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  • Generic Singleton Façade design pattern

    - by Paul
    Hi I try write singleton façade pattern with generics. I have one problem, how can I call method from generic variable. Something like this: T1 t1 = new T1(); //call method from t1 t1.Method(); In method SingletonFasadeMethod I have compile error: Error 1 'T1' does not contain a definition for 'Method' and no extension method 'Method' accepting a first argument of type 'T1' could be found (are you missing a using directive or an assembly reference?) Any advace? Thank, I am beginner in C#. All code is here: namespace GenericSingletonFasade { public interface IMyInterface { string Method(); } internal class ClassA : IMyInterface { public string Method() { return " Calling MethodA "; } } internal class ClassB : IMyInterface { public string Method() { return " Calling MethodB "; } } internal class ClassC : IMyInterface { public string Method() { return "Calling MethodC"; } } internal class ClassD : IMyInterface { public string Method() { return "Calling MethodD"; } } public class SingletonFasade<T1,T2,T3> where T1 : class,new() where T2 : class,new() where T3 : class,new() { private static T1 t1; private static T2 t2; private static T3 t3; private SingletonFasade() { t1 = new T1(); t2 = new T2(); t3 = new T3(); } class SingletonCreator { static SingletonCreator() { } internal static readonly SingletonFasade<T1,T2,T3> uniqueInstace = new SingletonFasade<T1,T2,T3>(); } public static SingletonFasade<T1,T2,T3> UniqueInstace { get { return SingletonCreator.uniqueInstace; } } public string SingletonFasadeMethod() { //Problem is here return t1.Method() + t2.Method() + t3.Method(); } } } I use this for my problem. public class SingletonFasade<T1, T2, T3> where T1 : class, IMyInterface, new() where T2 : class, IMyInterface, new() where T3 : class, IMyInterface, new() {//...} Is any solution without Interfaces ??

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  • Storing And Using Microsoft User Account Credentials in MS SQL Srv 2008 Database

    - by instantmusic
    I'm not exactly positive how to word this for the sake of the title so please forgive me. Also I can't seem to figure out how to even google this question, so I'm hoping that I can get a lead in the right direction. Part of my software(VB.NET App) requires the ability to access/read/write a shared network folder. I have an option for the user to specify any credentials that might be needed to access said folder. I want to store these credentials given in the MS SQL Database as part of the config(I have a table which contains configuration). My concern is that the password for the user account will be unencrpyted. Yet, if I encrypt the password the VB.NET App And/Or database will be unable to use the credentials for file i/o operations unless the Password is unencrypted before use. I'm fishing for suggestions on how to better handle this situation.

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  • how to listen for changes in Contact Database

    - by hap497
    Hi, I am trying to listen for any change in the contact database. So I create my contentObserver which is a child class of ContentObserver: private class MyContentObserver extends ContentObserver { public MyContentObserver() { super(null); } @Override public void onChange(boolean selfChange) { super.onChange(selfChange); System.out.println (" Calling onChange" ); } } MyContentObserver contentObserver = new MyContentObserver(); context.getContentResolver().registerContentObserver (People.CONTENT_URI, true, contentObserver); But When I use 'EditContactActivity' to change the contact database, My onChange function does not get called.

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  • Replicating MySQL DB to development machine - bad idea?

    - by Joel
    I am considering replicating a production MySQL database to my development machine so I've always got current data. The production database is externally hosted. My development machine is behind an unreliable internet connection. It is entirely possible that the development machine could be disconnected from the internet for extended periods of time (hours). Would there be any adverse effect on the production database by doing this? (I don't strictly need live data - but it would be nice, and good excuse to dabble with replication. If the consensus is that this is a bad idea, I'll set up a daily job to import the previous night's backup into my development database)

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  • Asynchronous event loop design and issues.

    - by Artyom
    Hello, I'm designing event loop for asynchronous socket IO using epoll/devpoll/kqueue/poll/select (including windows-select). I have two options of performing, IO operation: Non-blocking mode, poll on EAGAIN Set socket to non-blocking mode. Read/Write to socket. If operation succeeds, post completion notification to event loop. If I get EAGAIN, add socket to "select list" and poll socket. Polling mode: poll and then execute Add socket to select list and poll it. Wait for notification that it is readable writable read/write Post completion notification to event loop of sucseeds To me it looks like first would require less system calls when using in normal mode, especially for writing to socket (buffers are quite big). Also it looks like that it would be possible to reduce the overhead over number of "select" executions, especially it is nice when you do not have something that scales well as epoll/devpoll/kqueue. Questions: Are there any advantages of the second approach? Are there any portability issues with non-blocking operations on sockets/file descriptors over numerous operating systems: Linux, FreeBSD, Solaris, MacOSX, Windows. Notes: Please do not suggest using existing event-loop/socket-api implementations

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  • How should I store an Java Enum in JavaDB?

    - by Jonas
    How should I store an Java Enum in JavaDB? Should I try to map the enums to SMALLINT and keep the values in source code only? The embedded database is only used by a single application. Or should I just store the values as DECIMAL? None of these solutions feels good/robust for me. Is there any better alternatives? Here is my enum: import java.math.BigDecimal; public enum Vat { NORMAL(new BigDecimal("0.25")), FOOD(new BigDecimal("0.12")), BOOKS(new BigDecimal("0.06")), NONE(new BigDecimal("0.00")); private final BigDecimal value; Vat(BigDecimal val) { value = val; } public BigDecimal getValue() { return value; } } I have read other similar questions on this topic, but the problem or solution doesn't match my problem. Enum storage in Database field, Best method to store Enum in Database, Best way to store enum values in database - String or Int

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  • RESTful Design: Paging Collections

    - by Koen Bok
    I am designing a REST api that needs paging (per x) enforces from the server side. What would be the right way to page through any collection of resources: Option 1: GET /resource/page/<pagenr> GET /resource/tags/<tag1>,<tag2>/page/<pagenr> GET /resource/search/<query>/page/<pagenr> Option 2: GET /resource/?page=<pagenr> GET /resource/tags/<tag1>,<tag2>?page=<pagenr> GET /resource/search/<query>?page=<pagenr> If 1, what should I do with GET /resource? Redirect to /resource/page/0, reply with some error or reply with the exact same as /resource/page/0 without redirecting?

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  • aspnet_reqsql not working at all

    - by user252160
    I would like to create the ASP.NET User database template on a database of my own, because I'd like to fully untegrate the user system with the rest of my DB. As I've read, i needed to use the aspnet_regsql tool. I put all the options (because my database is running on SQLEXPRESS and is in an mdf file in my project's folder). the program starts and seemingly runs without any errors, however, when I open the database after that, not tables or stored procedures have been added. One more thing: I did one more test. I intentionally gave the -d option a wrong mdf file address, and surprisingly, the program "finished" correctly, yet no file was crated or modified whatsoever.

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  • C# Multithreaded Domain Design

    - by Thijs Cramer
    Let's say i have a Domain Model that im trying to make compatible with multithreading. The prototype domain is a game domain that consists of Space, SpaceObject, and Location objects. A SpaceObject has the Move method and Asteroid and Ship extend this object with specific properties for the object (Ship has a name and Asteroid has a color) Let's say i want to make the Move method for each object run in a seperate thread. That would be stupid because with 10000 objects, i would have 10000 threads. What would be the best way to seperate the workload between cores/threads? I'm trying to learn the basics of concurrency, and building a small game to prototype a lot of concepts. What i've already done, is build a domain, and a threading model with a timer that launches events based on intervals. If the event occurs i want to update my entire model with the new locations of any SpaceObject. But i don't know how and when to launch new threads with workloads when the event occurs. Some people at work told me that u can't update your core domain multithreaded, because you have to synch everything. But in that case i can't run my game on a dual quadcore server, because it would only use 1 CPU for the hardest tasks. Anyone know what to do here?

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  • Automatically deploying changes to a web application

    - by Adrian Pritchard
    What's the best way to automatically deploy changes to a database driven web application? Is there a single product out there that can modify the following... Website (dlls, aspx, css files etc) Database Schema (add tables, columns, etc) Database data (modify table contents) Reporting Services reports I've seen various separate products, but not one that does everything.

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  • How to migrate large amounts of data from old database to new

    - by adam0101
    I need to move a huge amount of data from a couple tables in an old database to a couple different tables in a new database. The databases are SQL Server 2005 and are on the same box and sql server instance. I was told that if I try to do it all in one shot that the transaction log would fill up. Is there a way to disable the transaction log per table? If not, what is a good method for doing this? Would a cursor do it? This is just a one-time conversion.

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  • Storing an image map in a database

    - by ColoradoRockie
    I have a requirement to allow users in a content management system to create their own image maps through a gui interface, which I have accomplished. But instead of saving the image map to the page code, I want to save the image map code to a database (sql), which I've also accomplished. When I started down this road in my head I was thinking the whole time that I'd just add the "usemap" attribute at runtime shown below where promo1.ImageMap holds the entire map code: if(promo1.HasImageMap) imgPromotion1.Attributes.Add("usemap", promo1.ImageMap); I guess I didn't think it though well enough, because it seems that "usemap" only expects the name of the existing map to use from the page code, and not the map code as a string. Does anyone have any clever ideas on how to apply the map from the database to the image at run time?

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  • Sorting the data returned by a database

    - by Rishabh Ohri
    hi all, In our project we have a requirement that when a set of records are returned by the database the records should be sorted with respect to the TITLE field in the record. The records will have to be sorted alphabetically but if the title of a record has a number in it then it should come after the records whose title only consists of alphabets. Details: we are using SQL Server , and c#. The data from the database comes to an Entity class whic forwards the data to other layers. So, What will be the possible and effective solution for this requirement.

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  • Resources for how to design graph/charts well

    - by wesgarrison
    One of my projects needs to show users where they rank in certain calculations. I inherited the graph structure from the previous programmer and had to leave it alone while I worked on other parts of the site. It's time to make the graphs more meaningful, so I'm looking for books/websites/etc about graphs. (Not graph theory!) Charts that convey comparisons at a glance. Everyone suggests The Visual Display of Quantitative Information by Edward Tufte and that's spot on for what I'm looking for, so anything related to that would be great. Naturally, personal experience about what to do or not would be helpful as well.

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  • error opening sql 2005 database in VS 2008

    - by Ken
    When I created my database using sql server 2005, i was able to connect and view it in Visual Studio 2008. I then detached the database onto my flash drive. Brought it home to work in VS 2008 - that worked. finally when i detached it from home and brought back to work, it will not open. It is saying that this version of sql server is not compatible with another version. I forget the exact wording of the error, as it was lengthy. any help you guys and provide would be very helpful! Thank you in advance!

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  • Inserting nil Values into Sqlite Database?

    - by Chris
    I am working on an iPhone App where I am pulling data from an XML file and inserting it into a sqlite database located in the App. I am able to successfully do this process, but it appears that if I try to sqlite3_bind_text with a NSString that has a value of "nil", the App quickly dies. This is an example of code that fails: (modified for this example) // idvar = 1 // valuevar = nil const char *sqlStatement = "insert into mytable (id, value) VALUES(?, ?)"; sqlite3_stmt *compiledStatement = nil; sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL); sqlite3_bind_int(compiledStatement, 1, [idvar intValue]);; sqlite3_bind_text(compiledStatement, 2, [valuevar UTF8String], -1, SQLITE_TRANSIENT);

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  • Connection Strings between Web Application and SQL Server

    - by Raven Dreamer
    Greetings. I'm writing a web application that is supposed to connect to a SQL Server database; the connection is formed from the following database string: <add key="DatabaseConnectionString" value="server=DEVPC1\SQLEXPRESS;uid=USERID;pwd=PASSWORD;database=DATABASE"/> However, whenever I try and run the web application, I get a connection error, specifically: An error occurred attempting this login: Login failed for user 'USERID'. Any suggestions on how to go about debugging this? I'm not really familiar with SQL, so any suggestions would be greatly appreciated.

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  • LINQ-to-SQL and SQL Compact - database file sharing problem

    - by Eye of Hell
    Hello. I'm learing LINQ-to-SQL right now and i have wrote a simple application that define SQL data: [Table( Name = "items" )] public class Item { [ Column( IsPrimaryKey = true, IsDbGenerated = true ) ] public int Id; [ Column ] public string Name; } I have launched 2 copy of application connected to the same .sdf file and tested if all database modifications in one application affects another application. But strange thing arise. If i use InsertOnSubmit() and DeleteOnSubmit() in one application, added/removed items are instantly visible in other application via 'select' LINQ queue. But if i try to modify 'Name' field in one application, it is NOT visible in other applicaton until it reconnects the database :(. The test code i use: var Items = from c in db.Items where Id == c.Id select c; foreach( var Item in Items ) { Item.Name = "new name"; break; } db.SubmitChanges(); Can anyone suggest what i'm doing wrong and why InsertOnSubmit()/DeleteOnSubmit works and SubmitChanges() don't?

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  • Multiprogramming in Django, writing to the Database

    - by Marcus Whybrow
    Introduction I have the following code which checks to see if a similar model exists in the database, and if it does not it creates the new model: class BookProfile(): # ... def save(self, *args, **kwargs): uniqueConstraint = {'book_instance': self.book_instance, 'collection': self.collection} # Test for other objects with identical values profiles = BookProfile.objects.filter(Q(**uniqueConstraint) & ~Q(pk=self.pk)) # If none are found create the object, else fail. if len(profiles) == 0: super(BookProfile, self).save(*args, **kwargs) else: raise ValidationError('A Book Profile for that book instance in that collection already exists') I first build my constraints, then search for a model with those values which I am enforcing must be unique Q(**uniqueConstraint). In addition I ensure that if the save method is updating and not inserting, that we do not find this object when looking for other similar objects ~Q(pk=self.pk). I should mention that I ham implementing soft delete (with a modified objects manager which only shows non-deleted objects) which is why I must check for myself rather then relying on unique_together errors. Problem Right thats the introduction out of the way. My problem is that when multiple identical objects are saved in quick (or as near as simultaneous) succession, sometimes both get added even though the first being added should prevent the second. I have tested the code in the shell and it succeeds every time I run it. Thus my assumption is if say we have two objects being added Object A and Object B. Object A runs its check upon save() being called. Then the process saving Object B gets some time on the processor. Object B runs that same test, but Object A has not yet been added so Object B is added to the database. Then Object A regains control of the processor, and has allready run its test, even though identical Object B is in the database, it adds it regardless. My Thoughts The reason I fear multiprogramming could be involved is that each Object A and Object is being added through an API save view, so a request to the view is made for each save, thus not a single request with multiple sequential saves on objects. It might be the case that Apache is creating a process for each request, and thus causing the problems I think I am seeing. As you would expect, the problem only occurs sometimes, which is characteristic of multiprogramming or multiprocessing errors. If this is the case, is there a way to make the test and set parts of the save() method a critical section, so that a process switch cannot happen between the test and the set?

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  • Load data from CSV to mySQL database Java+hibernate+spring

    - by mona
    I am trying to load a CSV file in to mySQL database using Java+Hibernate+Spring. I am using the following query in the DAO to help me load in to the database: entityManager.createQuery("LOAD DATA INFILE :fileName INTO TABLE test").setParameter("fileName", "C:\\samples\\test\\abcd.csv").executeUpdate(); I got some idea to use this from http://dev.mysql.com/doc/refman/5.1/en/load-data.html and how to import a csv file into a mysql from an hibernate+spring application? But I am getting the error: java.lang.IllegalArgumentException: node to traverse cannot be null! Please help! Thanks

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  • Unable to retrieve data from SQLite database iOS6.0

    - by kunalg
    When i run build ios5.0 or less then Sqlite response correct and retrieve data its work fine but when run on ios6.0 i am trying to fetch data from my.sqlite database but it is not executing my if case. It always enters in else condition. What wrong thing i am doing? I am not able to execute my if case i.e. if(sqlite3_prepare_v2(database, sqlQuerry, -1, &querryStatement, NULL)==SQLITE_OK). for reference check this code . NSLog(@"sqlite3_prepare_v2 = %d SQLITE_OK %d ",sqlite3_prepare_v2(sqlite, [strQuery UTF8String], -1, &compiledStatement, nil),SQLITE_OK); if(sqlite3_prepare_v2(sqlite, [strQuery UTF8String], -1, &compiledStatement, nil)==SQLITE_OK) { NSLog(@"sqlite3_step = %d SQLITE_ROW %d ",sqlite3_step(compiledStatement),SQLITE_ROW); while (sqlite3_step(compiledStatement)==SQLITE_ROW) { if(sqlite3_column_text(compiledStatement, 2) != nil) modelObj.Name = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)]; } } else { } ////////// in ios6.0 log Print sqlite3_prepare_v2 = 1 SQLITE_OK 0 sqlite3_step = 21 SQLITE_ROW 100 in iOS5.0 log Print sqlite3_prepare_v2 = 0 SQLITE_OK 0 sqlite3_step = 100 SQLITE_ROW 100

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