });

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  • LINQ to SQL: On load processing of lazy loaded associations

    - by Matt Holmes
    If I have an object that lazy loads an association with very large objects, is there a way I can do processing at the time the lazy load occurs? I thought I could use AssociateWith or LoadWith from DataLoadOptions, but there are very, very specific restrictions on what you can do in those. Basically I need to be notified when an EntitySet< decides it's time to load the associated object, so I can catch that event and do some processing on the loaded object. I don't want to simply walk through the EntitySet when I load the parent object, because that will force all the lazy loaded items to load (defeating the purpose of lazy loading entirely).

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  • DB4o Linq query - How to check for null strings

    - by Dave
    Hey there - simple query: var q = (from SomeObject o in container where o.SomeInt > 8 && o.SomeString != null //Null Ref here select o; I always get a null reference exception. If I use String.IsNullOrEmpty(o.SomeString) the query takes about 100 times as long, as if I use && o.SomeString != "" (which is way faster, but obviously not correct). I'm guessing because DB4o needs to activate the objects, in order to pass them in to the IsNullOrEmpty call, and can't use the indexes. My question is, what's a better way to check for nulls in this situation? Is there something like: mystring != Db4o.DBNull.Value, or something? Cheers, Dave

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  • LINQ Query returns nothing.

    - by gtas
    Why is this query returns 0 lines? There is a record matching the arguments. Deafkaw.Where(p => (p.ImerominiaKataxorisis >= aDate && p.ImerominiaKataxorisis <= DateTime.Now) && (p.Year == etos && p.IsYpodeigma == false) ).ToList(); Am i missing something?

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  • LINQ query null reference exception

    - by user289082
    Hi! I have the next query: var bPermisos = from b in ruc.Permisos where b.IdUsuario == cu.Id select new Permisos(){ Id=b.Id, IdUsuario=b.Id, IdPerfil=b.Id, Estatus=b.Estatus }; var qSisPer = from perm in bPermisos select new { perm.IdPerfil,perm.Cat_Perfil.Nivel,perm.Cat_Perfil.Nombre,Nombre_Sistem=perm.Cat_Perfil.Cat_Sistema.Nombre}; And is throwing me an exception, plz help!

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  • LINQ to Sql: Insert instead of Update

    - by Christina Mayers
    I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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  • linq to sql loadwith vs associatewith

    - by stackoverflowuser
    what is the difference between loadwith and associatewith. From the articles i read it seems that loadwith is used to load addition data (eg all orders for the customers). While AssociateWith is used to filter data. Is that a correct understanding? Also it will be nice if someone can explain this with an example based explanation.

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  • linq multiple order DESCENDING

    - by ile
    .OrderBy(y => y.Year).ThenBy(m => m.Month); How to set descending order? EDIT: I tried this: var result = (from dn in db.DealNotes where dn.DealID == dealID group dn by new { month = dn.Date.Month, year = dn.Date.Year } into date orderby date.Key.year descending orderby date.Key.month descending select new DealNoteDateListView { DisplayDate = date.Key.month + "-" + date.Key.year, Month = date.Key.month, Year = date.Key.year, Count = date.Count() }) //.OrderBy(y => y.Year).ThenBy(m => m.Month) ; And it seems working. Is it wrong to use orderby twice like I used it here?

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  • LINQ to SQL: making a "double IN" query crashes

    - by Alex
    I need to do the following thing: var a = from c in DB.Customers where (from t1 in DB.Table1 where t1.Date >= DataTime.Now select t1.ID).Contains(c.ID) && (from t2 in DB.Table2 where t2.Date >= DataTime.Now select t2.ID).Contains(c.ID) select a It doesn't want to run. I get the following error: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. But when I try to run var a = from c in DB.Customers where (from t1 in DB.Table1 where t1.Date >= DataTime.Now select t1.ID).Contains(c.ID) select a OR var a = from c in DB.Customers where (from t2 in DB.Table2 where t2.Date = DataTime.Now select t2.ID).Contains(c.ID) select a It works! I'm sure that there both IN queries contain some customers ids.

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  • LINQ, Left Join, Only Get where null in join table

    - by kmehta
    Hi. I am trying to do a left outer join on two tables, but I only want to return the results from the first table where the second table does not have a record (null). var agencies = from a in agencyList join aa in joinTable on a.AgencyId equals aa.AgencyId into joined from aa in joined.DefaultIfEmpty() where aa == null) select a; But this does not exclude the non null values of aa, and returns all the records just the same as if the 'where aa == null' was not there. Any help is appreciated. Thanks.

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  • Can i use join with let in linq - c#

    - by uno
    let order= _relationContext.Orders .Where(x => x.OrderNumber == orderNo) .Select(x => new { x.OrderNo, x.OrderDate }).Single() I want to try and do something like this let order = _relationContext.Orders join _relationContext.Products .Where(x => x.OrderNumber == orderNo && x.ProductId == Products.ProductID) .Select(x => new { x.OrderNo, x.OrderDate }).Single() Is this even possible?

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  • Comparison operators not supported for type IList when Paging data in Linq to Sql

    - by Dan
    I can understand what the error is saying - it can't compare a list. Not a problem, other than the fact that I don't know how to not have it compare a list when I want to page through a model with a list as a property. My Model: Event : IEvent int Id string Title // Other stuff.. LazyList<EventDate> Dates // The "problem" property Method which pages the data (truncated): public JsonResult JsonEventList(int skip, int take) { var query = _eventService.GetEvents(); // Do some filtering, then page data.. query = query.Skip(skip).Take(take); return Json(query.ToArray()); } As I said, the above is truncated quite a bit, leaving only the main point of the function: filter, page and return JSON'd data. The exception occurs when I enumerate (.ToArray()). The Event object is really only used to list the common objects of all the event types (Meetings, Birthdays, etc - for example). It still implements IEvent like the other types, so I can't just remove the LazyList<EventDate> Dates' property unless I no longer implementIEvent` Anyway, is there a way to avoid this? I don't really want to compare a LazyList when I page, but I do not know how to resolve this issue. Thank you in advance! :)

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  • LINQ-TO-XML not returning all value

    - by mmcglynn
    I am trying to get all values in the select. using item.Count shows the correct number of values, but only one .Value is returned from the loop. Why? Dim fooXML As XDocument = XDocument.Load(Server.MapPath("xml/foo.xml")) Dim query = _ From c In fooXML...<foobaryear> _ Select c...<event> For Each item In query Response.Write(item.Value) Next

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  • Linq Scope Problem + Reduce Repeated Code

    - by Tom Gullen
    If the parameter is -1, it needs to run a different query as to if an ID was specified... how do I do this? I've tried initialising var q; outside the If block but no luck! // Loads by Entry ID, or if -1, by latest entry private void LoadEntryByID(int EntryID) { IEnumerable<tblBlogEntry> q; if (EntryID == -1) { q = ( from Blog in db.tblBlogEntries orderby Blog.date descending select new { Blog.ID, Blog.title, Blog.entry, Blog.date, Blog.userID, Comments = ( from BlogComments in db.tblBlogComments where BlogComments.blogID == Blog.ID select BlogComments).Count(), Username = ( from Users in db.yaf_Users where Users.UserID == Blog.userID select new { Users.DisplayName }) }).FirstOrDefault(); } else { q = ( from Blog in db.tblBlogEntries where Blog.ID == EntryID select new { Blog.ID, Blog.title, Blog.entry, Blog.date, Blog.userID, Comments = ( from BlogComments in db.tblBlogComments where BlogComments.blogID == Blog.ID select BlogComments).Count(), Username = ( from Users in db.yaf_Users where Users.UserID == Blog.userID select new { Users.DisplayName }) }).SingleOrDefault(); } if (q == null) { this.Loaded = false; } else { this.ID = q.ID; this.Title = q.title; this.Entry = q.entry; this.Date = (DateTime)q.date; this.UserID = (int)q.userID; this.Loaded = true; this.AuthorUsername = q.Username; } } My main aim is to reduce repeating code

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  • Parallelizing some LINQ to XML

    - by Lol coder
    How can I make this code run in parallel? List<Crop> crops = new List<Crop>(); //Get up to 10 pages of data. for (int i = 1; i < 10; i++) { //i is basically used for paging. XDocument document = XDocument.Load(string.Format(url, i)); crops.AddRange(from c in document.Descendants("CropType") select new Crop { //The data here. }); }

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  • LINQ Data Context Not Showing Methods

    - by CccTrash
    For some reason my DataContext is not showing all the normal methods like SubmitChanges() etc in the intellisense. It also won't compile if I type in db.SubmitChanges(); Any idea what I'm doing wrong? Normally I don't have this issue, I have several other projects that work fine... Image of what I'm talking about:

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  • SQL & Linq To SQL Help

    - by cre-johnny07
    I have a table which is some thing like below.. Date ID 2009-07-01 1 2009-07-01 2 2009-07-01 3 2009-08-01 4 2009-08-01 5 2009-08-01 6 2009-09-01 7 2009-09-01 8 2009-10-01 9 2009-10-01 10 2009-11-01 11 .... Now I need to write a query which will show a output like below. Date Start End 2009-07 1 3 2009-08 4 6 2009-09 7 8 ... How can I do this.. Any help would be highly appreciated Thanking In Advance Johnny

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  • Linq Aggregate function

    - by Nyla Pareska
    I have a List like "test", "bla", "something", "else" But when I use the Aggrate on it and in the mean time call a function it seems to me that after 2 'iterations' the result of the first gets passed in? I am using it like : myList.Aggregate((current, next) => someMethod(current) + ", "+ someMethod(next)); and while I put a breakpoint in the someMethod function where some transformation on the information in the myList occurs, I notice that after the 3rd call I get a result from a former transformation as input paramter.

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