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  • LinqKit stack overflow exception using predicate builder

    - by MLynn
    I am writing an application in C# using LINQ and LINQKit. I have a very large database table with company registration numbers in it. I want to do a LINQ query which will produce the equivalent SQL: select * from table1 where regno in('123','456') The 'in' clause may have thousands of terms. First I get the company registration numbers from a field such as Country. I then add all the company registration numbers to a predicate: var predicate = PredicateExtensions.False<table2>(); if (RegNos != null) { foreach (int searchTerm in RegNos) { int temp = searchTerm; predicate = predicate.Or(ec => ec.regno.Equals(temp)); } } On Windows Vista Professional a stack overflow exception occured after 4063 terms were added. On Windows Server 2003 a stack overflow exception occured after about 1000 terms were added. I had to solve this problem quickly for a demo. To solve the problem I used this notation: var predicate = PredicateExtensions.False<table2>(); if (RegNosDistinct != null) { predicate = predicate.Or(ec => RegNos.Contains(ec.regno)); } My questions are: Why does a stack overflow occur using the foreach loop? I take it Windows Server 2003 has a much smaller stack per process\thread than NT\2000\XP\Vista\Windows 7 workstation versions of Windows. Which is the fastest and most correct way to achieve this using LINQ and LINQKit? It was suggested I stop using LINQ and go back to dynamic SQL or ADO.NET but I think using LINQ and LINQKit is far better for maintainability.

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  • load complex class/nested xml file into dataset

    - by iTayb
    I want to create a dataset and bind it with a repeater. My datasource is a class, which is itself loaded from an nested xml file. I can use both as datasources. How can I do it? This is my sample XML file: <?xml version="1.0" encoding="utf-8"?> <BookStore xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Book> <Name>??????? ????? 035006</Name> <Imageurl>math1.jpg</Imageurl> <Subject>???????</Subject> <Author>??? ????</Author> <Level>5</Level> <Year>2002</Year> <Rating>4</Rating> <BookSellers> <string>????? ?????</string> <string>?.?. ????? ??"?</string> <string>??? ?? ???? ????? ??????? ??"?</string> <string>?? ?????? ???? ?'????</string> <string>???? ??? ?????</string> <string>Garbage Collector</string> <string>???? ??????? ??????</string> </BookSellers> <BookPrices> <double>25</double> <double>48</double> <double>37</double> <double>52</double> <double>34</double> <double>22</double> <double>60</double> </BookPrices> </Book> </BookStore> Plus, how will I refer to this data? for example, DataBinder.Eval(Container.DataItem, "Imageurl" will bring me the url? Thank you very much!

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  • Cast MyEntity To LinqEntity throw a base controller class

    - by Mohammad Kani
    hi there i design a multilayer we appliction andusing LINQ a my data provider i need to user my own Entites instead o LINQ etities. so i created Entities Project and create my entities in it. when i get data from contex and cast them to my entities , everything is ok. but when i want to cast on of my entities to linq entity , an exception thrown. in my linq entity i add CTYPE operator from and to my entities Exp : Public Class BaseController(Of LinqEntity As {BaseEntity, New}, MyEntity As ModuleEntities.BaseEntityInfo) Implements Interfaces.Base(Of ServiceEntity) 'This methd work fine and cast LinqEntity to MyEntity Public Function GetAll() As List(Of MyEntity ) Dim q = (From x In Context.GetTable(Of LinqEntity)() _ Select x).Cast(Of MyEntityBase) End Function Public Sub Update(ByVal entity As MyEntity) 'here is problem 'cast , direct cast , or anything not work Dim x as LinqEntity = entity Me.Context.GetTable(Of LinqEntity).InsertOnSubmit(entity) Me.Context.SubmiChanges() End Sub

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  • extracting only elements with text (or value)

    - by guy
    hay all. i am trying to transform html to xml meaning extracting all elements with text using this code is not working maybe some one has the answer ? System.Xml.Linq.XElement query1 = new System.Xml.Linq.XElement("RawHTMLData", from q in hDoc.Descendants("TABLE") where q.HasElements select new System.Xml.Linq.XElement("TABLE" + (++i).ToString(), from j in q.Elements("TR") where j.HasElements && j.Descendants("div") != null select new System.Xml.Linq.XElement("Row", from hh in j.Descendants("div") where tt => j.Descendants("div").Contains(hh.Value) select(TT(hh)))));

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  • How to reflect over T to build an expression tree for a query?

    - by Alex
    Hi all, I'm trying to build a generic class to work with entities from EF. This class talks to repositories, but it's this class that creates the expressions sent to the repositories. Anyway, I'm just trying to implement one virtual method that will act as a base for common querying. Specifically, it will accept a an int and it only needs to perform a query over the primary key of the entity in question. I've been screwing around with it and I've built a reflection which may or may not work. I say that because I get a NotSupportedException with a message of LINQ to Entities does not recognize the method 'System.Object GetValue(System.Object, System.Object[])' method, and this method cannot be translated into a store expression. So then I tried another approach and it produced the same exception but with the error of The LINQ expression node type 'ArrayIndex' is not supported in LINQ to Entities. I know it's because EF will not parse the expression the way L2S will. Anyway, I'm hopping someone with a bit more experience can point me into the right direction on this. I'm posting the entire class with both attempts I've made. public class Provider<T> where T : class { protected readonly Repository<T> Repository = null; private readonly string TEntityName = typeof(T).Name; [Inject] public Provider( Repository<T> Repository) { this.Repository = Repository; } public virtual void Add( T TEntity) { this.Repository.Insert(TEntity); } public virtual T Get( int PrimaryKey) { // The LINQ expression node type 'ArrayIndex' is not supported in // LINQ to Entities. return this.Repository.Select( t => (((int)(t as EntityObject).EntityKey.EntityKeyValues[0].Value) == PrimaryKey)).Single(); // LINQ to Entities does not recognize the method // 'System.Object GetValue(System.Object, System.Object[])' method, // and this method cannot be translated into a store expression. return this.Repository.Select( t => (((int)t.GetType().GetProperties().Single( p => (p.Name == (this.TEntityName + "Id"))).GetValue(t, null)) == PrimaryKey)).Single(); } public virtual IList<T> GetAll() { return this.Repository.Select().ToList(); } protected virtual void Save() { this.Repository.Update(); } }

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  • DeleteOnSubmit doesnt exist?

    - by Anders Metnik
    using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; Thats my namespaces.. i was looking for System.Data.Linq; but it doesnt seem to be anywhere, and i guess that is what have been moved to System.Linq, since i have access to most other things in Linq. EDIT: found System.Data:Linq, no difference Here is my method: public void deleteStudienummer(int studienummer) { dbcontent = new DBEntities(); var dQry = from members in dbcontent.Medlemmer where members.Studienummer == studienummer select members; foreach (var member in dQry) { dbcontent.*** } dbcontent.AcceptAllChanges(); Console.WriteLine("delete member should have occured"); } The * was supposed to be DeleteOnSubmit, but i only have DeleteDatabase and DeleteObject, i tried with object but it doesnt work.. Have also tried dbcontent.Medlemmer.* but still not present. And AcceptAllChanges() was supposed to be .submitChanges() but that wasnt present either.

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  • LINQ. Grouping by days. How to do this easily?

    - by punkouter
    I can't seem to find any god reference on this. I have alot of data in SQL with dates. So I wanted to make a line chart to show this data over time. If I want to show it over a perioud of days then I need to group by days.. But the LOGDATE is the full date.. not the DAY.. So I have this below.. but LINQ doesnt know what 'DayOfYear' property is.. HELP var q = from x in dc.ApplicationLogs let dt = x.LogDate group x by new { dayofyear = dt.Value.DayOfYear } into g select new { iCount = g.Count(), strDate = g.Key };

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  • Store an image in a SQL Server CE database

    - by Vaccano
    Does any one know of an example on how to store an image in a SQL Server CE database? What data type should the column be? (I am guessing binary.) I use Linq-To-Datasets. Is it possible using that to put the image into the database and pull it out again later? Thanks for any advice.

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  • asp.net InsertCommand to return latest insert ID

    - by Stijn Van Loo
    Dear all, I'm unable to retrieve the latest inserted id from my SQL Server 2000 db using a typed dataset in asp.NET I have created a tableadapter and I ticked the "Refresh datatable" and "Generate Insert, Update and Delete statements". This auto-generates the Fill and GetData methods, and the Insert, Update, Select and Delete statements. I have tried every possible solution in this thread http://forums.asp.net/t/990365.aspx but I'm still unsuccesfull, it always returns 1(=number of affected rows). I do not want to create a seperate insert method as the auto-generated insertCommand perfectly suits my needs. As suggested in the thread above, I have tried to update the InsertCommand SQL syntax to add SELECT SCOPY_IDENTITY() or something similar, I have tried to add a parameter of type ReturnValue, but all I get is the number of affected rows. Does anyone has a different take on this? Thanks in advance! Stijn

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  • Object Reference Error filling a datarow

    - by JPJedi
    This is the code: Dim dr() As DataRow = DataSet.Tables("TableName").Select("EVENTNAME = '" & name & "'") I get an "Object reference not set to an instance of an object." Error when this line is executed. It is looping through a list of selected items in a listbox. I think it has to do with how I have the datarow declared because I can look at the name and I see it ok and I also do a null check on the name before I use it. Visual Studio 2008, VB.NET. Any ideas? Yep it was a wrong table name. I guess after looking at the code for 8 hours that minor detail I just wasn't thinking to check. Thanks!

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  • Mark row as deleted in dataTable on

    - by dav.evans
    I have a datatable bound to a winforms dataGridView via a BindingSourceControl. I want to be able handle the UserDeletingRow event from the dataGridView and mark the row in my dataTable as deleted. I need to then be able to retrieve the rows marked as deleted from the datatable so that I can delete them from my database when a Save button is clicked. Please not I dont want to delete from the database on each firing of UserDeletingRow, only mark that row as deleted in my dataset. Can anyone point out how to do this?

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  • Mark row as deleted in dataTable on UserDeletingRow

    - by dav.evans
    I have a datatable bound to a winforms dataGridView via a BindingSourceControl. I want to be able handle the UserDeletingRow event from the dataGridView and mark the row in my dataTable as deleted. I need to then be able to retrieve the rows marked as deleted from the datatable so that I can delete them from my database when a Save button is clicked. Please not I dont want to delete from the database on each firing of UserDeletingRow, only mark that row as deleted in my dataset. Can anyone point out how to do this?

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  • TableAdapter to return ONLY selected columns? (VS2008)

    - by MattSlay
    (VS2008) I'm trying to configure a TableAdapter in a Typed DataSet to return only a certain subset of columns from the main schema of the table on which it is based, but it always returns the entire schema (all columns) with blank values in the columns I have omitted. The TableAdpater has the default Fill and GetData() methods that come from the wizard, which contain every column in the table, which is fine. I then added a new parameterized query method called GetActiveJobsByCustNo(CustNo), and I only included a few columns in the SQL query that I actually want to be in this table view. But, again, it returns all the columns in the master table schema, with empty values for the columns I omitted. The reason I am wanting this, is so I can just get a few columns back to use that table view with AutoGenerateColumns in an ASP.NET GridView. With it giving me back EVERY column i nthe schema, my presentation GridView contains way more columns that I want to show th user. And, I want to avoid have to declare the columns in the GridView.

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  • How can I use multiple Datatables on my CrystalReport?

    - by Sergio Tapia
    I have a dataset that connects with three databases. How can I attach my Crystalreport viewer so all three are included? protected void Page_Load(object sender, EventArgs e) { ReportDocument X = new ReportDocument(); DataTable DTable = new DataTable(); DataSet1TableAdapters.TableAdapterManager ????? = new WebApplication1.DataSet1TableAdapters.TableAdapterManager(); DTable = ???????? string ubicacion = Server.MapPath("crystalReport1.rpt"); X.Load(ubicacion); X.SetDataSource(DTable); CrystalReportViewer1.ReportSource = X; }

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  • Best method for Binding ComboBox

    - by LnDCobra
    I am going to be developing a large project which will include a large number of ComboBoxes. Most of these combo boxes will be bound to a database field which is a related to another daataset/table. For instance. I have the following 2 tables: Company {CompanyID, CompanyName, MainContact} Contacts {ContactID, ContactName} And when the user clicks to edit a company, A TextBox will be there to edit a company name, but also a ComboBox will be there. The way I am currently doing it is binding the ComboBox to the Contacts dataset, and manually updating the Company MainContact field in code behind. Is there anyway for me to bind the selected item to the Company MainContact field in XAML and the items to the ContactName and eliminate the code behind? Reason for this is when you start making 100's combo boxes all over the application it gets long winded each time creating code behind to do the update.

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  • What data structure would be the least painful DataTable replacement?

    - by MatthewMartin
    I'm storing a lot of sorted ~10 row 2 column/key value pairs in ASP.NET cache-- they're the data for dropdownlists. Right now they are all DataTables, which isn't very space efficient (the rule of thumb is 10x increase in size when data is strored in a dataset). Old Code DataTable table = dataAccess.GetDataTable(); dropDownList.DataSource = table; Hoped for new Code Unknown data = dataAccess.GetSomethingMoreSpaceEfficient(); dropDownList.DataSource = data; What pre-existing datastructures are similar enough to DataTable that would minimize code breakage and reduce the serialized size when stored in ASP.NET cache?

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  • Where to find viterbi algorithm transition values for natural language processing?

    - by Rodrigo Salazar
    I just watched a video where they used Viterbi algorithm to determine whether certain words in a sentence are intended to be nouns/verbs/adjs etc, they used transition and emission probabilities, for example the probability of the word 'Time' being used as a verb is known (emission) and the probability of a noun leading onto a verb (transition). http://www.youtube.com/watch?v=O_q82UMtjoM&feature=relmfu (The video) How can I find a good dataset of transition and emission probabilities for this use-case? Or EVEN just a single example with all the probabilities displayed, I want to use realistic numbers in a demonstration.

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  • How to use Linq with Castle ActiveRecord

    - by Ronnie Overby
    I am playing around with Castle ActiveRecord and noticed that the download included the file, Castle.ActiveRecord.Linq.dll. I haven't found any documentation for using Linq with ActiveRecord, only some old blog posts. What is the usage pattern? Is Castle.ActiveRecord.Linq ready for production use? I'm using reflector, pending an answer.

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  • Extracting the Date from a DateTime in Entity Framework 4 and LINQ

    - by Ken Cox [MVP]
    In my current ASP.NET 4 project, I’m displaying dates in a GridDateTimeColumn of Telerik’s ASP.NET Radgrid control. I don’t care about the time stuff, so my DataFormatString shows only the date bits: <telerik:GridDateTimeColumn FilterControlWidth="100px"   DataField="DateCreated" HeaderText="Created"    SortExpression="DateCreated" ReadOnly="True"    UniqueName="DateCreated" PickerType="DatePicker"    DataFormatString="{0:dd MMM yy}"> My problem was that I couldn’t get the built-in column filtering (it uses Telerik’s DatePicker control) to behave.  The DatePicker assumes that the time is 00:00:00 but the data would have times like 09:22:21. So, when you select a date and apply the EqualTo filter, you get no results. You would get results if all the time portions were 00:00:00. In essence, I wanted my Entity Framework query to give the DatePicker what it wanted… a Date without the Time portion. Fortunately, EF4 provides the TruncateTime  function. After you include Imports System.Data.Objects.EntityFunctions You’ll find that your EF queries will accept the TruncateTime function. Here’s my routine: Protected Sub RadGrid1_NeedDataSource _     (ByVal source As Object, _      ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) _     Handles RadGrid1.NeedDataSource     Dim ent As New OfficeBookDBEntities1     Dim TopBOMs = From t In ent.TopBom, i In ent.Items _                   Where t.BusActivityID = busActivityID _       And i.BusActivityID And t.ItemID = i.RecordID _       Order By t.DateUpdated Descending _       Select New With {.TopBomID = t.TopBomID, .ItemID = t.ItemID, _                        .PartNumber = i.PartNumber, _                        .Description = i.Description, .Notes = t.Notes, _                        .DateCreated = TruncateTime(t.DateCreated), _                        .DateUpdated = TruncateTime(t.DateUpdated)}     RadGrid1.DataSource = TopBOMs End Sub Now when I select March 14, 2011 on the DatePicker, the filter doesn’t stumble on time values that don’t make sense. Full Disclosure: Telerik gives me (and other developer MVPs) free copies of their suite.

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  • Crazy Linq: performing System.ComponentModel.DataAnnotations validation in a single statement

    - by Daniel Cazzulino
    public static IEnumerable&lt;ValidationResult&gt; Validate(object component) { return from descriptor in TypeDescriptor.GetProperties(component).Cast&lt;PropertyDescriptor&gt;() from validation in descriptor.Attributes.OfType&lt;System.ComponentModel.DataAnnotations.ValidationAttribute&gt;() where !validation.IsValid(descriptor.GetValue(component)) select new ValidationResult( validation.ErrorMessage ?? string.Format(CultureInfo.CurrentUICulture, "{0} validation failed.", validation.GetType().Name), new[] { descriptor.Name }); } ...Read full article

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  • Fixing LINQ Error: Sequence contains no elements

    - by ChrisD
    I’ve read some posts regarding this error when using the First() or Single() command.   They suggest using FirstOrDefault() or SingleorDefault() instead. But I recently encountered it when using a Sum() command in conjunction with a Where():   Code Snippet var effectiveFloor = policies.Where(p => p.PricingStrategy == PricingStrategy.EstablishFloor).Max(p => p.Amount);   When the Where() function eliminated all the items in the policies collection, the Sum() command threw the “Sequence contains no elements” exception.   Inserting the DefaultIfEmpty() command between the Where() and Sum(), prevents this error: Code Snippet var effectiveFloor = policies.Where(p => p.PricingStrategy == PricingStrategy.EstablishFloor).DefaultIfEmpty().Max(p => p.Amount);   but now throws a Null Reference exception!   The Fix: Using a combination of DefaultIfEmpty() and a null check in the Sum() command solves this problem entirely: Code Snippet var effectiveFloor = policies.Where(p => p.PricingStrategy == PricingStrategy.EstablishFloor).DefaultIfEmpty().Max(p =>  p==null?0 :p.Amount);

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  • How to profile LINQ to Entities queries in your asp.net applications - part 3

    - by nikolaosk
    In this post I will continue exploring ways on how to profile database activity when using the Entity Framework as the data access layer in our applications. If you want to read the first post of the series click here . If you want to read the second post of the series click here . In this post I will use the excellent (best tool for EF profiling) which is called Entity Framework Profiler. You can download the trial - fully functional edition of this tool from here . I will use the previous example...(read more)

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