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  • Entity Framework: How to bind related products

    - by Waheed
    I am using the following Linq query from p in Product.Include("ProductDetails.Colors") where p.ProductID.Equals(18) select p; And then using the result of this query to bind the GridView. The productDetails are bind to the grid fine, but the Colors are not bind. To bind colors i am using <%# Eval("Colors.CategoryName") %. Error is " Field or property with the name 'Colors.CategoryName' was not found on the selected data source." But in a loop i am getting this fine. foreach (ProductDetails proDet in pd.ProductDetails) { string bar = proDet.BarCode; string color = proDet.Colors.CategoryName; }

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  • grouping data from two dataset

    - by Garcia Julien
    hi, i've got a problem with dataset: I've got two dataset from two different server but they have the same columns. so it's like that: First DataSet : asset description make jobtype jan feb ... dec 0001 mine ik Acc 0 0 10 0002 yours ic Over 0 0 10 Second dataset : asset description make jobtype jan feb ... dec 0001 mine ik Acc 10 0 10 0002 yours ic Gen 0 0 0 But i would like to merge the 2 dataset into one like that: asset description make jobtype lhjan imjan lhfeb lhfeb ... lhdec imdec 0001 mine ik Acc 0 10 0 0 10 10 0002 yours ic Over 0 0 0 0 10 0 so all the data from one is combine with the second with the same asset and the same jobtype. I try linq but i can't arrive to make it like i want. I'm working on vb.net framework 3.5. could you help me? Julien

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  • 2 listbox to exchange value with DBML

    - by Garcia Julien
    Hi, i'have two Listbox. the think is i do the transfert like : click on field in the left listbox, hit "move right" button and it wll display in the right list box.' The other think it's the first Listbox is bind on Dataset and the second on Entity (Linq-to sql). So when i click on the move next i do that : Dim newSite As New List(Of vw_SiteList) For Each row As SitesDataset.FDDSTRow In SiteAdsListBox.SelectedItems newSite.Add(New vw_SiteList With { _ .SITECODE = row.DEST_COD, _ .SiteDisplay = row.SiteDisplay, _ .CREATEDBY = Environment.GetEnvironmentVariable("USERNAM"), _ .DATECREATED = Now _ }) Next JCDataContext.vw_SiteLists.InsertAllOnSubmit(NewSite) I would like to see now the new field in the right listbox but it isn't there because the field itr's not yet added in the database. How can i do that? Thanks Ju

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  • How to include associative table information and still retain strong typing

    - by mwright
    I am using LINQ to SQL to create strongly typed objects in my project. Let's say I have an object that is represented by a database table. This object has a "Current State" that is kept in an associative table. I would like to make a single db call where I pull back the two tables joined but am unsure how I should be populating that information into some sort of object to preserve strong typing within my model so that the view using the information can just consume the information from the objects. I looked into creating a view model for this but it doesn't seem to quite fit. Am I thinking about this in the wrong way? What information can I include to help clarify my problem? Other details that may or may not be important: It's an MVC project....

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  • Compiled Queries and "Parameters cannot be sequences"

    - by David B
    I thought that compiled queries would perform the same query translation as DataContext. Yet I'm getting a run-time error when I try to use a query with a .Contains method call. Where have I gone wrong? //private member which holds a compiled query. Func<DataAccess.DataClasses1DataContext, List<int>, List<DataAccess.TestRecord>> compiledFiftyRecordQuery = System.Data.Linq.CompiledQuery.Compile <DataAccess.DataClasses1DataContext, List<int>, List<DataAccess.TestRecord>> ((dc, ids) => dc.TestRecords.Where(tr => ids.Contains(tr.ID)).ToList()); //this method calls the compiled query. public void FiftyRecordCompiledQueryByID() { List<int> IDs = GetRandomInts(50); //System.NotSupportedException //{"Parameters cannot be sequences."} List<DataAccess.TestRecord> results = compiledFiftyRecordQuery (myContext, IDs); }

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  • Automatically generate buddy classes from model in C#

    - by JohnnyO
    I use Linq to Sql (although this is equally applicable in Entity Framework) for my models, and I'm finding myself creating buddy classes for my models all the time. I find this time consuming and repetitive. Is there an easy way to automatically generate these buddy classes based on the models? Perhaps a visual studio macro? An example of a buddy class that I'd like to create: [MetadataType(typeof(PersonMetadata))] public partial class Person { } public class PersonMetadata { public object Id { get; set; } public object FirstName { get; set; } } Thanks in advance.

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  • Can't get results from a IQueryable.

    - by StackPointer
    Hi! I have the following code in Linq to Entity: var policy= from pol in conn.Policy where pol.Product.DESCRIPTION=="someProduct" SELECT pol; Then, the table Policy, has some dependencies for a table called Entity. If I do this: foreach(Policy p in policy){ if(!p.Entity.IsLoaded) p.Entity.Load(); IEnumerable<Entity> entities= from ent in p.Entity Where ent.EntityType.DESCRIPTION=="SomeEntityType" select ent; Console.Writeline(entities.ElementAt(0).NAME); } It says, "Object not set to an instance", but if I do: foreach(Policy p in policy){ if(!p.Entity.IsLoaded) p.Entity.Load(); foreach(Entity et in p.Entity)Console.Write(et.NAME); } It works! Can anyone tell me why? Thank you, Best regards.

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  • LINQ2SQL: orderby note.hasChildren(), name ascending

    - by Peter Bridger
    I have a hierarchical data structure which I'm displaying in a webpage as a treeview. I want to data to be ordered to first show nodes ordered alphabetically which have no children, then under these nodes ordered alphabetically which have children. Currently I'm ordering all nodes in one group, which means nodes with children appear next to nodes with no children. I'm using a recursive method to build up the treeview, which has this LINQ code at it's heart: var filteredCategory = from c in category orderby c.Name ascending where c.ParentCategoryId == parentCategoryId && c.Active == true select c; So this is the orderby statement I want to enhance. Shown below is the database table structure: [dbo].[Category]( [CategoryId] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](100) NOT NULL, [Level] [tinyint] NOT NULL, [ParentCategoryId] [int] NOT NULL, [Selectable] [bit] NOT NULL CONSTRAINT [DF_Category_Selectable] DEFAULT ((1)), [Active] [bit] NOT NULL CONSTRAINT [DF_Category_Active] DEFAULT ((1))

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  • Entity Framework (4.0) how to exclude a related table.

    - by Kohan
    I have just updated to using EF 4.0 where before i was using Linq 2 SQL. I have a query: var UserList = this.repository.GetUsers(); return Json(UserList, JsonRequestBehavior.AllowGet); This was generating an error: "A circular reference was detected while serializing an object of type" This prompted this code which worked fine in L2S: var UserList = this.repository.GetUsers(); foreach (User u in UserList){ u.Subscriptions = null; } return Json(UserList, JsonRequestBehavior.AllowGet); How can i stop EF from looking into the Subscriptions table, i just want the Userlist, none of the related properties and the above example does not seem to work for this. Cheers, Kohan

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  • Query Execution Plan - When is the Where clause executed?

    - by Alex
    I have a query like this (created by LINQ): SELECT [t0].[Id], [t0].[CreationDate], [t0].[CreatorId] FROM [dbo].[DataFTS]('test', 100) AS [t0] WHERE [t0].[CreatorId] = 1 ORDER BY [t0].[RANK] DataFTS is a full-text search table valued function. The query execution plan looks like this: SELECT (0%) - Sort (23%) - Nested Loops (Inner Join) (1%) - Sort (Top N Sort) (25%) - Stream Aggregate (0%) - Stream Aggregate (0%) - Compute Scalar (0%) - Table Valued Function (FullTextMatch) (13%) | | - Clustered Index Seek (38%) Does this mean that the WHERE clause ([CreatorId] = 1) is executed prior to the TVF ( full text search) or after the full text search? Thank you.

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  • How to group a period of time into yearly periods ? (split timespan into yearly periods)

    - by user315648
    I have a range of two datetimes: DateTime start = new DateTime(2012,4,1); DateTime end = new DateTime(2016,7,1); And I wish to get all periods GROUPED BY YEAR between this period. Meaning the output has to be: 2012-04-01 - 2012-12-31 2013-01-01 - 2013-12-31 2014-01-01 - 2014-12-31 2015-01-01 - 2015-12-31 2016-01-01 - 2016-07-01 Preferably the output would be in IList<Tuple<DateTime,DateTime>> list. How would you do this ? Is there anyway to do this with LINQ somehow ? Oh and daylight saving time is not absolutely critical, but surely a bonus. Thanks!

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  • Google I/O 2010: Google TV Keynote - Push Android Apps From Web To TV

    Google I/O 2010: Google TV Keynote - Push Android Apps From Web To TV Due to licensing and permissions issues, we are unable to show the full Google TV demonstration from the Day 2 keynote at Google I/O. Until we are able to get these permissions, please check out these clips. For Google I/O session videos, presentations, developer interviews and more, go to: code.google.com/io From: GoogleDevelopers Views: 1 0 ratings Time: 02:09 More in Science & Technology

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  • Point in polygon OR point on polygon using LINQ

    - by wageoghe
    As noted in an earlier question, How to Zip enumerable with itself, I am working on some math algorithms based on lists of points. I am currently working on point in polygon. I have the code for how to do that and have found several good references here on SO, such as this link Hit test. So, I can figure out whether or not a point is in a polygon. As part of determining that, I want to determine if the point is actually on the polygon. This I can also do. If I can do all of that, what is my question you might ask? Can I do it efficiently using LINQ? I can already do something like the following (assuming a Pairwise extension method as described in my earlier question as well as in links to which my question/answers links, and assuming a Position type that has X and Y members). I have not tested much, so the lambda might not be 100% correct. Also, it does not take very small differences into account. public static PointInPolygonLocation PointInPolygon(IEnumerable<Position> pts, Position pt) { int numIntersections = pts.Pairwise( (p1, p2) => { if (p1.Y != p2.Y) { if ((p1.Y >= pt.Y && p2.Y < pt.Y) || (p1.Y < pt.Y && p2.Y >= pt.Y)) { if (p1.X < p1.X && p2.X < pt.X) { return 1; } if (p1.X < pt.X || p2.X < pt.X) { if (((pt.Y - p1.Y) * ((p1.X - p2.X) / (p1.Y - p2.Y)) * p1.X) < pt.X) { return 1; } } } } return 0; }).Sum(); if (numIntersections % 2 == 0) { return PointInPolygonLocation.Outside; } else { return PointInPolygonLocation.Inside; } } This function, PointInPolygon, takes the input Position, pt, iterates over the input sequence of position values, and uses the Jordan Curve method to determine how many times a ray extended from pt to the left intersects the polygon. The lambda expression will yield, into the "zipped" list, 1 for every segment that is crossed, and 0 for the rest. The sum of these values determines if pt is inside or outside of the polygon (odd == inside, even == outside). So far, so good. Now, for any consecutive pairs of position values in the sequence (i.e. in any execution of the lambda), we can also determine if pt is ON the segment p1, p2. If that is the case, we can stop the calculation because we have our answer. Ultimately, my question is this: Can I perform this calculation (maybe using Aggregate?) such that we will only iterate over the sequence no more than 1 time AND can we stop the iteration if we encounter a segment that pt is ON? In other words, if pt is ON the very first segment, there is no need to examine the rest of the segments because we have the answer. It might very well be that this operation (particularly the requirement/desire to possibly stop the iteration early) does not really lend itself well to the LINQ approach. It just occurred to me that maybe the lambda expression could yield a tuple, the intersection value (1 or 0 or maybe true or false) and the "on" value (true or false). Maybe then I could use TakeWhile(anontype.PointOnPolygon == false). If I Sum the tuples and if ON == 1, then the point is ON the polygon. Otherwise, the oddness or evenness of the sum of the other part of the tuple tells if the point is inside or outside.

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  • Grafting LINQ onto C# 2 library

    - by P Daddy
    I'm writing a data access layer. It will have C# 2 and C# 3 clients, so I'm compiling against the 2.0 framework. Although encouraging the use of stored procedures, I'm still trying to provide a fairly complete ability to perform ad-hoc queries. I have this working fairly well, already. For the convenience of C# 3 clients, I'm trying to provide as much compatibility with LINQ query syntax as I can. Jon Skeet noticed that LINQ query expressions are duck typed, so I don't have to have an IQueryable and IQueryProvider (or IEnumerable<T>) to use them. I just have to provide methods with the correct signatures. So I got Select, Where, OrderBy, OrderByDescending, ThenBy, and ThenByDescending working. Where I need help are with Join and GroupJoin. I've got them working, but only for one join. A brief compilable example of what I have is this: // .NET 2.0 doesn't define the Func<...> delegates, so let's define some workalikes delegate TResult FakeFunc<T, TResult>(T arg); delegate TResult FakeFunc<T1, T2, TResult>(T1 arg1, T2 arg2); abstract class Projection{ public static Condition operator==(Projection a, Projection b){ return new EqualsCondition(a, b); } public static Condition operator!=(Projection a, Projection b){ throw new NotImplementedException(); } } class ColumnProjection : Projection{ readonly Table table; readonly string columnName; public ColumnProjection(Table table, string columnName){ this.table = table; this.columnName = columnName; } } abstract class Condition{} class EqualsCondition : Condition{ readonly Projection a; readonly Projection b; public EqualsCondition(Projection a, Projection b){ this.a = a; this.b = b; } } class TableView{ readonly Table table; readonly Projection[] projections; public TableView(Table table, Projection[] projections){ this.table = table; this.projections = projections; } } class Table{ public Projection this[string columnName]{ get{return new ColumnProjection(this, columnName);} } public TableView Select(params Projection[] projections){ return new TableView(this, projections); } public TableView Select(FakeFunc<Table, Projection[]> projections){ return new TableView(this, projections(this)); } public Table Join(Table other, Condition condition){ return new JoinedTable(this, other, condition); } public TableView Join(Table inner, FakeFunc<Table, Projection> outerKeySelector, FakeFunc<Table, Projection> innerKeySelector, FakeFunc<Table, Table, Projection[]> resultSelector){ Table join = new JoinedTable(this, inner, new EqualsCondition(outerKeySelector(this), innerKeySelector(inner))); return join.Select(resultSelector(this, inner)); } } class JoinedTable : Table{ readonly Table left; readonly Table right; readonly Condition condition; public JoinedTable(Table left, Table right, Condition condition){ this.left = left; this.right = right; this.condition = condition; } } This allows me to use a fairly decent syntax in C# 2: Table table1 = new Table(); Table table2 = new Table(); TableView result = table1 .Join(table2, table1["ID"] == table2["ID"]) .Select(table1["ID"], table2["Description"]); But an even nicer syntax in C# 3: TableView result = from t1 in table1 join t2 in table2 on t1["ID"] equals t2["ID"] select new[]{t1["ID"], t2["Description"]}; This works well and gives me identical results to the first case. The problem is if I want to join in a third table. TableView result = from t1 in table1 join t2 in table2 on t1["ID"] equals t2["ID"] join t3 in table3 on t1["ID"] equals t3["ID"] select new[]{t1["ID"], t2["Description"], t3["Foo"]}; Now I get an error (Cannot implicitly convert type 'AnonymousType#1' to 'Projection[]'), presumably because the second join is trying to join the third table to an anonymous type containing the first two tables. This anonymous type, of course, doesn't have a Join method. Any hints on how I can do this?

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  • Building an external list while filtering in LINQ

    - by Khnle
    I have an array of input strings that contains either email addresses or account names in the form of domain\account. I would like to build a List of string that contains only email addresses. If an element in the input array is of the form domain\account, I will perform a lookup in the dictionary. If the key is found in the dictionary, that value is the email address. If not found, that won't get added to the result list. The code below will makes the above description clear: private bool where(string input, Dictionary<string, string> dict) { if (input.Contains("@")) { return true; } else { try { string value = dict[input]; return true; } catch (KeyNotFoundException) { return false; } } } private string select(string input, Dictionary<string, string> dict) { if (input.Contains("@")) { return input; } else { try { string value = dict[input]; return value; } catch (KeyNotFoundException) { return null; } } } public void run() { Dictionary<string, string> dict = new Dictionary<string, string>() { { "gmail\\nameless", "[email protected]"} }; string[] s = { "[email protected]", "gmail\\nameless", "gmail\\unknown" }; var q = s.Where(p => where(p, dict)).Select(p => select(p, dict)); List<string> resultList = q.ToList<string>(); } While the above code works (hope I don't have any typo here), there are 2 problems that I do not like with the above: The code in where() and select() seems to be redundant/repeating. It takes 2 passes. The second pass converts from the query expression to List. So I would like to add to the List resultList directly in the where() method. It seems like I should be able to do so. Here's the code: private bool where(string input, Dictionary<string, string> dict, List<string> resultList) { if (input.Contains("@")) { resultList.Add(input); //note the difference from above return true; } else { try { string value = dict[input]; resultList.Add(value); //note the difference from above return true; } catch (KeyNotFoundException) { return false; } } } The my LINQ expression can be nicely in 1 single statement: List<string> resultList = new List<string>(); s.Where(p => where(p, dict, resultList)); Or var q = s.Where(p => where(p, dict, resultList)); //do nothing with q afterward Which seems like perfect and legal C# LINQ. The result: sometime it works and sometime it doesn't. So why doesn't my code work reliably and how can I make it do so?

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  • Parsing google feed with linq to xml

    - by the_V
    Hi I'm trying to parse XML feed that I get via Google Contacts API with LINQ 2 XML. That's what feed looks like: <feed xmlns="http://www.w3.org/2005/Atom" xmlns:openSearch="http://a9.com/-/spec/opensearchrss/1.0/" xmlns:gContact="http://schemas.google.com/contact/2008" xmlns:batch="http://schemas.google.com/gdata/batch" xmlns:gd="http://schemas.google.com/g/2005"> <id>[email protected]</id> <updated>2010-06-11T17:37:06.561Z</updated> <category scheme="http://schemas.google.com/g/2005#kind" term="http://schemas.google.com/contact/2008#contact" /> <title type="text">My Contacts</title> <link rel="alternate" type="text/html" href="http://www.google.com/" /> <link rel="http://schemas.google.com/g/2005#feed" type="application/atom+xml" href="http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/full" /> <link rel="http://schemas.google.com/g/2005#post" type="application/atom+xml" href="http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/full" /> <link rel="http://schemas.google.com/g/2005#batch" type="application/atom+xml" href="http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/full/batch" /> <link rel="self" type="application/atom+xml" href="http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/full?max-results=25" /> <author> <name>My NAme</name> <email>[email protected]</email> </author> <generator version="1.0" uri="http://www.google.com/m8/feeds">Contacts</generator> <openSearch:totalResults>19</openSearch:totalResults> <openSearch:startIndex>1</openSearch:startIndex> <openSearch:itemsPerPage>25</openSearch:itemsPerPage> <entry> <id>http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/base/0</id> <updated>2010-01-26T20:34:03.802Z</updated> <category scheme="http://schemas.google.com/g/2005#kind" term="http://schemas.google.com/contact/2008#contact" /> <title type="text">Contact name</title> <link rel="http://schemas.google.com/contacts/2008/rel#edit-photo" type="image/*" href="http://www.google.com/m8/feeds/photos/media/myemailaddress%40gmail.com/0/O-ydnzWMJcfZWqT-6gGetw" /> <link rel="http://schemas.google.com/contacts/2008/rel#photo" type="image/*" href="http://www.google.com/m8/feeds/photos/media/myemailaddress%40gmail.com/0" /> <link rel="self" type="application/atom+xml" href="http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/full/0" /> <link rel="edit" type="application/atom+xml" href="http://www.google.com/m8/feeds/contacts/myemailaddress%40gmail.com/full/0/1264538043802000" /> <gd:email rel="http://schemas.google.com/g/2005#other" address="[email protected]" primary="true" /> </entry> </feed> I've tried a number of things with linq 2 sql, but they didn't work. Even this simple code snipped doesn't work: using (FileStream stream = File.OpenRead("response.xml")) { XmlReader reader = XmlReader.Create(stream); XDocument doc = XDocument.Load(reader); XElement feed = doc.Element("feed"); if (feed == null) { Console.WriteLine("feed not found"); } XElement id = doc.Element("id"); if (id == null) { Console.WriteLine("id is null"); } } Problem is that both id and feed are null here. What wrong am I doing?

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  • Using LINQ to create a simple login

    - by JDWebs
    I'm an C# ASP.NET beginner, so please excuse anything that's... not quite right! In short, I want to create a really basic login system: one which runs through a database and uses sessions so that only logged in users can access certain pages. I know how to do most of that, but I'm stuck with querying data with LINQ on the login page. On the login page, I have a DropDownList to select a username, a Textbox to type in a password and a button to login (I also have a literal for errors). The DropDownList is databound to a datatable called DT_Test. DT_Test contains three columns: UsernameID (int), Username (nchar(30)) and Password (nchar(30)). UsernameID is the primary key. I want to make the button's click event query data from the database with the DropDownList and Textbox, in order to check if the username and password match. But I don't know how to do this... Current Code (not a lot!): Front End: <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login_Test.aspx.cs" Inherits="Login_Login_Test" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Login Test</title> </head> <body> <form id="LoginTest" runat="server"> <div> <asp:DropDownList ID="DDL_Username" runat="server" Height="20px" DataTextField="txt"> </asp:DropDownList> <br /> <asp:TextBox ID="TB_Password" runat="server" TextMode="Password"></asp:TextBox> <br /> <asp:Button ID="B_Login" runat="server" onclick="B_Login_Click" Text="Login" /> <br /> <asp:Literal ID="LI_Result" runat="server"></asp:Literal> </div> </form> </body> </html> Back End: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class Login_Login_Test : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { Binder(); } } private void Binder() { using (DataClassesDataContext db = new DataClassesDataContext()) { DDL_Username.DataSource = from x in db.DT_Honeys select new { x.UsernameID, txt = x.Username }; DDL_Username.DataBind(); } } protected void B_Login_Click(object sender, EventArgs e) { if (TB_Password.Text != "") { using (DataClassesDataContext db = new DataClassesDataContext()) { } } } } I have spent hours searching and trying different code, but none of it seems to fit in for this context. Anyway, help and tips appreciated, thank you very much! I am aware of security risks etc. but this is not a live website or anything, it is simply for testing purposes as a beginner. *

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  • Reconciling a new BindingList into a master BindingList using LINQ

    - by Neo
    I have a seemingly simple problem whereby I wish to reconcile two lists so that an 'old' master list is updated by a 'new' list containing updated elements. Elements are denoted by a key property. These are my requirements: All elements in either list that have the same key results in an assignment of that element from the 'new' list over the original element in the 'old' list only if any properties have changed. Any elements in the 'new' list that have keys not in the 'old' list will be added to the 'old' list. Any elements in the 'old' list that have keys not in the 'new' list will be removed from the 'old' list. I found an equivalent problem here - http://stackoverflow.com/questions/161432/ - but it hasn't really been answered properly. So, I came up with an algorithm to iterate through the old and new lists and perform the reconciliation as per the above. Before anyone asks why I'm not just replacing the old list object with the new list object in its entirety, it's for presentation purposes - this is a BindingList bound to a grid on a GUI and I need to prevent refresh artifacts such as blinking, scrollbars moving, etc. So the list object must remain the same, only its updated elements changed. Another thing to note is that the objects in the 'new' list, even if the key is the same and all the properties are the same, are completely different instances to the equivalent objects in the 'old' list, so copying references is not an option. Below is what I've come up with so far - it's a generic extension method for a BindingList. I've put comments in to demonstrate what I'm trying to do. public static class BindingListExtension { public static void Reconcile<T>(this BindingList<T> left, BindingList<T> right, string key) { PropertyInfo piKey = typeof(T).GetProperty(key); // Go through each item in the new list in order to find all updated and new elements foreach (T newObj in right) { // First, find an object in the new list that shares its key with an object in the old list T oldObj = left.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(newObj, null))); if (oldObj != null) { // An object in each list was found with the same key, so now check to see if any properties have changed and // if any have, then assign the object from the new list over the top of the equivalent element in the old list foreach (PropertyInfo pi in typeof(T).GetProperties()) { if (!pi.GetValue(oldObj, null).Equals(pi.GetValue(newObj, null))) { left[left.IndexOf(oldObj)] = newObj; break; } } } else { // The object in the new list is brand new (has a new key), so add it to the old list left.Add(newObj); } } // Now, go through each item in the old list to find all elements with keys no longer in the new list foreach (T oldObj in left) { // Look for an element in the new list with a key matching an element in the old list if (right.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(oldObj, null))) == null) { // A matching element cannot be found in the new list, so remove the item from the old list left.Remove(oldObj); } } } } It can be called like this: _oldBindingList.Reconcile(newBindingList, "MyKey") However, I'm looking for perhaps a method of doing the same using LINQ type methods such as GroupJoin<, Join<, Select<, SelectMany<, Intersect<, etc. So far, the problem I've had is that each of these LINQ type methods result in brand new intermediary lists (as a return value) and really, I only want to modify the existing list for all the above reasons. If anyone can help with this, would be most appreciated. If not, no worries, the above method (as it were) will suffice for now. Thanks, Jason

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  • Translating Where() to sql

    - by MBoros
    Hi. I saw DamienG's article (http://damieng.com/blog/2009/06/24/client-side-properties-and-any-remote-linq-provider) in how to map client properties to sql. i ran throgh this article, and i saw great potential in it. Definitely mapping client properties to SQL is an awesome idea. But i wanted to use this for something a bit more complicated then just concatenating strings. Atm we are trying to introduce multilinguality to our Business objects, and i hoped we could leave all the existing linq2sql queries intact, and just change the code of the multilingual properties, so they would actually return the given property in the CurrentUICulture. The first idea was to change these fields to XMLs, and then try the Object.Property.Elements().Where(...), but it got stuck on the Elements(), as it couldnt translate it to sql. I read somewhere that XML fields are actually regarded as strings, and only on the app server they become XElements, so this way the filtering would be on the app server anyways, not the DB. Fair point, it wont work like this. Lets try something else... SO the second idea was to create a PolyGlots table (name taken from http://weblogic.sys-con.com/node/102698?page=0,1), a PolyGlotTranslations table and a Culture table, where the PolyGlots would be referenced from each internationalized property. This way i wanted to say for example: private static readonly CompiledExpression<Announcement, string> nameExpression = DefaultTranslationOf<Announcement> .Property(e => e.Name) .Is(e=> e.NamePolyGlot.PolyGlotTranslations .Where(t=> t.Culture.Code == Thread.CurrentThread.CurrentUICulture.Name) .Single().Value ); now unfortunately here i get an error that the Where() function cannot be translated to sql, what is a bit disappointing, as i was sure it will go through. I guess it is failing, cause the IEntitySet is basically an IEnumerable, not IQueryable, am i right? Is there another way to use the compiledExpressions class to achieve this goal? Any help appreciated.

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  • Grouping a list of of entities which has a sublist in c#

    - by mikei
    I have a set of Entities which basically has this structure. {Stats Name="<Product name> (en)" TotalResources="10" ..} {DayStats Date="2009-12-10" TotalResources="5"} {DayStats Date="2009-12-11" TotalResources="5"} {Stats} {Stats Name="<Product name> (us)" TotalResources="10" ..} {DayStats Date="2009-12-10" TotalResources="5"} {DayStats Date="2009-12-11" TotalResources="5"} {Stats} ... What I wan't to extract from this set is a new set entities (or entity in the example above) where the first level has been grouped by the (ignoring the country label) where all/some of the properties has been summmed together, including the the sublist of {DayStas} on a per day basis. So the result set of the example would look something like this: {Stats Name="<Product name>" TotalResources="20" ..} {DayStats Date="2009-12-10" TotalResources="10"} {DayStats Date="2009-12-11" TotalResources="10"} {Stats} ... So my question is: Is it possible to do this in a more elegant way in LINQ rather than the vanilla "loop-trhough-each-entity-and-compare"-way? And I wan't the set to contain the same type of entities as the original set ({Stats}, {DayStats}), your answer doesn't need to include code for that, I can probably work that out by myself. Just letting you know incase you need to take that into account. (I'm sorry if this question has been discussed before, I tried searching to no avail. I guess my searching skills are fuubar ;)) Merry christmas =)

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  • LinqToSql Select to a class then do more queries

    - by fyjham
    I have a LINQ query running with multiple joins and I want to pass it around as an IQueryable<T> and apply additional filters in other methods. The problem is that I can't work out how to pass around a var data type and keep it strongly typed, and if I try to put it in my own class (EG: .Select((a,b) => new MyClass(a,b))) I get errors when I try to add later Where clauses because my class has no translations into SQL. Is there any way I can do one of the following: Make my class map to SQL? Make the var data-type implement an interface (So I can pass it round as though it's that)? Something I haven't though of that'll solve my issue? Example: public void Main() { using (DBDataContext context = new DBDataContext()) { var result = context.TableAs.Join( context.TableBs, a => a.BID, b => b.ID, (a,b) => new {A = a, B = b} ); result = addNeedValue(result, 4); } } private ???? addNeedValue(???? result, int value) { return result.Where(r => r.A.Value == value); } PS: I know in my example I can flatten out the function easily, but in the real thing it'd be an absolute mess if I tried.

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  • Linq2Sql: query - subquery optimisation

    - by Budda
    I have the following query: IList<InfrStadium> stadiums = (from sector in DbContext.sectors where sector.Type=typeValue select new InfrStadium(sector.TeamId) ).ToList(); and InfrStadium class constructor: private InfrStadium(int teamId) { IList<Sector> teamSectors = (from sector in DbContext.sectors where sector.TeamId==teamId select sector) .ToList<>(); ... work with data } Current implementation perform 1+n queries, where n - number of records fetched the 1st time. I want to optimize that. And another one I would love to do using 'group' operator in way like this: IList<InfrStadium> stadiums = (from sector in DbContext.sectors group sector by sector.TeamId into team_sectors select new InfrStadium(team_sectors.Key, team_sectors) ).ToList(); with appropriate constructor: private InfrStadium(int iTeamId, IEnumerable<InfrStadiumSector> eSectors) { IList<Sector> teamSectors = eSectors.ToList(); ... work with data } But attempt to launch query causes the following error: Expression of type 'System.Int32' cannot be used for constructor parameter of type 'System.Collections.Generic.IEnumerable`1[InfrStadiumSector]' Question 1: Could you please explain, what is wrong here, I don't understand why 'team_sectors' is applied as 'System.Int32'? I've tried to change query a little (replace IEnumerable with IQueryeable): IList<InfrStadium> stadiums = (from sector in DbContext.sectors group sector by sector.TeamId into team_sectors select new InfrStadium(team_sectors.Key, team_sectors.AsQueryable()) ).ToList(); with appropriate constructor: private InfrStadium(int iTeamId, IQueryeable<InfrStadiumSector> eSectors) { IList<Sector> teamSectors = eSectors.ToList(); ... work with data } In this case I've received another but similar error: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Collections.Generic.IEnumerable1[InfrStadiumSector]' of method 'System.Linq.IQueryable1[InfrStadiumSector] AsQueryableInfrStadiumSector' Question 2: Actually, the same question: can't understand at all what is going on here... P.S. I have another to optimize query idea (describe here: Linq2Sql: query optimisation) but I would love to find a solution with 1 request to DB).

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  • Grouping by property value and writing group members

    - by Will S
    I need to group the following list by the department value but am having trouble with the LINQ syntax. Here's my list of objects: var people = new List<Person> { new Person { name = "John", department = new List<fields> {new fields { name = "department", value = "IT"}}}, new Person { name = "Sally", department = new List<fields> {new fields { name = "department", value = "IT"}}}, new Person { name = "Bob", department = new List<fields> {new fields { name = "department", value = "Finance"}}}, new Person { name = "Wanda", department = new List<fields> {new fields { name = "department", value = "Finance"}}}, }; I've toyed around with grouping. This is as far as I've got: var query = from p in people from field in p.department where field.name == "department" group p by field.value into departments select new { Department = departments.Key, Name = departments }; So can iterate over the groups, but not sure how to list the Person names - foreach (var department in query) { Console.WriteLine("Department: {0}", department.Department); foreach (var foo in department.Department) { // ?? } } Any ideas on what to do better or how to list the names of the relevant departments?

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  • Split List into Sublists with LINQ

    - by Felipe Lima
    Hi all, I believe this is another easy one for you LINQ masters out there. Is there any way I can separe a List into several separate lists of SomeObject, using the item index as the delimiter of each split? Let me exemplify: I have a List<SomeObject> and I need a List<List<SomeObject>> or List<SomeObject>[], so that each of these resulting lists will contain a group of 3 items of the original list (sequentially). eg.: Original List: [a, g, e, w, p, s, q, f, x, y, i, m, c] Resulting lists: [a, g, e], [w, p, s], [q, f, x], [y, i, m], [c] I'd also need the resulting lists size to be a parameter of this function. Is it possible?? Thanks!

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