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  • DefaultIfEmpty doesn't work

    - by Freshblood
    Why is array still null after queried by DefaultIfEmpty ? class Program { static void Main(string[] args) { Program[] array = new Program[5]; Program[] query = array.DefaultIfEmpty(new Program()).ToArray(); foreach (var item in query) { Console.WriteLine(item.ToString()); } Console.ReadKey(); } }

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  • An analog of String.Join(string, string[]) for List<T> or other generic enumerable

    - by abatishchev
    class String contains very useful method - String.Join(string, string[]). It creates a string from an array, separating each element of array with a symbol given. But general - it doesn't add a separator after the last element! I uses it for ASP.NET coding for separating with "<br />" or Environment.NewLine. So I want to add an empty row after each row in asp:Table. What method of IEnumerable<TableRow> can I use for the same functionality?

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  • Formatting a query to enumerate through 2 different datatables

    - by boiler1974
    I have 2 datatables sendTable and recvTable They both have identical column names and numbers of columns "NODE" "DSP Name" "BUS" "IDENT" "STATION" "REF1" "REF2" "REF3" "REF4" "REF5" "REF6" "REF7" "REF8" I need to compare these 2 tables and separate out the mismatches I only need to check Columns 3-11 and Ignore col 1 and 2 I tried at first removing the 2 columns and then loop thru row by row and return matches and mismatches but the problem with this approach is that I no longer have the "NODE" and "DSP Name" associated with the row when I finalize my results So I need help with a query Here is my attempt var samerecordQuery = from r1 in sendTable.AsEnumerable() where r1.Field<int>("BUS").Equals(from r2 in recvTable.AsEnumerable() where r2.Field<int>("BUS")) this obviously doesn't work so how do I format the query to say from r1 cols[3-11] equals r2 cols [3-11] and once I have this I can use the except to pull out the mismatches

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  • validate linqtosql mapping to a model

    - by Coppermill
    I have generated a LinqtoSQL mapping xml file, which I have a valid XSD schema that I check to make sure the XML is correct. Now I want to check that the field type match the Model/Interface for example: checking that the nullable fields are nullable that int are int etc anyone got any ideas if I can do this?

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  • Exceptions by DataContext

    - by Bas
    I've been doing some searching on the internet, but I can't seem to find the awnser. What exceptions can a DataContext throw? Or to be more specific, what exceptions does the DataContext.SubmitChanges() method throw?

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  • Transform Two Lists into One Different List

    - by Ngu Soon Hui
    I have two lists of double List<double> X List<double> Y And I have a destination object: public class PointD { public double X {get;set;} public double Y {get;set;} } How to transform them into a single list? public static List<PointD> Transform(List<double> X, List<double> Y) { } All the errors checking must be there.

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  • BindableAttribute, Combobox, Selectedvalue property - WinForms

    - by user63891
    I am deriving from combobox (WinForms) and am providing a new implementation for the Selectedvalue property. It works fine as is, but any change to the selectedvalue property is not updating other controls bound to the same "binding context" to change their values accordingly. I did try adding the BindableAttribute(true) to the property, but still it does nottrigger the change in value to the other linked controls. The control's DataBindings.add(...) is all set up. And other controls are also bound to the same data filed on the same datasource. Any ideas what i am doing wrong.

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  • How do I convert int? into int

    - by Richard77
    Hello, I've create a SPROC that saves an object and returns the id of the new object saved. Now, I'd like to return an int not an int? public int Save(Contact contact) { int? id; context.Save_And_SendBackID(contact.FirstName, contact.LastName, ref id); //How do I return an int instead of an int? } Thanks for helping

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  • What could possibly be different between the table in a DataContext and an IQueryable<Table> when do

    - by Nate Bross
    I have a table, where I need to do a case insensitive search on a text field. If I run this query in LinqPad directly on my database, it works as expected Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase") In my application, I've got a repository which exposes IQueryable objects which does some initial filtering and it looks like this var dc = new MyDataContext(); public IQueryable<Table> GetAllTables() { var ret = dc.Tables.Where(t => t.IsActive == true); return ret; } In the controller (its an MVC app) I use code like this in an attempt to mimic the LinqPad query: var rpo = new RepositoryOfTable(); var tables = rpo.GetAllTables(); // for some reason, this does a CASE SENSITIVE search which is NOT what I want. tables = tables.Where(tbl => tbl.Title.Contains("StringWithAnyCase"); return View(tables); The column is defiend as an nvarchar(50) in SQL Server 2008. Any help or guidance is greatly appreciated!

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  • Timeout LinqToSql inserting millions of records

    - by Bas
    I'm inserting approximently 3 million records in a database using this solution. Eventually when the application has been inserting records for a while (my last run lasted around 4 hours), it gives a timeout with the following SqlException: "SqlExcepetion: Timeout expired. The timeoutperiod elapsed prior to completion of the operation or the server is not responding." What's the best way to handle this exception? Is there a way to prevent this from happening or should I catch the exception? Thanks in advance!

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  • C# Entity Framework Base Repository

    - by Andy
    I'm trying to create a base repository for use with Entity Framework 4.0 and having some trouble. In this code below, why is it not possible to do this in one line? public IEnumerable<T> GetAll<T>(Expression<Func<T, bool>> filter) { IEnumerable<T> allCustomers = this.GetAll<T>(); IEnumerable<T> result = allCustomers.Where(filter.Compile()); return result; } Won't this result in 2 SQL statements: one without a where clause that retrieves all rows, and one with a where clause that only retrieves the rows that match the predicate? How can this be done with a single SQL statement? I can't get it to compile if I try to cast the filter.Compile() to Func<Customer, bool>. Thanks, Andy

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  • What is your favorite way to read XML files?

    - by stacker
    Let's take this xml structure as example: <?xml version="1.0" encoding="utf-8"?> <Configuration-content> <XFile Name="file name 1" /> <XFile Name="name2" /> <XFile Name="name3" /> <XFile Name="name4" /> </Configuration-content> C# interface to implement: public class Configuration { public XFile[] Files { get; set; } } public interface IConfigurationRipository { Configuration Get(); void Save(Configuration entity); } I wonder what's the best way to do that. The task is to implement IConfigurationRipository using your favorite approach.

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  • Will my LinqToSql execution be deffered if i filter with IEnumerable<T> instead of IQueryable<T>?

    - by cottsak
    I have been using these common EntityObjectFilters as a "pipes and filters" way to query from a collection a particular item with an ID: public static class EntityObjectFilters { public static T WithID<T>(this IQueryable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } public static T WithID<T>(this IList<T> list, int ID) where T : IEntityObject { return list.SingleOrDefault<T>(item => item.ID == ID); } } ..but i wondered to myself: "can i make this simpler by just creating an extension for all IEnumerable<T> types"? So i came up with this: public static class EntityObjectFilters { public static T WithID<T>(this IEnumerable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } } Now while this appears to yield the same result, i want to know that when applied to IQueryable<T>s will the expression tree be passed to LinqToSql for evaluating as SQL code or will my qry be evaluated in it's entirety first, then iterated with Funcs? I'm suspecting that (as per Richard's answer) the latter will be true which is obviously what i don't want. I want the same result, but the added benefit of the delayed SQL execution for IQueryable<T>s. Can someone confirm for me what will actually happen and provide simple explanation as to how it would work?

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  • Most efficient way to bind a Listbox with SelectionMode=Multiple

    - by Draak
    Hi, I have an ASP.NET webform that has a listbox (lbxRegions) with multi-select option enabled. In my db, I have a table with an xml field that holds a list of regions. I need to populate the listbox with all available regions and then "check off" the list items that match the regions in the db table. The list options also need to be ordered by region name. So, I wrote the following code that works just fine -- no problems. But I was wondering if anyone can think of a better (more succinct, more efficient) way to have done the same thing. Thanks in advance. Dim allRegions = XElement.Load(Server.MapPath(Request.ApplicationPath) & "\Regions.xml").<country>.<regions>.<region> Dim selectedRegions = (From ev In dc.Events Where ev.EventId = 2951).Single.CEURegions.<country>.<regions>.<region> Dim unselectedRegions = allRegions.Except(selectedRegions) Dim selectedItems = From x In selectedRegions Select New ListItem() _ With {.Value = x.@code, .Text = x.Value, .Selected = True} Dim unselectedItems = From x In unselectedRegions Select New ListItem() _ With {.Value = x.@code, .Text = x.Value} Dim allItems = selectedItems.Union(unselectedItems).OrderBy(Function(x) x.Text) lbxRegions.Items.AddRange(allItems.ToArray()) P.S. You can post code in C# if you like.

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  • ControlCollection extension method optimization

    - by Johan Leino
    Hi, got question regarding an extension method that I have written that looks like this: public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance) where T : class { T control; foreach (Control ctrl in instance) { if ((control = ctrl as T) != null) { yield return control; } foreach (T child in FindControlsOfType<T>(ctrl.Controls)) { yield return child; } } } public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance, Func<T, bool> match) where T : class { return FindControlsOfType<T>(instance).Where(match); } The idea here is to find all controls that match a specifc criteria (hence the Func<..) in the controls collection. My question is: Does the second method (that has the Func) first call the first method to find all the controls of type T and then performs the where condition or does the "runtime" optimize the call to perform the where condition on the "whole" enumeration (if you get what I mean). secondly, are there any other optimizations that I can do to the code to perform better. An example can look like this: var checkbox = this.Controls.FindControlsOfType<MyCustomCheckBox>( ctrl => ctrl.CustomProperty == "Test" ) .FirstOrDefault();

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  • Generate dynamic UPDATE command from Expression<Func<T, T>>

    - by Rui Jarimba
    I'm trying to generate an UPDATE command based on Expression trees (for a batch update). Assuming the following UPDATE command: UPDATE Product SET ProductTypeId = 123, ProcessAttempts = ProcessAttempts + 1 For an expression like this: Expression<Func<Product, Product>> updateExpression = entity => new Product() { ProductTypeId = 123, ProcessAttempts = entity.ProcessAttempts + 1 }; How can I generate the SET part of the command? SET ProductTypeId = 123, ProcessAttempts = ProcessAttempts + 1

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  • Which fieldtype is best for storing PRICE values?

    - by BerggreenDK
    Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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  • Linq2SQL InfoMessage

    - by Paul Oakham
    Hi, is it possible to access the InfoMessage event handler in a Linq2SQL data context? All of our code uses these messages to display useful information to the end user and since moving to Linq2SQL I cannot figure out how to show these messages. I have checked the connection object of the data context as well as the classes properties with no luck so I'm wondering if it is possible. Thanks in advance.

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  • Filter list as a parameter in a compiled query

    - by JK
    I have the following compiled query that I want to return a list of "groups" that don't have a "GroupID" that's contained in a filtered list: CompiledQuery.Compile(ConfigEntities contexty, List list) = from c in context.Groups where (!csList.Contains(c.GroupID)) select c).ToList() However I'm getting the following run-time error: The specified parameter 'categories' of type 'System.Collections.Generic.List`1[[System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c261364e126]]' is not valid. Only scalar parameters (such as Int32, Decimal, and Guid) are supported. Any ideas?

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  • What is the correct method to load an XML file and re-write it as a CVS? (C# Only)

    - by codesmack
    Hello, I have a XML file that I want to load into an unknown object type. (I say unknown object type because I am not sure what direction to go) Once I have the data loaded I need to do some processing on certain elements that are now loaded into the new object. For sake of example, we can say that the xml file is full of elements named and within the car element I need to process the element. Then once this is all done I need to write the file as a CSV file. I would like to do this is the most direct way possible. (The less code the better) I am using VS 2008 C# Thank you, CodeSmack

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  • Entity Framework 4 missing features?

    - by Roger Alsing
    I'm well aware that similair topics have been brought up before e.g. http://stackoverflow.com/questions/1639043/entity-framework-4-vs-nhibernate But instead of arguments like: NHibernate have been around longer and is more mature EF4 is drag n drop and not enterprisy EF4 and LinqToSql are ... I would like to see a more detailed list of features that you consider missing from EF4. Personally, I think the lack of enum support is the biggest drawback of EF4.

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  • Adding integer value to a list from XML file

    - by Pramodh
    I've an Xml file like <SampleFile> <Data> <Element Val="8" /> <Element Val="10" /> <Element Val="12" /> <Element Val="14" /> <Element Val="16" /> <Element Val="9" /> <Element Val="11" /> <Element Val="13" /> <Element Val="15" /> <Element Val="17" /> </Data> </SampleFile> i need to read the attribute value of" Val" and convert it to Int32 , then sort and then add to the list now i'm using like: List<Int32> lst = (XDocument.Load("\\Sample.xml").Descendants("Element").Select(l_Temp => l_Temp.Attribute("Val").Value.ToString()).Cast<Int32>().OrderBy(nTemp => nTemp)).ToList(); but its not working properly please give me a better solution

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  • How can I pass in a params of Expression<Func<T, object>> to a method?

    - by Pure.Krome
    Hi folks, I have the following two methods :- public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params string[] associations) { ... } public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params Expression<Func<T, object>>[] expressions) { ... } Now, when I try and pass in a params of Expression<Func<T, object>>[], it always calls the first method (the string[]' and of course, that value isNULL`) Eg. Expression<Func<Order, object>> x1 = x => x.User; Expression<Func<Order, object>> x2 = x => x.User.Passport; var foo = _orderRepo .Find() .IncludeAssociations(new {x1, x2} ) .ToList(); Can anyone see what I've done wrong? Why is it thinking my params are a string? Can I force the type, of the 2x variables?

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  • Need help with this basic Contains<>() extension method and Lambda expressions

    - by Polaris878
    Hi, Say I have the following class: class Foo { // ctor etc here public string Bar { get; } } Now, I have a LinkedList of Foos declared like so: LinkedList<Foo> How would I write a basic Contains<() for this? I want to be able to do this: Foo foo = new Foo(someString); LinkedList<Foo> list = new LinkedList<foo>(); // Populate list with Foos bool contains = list.Contains<Foo>(foo, (x => foo.Bar == x.Bar)); Am I trying to do this correctly? Thanks

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