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• Saving Abstract and Sub classes to database

  - by bretddog

  Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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• Singleton Properties

  - by coffeeaddict

  Ok, if I create a singleton class and expose the singleton object through a public static property...I understand that. But my singleton class has other properties in it. Should those be static? Should those also be private? I just want to be able to access all properties of my singleton class by doing this: MySingletonClass.SingletonProperty.SomeProperty2 Where SingletonProperty returns me the single singleton instance. I guess my question is, how do you expose the other properties in the singleton class..make them private and then access them through your public singleton static property?

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• Asp.Net MVC best way to update cached table

  - by Eddy Mishiyev

  There are certain tables that get called often but updated rarely. One of these tables is Departments. So to save DB trips, I think it is ok to cache this table taking into consideration that the table has very small size. However, once you cached it an issue of keeping the table data fresh occurs. So what is the best way to determine that the table is dirty and therefore requires a reload and how that code should be invoked. I look for solution that will be scalable. So updating the cache right after inserting will not work. So if one machine inserted the record all other on network should get notified to reload the cache. I was thinking for calling corresponding web service from T-SQL but don't really like the idea of consuming recourses on sql server. So what are the best practices to resolve this type of problems. Thanks in advance Eddy

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• Domain model: should things like Logging, Audit, Persistence be in it

  - by hom.tanks

  I'm having a hard time convincing our architect that a Domain model should only have the essential elements of the business domain on it. Things like the fact that a class is persistable, that it needs logging and auditing and that it has a RESTful URI should not drive the domain model. They can be added later on, by using interfaces. Ours is a healthcare information management system. At the very coarse level, its a system where users login and access their healthcare information. They can share this information with others and be custodian for others' information (think Roles). But because of a few sound bytes that caught on early like "Everything should be a REST resource" the model now has a top level class called Resource that every other class extends from. I'm trying to make him see that the domain model should have well defined concepts like User Account, HealthDocument, UserRole etc which are distinct entities of the business , with specific associations between them. Clubbing everything under Resource class lets our model be inflexible besides being potentially incorrect. But he wants me to show him why its a bad idea to do it his way. I don't know how to articulate that properly but all my OO instincts tell me that its just not right. Any thoughts?

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• Are these jobs for developer or designers or for client itself?

  - by jitendra

  Spell checking grammar checking Descriptive alt text for big chart , graph images, technical images To write Table summary and caption Descriptive Link text Color Contrast checking Deciding in content what should be H2 ,H3, H4... and what should be <strong> or <span class="boldtext"> Meta Description and keywords for each pages Image compression To decide Filenames for images,PDf etc To decide Page's <title> for each page

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• PHP: Best solution for links breaking in a mod_rewrite app

  - by psil

  I'm using mod rewrite to redirect all requests targeting non-existent files/directories to index.php?url=* This is surely the most common thing you do with mod_rewrite yet I have a problem: Naturally, if the page url is "mydomain.com/blog/view/1", the browser will look for images, stylesheets and relative links in the "virtual" directory "mydomain.com/blog/view/". Problem 1: Is using the base tag the best solution? I see that none of the PHP frameworks out there use the base tag, though. I'm currently having a regex replace all the relative links to point to the right path before output. Is that "okay"? Problem 2: It is possible that the server doesn't support mod_rewrite. However, all public files like images, stylesheets and the requests collector index.php are located in the directory /myapp/public. Normally mod_rewrite points all request to /public so it seems as if public was actually the root directory too all users. However if there is no mod_rewrite, I then have to point the users to /public from the root directory with a header() call. That means, however that all links are broken again because suddenly all images, etc. have to be called via /public/myimage.jpg Additional info: When there is no mod_rewrite the above request would look like this: mydomain.com/public/index.php/blog/view/1 What would be the best solutions for both problems?

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• Migration solution for singletons in an OSGI environment

  - by Ido

  I'm working in a JEE Environment in which each application is in a war file of its own. In the WEB-INF/lib of each application war file there is a common jar that is shared by all applications. This common jar contains several Singletons which are accessed from many points in the code. Because of the war-file boundaries each application has its own instances of the Singletons. Which is how we operate today, since we want to configure some of the singletons differently in each application. Now we are moving towards an OSGi environment, where this solution will no longer work since each bundle has its own class loader, so if I try to access MySingleton which resides in bundle "common.jar" from bundle "appA.jar" or from bundle "appB.jar" I will get the same instance. Remember I "want" a different instance of a singleton per bundle. (as ironic as it sounds) Now I realize the ideal solution would be to fix the code to not rely on those singletons, however due to a tight schedule I was wondering if you guys can suggest some sort of a migration solution that would allow me to use bundle-wide singletons so each of them could be configured per bundle.

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• What to name column in database table that holds versioning number

  - by rwmnau

  I'm trying to figure out what to call the column in my database table that holds an INT to specific "record version". I'm currently using "RecordOrder", but I don't like that, because people think higher=newer, but the way I'm using it, lower=newer (with "1" being the current record, "2" being the second most current, "3" older still, and so on). I've considered "RecordVersion", but I'm afraid that would have the same problem. Any other suggestions? "RecordAge"? I'm doing this because when I insert into the table, instead of having to find out what version is next, then run the risk of having that number stolen from me before I write, I just insert insert with a "RecordOrder" of 0. There's a trigger on the table AFTER INSERT that increments all the "RecordOrder" numbers for that key by 1, so the record I just inserted becomes "1", and all others are increased by 1. That way, you can get a person's current record by selection RecordOrder=1, instead of getting the MAX(RecordOrder) and then selecting that. PS - I'm also open to criticism about why this is a terrible idea and I should be incrementing this index instead. This just seemed to make lookups much easier, but if it's a bad idea, please enlighten me! Some details about the data, as an example: I have the following database table: CREATE TABLE AmountDue ( CustomerNumber INT, AmountDue DECIMAL(14,2), RecordOrder SMALLINT, RecordCreated DATETIME ) A subset of my data looks like this: CustomerNumber Amountdue RecordOrder RecordCreated 100 0 1 2009-12-19 05:10:10.123 100 10.05 2 2009-12-15 06:12:10.123 100 100.00 3 2009-12-14 14:19:10.123 101 5.00 1 2009-11-14 05:16:10.123 In this example, there are three rows for customer 100 - they owed $100, then $10.05, and now they owe nothing. Let me know if I need to clarify it some more. UPDATE: The "RecordOrder" and "RecordCreated" columns are not available to the user - they're only there for internal use, and to help figure out which is the current customer record. Also, I could use it to return an appropriately-ordered customer history, though I could just as easily do that with the date. I can accomplish the same thing as an incrementing "Record Version" with just the RecordCreated date, I suppose, but that removes the convenience of knowing that RecordOrder=1 is the current record, and I'm back to doing a sub-query with MAX or MIN on the DateTime to determine the most recent record.

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• index 'enabled' fields good idea?

  - by sibidiba

  Content of a website is stored in a MySQL database. 99% of the content will be enabled, but some (users, posts etc.) will be disabled. Most of the queries end as WHERE (...) AND enabled Is it a good idea to create an index on the field 'enabled'?

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• Some questions regarding Flex

  - by Rachel

  For what real time scenarios/use cases one should go to Flex Technology ? What real time problems you have solved using Flex Technology ? What real time problems have you faced because of using Flex Technology and what was your work around for that use case ?

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• Understanding MongoDB(and NoSQL in general) and How to make the best use of it

  - by Earlz

  Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have 3 collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is what if the author's name changed. You'd have to go through updating a ton of posts and comments. But is this an ok thing to do with NoSQL?

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• Dealing with dependencies between WCF services when using Castle Windsor

  - by Georgia Brown

  I have several WCF services which use castle windsor to resolve their dependencies. Now I need some of these services to talk to each other. The typical structure is service -- Business Logic -- DAL The calls to the other services need to occur at Business Logic level. What is the best approach for implementing this? Should I simply inject a service proxy into the business logic? Is this wasteful if for example, only one of two method from my service need to use this proxy? What if the services need to talk to each other? - Will castle windsor get stuck in a loop trying to resolve each services dependencies?

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• What's you're favorite pet language-feature that specifically aids in maintainable code?

  - by Ross Charette

  What's you're favorite pet language-feature that specifically aids in maintainable code?

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• c# - pull records from database without timeout

  - by BhejaFry

  Hi folks, i have a sql query with multiple joins & it pulls data from a database for processing. This is supposed to be running on some scheduled basis. So day 1, it might pull 500, day 2 say 400. Now, if the service is stopped for some reason & the data not processed, then on day3 there could be as much as 1000 records to process. This is causing timeout on the sql query. How best to handle this situation without causing timeout & gradually reducing workload to process? TIA

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• What do you choose, protected or internal?

  - by brickner

  If I have a class with a method I want protected and internal. I want that only derived classes in the assembly would be able to call it. Since protected internal means protected or internal, you have to make a choice. What do you choose in this case - protected or internal?

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• Risking the exception anti-pattern.. with some modifications

  - by Sridhar Iyer

  Lets say that I have a library which runs 24x7 on certain machines. Even if the code is rock solid, a hardware fault can sooner or later trigger an exception. I would like to have some sort of failsafe in position for events like this. One approach would be to write wrapper functions that encapsulate each api a: returnCode=DEFAULT; try { returnCode=libraryAPI1(); } catch(...) { returnCode=BAD; } return returnCode; The caller of the library then restarts the whole thread, reinitializes the module if the returnCode is bad. Things CAN go horribly wrong. E.g. if the try block(or libraryAPI1()) had: func1(); char *x=malloc(1000); func2(); if func2() throws an exception, x will never be freed. On a similar vein, file corruption is a possible outcome. Could you please tell me what other things can possibly go wrong in this scenario?

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• Start thread with two parameters

  - by Matt

  I've got a method that gets called on an event, which presents me with two variables varA, varB (both strings). This method gets called with new information quite frequently, thus I have created a separate method that takes in the two parameters. I want to run this method in a thread, however have struck the issue that Thread.Start will not accept parameters. I've tried a few supposed methods, but have so far had no luck.. I think my best bet is to create a separate class, and handle it there.. However I have a List which I am inserting data into, and hit a dead end when the separate class tried to access that list, since it was in a different class. Can someone help me out here please?

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• Is it okay to use try catch inside finally?

  - by Hiral Lakdavala

  Hi, I am using a buffered writer and my code, closes the writer in the finally block. My code is like this. ........... BufferedWriter theBufferedWriter = null; try{ theBufferedWriter =..... .... ...... ..... } catch (IOException anException) { .... } finally { try { theBufferedWriter.close(); } catch (IOException anException) { anException.printStackTrace(); } } I have to use the try catch inside the clean up code in finally as theBufferedWriter might also throw an IOException. I do not want to throw this exception to the calling methos. Is it a good practice to use a try catch in finally? If not what is the alternative? Please suggest. Regards, Hiral

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• Pros / Cons displaying list of users at login page

  - by Radu094

  We seem to have a lot of clients asking us to change the login screen in this manner: Display a list of all available users (thumbnail picture + name) User selects a username from the list A password prompt appears near the username User enters password then presses enter This sounds remarcably similar to the Windows XP login, which is probably where they got the ideea in the first place. There are only about 4 - 5 different users that can login at any given station, so implementing that list on one screen is feasable. So I was wondering if there are any usability experts with some word on this method of login. As far as I can tell, MS droped this behaviour in Vista/Win7, didn't they?

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• Two Tables Serving as one Model in Rails

  - by matsko

  Is is possible in rails to setup on model which is dependant on a join from two tables? This would mean that for the the model record to be found/updated/destroyed there would need to be both records in both database tables linked together in a join. The model would just be all the columns of both tables wrapped together which may then be used for the forms and so on. This way when the model gets created/updated it is just one form variable hash that gets applied to the model? Is this possible in Rails 2 or 3?

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• Do I have to create a static library to test my application?

  - by Christopher Gateley

  I'm just getting started with TDD and am curious as to what approaches others take to run their tests. For reference, I am using the google testing framework, but I believe the question is applicable to most other testing frameworks and to languages other than C/C++. My general approach so far has been to do either one of three things: Write the majority of the application in a static library, then create two executables. One executable is the application itself, while the other is the test runner with all of the tests. Both link to the static library. Embed the testing code directly into the application itself, and enable or disable the testing code using compiler flags. This is probably the best approach I've used so far, but clutters up the code a bit. Embed the testing code directly into the application itself, and, given certain command-line switches either run the application itself or run the tests embedded in the application. None of these solutions are particularly elegant... How do you do it?

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• ASP.NET MVC: post-redirect-get pattern, with only two overloaded action methods

  - by Rafi

  Is it possible to implement post-redirect-get pattern, with two overloaded action methods(One for GET action and the other for POST action) in ASP.NET MVC. In all of the MVC post-redirect-get pattern samples, I have seen three different action methods for the post-redirect-get process, each having different names. Is this really required? For Eg:(Does the code shown below, follows Post-Redirect-Get pattern?) public class SalaryTransferController : Controller { // // GET: /SalaryTransfer/ [HttpGet] public ActionResult Index(int id) { SalaryTransferIndexViewModel vm = new SalaryTransferIndexViewModel(id) { SelectedDivision = DivisionEnum.Contracting }; //Do some processing here return View(vm); } // // POST: /SalaryTransfer/ [HttpPost] public ActionResult Index(SalaryTransferIndexViewModel vm) { bool validationsuccess = false; //validate if (validationsuccess) return RedirectToAction("Index", new {id=1234 }); else return View(vm); } } Thank you for your responses.

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• Are frameworks using byte-code generation creating leaky abstractions?

  - by Gabriel Šcerbák

  My point is, if you don't understand the abstraction of a framework, you can still decompile it and understand it, because you know the language e.g. Java. However, when byte-code generation happens, you have to understand even a lower level - JVM level byte-codes. I am really affraid of using any of such frameworks, which are many. Most of the time I think the reason for byte-code generation is simply lack of language features such as metaprogramming. Do you agree? What is your opinion and argument? How do you take over the problem with leaky abstractions in those frameworks?

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• Delegates in Action -Help

  - by Amutha

  I am learning delegates.I am very curious to apply delegates to the following chain-of-responsibility pattern. Kindly help me the way to apply delegates to the following piece. Thanks in advance.Thanks for your effort. #region Chain of Responsibility Pattern namespace Chain { public class Player { public string Name { get; set; } public int Score { get; set; } } public abstract class PlayerHandler { protected PlayerHandler _Successor = null; public abstract void HandlePlayer(Player _player); public void SetupHandler(PlayerHandler _handler) { _Successor = _handler; } } public class Employee : PlayerHandler { public override void HandlePlayer(Player _player) { if (_player.Score <= 100) { MessageBox.Show(string.Format("{0} is greeted by Employee", _player.Name)); } else { _Successor.HandlePlayer(_player); } } } public class Supervisor : PlayerHandler { public override void HandlePlayer(Player _player) { if (_player.Score >100 && _player.Score<=200) { MessageBox.Show(string.Format("{0} is greeted by Supervisor", _player.Name)); } else { _Successor.HandlePlayer(_player); } } } public class Manager : PlayerHandler { public override void HandlePlayer(Player _player) { if (_player.Score > 200) { MessageBox.Show(string.Format("{0} is greeted by Manager", _player.Name)); } else { MessageBox.Show(string.Format("{0} got low score", _player.Name)); } } } } #endregion #region Main() void Main() { Chain.Player p1 = new Chain.Player(); p1.Name = "Jon"; p1.Score = 100; Chain.Player p2 = new Chain.Player(); p2.Name = "William"; p2.Score = 170; Chain.Player p3 = new Chain.Player(); p3.Name = "Robert"; p3.Score = 300; Chain.Employee emp = new Chain.Employee(); Chain.Manager mgr = new Chain.Manager(); Chain.Supervisor sup = new Chain.Supervisor(); emp.SetupHandler(sup); sup.SetupHandler(mgr); emp.HandlePlayer(p1); emp.HandlePlayer(p2); emp.HandlePlayer(p3); } #endregion

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• How to map to tables in database PHPMyAdmin

  - by thegrede

  I'm working now on a project which a user can save their own coupon codes on the websites, so I want to know what is the best to do that, Lets say, I have 1 table with the users, like this, userId | firstName | lastName | codeId and then I have a table of the coupon codes, like this, codeId | codeNumber So what I can do is to connect the codeId to userId so when someone saves the coupons goes the codeId from the coupon table into the codeId of the users table, But now what if when a user have multiple coupons what do I do it should be connected to the user? I have 2 options what to do, Option 1, Saving the codeId from coupons table into the codeId of users table like 1,2,3,4,5, Option 2 To make a new row into the coupons table and to connect the user to the code with adding another field in the coupon table userId and putting into it the user which has added the coupon his userId of the users table, So what of the two options is better to do? Thanks you guys.

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