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  • Keeping Linq to SQL alive when using ViewModels (ASP.NET MVC)

    - by Kohan
    I have recently started using custom ViewModels (For example, CustomerViewModel) public class CustomerViewModel { public IList<Customer> Customers{ get; set; } public int ProductId{ get; set; } public CustomerViewModel(IList<Customer> customers, int productId) { this.Customers= customers; this.ProductId= productId; } public CustomerViewModel() { } } ... and am now passing them to my view instead of the Entities themselves (for example, var Custs = repository.getAllCusts(id) ) as it seems good practice to do so. The problem i have encountered is that when using ViewModels; by the time it has got to the the view i have lost the ability to lazy load on customers. I do not believe this was the case before using them. Is it possible to retain the ability of Lazy Loading while still using ViewModels? Or do i have to eager load using this method? Thanks, Kohan.

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  • What is the return type of my linq query?

    - by Ulhas Tuscano
    I have two tables A & B. I can fire Linq queries & get required data for individual tables. As i know what each of the tables will return as shown in example. But, when i join both the tables i m not aware of the return type of the Linq query. This problem can be solved by creating a class which will hold ID,Name and Address properties inside it. but,everytime before writing a join query depending on the return type i will have to create a class which is not a convinient way Is there any other mathod available to achieve this private IList<A> GetA() { var query = from a in objA select a; return query.ToList(); } private IList<B> GetB() { var query = from b in objB select b; return query.ToList(); } private IList<**returnType**?> GetJoinAAndB() { var query = from a in objA join b in objB on a.ID equals b.AID select new { a.ID, a.Name, b.Address }; return query.ToList(); }

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  • Manual Linq to SQL entity framework mapping

    - by kprobst
    I've been playing with the O/R designer in VS and I was wondering if someone could shed come light on this. I'm used to OR mappers that are largely manual (homegrown and e.g., NHibernate). I don't mind encoding the entity classes myself, since they don't change all that often to begin with, and I have this irrational fear of designers and auto generated code as it is. I have noticed that the generated entity classes contain a lot of boilerplate extensibility methods, e.g. On[Property]Changed() and so on where [Property] is a mapped member of the class. These are placed in the setters of the property accessors. I assume it's OK if I don't include these when I do my hand coding, correct? They would be nice if I needed some sort of interception pattern but that's certainly not the case. I guess I just need to know if any of those methods are required by the entity framework to keep track of changes to the mapping types in order for things to work when updating the database. Thanks!

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  • For-Loop and LINQ's deferred execution don't play well together

    - by Tim Schmelter
    The title suggests that i've already an idea what's going on, but i cannot explain it. I've tried to order a List<string[]> dynamically by each "column", beginning with the first and ending with the minimum Length of all arrays. So in this sample it is 2, because the last string[] has only two elements: List<string[]> someValues = new List<string[]>(); someValues.Add(new[] { "c", "3", "b" }); someValues.Add(new[] { "a", "1", "d" }); someValues.Add(new[] { "d", "4", "a" }); someValues.Add(new[] { "b", "2" }); Now i've tried to order all by the first and second column. I could do it statically in this way: someValues = someValues .OrderBy(t => t[0]) .ThenBy(t => t[1]) .ToList(); But if i don't know the number of "columns" i could use this loop(that's what I thought): int minDim = someValues.Min(t => t.GetLength(0)); // 2 IOrderedEnumerable<string[]> orderedValues = someValues.OrderBy(t => t[0]); for (int i = 1; i < minDim; i++) { orderedValues = orderedValues.ThenBy(t => t[i]); } someValues = orderedValues.ToList(); // IndexOutOfRangeException But that doesn't work, it fails with an IndexOutOfRangeException at the last line. The debugger tells me that i is 2 at that time, so the for-loop condition seems to be ignored, i is already == minDim. Why is that so?

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  • Linq grouping question

    - by Mike C.
    I have the following objects in a collection: Transaction: Type = "Widget" Date = "3/1/2011" Name = "Foo" Transaction: Type = "Widget" Date = "3/4/2011" Name = "Bar" Transaction: Type = "Gadget" Date = "3/2/2011" Name = "Baz" Transaction: Type = "Gizmo" Date = "3/1/2011" Name = "Who" Transaction: Type = "Gizmo" Date = "3/2/2011" Name = "What" Transaction: Type = "Gizmo" Date = "3/6/2011" Name = "When" I want to end up with the following, grouped by Type. If there are multiple, return only the first one chronologically by date. Transaction: Type = "Widget" Date = "3/1/2011" Name = "Foo" Transaction: Type = "Gadget" Date = "3/2/2011" Name = "Baz" Transaction: Type = "Gizmo" Date = "3/1/2011" Name = "Who"

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  • Linq to Sql query reuse

    - by UserControl
    Let's say we have a view V1 and V2 that is declared like: create view V2 as select V1.*, V2.C1, V2.C2, V2.C3 from V1 join V2 on V1.Key = V2.Key where bla-bla So V2 narrows down the result set of V1 and adds some joins. And there is a retrieval routine in C# IEnumerable<V1> GetData(MyFilter filter, MySortOrder order) {} I want to reuse with V2. Is it possible without performing joins in L2S rather than in database? Should i manually create a base class in the database context or something?

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  • Forcing LINQ to SQL to make one single call for all child rows

    - by zaph0d
    Let say I have a method (example taken from another post): public IQueryable<CityBlock> GetCityBlocks(){ var results = from o in db.city_blocks let buildings = GetBuildingsOnBlock(o.block_id) //returns Iqueryable select new CityBlock { BuildingsOnBlock = buildings, BlockOwner = o.block_owner }; return results; } In the calling method I add Skip() and Take() methods plus some filtering and then do a ToList(). The trouble is that I am getting dozens of database calls - one for all the city blocks and then a separate one for each building. Is there a way that I can refactor this code to just make two calls: one for the city blocks and one for all the buildings

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  • Linq Having Sum(Quantity) = x?

    - by molgan
    Hello I have a function that returns IQueryable, and I would like to add "HAVING SUM(Quantity) = X" to it, but I get error if I try like this: _rep.GetBookings().ByBookingObjectID(bookingObjectID).Sum(x => x.Quantity == somevariablehere); I cant seem to find functions for it to find by sum /M

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  • Is Linq Faster, Slower or the same?

    - by Vaccano
    Is this: Box boxToFind = AllBoxes.Where(box => box.BoxNumber == boxToMatchTo.BagNumber); Faster or slower than this: Box boxToFind ; foreach (Box box in AllBoxes) { if (box.BoxNumber == boxToMatchTo.BoxNumber) { boxToFind = box; } } Both give me the result I am looking for (boxToFind). This is going to run on a mobile device that I need to be performance conscientious of.

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  • C# Linq - Cannot implicitly convert IEnumerable<string> to List<string>

    - by JL
    I have a List defined like this : public List<string> AttachmentURLS; I am adding items to the list like this: instruction.AttachmentURLS = curItem.Attributes["ows_Attachments"].Value.Split(';').ToList().Where(Attachment => !String.IsNullOrEmpty(Attachment)); But I am getting this error: Cannot implicitly convert IEnumerable to List What am I doing wrong?

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  • Storing records in a dropdownlist from DB without using LINQ Data source

    - by user1318369
    I have a website for dance academy where Users can register and add/drop dance classes. In the web page to drop a particular dance, for a particular user, the dropdown displays her registered dances. Now I want to delete one of the dances from the list. So i'll remove the row from the table and also from the dropdownlist. The problem is that everytime the item with the lowest ID (index) is getting deleted, no matter which one the user selects. I think I am storing the DataTextField and DataValueField for the dropdown incorrectly. Can someone please help me out? The code is: private void PopulateDanceDropDown() { var registereddanceList = from dd in context.DANCER_AND_DANCE where dd.UserId == dancerId select new { Text = dd.DanceName, Value = dd.DanceId }; dances.DataSource = registereddanceList; dances.DataTextField = "Text"; dances.DataValueField = "Value"; dances.DataBind(); } protected void dropthedance(object o, EventArgs e) { String strDataValueField = dances.SelectedItem.Value; int danceIDFromDropDown = Convert.ToInt32(strDataValueField); var dancer_dance = from dd in context.DANCER_AND_DANCE where dd.DanceId == danceIDFromDropDown select dd; foreach (var dndd in dancer_dance) { context.DANCER_AND_DANCE.DeleteOnSubmit(dndd); } try { context.SubmitChanges(); } catch (Exception ex) { Console.WriteLine(ex); } PopulateDanceDropDown(); }

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  • VB.NET and linQ: How to delete entries from a dictionary using the value

    - by user350233
    I have a dictionary collection as bleow: mydic.addvalue(key1, val1) mydic.addvalue(key2, val1) mydic.addvalue(key3, val1) mydic.addvalue(key4, val2) mydic.addvalue(key5, val2) From the above dictionary I want to delete all the entries where value == "val1", so that the result would have only following entry: mydic.addvalue(key4, val2) mydic.addvalue(key5, val2) My VB source code is on VS2008 and targeted for 3.5

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  • Grabbing Just The Top Entry From A LINQ Query

    - by Soo
    I basically have a lot of poorly designed code to do something that, I'm sure, can be done far more elegantly. What I'm trying to do is grab the last date from a database table. var Result = from a in DB.Table orderby a.Date descending select new {Date = a}; foreach(var Row in Result) { LastDate = Row.Date.Date; break; } Basically, there's a foreach loop that is designed to run only once. Crappy code! What's a "best practice" way to accomplish the same thing?

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  • Exploding a range of dates with LINQ

    - by Robert Gowland
    If I have a pair of dates, and I want to generate a list of all the dates between them (inclusive), I can do something like: System.DateTime s = new System.DateTime(2010, 06, 05); System.DateTime e = new System.DateTime(2010, 06, 09); var list = Enumerable.Range(0, (e - s).Days) .Select(value => s.AddDays(value)); What I'm stuck on is that I've got a list of pairs of dates that I want to explode into a list of all the dates between them. Example: {2010-05-06, 2010-05-09}, {2010-05-12, 2010-05-15} should result in {2010-05-06, 2010-05-07, 2010-05-08, 2010-05-09, 2010-05-12, 2010-05-13, 2010-05-14, 2010-05-15} Note the pairs of dates are guaranteed not to overlap each other.

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  • LINQ Expression help with Func TEntity,TType

    - by Chris Conway
    I have a repository method that accepts an order by parameter in the form: public IEnumerable<TEntity> Get<TEntity>(Expression<Func<TEntity,string>> orderBy) Now that works fine when trying to sort by a property of type string, var entities = rep.Get(x => x.Name); but what if i want to sort by double or int or any other type. Doing something like var entities = rep.Get(x => x.Price); obviously throws a compile error saying I can't convert double to string. How can I make this more generic so I can sort by any property in my entity, or at least the properties where the type implements IComparable or something similar?

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  • Linq Return node level of hierarchical xml

    - by Ryan
    In a treeview you can retrieve the level of an item. I am trying to accomplish the same thing with the given input being an object. The XML data I will use for this example would be something like the following <?xml version="1.0" encoding="utf-8" ?> <Testing> <Numbers> <Number val="1"> <Number val="1.1"> <Number val="1.1.1"> <Number val="1.1.2" /> <Number val="1.1.3" /> <Number val="1.1.4" /> </Number> </Number> <Number val="1.2" /> <Number val="1.3" /> <Number val="1.4" /> </Number> <Number val="2" /> <Number val="3" /> <Number val="4" /> </Numbers> <Numbers> <Number val="5" /> <Number val="6" /> <Number val="7" /> <Number val="8" /> </Numbers> </Testing> This one is kicking my butt!

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  • C# - LINQ Including headache...

    - by ebb
    Case can have many Replies and one User, Replies can have one Case and one User, One User can have many Replies and many Cases. ObjectSet <= Case Object (IDbSet) ObjectSet.Include(x => x.User).Include(x => x.Replies).FirstOrDefault(x => x.Id == caseId); But the User Object for each Reply are not included? Only the User object for Case is Included? How would I include the User objects for the Replies too? Thanks in advance!

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  • SQL and/or LINQ query for determining daily increases in viewers

    - by Gio
    We're montioring usage of a certain resources by monitoring users logins (We can see user logins growing daily). After filtering out repeat inter day logins for users, we'd like to track the # of users using the service each day, and then using that info to determine overall incremental gains for each calendar day. Our table is pretty simple: class ServiceLogin { String login; DateTime loginTime; }

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  • How do I switch the table that is queried with linq-to-sql

    - by Ian Ringrose
    We have two tables with the same set of columns; depending on the “type” of object the value is stored in one of the two tables. I wish to use common code to access these two tables. If I was using “raw sql” I could just use String.Format() to change the table name. (Likewise for updates etc) The two separate tables are needed as the data access patterns are very different for the common queries on the two tables and therefore different indexes are needed. “Views” and “instead of triggers” etc to make the tables look like a single table are not liked here. A lot of our customers use low end version of SqlServer so we cannot use partition tables.

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  • 'Random' Orderby in webservice using LINQ To Entities

    - by MrDean
    Morning all Now I know there is a reason to this odering but my tiny little brain can't get my head around it. I am using a webservice to pull through data to a webp[age and have the following that is so far pulling data through from UUF1: public string[] GetBuyer(string Memberkey) { try { WebService.EntitiesConnection buyer = new WebService.EntitiesConnection(); return buyer.tblProducts .Where(p => p.MemberId == Memberkey) .OrderBy(p => p.UnitUserfield1) .Select(p => p.UnitUserfield1) .Distinct() .ToArray(); } catch (Exception) { return null; } } This works fine and pulls the data through but in a strange order. Where I would expect results of A B C D E F, it appears to be returning A C E B D F. Could someone point out the error in my ways please?

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  • LINQ Query to filter DTO

    - by brabone
    I have an array...and I need to exclude all the items in this array of string from the masterList.customField as shown below string[] excludeItem = {"a","b","c"}; CustomDTO[] masterList = service.LoadMasterList(); masterList.Where(c=> masterList.customField NOT IN excludeItem How do I achieve the NOT IN part above?

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  • Linq.Where-to-SQL on a text field comparing to a list of values

    - by StampedeXV
    Customer.text is a field in an T-SQL DB (that I do not control and thus may not alter) of type "text". I'd like to do something like this: List<string> compare = new List<string>(); compare.Add("one"); compare.Add("two"); var q = from t in customer where t.text.Contains( compare.First()) select t; this will work. But now I'd like to do something like: (!NOT WORKING!) var q = from t in customer where compare.Contains( t.text ) select t; How can I achieve this? Is it even possible?

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  • EF 4 Query - Issue with Multiple Parameters

    - by Brian
    Hello, A trick to avoiding filtering by nullable parameters in SQL was something like the following: select * from customers where (@CustomerName is null or CustomerName = @CustomerName) This worked well for me in LINQ to SQL: string customerName = "XYZ"; var results = (from c in ctx.Customers where (customerName == null || (customerName != null && c.CustomerName == customerName)) select c); But that above query, when in ADO.NET EF, doesn't work for me; it should filter by customer name because it exists, but it doesn't. Instead, it's querying all the customer records. Now, this is a simplified example, because I have many fields that I'm utilizing this kind of logic with. But it never actually filters, queries all the records, and causes a timeout exception. But the wierd thing is another query does something similarly, with no issues. Any ideas why? Seems like a bug to me, or is there a workaround for this? I've since switched to extension methods which works. Thanks.

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  • LINQ to Entites: Doing a count over one-to-many relationships

    - by chris
    I have a couple of tables where there are one to many relationships. Let's say I have a Country table, a State table with a FK to Country, and a City table with a FK to State. I'd like to be able to create a count of all Cities for a given country, and also a count of cities based on a filter - something like: foreach( var country in Model.Country ) { total = country.State.All().City.All().Count() ; filtered = country.State.All().City.Any(c=>c.field == value).Count(); } Obviously, this doesn't work - is there any way to do this?

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  • Using LINQ, need help splitting a byte array on data received from Silverlight sockets

    - by gcadmes
    The message packats received contains multiple messages deliniated by a header=0xFD and a footer=0xFE // sample message packet with three // different size messages List<byte> receiveBuffer = new List<byte>(); receiveBuffer.AddRange(new byte[] { 0xFD, 1, 2, 0xFE, 0xFD, 1, 2, 3, 4, 5, 6, 7, 8, 0xFE, 0xFD, 33, 65, 25, 44, 0xFE}); // note: this sample code is without synchronization, // statements, error handling...etc. while (receiveBuffer.Count > 0) { var bytesInRange = receiveBuffer.TakeWhile(n => n != 0xFE); foreach (var n in bytesInRange) Console.WriteLine(n); // process message.. // 1) remove bytes read from receive buffer // 2) construct message object... // 3) etc... receiveBuffer.RemoveRange(0, bytesInRange.Count()); } As you can see, (including header/footer) the first message in this message packet contains 4 bytes, and the 2nd message contains 10 bytes,a and the 3rd message contains 6 bytes. In the while loop, I was expecting the TakeWhile to add the bytes that did not equal the footer part of the message. Note: Since I am removing the bytes after reading them, the header can always be expected to be at position '0'. I searched examples for splitting byte arrays, but non demonstrated splitting on arrays of unknown and fluctuating sizes. Any help will be greatly appreciated. thanks much!

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