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  • How do I avoid boxing/unboxing when extending System.Object?

    - by Robert H.
    I'm working on an extension method that's only applicable to reference types. I think, however, it's currently boxing and unboxing the the value. How can I avoid this? namespace System { public static class SystemExtensions { public static TResult GetOrDefaultIfNull<T, TResult>(this T obj, Func<T, TResult> getValue, TResult defaultValue) { if (obj == null) return defaultValue; return getValue(obj); } } } Example usage: public class Foo { public int Bar { get; set; } } In some method: Foo aFooObject = new Foo { Bar = 1 }; Foo nullReference = null; Console.WriteLine(aFooObject.GetOrDefaultIfNull((o) => o.Bar, 0)); // results: 1 Console.WriteLine(nullReference.GetOrDefaultIfNull((o) => o.Bar, 0)); // results: 0

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  • Dynamically add rows to listbox

    - by Ivan S
    I have a list box that displays information off of a column of a dataset. I would like the number of rows displayed to be all the rows that are in the dataset (the number of datasets in the rows vary). I'm figuring it has something to do with ListBox.Rows = Dataset.Tables[0].Rows.Count; But it seems to just always default to 4 even when it is only 2. This is what I have in my aspx.cs file. pirateBox.DataTextField = Pirateship.Tables[0].Columns["displayName"].ToString(); pirateBox.DataValueField = pirateship.Tables[0].Columns["PKID"].ToString(); pirateBox.DataSource = pirateship.Tables[0]; pirateBox.DataBind(); pirateBox.Rows = pirateship.Tables[0].Rows.Count; I've been trying a few things and this is what I have so far in .aspx <asp:ListBox ID="pirateBox" runat="server" Rows="1"></asp:ListBox>

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  • How can I (both) create a row and accessing that row in the same 'Stored Procedure'?

    - by Richard77
    Hello, I'd like to get the value of the id column for an object just after I've created it. But I don't want to run another query for that. My book for beginner (SQL Server 2008 for Dummies) says that there are 2 tables (inserted and deleted) that hold the last row(s) that have been inserted, updated, or deleted. Unfortunately, only Triggers (says the book) can access those tables. But, if I use triggers, they will go off each time I "insert" a row even when I don't need them that functionality. Can I obtain the same effect with a Store Procedure (without having to run a separate query?) This is what I'm trying to do CREATE PROCEDURE myProcedure DECLARE @OrganizationName @ColumnID OUTPUT AS INSERT INTO Organization (OrganizationName) VALUES (@OrganizationName) SET @ColumnID = (// Please, I need Help here ...) Thanks for helping

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  • How to insert null value for numeric field of a datatable in c#?

    - by Pandiya Chendur
    Consider My dynamically generated datatable contains the following fileds Id,Name,Mob1,Mob2 If my datatable has this it get inserted successfully, Id Name Mob1 Mob2 1 acp 9994564564 9568848526 But when it is like this it gets failed saying, Id Name Mob1 Mob2 1 acp 9994564564 The given value of type String from the data source cannot be converted to type decimal of the specified target column. I generating my datatable by readingt a csv file, CSVReader reader = new CSVReader(CSVFile.PostedFile.InputStream); string[] headers = reader.GetCSVLine(); DataTable dt = new DataTable(); foreach (string strHeader in headers) { dt.Columns.Add(strHeader); } string[] data; while ((data = reader.GetCSVLine()) != null) { dt.Rows.Add(data); } Any suggestion how to insert null value for numeric field during BulkCopy in c#... EDIT: I tried this dt.Columns["Mob2"].AllowDBNull = true; but it doesn't seem to work...

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  • Ideas for Quick Hierarchical Listing - .NET

    - by Robert
    I have a table in SQL Server listing corporate departments and their sections and subsections (3 levels). I would like to create some web-based listing of this, but similar to a TreeList. I was thinking to set up nested Ajax Accordions, but it was taking me way too long to put together. I would even settle for a GridView with non-repeating column values. Is there a way I can implement my idea without it taking me more than an hour or so for a newbie to complete? Any controls in ASP.NET or Ajax I can bind to would be great.

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  • How to make schema and code dynamic?

    - by Jonarch
    I want to make my database schema and application code as dynamic as possible to handle "unknown" use cases and changes. Developing in PHP and MySQL. Twice now I have had to change my entire schema including table and column names and this means the developers have to go back to the application code and modify all the SQL queries and table/columns names. So to prevent this I want to if just like we do on pages where we have page content, title bar etc dynamic like a %variable%, can we do it for the schema and maybe even for the php code functions and classes somehow? It takes weeks to re-do all changes like this vs if it is dynamic it can be done in under a day.

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  • R get rid of rows with duplicate attribute

    - by CatholicEvangelist
    hi there I have a big dataframe with columns such as: ID, time, OS, IP Each row of that dataframe corresponds to one entry. Within that dataframe for some IDs serveral entries (rows) exist. I would like to get rid of those multiple rows (obviously the other attributes will differ for the same ID). Or put different: I only want one single entry (row) for each ID. Could anyone be so kind and help me out on this one? When I use unique, on the ID column, I only recieve the levels (or each unique ID), but I want to keep the other attributes as well... I have tried to use apply(x,2,unique(data$ID)), but this does not work either... Any help is highly appreciated!

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  • SQL Server JOIN with optional NULL values

    - by Paul McLoughlin
    Imagine that we have two tables as follows: Trades ( TradeRef INT NOT NULL, TradeStatus INT NOT NULL, Broker INT NOT NULL, Country VARCHAR(3) NOT NULL ) CTMBroker ( Broker INT NOT NULL, Country VARCHAR(3) NULL ) (These have been simplified for the purpose of this example). Now, if we wish to join these two tables on the Broker column, and if a country exists in the CTMBroker table on the Country, we have the following two choices: SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND ISNULL(B.Country, T.Country) = T.Country or SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND (B.COUNTRY=T.Country OR B.Country IS NULL) These are both logically equivalent, however in this specific circumstance for our database (SQL Server 2008, SP1) two different execution plans are produced for these two queries with the second version significantly outperforming the first version in terms of both time and logical reads. My question really is as follows: as a general rule would (2) be preferred to (1), or does this just happen to be exploiting some particular idiosyncracy of the optimiser in 2008 SP1 (that could therefore change with future versions of SQL Server).

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  • Programatically find out a file type by looking its binary content. Possible?

    - by daemonkid
    I have a c# component that will recieve a file of the following types .doc, .pdf, .xls, .rtf These will be sent by the calling siebel legacy app as a filestream. So... [LegacyApp] {Binary file stream} [Component] The legacy app is a black box that cant be modified to tell the component what file type (doc,pdf,xls) it is sending. The component needs to read this binary stream and create a file on the filesystem with the right extension. Any ideas? Thanks for your time.

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  • mac, java 1.5: javax.mail not recognized as a jar file

    - by Helpme
    hello fellow java developers, Having a little issue with creating a java application on a macintosh computer (snow leopard). I've set up my application in eclipse, added all of the appropriate jar files, but for some reason the code is not recognizing some of my variables as valid types. I've imported the libraries via import javax.mail.*; import javax.mail.internet.*; These libraries are not recognized by the application. BUT I've put them on the build path! Any advice on how to fix this?

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  • Phonegap 2.1 for Android - Hello World App 3 errors at launch

    - by noway
    I developed something with Phonegap for iOS, but this is my first trial for Android. I created my hello world application with CLI sth like this mentioned here: $ /path/to/cordova-android/bin/create /path/to/my_new_cordova_project com.example.cordova_project_name CordovaProjectName Even though I created this app in Eclipse Workspace, I needed to import it to Eclipse. I created two AVDs. One for API level 8, one for API level 16. When I try to build, it gives me these three errors and a warning. What is wrong with my setup? Description Resource Path Location Type error: No resource identifier found for attribute 'hardwareAccelerated' in package 'android' AndroidManifest.xml /com.example.test.testprojectname line 20 Android AAPT Problem error: No resource identifier found for attribute 'xlargeScreens' in package 'android' AndroidManifest.xml /com.example.test.testprojectname line 22 Android AAPT Problem error: Error: String types not allowed (at 'configChanges' with value 'orientation|keyboardHidden|keyboard|screenSize|locale'). AndroidManifest.xml /com.example.test.testprojectname line 51 Android AAPT Problem The import android.app.Activity is never used testprojectname.java /com.example.test.testprojectname/src/com/example/test line 22 Java Problem

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  • Design pattern: polymorphisim for list of objects

    - by ziang
    Suppose I have a class A, and A1, A2 inherits from A. There are 2 functions: List<A1> getListA1(){...} List<A2> getListA2(){...} Now I want to do something similar to both A1 and A2 in another function public void process(List<A>){...} If I want to pass the instance of either ListA1 or ListA2, of course the types doesn't match because the compiler doesn't allow the coercion from List< A1 to List< A. I can't do something like this: List<A1> listA1 = getListA1(); List<A> newList = (List<A>)listA1; //this is not allowed. So what is the best approach to the process()? Is there any way to do it in a universal way rather than write the similar code to both List and List?

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  • Amazon EC2 prices for Windows Instance?

    - by Abhishek Gupta
    Hello Guys , I want to ask from some Amazon cloud technology Experts , that is it profitable to deploy our web application on amazon cloud as compared to normal server? Currently there are micro,small, large and other types of instances available , if we start from micro instance then we realize that our app needs some more CPU cycle and Ram then how can we dynamically move to next more powerful instance automatically at runtime. What is the approx minimum yearly cost for a single EC2 windows small instance? I wnat to deploy a simple Online quiz application (ASP.net based) on Amazon Cloud which at a time can have maximum of 500 users only. Please suggest me as I m very new to Cloud .Should I go for Azure or Amazon?

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  • C error expected specifier-qualifier-list before ‘time_t’

    - by ambika
    I got the error from error.c:31: /usr/include/ap/mas.h:254: error: expected specifier-qualifier-list before ‘time_t’ make: *** [error.o] Error 1 Feedback We at least need to see line 31 of error.c and line 254 of mas.h, with preferably a few lines of context around each. This error may have nothing to do with how time_t is being declared. – John Bode Then I check in error.c (line no 31) -- #include "mas.h" then I check line no 254 in mas.h. in mas.h #include <sys/types.h> typedef struct _x{ time_t time; }x; Can anybody suggest where I am going wrong?

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  • Shared WCF client code between .NET and Silverlight apps?

    - by Eduardo Scoz
    I'm developing a .NET application that will have both a WinForms and a Silverlight client. Although the majority of code will be in the server, I'll need to have quite a bit of logic in the clients as well, and I would like to keep the client library code the same. From what I could figure out so far, I need to have two different project types, a class library and a Silverlight class library, and link the files from one project to the other. This seems kind of lame, but it works for simple code. My problem, though, is that the code generated by the SVCUtil.exe to access WCF services is different from the code generated by the slsvcutil.exe, and the silverlight code is actually incompatible with the .NET one: I get a bunch of problems with the System.ServiceModel.Channel classes when I try to import the class into .NET. Has anybody done anything similar to this before? What am I doing wrong?

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  • Create or override Rails Active Record macros (

    - by Jocelyn
    In a Rails app, Active Record creates created_at and updated_at columns thank to macros, (it seems to be also called "magic columns"). See Active Record Migrations I have some questions about that mecanism: Is it possible to override that to get a third column (e.g. deleted_at) ? Is it possible to create a new macro t.publishing that will create publish_up and publish_down columns, for example? And where to code that? Obviously, I know I can add those columns manually, but I wonder how to achieve it with macros. Working on Rails 4.

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  • Can I serialize a BitArray to XML?

    - by SimonNet
    Hello I have a business class which I need to serialize to xml. It has a BitArray property. I have decorated it with [XmlAttribute] but the serialization is failing with To be XML serializable, types which inherit from ICollection must have an implementation of Add(System.Boolean) at all levels of their inheritance hierarchy. System.Collections.BitArray does not implement Add(System.Boolean). I am not sure whether its possible to serialize to xml? If not what would be an efficient means of serializing the BitArray Thanks for looking

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  • Can functions like sin() be redefined, in Fortran, C or Java?

    - by EOL
    Can a mathematical function like sin() be redefined, in Fortran, C or Java code, while preserving the default behavior of other mathematical functions like cos()? Or can another function named sin() but that accepts different argument types be defined in addition to the built-in sin()? I am interested in general features of these languages (I am thinking of applications like the implementation of non-usual number algebras). I tried to define a sin() function in a Fortran 95 program, but the intrinsic sin() function was called instead… Is there a way around this? what about C and Java?

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  • Regarding Standard Oxford Format for vlfeat sift

    - by Karl
    One of my upper classmen has gave me a data set for experimenting with vlfeat's SIFT, however, her extracted SIFT data for the frame part contains 5 dimensions. Recall from vl_sift function: [F,D] = VL_SIFT(I) Each column of D is the descriptor of the corresponding frame in F. F normally contains 4 dimensions which consists of x-coordinate, y-coordinate, scale, and orientation. So I asked her what is this 5th dimension, and she pointed me to search for "standard oxford format" for sift feature. The thing is I tried to search around regarding this standard oxford format and sift feature, but I got no luck in finding it at all. If somebody knows regarding this, could you please point me to the right direction?

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  • optimized grid for rectangular items

    - by peterchen
    I have N rectangular items with an aspect ratio Aitem (X:Y). I have a rectangular display area with an aspect ratio Aview The items should be arranged in a table-like layout (i.e. r rows, c columns). what is the ideal grid rows x columns, so that individual items are largest? (rows * colums = N, of course - i.e. there may be "unused" grid places). A simple algorithm could iterate over rows = 1..N, calculate the required number of columns, and keep the row/column pair with the largest items. I wonder if there's a non-iterative algorithm, though (e.g. for Aitem = Aview = 1, rows / cols can be approximated by sqrt(N)).

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  • Generic TypeIdenitifier convertion.How?

    - by John
    How do I convert the TypeIdenitifier to a class type? I need to use implicit convertion. type TMyChildArray<T>=class(TMyArray<T>) private FData:Array of T; procedure AddEnd(); end; TTypeIdenitifierParentClass=class(TAnotherParentClass) protected TestField:Cardinal; end; procedure TMyChildArray<T>.AddEnd(); var elem:T; begin for elem in Fdata do TTypeIdenitifierParentClass(elem).TestField:=0; end; I get "Invalid typecast" on the implicit convertion "TTypeIdenitifierParentClass(elem).TestField:=0;". The principle I want to use is that the TypeIdenitifier will represent a class that descends from TTypeIdenitifierParentClass.There are many class types,but all of them descend that class. How do I do this?

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  • Validation for selected row in JSF h:datatable

    - by Barun
    Hi all, I am having a tough time trying to find a solution to the following design related to h:dataTable. I have certain number of rows predisplayed. The first column is only checkboxes. The rest of the columns are disabled by default. On selecting a checkbox the elements in the corresponding rows get enabled. On submit of the for the values in the enabled row have to be validated on the server side. I am able to validate for invalid inputs but am not finding a method to use required="true" conditionally. Or any other method. Could anyone please help me on this. Thanks Barun

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  • Copy new records from datatable and identify changes in old records

    - by Betite
    Assume there are two tables: Remote_table and My_table. Remote_table has 6 columns: **PROJECT JOB_TYPE MONTH YEAR** HOURS IS_DELETED 134393 70 1 2013 30 0 134393 70 2 2013 50 0 134393 70 3 2013 80 0 134393 70 10 2012 10 0 134393 70 11 2012 0 0 134393 70 12 2012 15 0 My_table is a copy of remote_table. I tried to copy only the new records from the remote_table by this query: SELECT * FROM [remote_DB].[LudanProjectManager].[dbo].Remote_table EXCEPT SELECT * FROM My_table It works OK but I get a duplicate primary key exception when changes have been made on the remote_table on the hours column. Can anyone think of a way to copy only the new records from remote_table and if changes has been made on old records, to identify them and update the my_table to correspond?

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  • I don't see any stacktrace running webapp with JBoss

    - by anna
    hi everyone. I have some very annoying trouble with jboss. I'm developing simple web-app using richfaces and I'm facing the problem that when I deploy and run application in browser jboss shows just following message: This page contains the following errors: error on line 12 at column 16: internal error Below is a rendering of the page up to the first error. And that's all. No stacktrace! It's so uneasy to search for a source of problem. Could anyone help me to "turn on" stacktracing?

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  • Devise role based routing

    - by teknull
    I have an app with multiple users. Each user as a theoretical role (user, client, etc). I've designed a view/controller for each user type. I want to be able to login each type of user do a different root url and lock them to it. Originally I was going to add a column to Users in Devise called role and so I can differentiate the users. The problem I'm having is how to say in routes.rb if current_user.role == "client" root :to = 'controller#index' Once they are logged in to the page I also want to keep them from being able to visit any of my other paths ie: domain.com/calls domain.com/units I've been looking into cancan to run alongside Devise but I'm not sure if this is the answer.

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