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• Database structure for ecommerce site

  - by imanc

  Hey Guys, I have been tasked with designing an ecommerce solution. The aspect that is causing me the most problems is the database. Currently the site consists of 10+ country based shops each with their own database (all residing on the same mysql instance). For the new site I'd rather all these shop databases be merged into one database so that all tables (products, orders, customers etc.) have a shop_id field. From a programming perspective this seems to make the most sense as we won't have to manage data across multiple databases. Currently the entire site generates about 120k orders a year, but is experiencing fairly heavy growth and we need to design a solution that will scale. In 5 years there may be more than a million orders per year and a database that contains 5 years order history (archiving maybe a solution here). The question is - do we use a single database, or do we keep the database-per-shop structure? I am currently trying to find supporting evidence for either avenue. The company I am designing the solution for prefer the per-shop database structure because they believe it will allow the sites to scale. But my argument is that the shop's database probably won't get that busy over the next few years that they exceed the capacity of a mysql database and a "no expenses spared" hardware set-up. I am wondering if anyone has any advice either way? Does anyone have experience with websites / ecommerce sites that have tables containing millions of records? I know there is probably not a clear answer here, but at what stage do we have too many records or too large table files to have a fast loading site? Also, if anyone has any advice on sources of information - books, websites, etc. where I can do further research, it would be highly appreciated! Cheers, imanc

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• Http authentication with apache httpcomponents

  - by matdan

  Hi, I am trying to develop a java http client with apache httpcomponents 4.0.1. This client calls the page "https://myHost/myPage". This page is protected on the server by a JNDIRealm with a login form authentication, so when I try to get https://myHost/myPage I get a login page. I tried to bypass it unsuccessfully with the following code : //I set my proxy HttpHost proxy = new HttpHost("myProxyHost", myProxyPort); //I add supported schemes SchemeRegistry supportedSchemes = new SchemeRegistry(); supportedSchemes.register(new Scheme("http", PlainSocketFactory .getSocketFactory(), 80)); supportedSchemes.register(new Scheme("https", SSLSocketFactory .getSocketFactory(), 443)); // prepare parameters HttpParams params = new BasicHttpParams(); HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1); HttpProtocolParams.setContentCharset(params, "UTF-8"); HttpProtocolParams.setUseExpectContinue(params, true); ClientConnectionManager ccm = new ThreadSafeClientConnManager(params, supportedSchemes); DefaultHttpClient httpclient = new DefaultHttpClient(ccm, params); httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy); //I add my authentication information httpclient.getCredentialsProvider().setCredentials( new AuthScope("myHost/myPage", 443), new UsernamePasswordCredentials("username", "password")); HttpHost host = new HttpHost("myHost", 443, "https"); HttpGet req = new HttpGet("/myPage"); //show the page ResponseHandler<String> responseHandler = new BasicResponseHandler(); String rsp = httpClient.execute(host, req, responseHandler); System.out.println(rsp); When I run this code, I always get the login page, not myPage. How can I apply my credential parameters to avoid this login form? Any help would be fantastic

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• NSDrawer delegate pointing to deallocated object?

  - by Isaac

  A user has sent in a crash report with the stack trace listed below (I have not been able to reproduce the crash myself, but every other crash this user has reported has been a valid bug, even when I couldn't reproduce the effect). The application is a reference-counted Objective-C/Cocoa app. If I am interpreting it correctly, the crash is caused by attempting to send a drawerDidOpen: message to a deallocated object. The only object that should be receiving drawerDidOpen: is the drawer's delegate object (nowhere does any object register to receive drawer notifications), and the drawer's delegate object is instantiated via the XIB/NIB file, wired to the delegate outlet of the drawer, and not referenced anywhere else. Given that, how can I protect against the delegate getting dealloc'd before the drawer notification? Or, alternately, what have I misinterpreted that might be causing the crash? Crash log/stack trace: Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000010 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Application Specific Information: objc_msgSend() selector name: drawerDidOpen: Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 libobjc.A.dylib 0x00007fff8272011c objc_msgSend + 40 1 com.apple.Foundation 0x00007fff87d0786e _nsnote_callback + 167 2 com.apple.CoreFoundation 0x00007fff831bcaea __CFXNotificationPost + 954 3 com.apple.CoreFoundation 0x00007fff831a9098 _CFXNotificationPostNotification + 200 4 com.apple.Foundation 0x00007fff87cfe7d8 -[NSNotificationCenter postNotificationName:object:userInfo:] + 101 5 com.apple.AppKit 0x00007fff8512e944 _NSDrawerObserverCallBack + 840 6 com.apple.CoreFoundation 0x00007fff831d40d7 __CFRunLoopDoObservers + 519 7 com.apple.CoreFoundation 0x00007fff831af8c4 CFRunLoopRunSpecific + 548 8 com.apple.HIToolbox 0x00007fff839b8ada RunCurrentEventLoopInMode + 333 9 com.apple.HIToolbox 0x00007fff839b883d ReceiveNextEventCommon + 148 10 com.apple.HIToolbox 0x00007fff839b8798 BlockUntilNextEventMatchingListInMode + 59 11 com.apple.AppKit 0x00007fff84de8a2a _DPSNextEvent + 708 12 com.apple.AppKit 0x00007fff84de8379 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 155 13 com.apple.AppKit 0x00007fff84dae05b -[NSApplication run] + 395 14 com.apple.AppKit 0x00007fff84da6d7c NSApplicationMain + 364 15 (my app's identifier) 0x0000000100001188 start + 52

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• How to change XmlSchemaElement.SchemaType (or: difference between SchemaType and ElementSchemaType)

  - by Gregor

  Hey, I'm working on a XML Editor which gets all his information from the corresponding XSD file. To work with the XSD files I use the System.Xml.Schema Namespace (XmlSchema*). Because of an 'xsi:type' attribute in the XML I've to change the XmlSchemaType of an XmlSchemaElement. Until now I use in my code the 'ElementSchemaType' property of 'XmlSchemaElement'. The nice thing about it: it's read only. There is also in 'XmlSchemaElement' an 'SchemaType' property which is not read only, but always null (yes, XmlSchema and XmlSchemaSet are compiled). So how can I change the type of the 'XmlSchemaElement'? Or, also the same question: What is the diffrence between this two porperties? Some technical data: C#, .NET 3.5 The MSDN documentation is nearly the same for both: SchemaType Documentation: Gets or sets the type of the element. This can either be a complex type or a simple type. ElementSchemaType Documentation: Gets an XmlSchemaType object representing the type of the element based on the SchemaType or SchemaTypeName values of the element.

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• barebones sort algorithm

  - by user309322

  i have been asked to make a simple sort aglorithm to sort a random series of 6 numbers into numerical order. However i have been asked to do this using "Barebones" a theoretical language put forward in the Book Computer Science an overview. Some information on the language can be found here http://www.brouhaha.com/~eric/software/barebones/ Just to clarify i am a student teacher and have been doing anaysis on "mini-programing languages" and their uses in a teaching environment, i suggested to my tutor that i look at barebones and asked what sort of exmaple program i should write . He suggested a simple sort algorithm. Now since looking at the language i cant understand how i can do this without using arrays and if statements. The code to swap the value of variables would be while a not 0 do; incr Aux1; decr a; end; while b not 0 do; incr Aux2 decr b end; while Aux1 not 0 do; incr a; decr Aux1; end; while Aux2 not 0 do; incr b; decr Aux2; end; however the language does not provide < or operators

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• C# Minimize all running windows when application runs

  - by Derek

  I am working on a C# windows form application. How can i edit my code in a way that when more than 2 faces is being detected by my webcam. More information: When "FaceDetectedLabel.Text = "Faces Detected : " + cam.facesdetected.ToString();" becomes Face Detected: 2 or more... How can i do the following: Minimize all program running except my application. Log out of my computer Here is my code: namespace PBD { public partial class MainPage : Form { //declaring global variables private Capture capture; //takes images from camera as image frames public MainPage() { InitializeComponent(); } private void ProcessFrame(object sender, EventArgs arg) { Wrapper cam = new Wrapper(); //show the image in the EmguCV ImageBox WebcamPictureBox.Image = cam.start_cam(capture).Resize(390, 243, Emgu.CV.CvEnum.INTER.CV_INTER_CUBIC).ToBitmap(); FaceDetectedLabel.Text = "Faces Detected : " + cam.facesdetected.ToString(); } private void MainPage_Load(object sender, EventArgs e) { #region if capture is not created, create it now if (capture == null) { try { capture = new Capture(); } catch (NullReferenceException excpt) { MessageBox.Show(excpt.Message); } } #endregion Application.Idle += ProcessFrame; }

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• Django + jquery : getting 301

  - by llazzaro

  Hello, I have tabs that calls via javascript urls of django to complete the "container" But i am getting 301, any idea why this is happening? Server misconfiguration? urls.py urlpatterns = patterns('', (r'^admin/', include(admin.site.urls)), (r'^list/', 'carsproj.cars.views.list'), ) view def list(request): if request.is_ajax(): return render_to_response('templates/generic_list.html', { 'items' : Cars.objects.all(), 'name' : 'List - Cars' }, context_instance = RequestContext(request)) javascript the_tabs.click(function(e){ var element = $(this); if(element.find('#overLine').length) return false; var bg = element.attr('class').replace('tab ',''); $('#overLine').remove(); $('<div>',{ id:'overLine', css:{ display:'none', width:element.outerWidth()-2, background:topLineColor[bg] || 'white' }}).appendTo(element).fadeIn('slow'); if(!element.data('cache')) { $('#contentHolder').html('<img src="/media/img/ajax_preloader.gif" width="64" height="64" class="preloader" />'); $.get(element.data('page'),function(msg){ $('#contentHolder').html(msg); element.data('cache',msg); }); } else $('#contentHolder').html(element.data('cache')); e.preventDefault(); }) Please tell me what more information you need, js code? template? url.py? I WILL EDIT THIS POST FOR ADD MORE DATA

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• Find and replace certain part of value (jquery)

  - by Hakan

  This might be a little complicated. See code below. When image is clicked I want to change "MY-ID-NUMBER" in "value" and "src" of object. But I want the other information to remain. When link is clicked I want to restore "value" and "src" so I can use the same function for next image that is clicked. Is it possible? Please help! My HTML: <img height="186" width="134" alt="4988" src="i123.jpg"> <img height="186" width="134" alt="4567" src="i124.jpg"> <a class="restore-to-default" href="#">DVD</a> <div class="tdt"> <object width="960" height="540"><param name="movie" value="http://www.domain.com/v3.4/player.swf?file=http://se.player-feed.domain.com/cinema/MY-ID-NUMBER/123-1/><param name="wmode" value="transparent" /><param name="allowFullScreen" value="true" /><param name="allowScriptAccess" value="always" /><embed id="player" name="player" type="application/x-shockwave-flash" src="http://www.player.domain.com/v3.4/player.swf?file=http://se.player-feed.domain.com/cinema/MY-ID-NUMBER/123-1/&display_title=over&menu=true&enable_link=true&default_quality=xxlarge&controlbar=over&autostart=true&backcolor=000000&frontcolor=ffffff&share=0&repeat=always&displayclick=play&volume=80&linktarget=_blank" width="960" height="540"allowFullScreen="true" allowScriptAccess="always"></embed></object> My jquery: $('img').click(function(){ var alt = $(this).attr("alt"); $('.tdt object').val("alt", alt); // Some how change "MY-ID-NUMBER" into the "alt-value" of image }); $('a').click(function(){ //restore to "MY-ID-NUMBER" }); Thanks!

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• How to organize and manage multiple database credentials in application?

  - by Polaris878

  Okay, so I'm designing a stand-alone web service (using RestLET as my framework). My application is divided in to 3 layers: Data Layer (just above the database, provides APIs for connecting to/querying database, and a database object) Object layer (responsible for serialization from the data layer... provides objects which the client layer can use without worrying about database) Client layer (This layer is the RestLET web service... basically just creates objects from the object layer and fulfills webservice request) Now, for each object I create in the object layer, I want to use different credentials (so I can sandbox each object...). The object layer should not know the exact credentials (IE the login/pw/DB URL etc). What would be the best way to manage this? I'm thinking that I should have a super class Database object in my data layer... and each subclass will contain the required log-in information... this way my object layer can just go Database db = new SubDatabase(); and then continue using that database. On the client level, they would just be able to go ItemCollection items = new ItemCollection(); and have no idea/control over the database that gets connected. I'm asking this because I am trying to make my platform extensible, so that others can easily create services off of my platform. If anyone has any experience with these architectural problems or how to manage this sort of thing I'd appreciate any insight or advice... Feel free to ask questions if this is confusing. Thanks! My platform is Java, the REST framework I'm using is RestLET, my database is MySQL.

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• How to format individual DropDownlist Items (color, etc.) during onDataBinding event

  - by LesterDove

  Hi, I have a basic DropDownList bound to a ObjectDataSource: <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="objDataSource1" DataTextField="FieldName" DataValueField="FieldID" /> The DataTable from which it receives the DataTextField and DataValueField values also returns some other interesting information about the records. Say Active = Y/N for simplicity's sake. What I'd like to do is to set the background-color property of the DropDownList Item based on that Active field in the DataSource results. Further, I'd like to do this "in the same pass" as when the DropDownList is bound to the data. So my guess is that it has to happen during OnDataBinding. Things I already know/tried: I could go back and loop through the DropDownList items later. But it would involve embedding loops and re-visiting the DataTable rows and it just seems inefficient int row; for (row = 0; row < DropDownList1.Items.Count - 1; row++) { [[if this row = that data row]] DropDownList1.Items[row].[[DoStuffHere, etc.]] } We already do stuff like this with the GridView OnRowDataBound event, by accessing the GridViewRowEventArgs e. What I seem to be missing is an "OnDropDownListItemBound" event, so to speak. Hope I've been clear and concise. Seems as though it should be easy...

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• increase number of photos from flickr using json

  - by Andrew Welch

  Hi this is my code: Is is possible to get more photos from flickr. What is the standard / default number? $(document).ready(function(){ $.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?id=48719970@N07&lang=en-us&format=json&jsoncallback=?", function(data){ $.each(data.items, function(i, item){ var newurl = 'url(' + item.media.m + ')'; $("<div class='images'/>").css('background', newurl).css('backgroundPosition','top center').css('backgroundRepeat','no-repeat').appendTo("#images").wrap("<a target=\"_blank\ href='" + item.link + "'></a>"); }) $("#title").html(data.title); $("#description").html(data.description); $("#link").html("<a href='" + data.link + "' target=\"_blank\">Visit the Viget Inspiration Pool!</a>"); //Notice that the object here is "data" because that information sits outside of "items" in the JSON feed $('.jcycleimagecarousel').cycle({ fx: 'fade', speed: 300, timeout: 3000, next: '#next', prev: '#prev', pause: 1, random: 1 }); }); });

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• Stop CDATA tags from being output-escaped when writing to XML in C#

  - by Smallgods

  We're creating a system outputting some data to an XML schema. Some of the fields in this schema need their formatting preserved, as it will be parsed by the end system into potentially a Word doc layout. To do this we're using <![CDATA[Some formatted text]]> tags inside of the App.Config file, then putting that into an appropriate property field in a xsd.exe generated class from our schema. Ideally the formatting wouldn't be out problem, but unfortunately thats just how the system is going. The App.Config section looks as follows: <header> <![CDATA[Some sample formatted data]]> </header> The data assignment looks as follows: HeaderSection header = ConfigurationManager.GetSection("header") as HeaderSection; report.header = "<[CDATA[" + header.Header + "]]>"; Finally, the Xml output is handled as follows: xs = new XmlSerializer(typeof(report)); fs = new FileStream (reportLocation, FileMode.Create); xs.Serialize(fs, report); fs.Flush(); fs.Close(); This should in theory produce in the final Xml a section that has information with CDATA tags around it. However, the angled brackets are being converted into &lt; and &gt; I've looked at ways of disabling Outout Escaping, but so far can only find references to XSLT sheets. I've also tried @"<[CDATA[" with the strings, but again no luck. Any help would be appreciated!

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• Reservation Solution for RealEstate integrating with Joomla

  - by Pennf0lio

  Hi, My client needs a Property (Just Land NO Houses) Reservation solution for their existing website (It runs in Joomla). I need some advice/Tips on what approach should I use. I'm looking for an Opensource solution that I can customize to my need. The Scenario: A buyer reserves a lot, A form appears gathers his details after that he/she pays for the reservation. FrontEnd: I need a form builder extension in Joomla that I could build custom form in gathering information (name, email, contact info, address...) from the buyer or the person who is reserving it. After I gather the info I need another extension that will handle the payment for reserving it. This is kinda shopping cart type approach, you see a product and the buy it. But would just need extra details. Backend: I can see all the details of the buyer from their name to the time they paid for a reservation. Thanks! P.S. I'm open to all Ideas. I'm not sure of this approach. Please let me know If you have some good Ideas or example.

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• Is this WPF error handling a good idea ?

  - by Adiel

  I have a multi threaded wpf application with various HW interfaces. I want to react to several HW failures that can happen. For example : one of the interfaces is a temperature sensor and i want that from a certain temp. a meesage would appear and notify the user that it happened. i came up with the follwing design : /// <summary> /// This logic reacts to errors that occur during the system run. /// The reaction is set by the component that raised the error. /// </summary> public class ErrorHandlingLogic : Logic { } the above class would consume ErrorEventData that holds all the information about the error that occurred. public class ErrorEventData : IEventData { #region public enum public enum ErrorReaction { } #endregion public enum #region Private Data Memebers and props private ErrorReaction m_ErrorReaction; public ErrorReaction ErrorReactionValue { get { return m_ErrorReaction; } set { m_ErrorReaction = value; } } private string m_Msg; public string Msg { get { return m_Msg; } set { m_Msg = value; } } private string m_ComponentName; public string ComponentName { get { return m_ComponentName; } set { m_ComponentName = value; } } #endregion Private Data Memebers and props public ErrorEventData(ErrorReaction reaction, string msg, string componenetName) { m_ErrorReaction = reaction; m_Msg = msg; m_ComponentName = componenetName; } } the above ErrorHandlingLogic would decide what to do with the ErrorEventData sent to him from various components of the application. if needed it would be forwarded to the GUI to display a message to the user. so what do you think is it a good design ? thanks, Adiel.

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• How to check if something is stored in CoreData

  - by Terrel Gibson

  Hi I want to be able to tore some information in core data and but i am unsure of how to check if the file was saved properly. I tried using NSLog but it returns null when its called. I have a dictionary which has a uniqueID and a title which I want to save. I pass this in along with the context of the database. I then sort the database to check if it has any duplicates or not, if not then I add the file. +(VacationPhoto*) photoWithFlickrInfo: (NSDictionary*) flickrInfo inManagedObjectContext: (NSManagedObjectContext*) context{ //returns the dictionary NSLog(@"Photo To Store =%@", flickrInfo); VacationPhoto * photo = nil; NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"VacationPhoto"]; request.predicate = [NSPredicate predicateWithFormat:@"uniqueID = %@", [flickrInfo objectForKey:FLICKR_PHOTO_ID]]; NSSortDescriptor * descriptor = [NSSortDescriptor sortDescriptorWithKey:@"title" ascending:YES]; request.sortDescriptors = [NSArray arrayWithObject:descriptor]; NSError *error = nil; NSArray *matches = [context executeFetchRequest:request error:&error]; if (!matches || [matches count] > 1) { // handle error } else if ( [matches count] == 0){ photo.title = [flickrInfo objectForKey:FLICKR_PHOTO_TITLE]; //Returns NULL when called NSLog(@"title = %@", photo.title); photo.uniqueID = [flickrInfo objectForKey:FLICKR_PHOTO_ID]; //Returns NULL when called NSLog(@"ID = %@", photo.uniqueID); } else { //If photo already exists this is called photo = [matches lastObject]; } return photo; }

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• .htaccess redirect or rewrite to default language url

  - by Saif Bechan

  I have a website that is currently in Dutch. Now I want to make the website multi-language starting with English. I am not that good at .htaccess files and the information on the web is quite confusing. The website I have now uses pretty urls, so all my urls look like this: http://mydomain.com/about/info http://mydomain.com/about/contact The code that I use for that is the following: <IfModule mod_rewrite.c> RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-l RewriteRule ^(.*)$ index.php?rt=$1 [L,QSA] </IfModule> I really do not know what this means, esp the [L,QSA]. But it's ok, it works for now. But now I want to add a default redirect to the code. So it becomes as follow http://mydomain.com becomes http://mydomain.com/nl I assume all my old links http://mydomain.com/about/info will not work anymore, but that is a step I am willing to take. Can someone please help me with this code. I have seen a lot of peaces of code, but I can not find the right one.

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• Can I commit changes to actual database while debugging C# in Visual Studio?

  - by nathant23

  I am creating a C# application using Visual Studio that uses an SQLExpress database. When I hit f5 to debug the application and make changes to the database I believe what is happening is there is a copy of the database in the bin/debug folder that changes are being made to. However, when I stop the debugging and then hit f5 the next time a new copy of the database is being put in the bin/debug folder so that all the changes made the last time are gone. My question is: Is there a way that when I am debugging the application I can have it make changes to the actual database and those changes are actually saved or will it only make changes to the copy in the bin/debug folder (if that is what is actually happening)? I've seen similar questions, but I couldn't find an answer that said if it's possible to make those changes persistent in the actual .mdf file. The reason I ask is because as I build this application I am continuously adding pieces and testing to make sure they all work together. When I put in test data I am using actual data that I would like to stay in the database. This would just help me not have to reenter the data later. Thanks in advance for any help or information that could help me better understand the process.

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• Can't use my form

  - by Alexandr

  I have class with my form in folder /application/forms/Auth.php it looks like class Form_Auth extends Zend_Form { public function __construct() { $this->setName(); parent::__construct(); $username = new Zend_Form_Element_Text('username'); $password = new Zend_Form_Element_Password('password'); $mail = new Zend_Form_Element_Text('mail'); $submit = new Zend_Form_Element_Submit('submit'); $this->addElements(array($username,$password,$mail,$submit)); } } When i try create object $this->view->form = new Form_Auth(); is see exeption Application error Exception information: Message: Invalid name provided; must contain only valid variable characters and be non-empty Stack trace: D:\WWW\zends\application\Forms\Auth.php(8): Zend_Form-setName() d:\WWW\zends\application\controllers\RegistrationController.php(49): Form_Auth-__construct() D:\WebServer\ZendFramework\ZendFramework\library\Zend\Controller\Action.php(513): RegistrationController-indexAction() D:\WebServer\ZendFramework\ZendFramework\library\Zend\Controller\Dispatcher\Standard.php(289): Zend_Controller_Action-dispatch('indexAction') D:\WebServer\ZendFramework\ZendFramework\library\Zend\Controller\Front.php(954): Zend_Controller_Dispatcher_Standard-dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http)) D:\WebServer\ZendFramework\ZendFramework\library\Zend\Application\Bootstrap\Bootstrap.php(97): Zend_Controller_Front-dispatch() D:\WebServer\ZendFramework\ZendFramework\library\Zend\Application.php(366): Zend_Application_Bootstrap_Bootstrap-run() D:\WWW\zends\public\index.php(26): Zend_Application-run() {main} Request Parameters: array ( 'controller' = 'registration', 'action' = 'index', 'module' = 'default', ) the version zf is 1.10.3 what i do wrong ?

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• C++ Declarative Parsing Serialization

  - by Martin York

  Looking at Java and C# they manage to do some wicked processing based on special languaged based anotation (forgive me if that is the incorrect name). In C++ we have two problems with this: 1) There is no way to annotate a class with type information that is accessable at runtime. 2) Parsing the source to generate stuff is way to complex. But I was thinking that this could be done with some template meta-programming to achieve the same basic affect as anotations (still just thinking about it). Like char_traits that are specialised for the different types an xml_traits template could be used in a declaritive way. This traits class could be used to define how a class is serialised/deserialized by specializing the traits for the class you are trying to serialize. Example Thoughs: template<typename T> struct XML_traits { typedef XML_Empty Children; }; template<> struct XML_traits<Car> { typedef boost::mpl::vector<Body,Wheels,Engine> Children; }; template<typename T> std::ostream& Serialize(T const&) { // my template foo is not that strong. // but somthing like this. boost::mpl::for_each<typename XML_Traits<T>::Children,Serialize>(data); } template<> std::ostream& Serialize<XML_Empty>(T const&) { /* Do Nothing */ } My question is: Has anybody seen any projects/decumentation (not just XML) out there that uses techniques like this (template meta-programming) to emulate the concept of annotation used in languges like Java and C# that can then be used in code generation (to effectively automate the task by using a declaritive style). At this point in my research I am looking for more reading material and examples.

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• Numerical calculations in Prolog

  - by user8472

  While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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• Ideas Needed for a Base Code System

  - by Tegan Snyder

  I've developed a PHP web application that is currently in need of a strategic restructuring. Currently when we setup new clients we give them the entire code base on a subdomain of our main domain and create a new table for them in the database. This results in each client having the entire codebase, meaning when we make bug changes, fixes we have to go back and apply them independently across all clients and this is a pain. What I'd like to create is a base code server that holds all the core PHP files. base.domain.com Then all of our clients (client.domain.com) will only need a few files: config.php would have the database connection information. index.php - displays the login box if session non-existant, otherwise it loads baseline code via remote includes to base.domain.com. My question is does my logic seem feasible? How do other people handle similar situations by having a base code? Also.... Is it even possbile to remotely include PHP files from base.domain.com and include them in client.domain.com? Thanks, Tegan

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• Java: Help constructing a fillTextFields() method

  - by Holly

  I have a Java project where I am to connect to a database and create buttons (next, new, save, delete, previous) to navigate through the database content where there are appropriate text fields and labels for the specific information. I'll use the code below as an example (each button is set up very similar)... I have it as follows: JButton jbtnNext = new JButton("Next ->"); jbtnNext.addActionListener(this); if (e.getSource() == jbtnNext) jbtnNext_Click(); private void jbtnNext_Click() { JOptionPane.showMessageDialog(null, "Next" ,"Button Pressed", JOptionPane.INFORMATION_MESSAGE); try { if (rset.next()) { fillTextFields(true); }else{ //Display result in a dialog box JOptionPane.showMessageDialog(null, "Not found"); } } catch (SQLException ex) { ex.printStackTrace(); } } The professor gave the following outline of logic to construct the fillTextFields() method: Construct the method to provide reusable code that would fill the JTextFields on the GUI with appropriate values from current record from the database (when "Previous or "Next" buttons are pressed) or blank values (when the new Button is pressed). To determine when the current record was to provide values (next and previous) or the value would be blank (new button) pass a boolean argument into the method. If data from the current record was to be used as fill values, pass true for both previous and next button code after moving the record pointer. If the new button was pressed and want to fill with blank values, pass false to the method. Inside the method, use a conditional expression to evaluate the boolean variable. If true, The appropriate get----() resultset method is used to fill the JTextFields. If false, fill them with "". The .setText() method of the JTextField is used to fill each JTextField. Make sure the fillTextFields method throws the appropriate exception. I understand and have the previous and next button methods passing true, while the new button method is passing false, but I don't quite understand how to set up the fillTextFields() method correctly or how to "throw the appropriate exception"... Any help would really be appreciated, thank you!

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• LINQ to SQL: Reusable expression for property?

  - by coenvdwel

  Pardon me for being unable to phrase the title more exact. Basically, I have three LINQ objects linked to tables. One is Product, the other is Company and the last is a mapping table Mapping to store what Company sells which products and by which ID this Company refers to this Product. I am now retrieving a list of products as follows: var options = new DataLoadOptions(); options.LoadWith<Product>(p => p.Mappings); context.LoadOptions = options; var products = ( from p in context.Products select new { ProductID = p.ProductID, //BackendProductID = p.BackendProductID, BackendProductID = (p.Mappings.Count == 0) ? "None" : (p.Mappings.Count > 1) ? "Multiple" : p.Mappings.First().BackendProductID, Description = p.Description } ).ToList(); This does a single query retrieving the information I want. But I want to be able to move the logic behind the BackendProductID into the LINQ object so I can use the commented line instead of the annoyingly nested ternary operator statements for neatness and re-usability. So I added the following property to the Product object: public string BackendProductID { get { if (Mappings.Count == 0) return "None"; if (Mappings.Count > 1) return "Multiple"; return Mappings.First().BackendProductID; } } The list is still the same, but it now does a query for every single Product to get it's BackendProductID. The code is neater and re-usable, but the performance now is terrible. What I need is some kind of Expression or Delegate but I couldn't get my head around writing one. It always ended up querying for every single product, still. Any help would be appreciated!

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• Initialize Static Array of Structs in C

  - by russell_h

  I implementing a card game in C. There are lots of types of cards and each has a bunch of information, including some actions that will need to be individually scripted associated with it. Given a struct like this (and I'm not certain I have the syntax right for the function pointer) struct CARD { int value; int cost; // This is a pointer to a function that carries out actions unique // to this card int (*do_actions) (struct GAME_STATE *state, int choice1, int choice2); }; I would like to initialize a static array of these, one for each card. I'm guessing this would look something like this int do_card0(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } int do_card1(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } extern static struct cardDefinitions[] = { {0, 1, do_card0}, {1, 3, do_card1} }; Will this work, and am I going about this the right way at all? I'm trying to avoid huge numbers of switch statements. Do I need to define the 'do_cardN' functions ahead of time, or is there some way to define them inline in the initialization of the struct (something like a lambda function in python)? I'll need read-only access to cardDefinitions from a different file - is 'extern static' correct for that? I know this is a lot of questions rolled into one but I'm really a bit vague about how to go about this. Thanks.

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• LDAP/AD Integrated Group/Membership Management Package suitable for embedding in an application

  - by Ernest

  In several web applications, it is often necessary to define groups of users for purposes of membership as well as role management. For example, in one of our applications we would like to user a group of "Network Engineers" and another group that consists of "Managers" of such Network Engineers. The information we need is contact details of members of each group. So far, we have written our own tools to allow the administrator of the application to add/delete/move groups and their memberships and either store them in a XML file or a database. Increasingly, companies already have the groups we want defined in LDAP/AD, so it would be best to create a pointer in our application to the correspoding group in LDAP. Although there are a number of LDAP libraries and LDAP browsers available and we could code this and provide a web front end to get a list of available groups and their members, we are wondering if there is already a "component framework" available that would readily provide this LDAP browsing functionality that we could just embed this into our application. Something between a library and a full LDAP browser product ? (To clarify, the use case is for an admin of our web application to create a locally relevant group name and then map it to an exiting LDAP group. To enable this in the UI, we would like to present a way for the admin to browse available groups in the company LDAP server, view their membership, and select the LDAP group they would like to map to the locally relevant group name. In a second step, we would then synchronize the members of that LDAP group and their contact details to a store in our application ) Appreciate any pointers.

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