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  • Using Reflection Invoke static generic method passing a Lamba as parameter

    - by Nikos Baxevanis
    Is it possible to write the following code via Reflection? var fake = A.Fake<Foo>( o => o.WithArgumentsForConstructor(new[] { "Hello" })); Where o is: Action<IFakeOptionsBuilder<T>> Where WithArgumentsForConstructor is: IFakeOptionsBuilder<T> WithArgumentsForConstructor(IEnumerable<object> argumentsForConstructor); The Foo class is: class Foo { public Foo(string s) { } } What I did was: object fake = typeof(A) .GetMethod("Fake", new Type[] { }) .MakeGenericMethod(new[] { this.targetType }) .Invoke(null, /* Here I need to pass the lambda. */);

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  • Override comparison for F# set

    - by Mauricio Scheffer
    Is there any way to override the comparison function in a F# set? I don't see any set construction functions that take a IComparer<T> or comparison function: Set.ofSeq et al don't take a comparison function FSharpSet(IComparer<T> comparer, SetTree<T> tree) constructor is internal, because SetTree is internal and SetTreeModule.ofSeq<a>(IComparer<a> comparer, IEnumerable<a> c) is obviously internal too. My actual problem is that I have a set of ('a * 'a) and I want a comparison such that for example (1,3) = (3,1). I know I could wrap this in a type implementing IComparable<T>, but is there any way to avoid this?

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  • Can't Use Path in ASP MVC Action

    - by user1477388
    I am trying to use Path() but it has a blue line under it and says, "local variable (path) cannot be referred to until it is declared." How can I use Path()? Imports System.Globalization Imports System.IO Public Class MessageController Inherits System.Web.Mvc.Controller <EmployeeAuthorize()> <HttpPost()> Function SendReply(ByVal id As Integer, ByVal message As String, ByVal files As IEnumerable(Of HttpPostedFileBase)) As JsonResult ' upload files For Each i In files If (i.ContentLength > 0) Then Dim fileName = path.GetFileName(i.FileName) Dim path = path.Combine(Server.MapPath("~/App_Data/uploads"), fileName) i.SaveAs(path) End If Next End Function End Class

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  • What are the Hot and Cold observables?

    - by Sergey Aldoukhov
    I watched the video and I know the general principles - hot happens even when nobody is subscribed, cold happens "on demand". Also, Publish() converts cold to hot and Defer() converts hot to cold. But still, I feel I am missing the details. Here are some questions I'd like to have answered: Can you give a comprehensive definition for these terms? Does it ever make sense to call Publish on hot observable or Defer on cold? Is there differences between hot and cold definitions for IObservable and IEnumerable? What are the general principles you should take into account when programming for cold or hot? Any other tips on hot/cold observables?

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  • LINQ: why does this query not work on an ArrayList?

    - by Benny
    public static ArrayList GetStudentAsArrayList() { ArrayList students = new ArrayList { new Student() { RollNumber = 1,Name ="Alex " , Section = 1 ,HostelNumber=1 }, new Student() { RollNumber = 2,Name ="Jonty " , Section = 2 ,HostelNumber=2 } }; return students; } The following code doesn't compile. The error is ArrayList is not IEnumerable ArrayList lstStudents = GetStudentAsArrayList(); var res = from r in lstStudents select r; This compiles: ArrayList lstStudents = GetStudentAsArrayList(); var res = from Student r in lstStudents select r; Can anybody explain what the difference is between these two snippets? Why the second works?

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  • How does the method overload resolution system decide which method to call when a null value is passed?

    - by Joan Venge
    So for instance you have a type like: public class EffectOptions { public EffectOptions ( params object [ ] options ) {} public EffectOptions ( IEnumerable<object> options ) {} public EffectOptions ( string name ) {} public EffectOptions ( object owner ) {} public EffectOptions ( int count ) {} public EffectOptions ( Point point ) {} } Here I just give the example using constructors but the result will be the same if they were non-constructor methods on the type itself, right? So when you do: EffectOptions options = new EffectOptions (null); which constructor would be called, and why? I could test this myself but I want to understand how the overload resolution system works (not sure if that's what it's called).

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  • Different return XML in a WCF Operation

    - by Sean Hederman
    I am writing a service to a international HTTP standard, and there is one method that can return three different XML results, call them Single, Multiple and Error. Now I've written an IXmlSerializable class that can consume each of these results and generate them. However, WCF seems to insist that I can only have a single return XML root name. I have to choose an XmlRoot for my custom object of either Single, Multiple or Error. How can I set up WCF so that I can choose at runtime what the root will be? This is what I have currently. /// <summary> /// A collection of items. /// </summary> [XmlRoot("Multiple", Namespace = "DAV:")] public sealed class ItemCollection : IEnumerable<Item>, IXmlSerializable /// <summary> /// Processes and returns the items. /// </summary> [WebInvoke(Method = "POST", UriTemplate = "{*path}", BodyStyle = WebMessageBodyStyle.Bare)] [OperationContract] [XmlSerializerFormat] ItemCollection Process(string path);

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  • Which LINQ query is more effective?

    - by Danny Chen
    I have a huge IEnumerable(suppose the name is myItems), which way is more effective? Solution 1: Filter it first then ForEach. Array.ForEach(myItems.Where(FILTER-IT-HERE).ToArray(),MY-ACTION); Solution 2: Do RETURN in MY-ACTION if the item is not up to the mustard. Array.ForEach(myItems.ToArray(),MY-ACTION-WITH-FILTER); Is one of them always better than another? Or any other good suggestions? Thanks in advance.

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  • How do I improve the efficiency of the queries executed by this generic Linq-to-SQL data access clas

    - by Lee D
    Hi all, I have a class which provides generic access to LINQ to SQL entities, for example: class LinqProvider<T> //where T is a L2S entity class { DataContext context; public virtual IEnumerable<T> GetAll() { return context.GetTable<T>(); } public virtual T Single(Func<T, bool> condition) { return context.GetTable<T>().SingleOrDefault(condition); } } From the front end, both of these methods appear to work as you would expect. However, when I run a trace in SQL profiler, the Single method is executing what amounts to a SELECT * FROM [Table], and then returning the single entity that meets the given condition. Obviously this is inefficient, and is being caused by GetTable() returning all rows. My question is, how do I get the query executed by the Single() method to take the form SELECT * FROM [Table] WHERE [condition], rather than selecting all rows then filtering out all but one? Is it possible in this context? Any help appreciated, Lee

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  • Why is e.Item.DataItem null on ItemDataBound event when binding an asp:net Repeater to a Collection?

    - by Clean
    Hi, I'm trying to bind a collection implementing the ICollection, IEnumerable and IList interface to an asp.net repeater. The Collection is named CustomCollection. So I'm setting the datasource of the repeater to the collection, as follows: rptRepeater.DataSource = customCollection; rptRepeater.Databind(); Then, on the ItemDataBound event, I'm trying to access the DataItem object, as follow: void rptRepeater_ItemDataBound(object sender, RepeaterItemEventArgs e){ object obj = e.Item.DataItem; // DataItem is null for some reason } For some reason the e.Item.DataItem object is null. Do anyone know why this is, and/or what I could do to get hold of the object in the collection that is to be databound to the repeater? Thanx!

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  • C# LINQ Where Predicate Type Arguments

    - by blu
    I have an XElement with values for mock data. I have an expression to query the xml: Expression<Func<XElement, bool>> simpleXmlFunction = b => int.Parse(b.Element("FooId").Value) == 12; used in: var simpleXml = xml.Elements("Foo").Where(simpleXmlFunction).First(); The design time error is: The type arguments for method 'System.Linq.Enumerable.Where(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly' The delegate supplied to Where should take in an XElement and return a bool, marking if the item matches the query, I am not sure how to add anything more to the delegate or the where clause to mark the type. Also, the parallel method for the real function against the Entity Framework does not have this issue. What is not correct with the LINQ-to-XML version?

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  • Fastest way of creating XML from parent-child table in c#?

    - by rudnev
    Assume we have some DataTable or IEnumerable with ChildID, ParentID and Title. We need to serialize it to XML like <Entity title=""> <Entity title=""></Entity> <Entity title=""></Entity> </Entity> As i found out, standard DataTable.GetXML() returns something different. I thought about initializing class tree like Entity e = new Entity(ID, Title, ParentEntityID) and then serializing it. Table is about 3000 elems. Is there faster way?

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  • error when calling the webservice

    - by xrx215
    i am getting a list of pagepack assistant by calling a webservice. I have added the web reference. using org.xerox.xde3.na.sdi.amiller_v_vista; public org.xerox.xde3.na.sdi.amiller_v_vista.DDCControl proxy; in page load method i am calling the web method as follows proxy = new DDCControl(); Guid y = new Guid("45a5b1c2-2fa5-4136-abdd-bc213b694848"); DataList1.DataSource = proxy.GetAllDDCs(this.AccountID, y); DataList1.DataBind(); I am getting the following error: An invalid data source is being used for DataList1. A valid data source must implement either IListSource or IEnumerable Can you please help me with this issue?

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  • Get All Users in an Active Directory Group

    - by Matt Hanson
    I'm using the following code sample to get a list of all users in a specified AD group (in this case, all users in the "Domain Users" group). My listed code works great, with one exception: it won't return users who have their primary group set to "Domain Users". How can I get a list of all users in the group, including those who have it set as their primary group? Private Sub GetUsers() Dim groupSearcher As New DirectorySearcher Dim groupSearchRoot As New DirectoryEntry("LDAP://OU=Users,DC=domain,DC=com") With groupSearcher .SearchRoot = groupSearchRoot .Filter = "(&(ObjectClass=Group)(CN=Domain Users))" End With Dim members As Object members = groupSearcher.FindOne.GetDirectoryEntry.Invoke("Members", Nothing) For Each member As Object In CType(members, IEnumerable) Console.WriteLine(New DirectoryEntry(member).Name.Remove(0, 3)) Next End Sub

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  • Why no ArgumentEmptyException in .NET ?

    - by Andrei Rinea
    I am beginning to think I am doing something wrong. I mean they did place System.String.IsNullOrWhitespace finally but no ArgumentEmptyException class. public FilterItem(string name, IEnumerable<string> extensions) { if (string.IsNullOrWhiteSpace(name)) { throw new ArgumentNullException("name"); } if (extensions == null) { throw new ArgumentNullException("extensions"); } if (extensions.Count() == 0) { throw new ArgumentOutOfRangeException("extensions"); } this.Name = name; this.Extensions = extensions; } throwing an ArgumentOutOfRangeException feels unnatural. Also an instance of ArgumentException is too general in my opinion. It's easy to me to create a new exception class call it this way and have it over with. What bugs me is that it's not in the BCL/FCL and I am beginning to think there's a good reason not to have it. Should there be one?

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  • Groupby in relationtable

    - by Dofs
    I am creating some tag functionality for a forum using linq2sql, and I have two tables [Tag] TagId TagName [ForumTagRelation] TagId ForumId I would like to retrieve, like SO, the most popular tags. I have tried to do this by: List<Tag> popularTags = db.Tags.Select(x => x.ForumTagRelations.GroupBy(y => y.TagId).OrderByDescending(z => z.Count())).Take(count).ToList(); But this just returns the following error: Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<System.Linq.IOrderedEnumerable<System.Linq.IGrouping<System.Guid?,SampleWebsite.ForumTagRelation>>>' to 'System.Collections.Generic.IEnumerable<SampleWebsite.Tag>'. An explicit conversion exists (are you missing a cast?) The question is how I easily can return a list of tags which has the most counts in the ForumTagRelation table?

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  • Can Fluent nhibernate's automapper be configured to handle private readonly backing fields?

    - by Mark Rogers
    I like private readonly backing fields because some objects are mostly read-only after creation, and for collections, which rarely need to be set wholesale (instead using collection methods to modify the collection). For example: public class BuildingType : DomainEntity { /* rest of class */ public IEnumerable<ActionType> ActionsGranted { get { return _actionsGranted; } } private readonly IList<ActionType> _actionsGranted = new List<ActionType>(); private readonly Image _buildingTile; public virtual Image BuildingTile { get { return _buildingTile; } } } But as far as I remember fluent-nhibernate's automapper never had a solution for private readonly backing fields, I'm wondering if that's changed in the last few months. So here's my question: How do I configure automapper or create an automapping convention to map private readonly backing fields?

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  • NHibernate Collection Mapping - Read Only Properties

    - by Chris Meek
    I have the following class public class Person { private IList<Person> _children; public IEnumerable<Person> Children { get; } public void AddChild(Person child) { // Some business logic and adding to the internal list } } What changes would I have to make for NHibenrate to be able to persist the Child collection (apart from making everything virtual, I know that one). Do I have to add a setter to the children property which does something like a _children.Clear(); _children.AddRange(value). Currently the model expresses my intent quite nicely but I'm not sure how much alteration is need for NH to be able to help me out with persistence.

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  • Is it possible to create ICriteria/ICriterion from LINQ or HQL?

    - by adrin
    I am creating a method that can create filter understood by NHibernate (by filter i mean a set of ICriteria object for example) from my abstract filter object. public static IEnumerable<ICriterion> ToNhCriteria(this MyCriteria criteria) { // T4 generated function // lots of result.Add(Expression.Or(Expression.Eq(),Expression.Eq)) expression trees - hard to generate // Is there a way to generate HQL/Linq query here istead? } then i want to do something like session.CreateCriteria<Entity>().Add(myCriteria.ToNhCriteria()) to filter entities. The problem is that using Expression. methods (Expression.Or etc) is quite tedious (the method is generated and i have multiple or statements that have to be joined into an expression somehow). Is there a way to avoid using Expression.Or() and create ICrietrion / ICriteria using LINQ or HQL?

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  • Hos to group the complex list objects by using Linq

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

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  • LINQ - Contains with anonymous type

    - by Marlos
    When using this code (simplified for asking): var rows1 = (from t1 in db.TABLE1 where (t1.COLUMN_A == 1) select new { t1.COLUMN_B, t1.COLUMN_C }); var rows2 = (from t2 in db.TABLE2 where (rows1.Contains(t2.COLUMN_A)) select t2; I got the following error: The type arguments for method 'System.Linq.Enumerable.Contains(System.Collections.Generic.IEnumerable, TSource)' cannot be inferred from the usage. Try specifying the type arguments explicitly. I need to filter the first result by COLUMN_B, but I don't know how. Is there a way to filter it?

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  • Recursion with Func

    - by David in Dakota
    Is it possible to do recursion with an Func delegate? I have the following, which doesn't compile because the name of the Func isn't in scope... Func<long, long, List<long>, IEnumerable<long>> GeneratePrimesRecursively = (number, upperBound, primeFactors) => { if (upperBound > number) { return new List<long>(); } else { if (!primeFactors.Any(factor => number % factor == 0)) primeFactors.Add(number); return GeneratePrimesRecursively(++number, upperBound, primeFactors); // breaks here. } };

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  • Problem with ASP.NET MVC DropDownList not displaying selected value

    - by Jova
    I have an aspx page which allows me to edit articles. Among things I can edit is which category the article belongs to. The category is chosen through a DropDownList as shown here, <%= Html.DropDownList("categoryID", (IEnumerable<SelectListItem>)ViewData["CategoryID"], new { @class = "textbox" }) %> However, the articles category isn't selected when I go to that page. The ViewData I use for the DropDownList looks like this, ViewData["CategoryID"] = new SelectList(categories, "CategoryID", "Title", article.CategoryID); Which should select the article.CategoryID as it's selected value. Have I done this wrong?

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  • Cannot implicitly convert type System.Collection.Generic.IEnumberable

    - by Cen
    I'm receiving this error in my Linq statement --- Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'hcgames.ObjectClasses.ShoppingCart.ShoppingCartCartAddon'. An explicit conversion exists (are you missing a cast?) From this query ShoppingCartItems items = Cart.GetAllItems(); ShoppingCartCartAddons addons = Cart.GetAllAddons(); var stuff = from x in items select new ShoppingCartItem() { ProductID = x.ProductID, Quantity = x.Quantity, Name = x.Name, Price = x.Price, Weight = x.Weight, Addons = (from y in addons where y.ShoppingCartItemID == x.ID select y) }; I can not figure out how to cast this properly. Any suggestions? Thanks for your help!

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  • How to code a C# Extension method to turn a Domain Model object into an Interface object?

    - by Dr. Zim
    When you have a domain object that needs to display as an interface control, like a drop down list, ifwdev suggested creating an extension method to add a .ToSelectList(). The originating object is a List of objects that have properties identical to the .Text and .Value properties of the drop down list. Basically, it's a List of SelectList objects, just not of the same class name. I imagine you could use reflection to turn the domain object into an interface object. Anyone have any suggestions for C# code that could do this? The SelectList is an MVC drop down list of SelectListItem. The idea of course is to do something like this in the view: <%= Html.DropDownList("City", (IEnumerable<SelectListItem>) ViewData["Cities"].ToSelectList() )

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