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Could not determine metatable error binding list to asp.net datagridview

- by Scott Vercuski

I am working with the following block of code ... List<ThemeObject> themeList = (from theme in database.Themes join image in database.DBImages on theme.imageID equals image.imageID into resultSet from item in resultSet select new ThemeObject { Name = theme.Name, ImageID = item.imageID}).ToList(); dgvGridView.DataSource = themeList; dgvGridView.DataBind(); The list object populates fine. The datagrid is setup with 2 columns. A textbox column for the "Name" which is bound to "Name" An image column which is bound to the "ImageID" field When I execute the code I receive the following error on the DataBind() Could not determine a MetaTable. A MetaTable could not be determined for the data source '' and one could not be inferred from the request URL. Make sure that the table is mapped to the dats source, or that the data source is configured with a valid context type and table name, or that the request is part of a registered DynamicDataRoute. I'm not using any dynamicdataroutes as far as I can tell. Has anyone experienced this error before?

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How do I use a relative path in XDocument.Load?

- by PaulC

I have an XML file named PageData.xml in my App_Data folder. I want to populate an XDocument with this file using XDocument.Load. If I supply the full physical path it works, i.e.: XDocument vXDoc = XDocument.Load("/Work/Project/Web/100413 Dev/App_Data/PageData.xml"); ...where "Work" is a folder on my C: drive. If I try a relative path like this, though, I get a DirectoryNotFoundException: XDocument vXDoc = XDocument.Load("AppData/PageData.xml"); "Could not find a part of the path 'C:\Program Files (x86)\Common Files\Microsoft Shared\DevServer\10.0\AppData\PageData.xml'." This is obviously wrong, but there must be an easy way to set the correct relative path? What am I overlooking? Your help is appreciated.

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ConcurrentDictionary and updating values

- by rboarman

Hello, After searching via Google and coming up empty, I decided to ask the gurus here on StackOverflow. I am trying to update entries in a ConcurrentDictionary something like this: class Class1 { public int Counter { get; set; } } class Test { private ConcurrentDictionary<int, Class1> dict = new ConcurrentDictionary<int, Class1>(); public void TestIt() { foreach (var foo in dict) { foo.Value.Counter = foo.Value.Counter + 1; // Simplified example } } } Essentially I need to iterate over the dictionary and update a field on each Value. I understand from the documentation that I need to avoid using the Value property. Instead I think I need to use TryUpdate except that I don’t want to replace my whole object. Instead, I want to update a field on the object. After reading this: http://blogs.msdn.com/b/pfxteam/archive/2010/01/08/9945809.aspx Perhaps I need to use AddOrUpdate and simply do nothing in the add delegate. Does anyone have any insight as to how to do this? Thank you, Rick

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IQueryable<T> Extension Method not working

- by Micah

How can i make an extension method that will work like this public static class Extensions<T> { public static IQueryable<T> Sort(this IQueryable<T> query, string sortField, SortDirection direction) { // System.Type dataSourceType = query.GetType(); //System.Type dataItemType = typeof(object); //if (dataSourceType.HasElementType) //{ // dataItemType = dataSourceType.GetElementType(); //} //else if (dataSourceType.IsGenericType) //{ // dataItemType = dataSourceType.GetGenericArguments()[0]; //} //var fieldType = dataItemType.GetProperty(sortField); if (direction == SortDirection.Ascending) return query.OrderBy(s => s.GetType().GetProperty(sortField)); return query.OrderByDescending(s => s.GetType().GetProperty(sortField)); } } Currently that says "Extension methods must be defined in a non-generic static class". How do i do this?

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IQueryable<> from stored procedure (entity framework)

- by mmcteam

I want to get IQueryable<> result when executing stored procedure. Here is peace of code that works fine: IQueryable<SomeEntitiy> someEntities; var globbalyFilteredSomeEntities = from se in m_Entities.SomeEntitiy where se.GlobalFilter == 1234 select se; I can use this to apply global filter, and later use result in such way result = globbalyFilteredSomeEntities .OrderByDescending(se => se.CreationDate) .Skip(500) .Take(10); What I want to do - use some stored procedures in global filter. I tried: Add stored procedure to m_Entities, but it returns IEnumerable<> and executes sp immediately: var globbalyFilteredSomeEntities = from se in m_Entities.SomeEntitiyStoredProcedure(1234); Materialize query using EFExtensions library, but it is IEnumerable<>. If I use AsQueryable() and OrderBy(), Skip(), Take() and after that ToList() to execute that query - I get exception that DataReader is open and I need to close it first(can't paste error - it is in russian). var globbalyFilteredSomeEntities = m_Entities.CreateStoreCommand("exec SomeEntitiyStoredProcedure(1234)") .Materialize<SomeEntitiy>(); //.AsQueryable() //.OrderByDescending(se => se.CreationDate) //.Skip(500) //.Take(10) //.ToList(); Also just skipping .AsQueryable() is not helpful - same exception. When I put ToList() query executes, but it is too expensive to execute query without Skip(), Take().

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Help Understanding Enumerable.Join Method

- by lush

Yesterday I posted this question regarding using lambdas inside of a Join() method to check if 2 conditions exist across 2 entities. I received an answer on the question, which worked perfectly. I thought after reading the MSDN article on the Enumerable.Join() method, I'd understand exactly what was happening, but I don't. Could someone help me understand what's going on in the below code (the Join() method specifically)? Thanks in advance. if (db.TableA.Where( a => a.UserID == currentUser ) .Join( db.TableB.Where( b => b.MyField == someValue ), o => o.someFieldID, i => i.someFieldID, (o,i) => o ) .Any()) { //... }

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How to Edit data in nested Listview

- by miti737

I am using listview to display a list of items and a nested listview to show list of features to each item. Both parent and child listview need to able Insert,Edit and delete operation. It works fine for parent listview. But when I try to edit an child item, The edit button does not take it into Edit mode. Can you please suggest me what I am missing in my code? <asp:ListView ID="lvParent" runat="server" OnItemDataBound="lvParent_ItemDataBound" onitemcanceling="lvParent_ItemCanceling" onitemcommand="lvParent_ItemCommand" DataKeyNames="ItemID" onitemdeleting="lvParent_ItemDeleting" oniteminserting="lvParent_ItemInserting" > <LayoutTemplate> <asp:PlaceHolder ID="itemPlaceholder" runat="server"></asp:PlaceHolder> <div align="right"> <asp:Button ID="btnInsert" runat="server" Text="ADD Item" onclick="btnInsert_Click"/> </div> </LayoutTemplate> <ItemTemplate> <table runat="server" cellpadding="0" cellspacing="0" border="0" width="100%"> <tr> <td> <div id="dvDetail"> <span >Description</span> <asp:TextBox ID="txtDescription" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Description") %>' TextMode="MultiLine" ></asp:TextBox> </div> <div id="dvFeature" > <span>Feature List</span> <asp:ListView ID="lvChild" runat="server" InsertItemPosition="LastItem" DataKeyNames="FeatureID" OnItemCommand="lvChild_ItemCommand" OnItemCanceling="lvChild_ItemCanceling" OnItemDeleting="lvChild_ItemDeleting" OnItemEditing="lvChild_ItemEditing" OnItemInserting="lvChild_ItemInserting" OnItemUpdating="lvChild_ItemUpdating" DataSource='<%# DataBinder.Eval(Container.DataItem, "FeatureList") %>' > <LayoutTemplate> <ul > <asp:PlaceHolder runat="server" ID="itemPlaceHolder" ></asp:PlaceHolder> </ul> </LayoutTemplate> <ItemTemplate> <li> <span class="dvList"><%# DataBinder.Eval(Container.DataItem, "FeatureTitle")%></span> <div class="dvButton" > <asp:ImageButton ID="btnEdit" runat="server" ImageUrl="/Images/edit_16x16.gif" AlternateText= "Edit" CommandName="Edit" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "FeatureID") %>' Width="12" Height="12" /> <asp:ImageButton ID="btnDelete" runat="server" ImageUrl="/Images/delete_16x16.gif" AlternateText= "Delete" CommandName="Delete" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "FeatureID") %>' Width="12" Height="12" /> </div> </li> </ItemTemplate> <EditItemTemplate> <li> <asp:TextBox ID="txtFeature" Text='<%# DataBinder.Eval(Container.DataItem, "FeatureTitle")%>' runat="server"></asp:TextBox> <div class="dvButton"> <asp:ImageButton ID="btnUpdate" runat="server" ImageUrl="/Images/ok_16x16.gif" AlternateText= "Update" CommandName="Update" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "FeatureID") %>' Width="12" Height="12" /> <asp:ImageButton ID="btnCancel" runat="server" ImageUrl="/Images/delete_16x16.gif" AlternateText= "Cancel" CommandName="Cancel" Width="12" Height="12" CausesValidation="false" /> </div> </li> </EditItemTemplate> <InsertItemTemplate> <asp:TextBox ID="txtFeature" runat="server"></asp:TextBox> <div class="dvButton"> <asp:ImageButton ID="btnInsert" runat="server" ImageUrl="/Images/ok_16x16.gif" AlternateText= "Insert" CommandName="Insert" Width="12" Height="12" /> <asp:ImageButton ID="btnCancel" runat="server" ImageUrl="/Images/delete_16x16.gif" AlternateText= "Cancel" CommandName="Cancel" Width="12" Height="12" CausesValidation="false" /> </div> </InsertItemTemplate> </asp:ListView> </div> </td> </tr> <tr> <td align="right"> <div id="dvButton" > <asp:Button ID="btnSave" runat="server" Text="Save" CommandName="Save" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "ItemID") %>' /> <asp:Button ID="btnDelete" runat="server" Text="Delete" CssClass="Cancel" CommandName="Delete" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "ItemID") %>' /> </div> </td> </tr> </table> </ItemTemplate> </asp:ListView> Code Behind: protected void Page_Load(object sender, EventArgs e) { if (Page.IsPostBack == false) { BindData(); } } private void BindData() { MyDataContext data = new MyDataContext(); var result = from itm in data.ItemLists where itm.ItemID == iItemID select new { itm.ItemID, itm.Description, FeatureList = itm.Features }; lvParent.DataSource = result; lvParent.DataBind(); } protected void lvChild_ItemEditing(object sender, ListViewEditEventArgs e) { ListView lvChild = sender as ListView; lvChild.EditIndex = e.NewEditIndex; lvChild.DataBind(); } Edit: protected void lvChild_ItemEditing(object sender, ListViewEditEventArgs e) { ListView lvChild = sender as ListView; lvChild.EditIndex = e.NewEditIndex; lvChild.DataBind(); } If I use "lvChild.DataBind()" in 'ItemEditing' event, the total list of child items goes away if I click 'edit' protected void lvChild_ItemEditing(object sender, ListViewEditEventArgs e) { ListView lvChild = sender as ListView; lvChild.EditIndex = e.NewEditIndex; } if I get rid of 'lvChild.Databind' in ItemEditing event, it goes to Edit mode after clicking the 'edit' button twice . And though it shows textbox control of EditItemTemplate, it appears as a blank textbox (does not bind existing value to edit).

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Cannot Open Shared Object cygmpfr-1.dll

- by Nathan Campos

I'm testing CeGCC, that is a gcc built to cross-compile applications to Windows CE devices. As everyone do to test compilers, I've done a Hello World program: #include <stdio.h> int main() { printf("Hello, World!"); return 0; } As I'm using Windows now(because this is my other laptop), I'm using Cygwin. But when I tried to compile I got some errors, as you can see on the terminal log: C:\Dev\WinCE\Testarm-mingw32ce-gcc test.c /opt/mingw32ce/libexec/gcc/arm-mingw32ce/4.4.0/cc1.exe: error while loading shared libraries: cygmpfr-1.dll: cannot open shared object file: No such file or directory C:\Dev\WinCE\Test What can I do?

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Is there a way of recover from an Exception in Directory.EnumerateFiles ?

- by Magnus Johansson

In .NET 4, there's this Directory.EnumerateFiles() method with recursion that seems handy. However, if an Exception occurs within a recursion, how can I continue/recover from that and continuing enumerate the rest of the files? try { var files = from file in Directory.EnumerateFiles(@"c:\", "*.*", SearchOption.AllDirectories) select new { File = file }; Console.WriteLine(files.Count().ToString()); } catch (UnauthorizedAccessException uEx) { Console.WriteLine(uEx.Message); } catch (PathTooLongException ptlEx) { Console.WriteLine(ptlEx.Message); }

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Remove duplicates from DataTable and custom IEqualityComparer<DataRow>

- by abatishchev

How have I to implement IEqualityComparer<DataRow> to remove duplicates rows from a DataTable with next structure: ID primary key, col_1, col_2, col_3, col_4 The default comparer doesn't work because each row has it's own, unique primary key. How to implement IEqualityComparer<DataRow> that will skip primary key and compare only data remained. I have something like this: public class DataRowComparer : IEqualityComparer<DataRow> { public bool Equals(DataRow x, DataRow y) { return x.ItemArray.Except(new object[] { x[x.Table.PrimaryKey[0].ColumnName] }) == y.ItemArray.Except(new object[] { y[y.Table.PrimaryKey[0].ColumnName] }); } public int GetHashCode(DataRow obj) { return obj.ToString().GetHashCode(); } } and public static DataTable RemoveDuplicates(this DataTable table) { return (table.Rows.Count > 0) ? table.AsEnumerable().Distinct(new DataRowComparer()).CopyToDataTable() : table; } but it calls only GetHashCode() and doesn't call Equals()

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How to get record value from LinqDataSource via Code Behind

- by rockinthesixstring

I've got a LinqDataSource that retrieves a single record. Protected Sub LinqDataSource1_Selecting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.LinqDataSourceSelectEventArgs) Handles LinqDataSource1.Selecting Dim BizForSaleDC As New DAL.BizForSaleDataContext e.Result = BizForSaleDC.bt_BizForSale_GetByID(e.WhereParameters("ID")).FirstOrDefault End Sub I'd like to be able to retrieve the values of said DataSource using the Page_Load function. Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load 'Get the right usercontrol' Dim ctrl As UserControl Select Case DataBinder.Eval(LINQDATASOURCE_SOMETHING.DataItem, "AdType") Case 1 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 2 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 3 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case 4 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case Else : ctrl = Nothing End Select 'set the control to visible' ctrl.Visible = True End Sub But obviously the code above doesn't work... I'm just wondering if there's a way to make it work. Here is the full markup <body> <form id="form1" runat="server"> <asp:LinqDataSource ID="LinqDataSource1" runat="server"> <WhereParameters> <asp:QueryStringParameter ConvertEmptyStringToNull="true" Name="ID" QueryStringField="ID" Type="Int32" /> </WhereParameters> </asp:LinqDataSource> <uc:Default ID="Default1" runat="server" Visible="false" /> <uc:ValuPro ID="ValuPro1" runat="server" Visible="false" /> </form> </body> </html> Basically what happens is the appropriate usercontrol is enabled and that usercontrol inherits the LinqDataSource and displays the appropriate information. EDIT: It's working now with the code below, however, since I'm really not into hitting the database multiple times for the same info, I'd prefer to get the value from the DataSource. 'Query the database' Dim _ID As Integer = Convert.ToInt32(Request.QueryString("ID")) Dim BizForSaleDC As New BizForSaleDataContext Dim results = BizForSaleDC.bt_BizForSale_GetByID(_ID).FirstOrDefault 'Get the right usercontrol' Dim ctrl As UserControl Select Case results.AdType Case 1 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 2 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 3 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case 4 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case Else : ctrl = Nothing End Select

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How can I extend DynamicQuery.cs to implement a .Single method?

- by Yoenhofen

I need to write some dynamic queries for a project I'm working on. I'm finding out that a significant amount of time is being spent by my program on the Count and First methods, so I started to change to .Single, only to find out that there is no such method. The code below was my first attempt at creating one (mostly copied from the Where method), but it's not working. Help? public static object Single(this IQueryable source, string predicate, params object[] values) { if (source == null) throw new ArgumentNullException("source"); if (predicate == null) throw new ArgumentNullException("predicate"); LambdaExpression lambda = DynamicExpression.ParseLambda(source.ElementType, typeof(bool), predicate, values); return source.Provider.CreateQuery( Expression.Call( typeof(Queryable), "Single", new Type[] { source.ElementType }, source.Expression, Expression.Quote(lambda))); }

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modify InnerXml of a XElement

- by voodoomsr

is there a simple way to modify the InnerXml of a XElement? supose we have this extremely simple xml and we want to append some xml that come from another source that comes like a string ".....blablabla" into the earth node. I read related questions but they talk about retrieving the innerxml of a XElement and i don't understand how "modify" the actual Xelement :(

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Silverlight: After adding table no datacontext classes are available for the new DomainService class

- by Gabriel

I'm using a Silverlight 4 WCF RIA Services demo application that uses LinqToSql, that works well. I add a new database table, move the new table to the LinqToSql designer and build the project I add a new DomainService class I get a dialog with the only option to create an empty DomainService and no DataContext classes are available. What am I missed? Thanks in advance Gabriel

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Binding a DropDownList in ListView InsertItemTemplate throwing an error

- by Telos

I've got a ListView which binds to a LinqDataSource and displays selected locations. The insert item Contains a dropdownlist that pulls from another LinqDataSource to give all the unselected locations. The problem is that I get the following error when loading the page: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. I'm doing a very similar setup in another page of the website, and it isn't giving us this error so I'm pretty confused. I know I can work around this by not binding, manually finding the control and getting the value, but this should work and I don't understand why it isn't. Any thoughts? The better part of the source code is below. <asp:LinqDataSource ID="ldsLocations" runat="server" ContextTypeName="ClearviewInterface.ESLinqDataContext" EnableDelete="true" EnableInsert="true" OnInserting="ldsLocations_Inserting" OnDeleting="ldsLocations_Deleting" TableName="crmLocations" OrderBy="addr1" OnSelecting="ldsLocations_Selecting" /> <asp:LinqDataSource ID="ldsFreeLocations" runat="server" ContextTypeName="ClearviewInterface.ESLinqDataContext" OrderBy="addr1" TableName="v_CVLocations" OnSelecting="ldsFreeLocations_Selecting" /> <asp:ListView ID="lvLocations" DataSourceID="ldsLocations" DataKeyNames="ID" InsertItemPosition="LastItem" runat="server" > <InsertItemTemplate> <tr> <td colspan="6"><hr /></td> </tr> <tr> <td colspan="2"> <asp:DropDownList ID="ddlFreeLocations" DataSourceID="ldsFreeLocations" DataTextField="addr1" DataValueField="record" MarkFirstMatch="true" SelectedValue='<%# Bind("record") %>' runat="server" /> </td> <td><asp:ImageButton ID="btnAdd" CommandName="Insert" SkinID="Insert" runat="server" /></td> </tr> </InsertItemTemplate>

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Transaction timeout expired while using Linq2Sql DataContext.SubmitChanges()

- by user68923

Hi guys, please help me resolve this problem: There is an ambient MSMQ transaction. I'm trying to use new transaction for logging, but get next error while attempt to submit changes - "Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding." Here is code: public static void SaveTransaction(InfoToLog info) { using (TransactionScope scope = new TransactionScope(TransactionScopeOption.RequiresNew)) { using (TransactionLogDataContext transactionDC = new TransactionLogDataContext()) { transactionDC.MyInfo.InsertOnSubmit(info); transactionDC.SubmitChanges(); } scope.Complete(); } } Please help me. Thx.

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List<T>.RemoveAll Doesn't Exist in Silverlight?

- by ashes999

I'm working on a Silverlight 2/3 application. I would like to use List.RemoveAll (or maybe it's IList.RemoveAll?) and specify a predicate so that I can remove a bunch of elements from a list in one sweep. It seems like this function doesn't exist in Silverlight, though. Am I missing something here? Is there an alternative approach that's equally easy? Right now, I'm manually iterating over my elements in a foreach and keeping a second list (because you can't delete while iterating), and it's quite ... cumbersome.

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Why does this render as a list of "System.Web.Mvc.SelectListItem"s?

- by JMT

I'm trying to populate a DropDownList with values pulled from a property, and my end result right now is a list of nothing but "System.Web.Mvc.SelectListItem"s. I'm sure there's some minor step I'm omitting here, but for the life of me I can't figure out what it is. The property GET generating the list: public IEnumerable<SelectListItem> AllFoo { get { var foo = from g in Bar orderby g.name select new SelectListItem { Value = g.fooid.ToString(), Text = g.name }; return foo.AsEnumerable(); } } The controller code: public ActionResult Edit(string id) { // n/a code ViewData["fooList"] = new SelectList(g.AllFoo, g.fooid); return View(model); } The view code: <%= Html.DropDownListFor(model => model.fooid, ViewData["fooList"] as SelectList) %>

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RIA Services query: Nested "from" and include children

- by Stéphane Bebrone

Hi guys, I have the following schema. What I'd like to do is to retrieve all customers (and children properties) from a selected StaffAssignment by StaffId. So I've written the following query: from c in ObjectContext.Customers.Include("Assignments.Activities") from a in c.Assignments from sa in a.StaffAssignments where sa.StaffId == staffId select c But children properties aren't loaded (I added the [Include] in service metadata file as well). What did I do wrong? Gtz, Stéphane.

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Asp.Net MVC - Rob Conery's LazyList - Count() or Count

- by Adam

I'm trying to create an html table for order logs for customers. A customer is defined as (I've left out a lot of stuff): public class Customer { public LazyList<Order> Orders { get; set; } } The LazyList is set when fetching a Customer: public Customer GetCustomer(int custID) { Customer c = ... c.Orders = new LazyList<Order>(_repository.GetOrders().ByOrderID(custID)); return c; } The order log model: public class OrderLogTableModel { public OrderLogTableModel(LazyList<Order> orders) { Orders = orders; Page = 0; PageSize = 25; } public LazyList<Order> Orders { get; set; } public int Page { get; set; } public int PageSize { get; set; } } and I pass in the customer.Orders after loading a customer. Now the log i'm trying to make, looks something like: <table> <tbody> <% int rowCount = ViewData.Model.Orders.Count(); int innerRows = rowCount - (ViewData.Model.Page * ViewData.Model.PageSize); foreach (Order order in ViewData.Model.Orders.OrderByDescending(x => x.StartDateTime) .Take(innerRows).OrderBy(x => x.StartDateTime) .Take(ViewData.Model.PageSize)) { %> <tr> <td> <%= order.ID %> </td> </tr> <% } %> </tbody> </table> Which works fine. But the problem is evaluating ViewData.Model.Orders.Count() literally takes about 10 minutes. I've tried with the ViewData.Model.Orders.Count property instead, and the results are the same - takes forever. I've also tried calling _repository.GetOrders().ByCustomerID(custID).Count() directly from the view and that executes perfectly within a few ms. Can anybody see any reason why using the LazyList to get a simple count would take so long? It seems like its trying to iterate through the list when getting a simple count.

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Returning IQueryable or Enumerated Object

- by Tarik

Hello everyone, I was wondering about the performance difference between these two scenarios and what could the disadvantages be over each other? First scenario : public class Helper //returns IQueryable { public IQueryable<Customer> CurrentCustomer { get{return new DataContext().Where(t=>t.CustomerId == 1); } } public class SomeClass { public void Main() { Console.WriteLine(new Helper().CurrentCustomer.First().Name; } } The second scenario : public class Helper //returns Enumerated result { public Customer CurrentCustomer { get{return new DataContext().First(t=>t.CustomerId == 1); } } public class SomeClass { public void Main() { Console.WriteLine(new Helper().CurrentCustomer.Name; } } Thanks in advance.

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building median for each string in IList<IDictionary<string, double>>

- by Oliver

Actually i have a little brain bender and and just can't find the right direction to get it to work: Given is an IList<IDictionary<string, double>> and it is filled as followed: Name|Value ----+----- "x" | 3.8 "y" | 4.2 "z" | 1.5 ----+----- "x" | 7.2 "y" | 2.9 "z" | 1.3 ----+----- ... | ... To fill this up with some random data i used the following methods: var list = CreateRandomPoints(new string[] { "x", "y", "z" }, 20); This will work as followed: private IList<IDictionary<string, double>> CreateRandomPoints(string[] variableNames, int count) { var list = new List<IDictionary<string, double>>(count); list.AddRange(CreateRandomPoints(variableNames).Take(count)); return list; } private IEnumerable<IDictionary<string, double>> CreateRandomPoints(string[] variableNames) { while (true) yield return CreateRandomLine(variableNames); } private IDictionary<string, double> CreateRandomLine(string[] variableNames) { var dict = new Dictionary<string, double>(variableNames.Length); foreach (var variable in variableNames) { dict.Add(variable, _Rand.NextDouble() * 10); } return dict; } Also i can say that it is already ensured that every Dictionary within the list contains the same keys (but from list to list the names and count of the keys can change). So that's what i got. Now to the things i need: I'd like to get the median (or any other math aggregate operation) of each Key within all the dictionaries, so that my function to call would look something like: IDictionary<string, double> GetMedianOfRows(this IList<IDictionary<string, double>> list) The best would be to give some kind of aggregate operation as a parameter to the function to make it more generic (don't know if the func has the correct parameters, but should imagine what i'd like to do): private IDictionary<string, double> Aggregate(this IList<IDictionary<string, double>> list, Func<IEnumerable<double>, double> aggregator) Also my actual biggest problem is to do the job with a single iteration over the list, cause if within the list are 20 variables with 1000 values i don't like to iterate 20 times over the list. Instead i would go one time over the list and compute all twenty variables at once (The biggest advantage of doing it that way would be to use this also as IEnumerable<T> on any part of the list in a later step). So here is the code i already got: public static IDictionary<string, double> GetMedianOfRows(this IList<IDictionary<string, double>> list) { //Check of parameters is left out! //Get first item for initialization of result dictionary var firstItem = list[0]; //Create result dictionary and fill in variable names var dict = new Dictionary<string, double>(firstItem.Count); //Iterate over the whole list foreach (IDictionary<string, double> row in list) { //Iterate over each key/value pair within the list foreach (var kvp in row) { //How to determine median of all values? } } return dict; } Just to be sure here is a little explanation about the Median.

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Force validation on bound controls in WPF

- by Valentin Vasilyev

Hello. I have a WPF dialog with a couple of textboxes on it. Textboxes are bound to my business object and have WPF validation rules attached. The problem is that user can perfectly click 'OK' button and close the dialog, without actually entering the data into textboxes. Validation rules never fire, since user didn't even attempt entering the information into textboxes. Is it possible to force validation checks and determine if some validation rules are broken? I would be able to do it when user tries to close the dialog and prohibit him from doing it if any validation rules are broken. Thank you.

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Properly handling possible System.NullReferenceException in lambda expressions

- by Travis Johnson

Here's the query in question return _projectDetail.ExpenditureDetails .Where(detail => detail.ProgramFund == _programFund && detail.Expenditure.User == _creditCardHolder) .Sum(detail => detail.ExpenditureAmounts.FirstOrDefault( amount => amount.isCurrent && !amount.requiresAudit) .CommittedMonthlyRecord.ProjectedEac); Table Structure ProjectDetails (1 to Many) ExpenditureDetails ExpenditureDetails (1 to Many) ExpenditureAmounts ExpenditureAmounts (1 to 1) CommittedMonthlyRecords ProjectedEac is a decimal field on the CommittedMonthlyRecords. The problem I discovered in a Unit test (albeit an unlikely event), that the following line could be null: detail.ExpenditureAmounts.FirstOrDefault( amount => amount.isCurrent && !amount.requiresAudit) My original query was a nested loop, in where I would be making multiple trips to the database, something I don't want to repeat. I've looked in to what seemed like some similar questions here, but the solution didn't seem to fit. Any ideas?

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Crystal Reports Xi - Sorting a CrossTab Report by a Summary Field

- by Albert

So I have a simple crosstab report that calculates number of sales in the columns, and the rows are each office. The last column on the right is a total column, which contains a summary field (via a count of the identity field) that adds up the total number of sales per office. How can I sort the crosstab data so the office with the most sales is the top row, and the rest in order under it?

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