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• What's the best way to store Logon User information for Web Application?

  - by Morgan Cheng

  I was once in a project of web application developed on ASP.NET. For each logon user, there is an object (let's call it UserSessionObject here) created and stored in RAM. For each HTTP request of given user, matching UserSessoinObject instance is used to visit user state information and connection to database. So, this UserSessionObject is pretty important. This design brings several problems found later: 1) Since this UserSessionObject is cached in ASP.NET memory space, we have to config load balancer to be sticky connection. That is, HTTP request in single session would always be sent to one web server behind. This limit scalability and maintainability. 2) This UserSessionObject is accessed in every HTTP request. To keep the consistency, there is a exclusive lock for the UserSessionObject. Only one HTTP request can be processed at any given time because it must to obtain the lock first. The performance and response time is affected. Now, I'm wondering whether there is better design to handle such logon user case. It seems Sharing-Nothing-Architecture helps. That means long user info is retrieved from database each time. I'm afraid that would hurt performance. Is there any design pattern for long user web app? Thanks.

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• What does it mean to pass a &variable to a function? E.g., string& insert ( size_t pos1, const strin

  - by Bob Montgomery

  I understand passing a pointer, and returning a pointer: char * strcat ( char * destination, const char * source ); You're passing a variable that contains the address to a char; returning the same. But what does it mean to pass something using the reference operator? Or to return it? string& insert ( size_t pos1, const string& str ); I mean, I understand what actually happens, I just don't understand the notation. Why isn't the notation this instead: string * insert ( size_t pos1, const string * str ); //made up I presume it has something to do with passing/returning the instance of a class, but what? Is this syntax valid; if not why not and if so what does it mean? char & strcat ( char & destination, const char & source ); //made up (all of the function declarations, except the last made-up two, are from http://www.cplusplus.com )

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• Run-time error 459 when using WithEvents with a class that implements another

  - by Ken Keenan

  I am developing a VBA project in Word and have encountered a problem with handling events when using a class that implements another. I define an empty class, IMyInterface: Public Sub Xyz() End Sub Public Event SomeEvent() And a class, MyClass that implements the above: Implements IMyInterface Public Event SomeEvent() Public Sub Xyz() ' ... code ... RaiseEvent SomeEvent End Sub Private Sub IMyInterface_Xyz() Xyz End Sub If I create a third class, OtherClass, that declares a member variable with the type of the interface class: Private WithEvents mMy As IMyInterface and try to initialize this variable with an instance of the implementing class: Set mMy = New MyClass I get a run-time error '459': This component doesn't support this set of events. The MSDN page for this error message states: "You tried to use a WithEvents variable with a component that can't work as an event source for the specified set of events. For example, you may be sinking events of an object, then create another object that Implements the first object. Although you might think you could sink the events from the implemented object, that isn't automatically the case. Implements only implements an interface for methods and properties." The above pretty much sums up what I'm trying to do. The wording, "that isn't automatically the case", rather than "this is flat-out impossible", seems to suggest that there is some bit of manual work I need to do to get it to work, but it doesn't tell me what! Does anybody know if this is possible in VBA?

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• How do actually castings work at the CLR level?

  - by devoured elysium

  When doing an upcast or downcast, what does really happen behind the scenes? I had the idea that when doing something as: string myString = "abc"; object myObject = myString; string myStringBack = (string)myObject; the cast in the last line would have as only purpose tell the compiler we are safe we are not doing anything wrong. So, I had the idea that actually no casting code would be embedded in the code itself. It seems I was wrong: .maxstack 1 .locals init ( [0] string myString, [1] object myObject, [2] string myStringBack) L_0000: nop L_0001: ldstr "abc" L_0006: stloc.0 L_0007: ldloc.0 L_0008: stloc.1 L_0009: ldloc.1 L_000a: castclass string L_000f: stloc.2 L_0010: ret Why does the CLR need something like castclass string? There are two possible implementations for a downcast: You require a castclass something. When you get to the line of code that does an castclass, the CLR tries to make the cast. But then, what would happen had I ommited the castclass string line and tried to run the code? You don't require a castclass. As all reference types have a similar internal structure, if you try to use a string on an Form instance, it will throw an exception of wrong usage (because it detects a Form is not a string or any of its subtypes). Also, is the following statamente from C# 4.0 in a Nutshell correct? Upcasting and downcasting between compatible reference types performs reference conversions: a new reference is created that points to the same object. Does it really create a new reference? I thought it'd be the same reference, only stored in a different type of variable. Thanks

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• jsf, richfaces, popup window

  - by Hubidubi

  Hi I would like to make a list-detail view with richfaces. There will be a link for every record in the list that should open a new window containing record details. I tried to implement the link this way: <a4j:commandLink oncomplete="window.open('/pages/serviceDetail.jsf','popupWindow', 'dependent=yes, menubar=no, toolbar=no, height=500, width=400')" actionListener="#{monitoringBean.recordDetail}" value="details" /> I use <a4j:keepAlive beanName="monitoringBean" ajaxOnly="false" /> for both the list and the detail page. recordDetail method fills the data of the selected record to a variable of the bean that I would like to display on the detail page. The problem is that keepalive doesn't work, so I get new bean instance on the detail page every time. So the the previously selected record from the other bean is not accessible here. Is there a way to pass parameter (id) to the detail page to handle record selection. Or is there any way to make keepalive work? (I this this would be the easiest). Thanks

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• Save Xml in an Excel cell value causes ComException

  - by mas_oz2k1

  I am trying to save an object (Class1) as string in a cell value. My issue is that from time to time I have a ComException: HRESULT: 0x8007000E (E_OUTOFMEMORY) (It is kind of random but I have not identified any particular pattern yet) when I write the value into a cell. Any ideas will be welcome For illustration purposes: Let Class1 be the class to be converted to an Xml string. (Notice that I removed the xml declaration at the start of the string to avoid having the preamble present- non printable character) <Class1 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" <ElementID HL690375</ElementID </Class1" Class1 myClass = new Class1(); this class is converted to a string s. s= ConvertObjectToXmlString(myClass); then s is assigned to a cell Range r = Application.ActiveCell; r.Value2 = s; Note: (1) If the string is too big, I limit it to 32000 chars and split the string in chunks of 32000 chars and save the chunks in multiple cells. (2) I do not to quote the string before adding to a cell. Do I need to? If so how it can be done? (3) All object contents are English. (4) C# code sample will be great but VB.net code is OK.

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• Clear tableView cell cache (or remove an entry)

  - by ManniAT

  Hi, I have the same question problem as described here http://stackoverflow.com/questions/2286669/iphone-how-to-purge-a-cached-uitableviewcell But my problem can't be solved with "resetting content". To be precise - I use a custom cell (own class). While running the application it is possible that I have to use a different "cell type". It's the same class - but it has (a lot of) differnt attributes. Of course I could always reset all the things at "PrepareForReuse" but that's not a good idea I guess (there are a lot things to reset). My idea - I do all these things in the constructor of the cell. And all the rows will use this "type of cell" later. When the (seldom) situation comes that I have to change the look of all rows I create a new instance of this kind of cell with different settings. And now I want to replace the queued cell with this new one. I tried it with simply calling the constructor with the same cellidentifier (in the hope it will replace the existing one) but that doesn't work. I also didn't find a "ClearReusableCells" or something like this. Is there a way to clear the cache - or to remove / replace a specific item? Manfred

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• Subversion commands not being run by Ubuntu rc.local

  - by talentedmrjones

  Here is my rc.local for an autoscaling amazon ec2 instance based on ubuntu: (Note that user names, domains, and paths have been changed for security purposes) logger "Begin rc.local startup script:" logger "svn checkout" sudo -u nonRootUser /usr/bin/svn co svn+ssh://[email protected]/path/to/repo /var/www/html | logger logger "chown writeable folder" chown www-data /var/www/html/writeableFolder logger "restart apache" /etc/init.d/apache2 restart | logger exit 0 And here is the output of sudo tail -n 40 /var/log/syslog Mar 10 22:05:20 ubuntu logger: Begin rc.local startup script: Mar 10 22:05:20 ubuntu logger: svn checkout Mar 10 22:05:20 ubuntu logger: chown writeable folder Of course its not getting to apache2 restart because it error'd on the chown. I did find however that if I do a checkout beforehand, and set the rc.local svn command to an svn update, that it still does not run the svn command but does output apache2 restart successfully. These same svn commands work perfectly when I run them manually, tho it's strange that within rc.local they do not produce any output whatsoever to logger yet apache2 restart does. I've also tried running the svn co and svn update both with sudo -u and without. How do I get the svn command to run? Either a full checkout or an update. At this point either would be better than nothing!

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• ASP.NET MVC - Wrong redirecting, how to debug?

  - by Xorty

  I am stuck with redirecting problem in ASP.NET MVC project. I have mapped tables via LINQtoSQL and each has unique ID as primary key. I am implementing functionallity of 'CREATE'. Basically, after new value is added into SQL table (which means I pressed Save button), I want to be redirected to Details of this freshly added item. Here's little code how I am doing it : [AcceptVerbs(HttpVerbs.Post), Authorize] public ActionResult Create(Item item) { .... return RedirectToAction("Details", new { id = item.ItemID }); Trouble is, I am never redirected to Details view (I have Details.aspx view for items). When I check CallHierarchy in Visual Studio (2010 pro) the hierarchy is indeed little strange, like this : RedirectToAction(string,object) Calls To 'RedirectToAction' Create Calls To Create (no results) Calls From Create (methods of created instance. From there I'll get back to 'RedirectToAction' and to 'Calls to Create' and 'Calls From Create' etc. etc. - loop Edit Calls From 'RedirectToAction' Not supported I am looking for some tools or more specifically 'know how' (since VS probably has some tools) to debug this kind of situations. PS: rooting is default :"{controller}/{action}/{id}", Thanks

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• passing an "unknown enumeration" to a method

  - by firoso

  I'm currently trying to make a class that can register strings as identifiers and accociate them with different types of Enumerations, these enumerations are being evaluated only in so much that I am ensuring that when it's used, that the parameter passed to broadcast (messageType) is an instance of the associated Enum Type. This would work something like this: Diagnostics.RegisterIdentifier("logger", typeof(TestEnum)); Diagnostics.Broadcast("logger", TestEnum.Info, null, "Hello World", null); here's the code I currently have, I need to be able to verify that messageTypesEnum is contained in messageTypesFromIdentifier. private static Dictionary<string, Type> identifierMessageTypeMapping = new Dictionary<string, Type>(); private static List<IListener> listeners = new List<IListener>(); public static void RegisterIdentifier(string identifier, Type messageTypesEnum) { if (messageTypesEnum.BaseType.FullName == "System.Enum") { identifierMessageTypeMapping.Add(identifier, messageTypesEnum); } else { throw new ArgumentException("Expected type of messageTypesEnum to derive from System.Enum", "messageTypesEnum"); } } public static void Broadcast(string identifier, object messageType, string metaIdentifier, string message, Exception exception) { if (identifierMessageTypeMapping.ContainsKey(identifier)) { Type messageTypesFromIdentifier = identifierMessageTypeMapping[identifier]; foreach (var listener in listeners) { DiagnosticsEvent writableEvent = new DiagnosticsEvent(identifier, messageType, metaIdentifier, message, exception); listener.Write(writableEvent); } } }

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• Regarding the ViewModel

  - by mizipzor

  Im struggling to understand the ViewModel part of the MVVM pattern. My current approach is to have a class, with no logic whatsoever (important), except that it implements INotifyPropertyChanged. The class is just a collection of properties, a struct if you like, describing an as small part of the data as possible. I consider this my Model. Most of the WPF code I write are settings dialogs that configure said Model. The code-behind of the dialog exposes a property which returns an instance of the Model. In the XAML code I bind to subproperties of that property, thereby binding directly to the Model's properties. Which works quite well since it implements the INotifyPropertyChanged. I consider this settings dialog the View. However, I havent really been able to figure out what in all this is the ViewModel. The articles Ive read suggests that the ViewModel should tie the View and the Model together, providing the logic the Model lacks but is still to complex to go directly into the View. Is this correct? Would, in my example, the code-behind of the settings dialog be considered the ViewModel? I just feel a bit lost and would like my peers to debunk some of my assumptions. Am I completely off track here?

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• UILabel + IRR, KRW and KHR currencies with wrong symbol

  - by serb

  Hi, I'm experiencing issues when converting decimal to currency for Korean Won, Cambodian Riel and Iranian Rial and showing the result to the UILabel text. Conversion itself passes just fine and I can see correct currency symbol at the debugger, even the NSLog prints the symbol well. If I assign this NSString instance to the UILabel text, the currency symbol is shown as a crossed box instead of the correct symbol. There is no other code between, does not matter what font I use. I tried to print ? (Korean Won) using the unicode value (0x20A9) or even using UTF8 representation (\xe2\x82\xa9), but all I get is the crossed box on the label. Any other supported currency in iPhone SDK and NSLocale (nearly 170 currencies) works perfectly fine no matter how exotic the currency is. Anyone else experiencing the same problem? Is there a "cure" for this? Thanks EDIT: -(NSString *)decimalToCurrency:(NSDecimalNumber *)value byLocale:(NSLocale *)locale { NSNumberFormatter *fmt = [[NSNumberFormatter alloc] init]; [fmt setLocale: locale]; [fmt setNumberStyle: NSNumberFormatterCurrencyStyle]; NSString *res = [fmt stringFromNumber: value]; [fmt release]; return res; } lbValue.text = [self decimalToCurrency: price byLocale: koreanLocale];

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• pulling a value from NSMutableDictionary

  - by Jared Gross

  I have a dictionary array with a key:@"titleLabel". I am trying to load a pickerView with ONE instance of each @"titleLabel" key so that if there are multiple objects with the same @"titleLabel" only one title will be displayed. I've done some research on this forum and looked at apples docs but haven't been able to put the puzzle together. Below is my code but I am having trouble pulling the values. Right now when I run this code it throws an error Incompatible pointer types sending 'PFObject *' to parameter of type 'NSString' which i understand but am just not sure how to remedy. Cheers! else { // found messages! self.objectsArray = objects; NSMutableDictionary *dict = [[NSMutableDictionary alloc] init]; for(id obj in self.objectsArray){ PFObject *key = [self.objectsArray valueForKey:@"titleLabel"]; if(![dict objectForKey:@"titleLabel"]){ [dict setValue:obj forKey:key]; } } for (id key in dict) { NSLog(@"Objects array is %d", [self.objectsArray count]); NSLog(@"key: %@, value: %@ \n", key, [dict objectForKey:key]); } [self.pickerView reloadComponent:0]; } }];` Here is where I define the PFObject and keys: PFObject *image = [PFObject objectWithClassName:@"Images"]; [image setObject:file forKey:@"file"]; [image setObject:fileType forKey:@"fileType"]; [image setObject:title forKey:@"titleLabel"]; [image setObject:self.recipients forKey:@"recipientIds"]; [image setObject:[[PFUser currentUser] objectId] forKey:@"senderId"]; [image setObject:[[PFUser currentUser] username] forKey:@"senderName"]; [image saveInBackground];

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• Blackberry (Java) - Can't get KeyListener to work

  - by paullb

  I am trying to get the KeyListener working for Blackberry, but none of the Dialogs pop up indicating that a key has been pressed (see code below, each action has a dialog popup in them). Any ideas on what i might be doing wrong? public class CityInfo extends UiApplication implements KeyListener { static CityInfo application; public static void main(String[] args) { //create a new instance of the application //and start the application on the event thread application.enterEventDispatcher(); } public CityInfo() { //display a new screen application = new CityInfo(); pushScreen(new WorkflowDisplayScreen()); this.addKeyListener(this); } public boolean keyChar(char arg0, int arg1, int arg2) { // TODO Auto-generated method stub Dialog.alert("key pressed : " + arg0); return true; } public boolean keyDown(int keycode, int time) { // TODO Auto-generated method stub Dialog.alert("keyDown : " + keycode); return false; } public boolean keyRepeat(int keycode, int time) { // TODO Auto-generated method stub Dialog.alert("keyRepeat : " + keycode); return false; } public boolean keyStatus(int keycode, int time) { // TODO Auto-generated method stub Dialog.alert("keyStatus : " + keycode); return false; } public boolean keyUp(int keycode, int time) { Dialog.alert("keyUp : " + keycode); // TODO Auto-generated method stub return false; } } I also tried implementing keyChar on the MainScreen class but that did not yield any results either.

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• Fastest XML parser for small, simple documents in Java

  - by Varkhan

  I have to objectify very simple and small XML documents (less than 1k, and it's almost SGML: no namespaces, plain UTF-8, you name it...), read from a stream, in Java. I am using JAXP to process the data from my stream into a Document object. I have tried Xerces, it's way too big and slow... I am using Dom4j, but I am still spending way too much time in org.dom4j.io.SAXReader. Does anybody out there have any suggestion on a faster, more efficient implementation, keeping in mind I have very tough CPU and memory constraints? [Edit 1] Keep in mind that my documents are very small, so the overhead of staring the parser can be important. For instance I am spending as much time in org.xml.sax.helpers.XMLReaderFactory.createXMLReader as in org.dom4j.io.SAXReader.read [Edit 2] The result has to be in Dom format, as I pass the document to decision tools that do arbitrary processing on it, like switching code based on the value of arbitrary XPaths, but also extracting lists of values packed as children of a predefined node. [Edit 3] In any case I eventually need to load/parse the complete document, since all the information it contains is going to be used at some point. (This question is related to, but different from, http://stackoverflow.com/questions/373833/best-xml-parser-for-java )

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• LINQ-to-XML Error "is not a member of 'String'"

  - by mmcglynn

  The following code returns the error from the For Each loop. I have similar code that does not return the error. 'DisplayTitle' is not a member of 'Sting' Dim evXML As XDocument = XDocument.Load(Server.MapPath("~/App_Data/event.xml")) Dim sbEventDetail As New StringBuilder() Dim summary = _ From sum In evXML.<root>.Elements() _ Select sum...<DisplayTitle>.Value For Each item In summary sbEventDetail.Append("<h4>" & item.DisplayTitle & "</h4>") Next The XML: <root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <StartTime>2010-03-05T16:00:00</StartTime> <EndTime>2010-03-06T02:00:00</EndTime> <Duration>10:00:00</Duration> <DisplayTitle>MARCH MADNESS</DisplayTitle> <Location>565 Main St</Location> <IsAllDay>False</IsAllDay> <Recurrence> <OriginatingTimeZone>Eastern Standard Time</OriginatingTimeZone> <RecurrenceType>0</RecurrenceType> <RecurrenceEndDate>9999-12-31T23:59:59</RecurrenceEndDate> </Recurrence> <IsVariance>False</IsVariance> <IsCancelled>False</IsCancelled> <OriginalStart>0001-01-01T00:00:00</OriginalStart> </root>

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• grailsApplication access in Grails unit Test

  - by Reza

  I am trying to write unit tests for a service which use grailsApplication.config to do some settings. It seems that in my unit tests that service instance could not access the config file (null pointer) for its setting while it could access that setting when I run "run-app". How could I configure the service to access grailsApplication service in my unit tests. class MapCloudMediaServerControllerTests { def grailsApplication @Before public void setUp(){ grailsApplication.config= ''' video{ location="C:\\tmp\\" // or shared filesystem drive for a cluster yamdi{ path="C:\\FFmpeg\\ffmpeg-20121125-git-26c531c-win64-static\\bin\\yamdi" } ffmpeg { fileExtension = "flv" // use flv or mp4 conversionArgs = "-b 600k -r 24 -ar 22050 -ab 96k" path="C:\\FFmpeg\\ffmpeg-20121125-git-26c531c-win64-static\\bin\\ffmpeg" makethumb = "-an -ss 00:00:03 -an -r 2 -vframes 1 -y -f mjpeg" } ffprobe { path="C:\\FFmpeg\\ffmpeg-20121125-git-26c531c-win64-static\\bin\\ffprobe" params="" } flowplayer { version = "3.1.2" } swfobject { version = "" qtfaststart { path= "C:\\FFmpeg\\ffmpeg-20121125-git-26c531c-win64-static\\bin\\qtfaststart" } } ''' } @Test void testMpegtoFlvConvertor() { log.info "In test Mpg to Flv Convertor function!" def controller=new MapCloudMediaServerController() assert controller!=null controller.videoService=new VideoService() assert controller.videoService!=null log.info "Is the video service null? ${controller.videoService==null}" controller.videoService.grailsApplication=grailsApplication log.info "Is grailsApplication null? ${controller.videoService.grailsApplication==null}" //Very important part for simulating the HTTP request controller.metaClass.request = new MockMultipartHttpServletRequest() controller.request.contentType="video/mpg" controller.request.content= new File("..\\MapCloudMediaServer\\web-app\\videoclips\\sample3.mpg").getBytes() controller.mpegtoFlvConvertor() byte[] videoOut=IOUtils.toByteArray(controller.response.getOutputStream()) def outputFile=new File("..\\MapCloudMediaServer\\web-app\\videoclips\\testsample3.flv") outputFile.append(videoOut) } }

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• ADO.NET DataTable/DataRow Thread Safety

  - by Allen E. Scharfenberg

  Introduction A user reported to me this morning that he was having an issue with inconsistent results (namely, column values sometimes coming out null when they should not be) of some parallel execution code that we provide as part of an internal framework. This code has worked fine in the past and has not been tampered with lately, but it got me to thinking about the following snippet: Code Sample lock (ResultTable) { newRow = ResultTable.NewRow(); } newRow["Key"] = currentKey; foreach (KeyValuePair<string, object> output in outputs) { object resultValue = output.Value; newRow[output.Name] = resultValue != null ? resultValue : DBNull.Value; } lock (ResultTable) { ResultTable.Rows.Add(newRow); } (No guarantees that that compiles, hand-edited to mask proprietery information.) Explanation We have this cascading type of locking code other places in our system, and it works fine, but this is the first instance of cascading locking code that I have come across that interacts with ADO .NET. As we all know, members of framework objects are usually not thread safe (which is the case in this situation), but the cascading locking should ensure that we are not reading and writing to ResultTable.Rows concurrently. We are safe, right? Hypothesis Well, the cascading lock code does not ensure that we are not reading from or writing to ResultTable.Rows at the same time that we are assigning values to columns in the new row. What if ADO .NET uses some kind of buffer for assigning column values that is not thread safe--even when different object types are involved (DataTable vs. DataRow)? Has anyone run into anything like this before? I thought I would ask here at StackOverflow before beating my head against this for hours on end :) Conclusion Well, the consensus appears to be that changing the cascading lock to a full lock has resolved the issue. That is not the result that I expected, but the full lock version has not produced the issue after many, many, many tests. The lesson: be wary of cascading locks used on APIs that you do not control. Who knows what may be going on under the covers!

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• Concept: Is mongo right for applying schemas?

  - by Jan

  I am currently in charge of checking wether it is valuable for one of our upcoming products to be developed on mongo. Without going too much into detail, I'll try to explain, what the app does. The app simply has "entities". These entities are technical stuff, like cell phones, TVs, Laptops, tablet pcs, and so forth. Of course, a cell phone has other attributes than a Tablet PCs and a Laptop has even other attributes, like RAM, CPU, display size and so on. Now I want to have something that we wanna call a scheme: We define that we need to have saved the display size, amount of ram size of flash devices, processor type, processor speed and so on for tablet pcs. For cell phone we might save display size, GSM, Edge, 3g, 4g, processor, ram, touch screen technology, bla bla bla. I think you got it :) What I want to realize is, that each "category" has a schema and when one of the system's users enters a new product (let's say the new iphone 4), the app constructs the form to be filled out with the appropriate attributes. So far it sounds nice and should not be a problem with mongo. But now the tough for which I could not find a clean solution.... An attribute modeled in mongo looks like: { _id: 1234456, name: "Attribute name", type: 0, "description" } But what to do, if i need this attribute in several languages, like: { en: {name: "Attribute name", type: 0, "description"}, de: {name: "Name des Attributs, type: 0, "Beschreibung"} } I also need to ensure that the german attribute gets updated as soon as the english gets updated, for instance when type changes from 0 to 1. Any ideas on that?

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• Java: using generic wildcards with subclassing

  - by gibberish

  Say I have a class Foo, a class A and some subclass B of A. Foo accepts A and its sublclasses as the generic type. A and B both require a Foo instance in their constructor. I want A's Foo to be of type A , and B's Foo to be of type B or a superclass of B. So in effect, So I only want this: Foo<X> bar = new Foo<X>; new B(bar); to be possible if X is either A, B, or a both subclass of A and superclass of B. So far this is what I have: class Foo<? extends A>{ //construct } class A(Foo<A> bar){ //construct } class B(Foo<? super B> bar){ super(bar); //construct } The call to super(...) doesn't work, because <A> is stricter than <? super B>. Is it somehow possible to use the constructor (or avoid code duplication by another means) while enforcing these types? Edit: Foo keeps a collection of elements of the generic parameter type, and these elements and Foo have a bidirectional link. It should therefore not be possible to link an A to a Foo.

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• Is there a more elegant way to act on the first and last items in a foreach enumeration than count++

  - by Edward Tanguay

  Is there a more elegant way to act on the first and last items when iterating through a foreach loop than incrementing a separate counter and checking it each time? For instance, the following code outputs: >>> [line1], [line2], [line3], [line4] <<< which requires knowing when you are acting on the first and last item. Is there a more elegant way to do this now in C# 3 / C# 4? It seems like I could use .Last() or .First() or something like that. using System; using System.Collections.Generic; using System.Text; namespace TestForNext29343 { class Program { static void Main(string[] args) { StringBuilder sb = new StringBuilder(); List<string> lines = new List<string> { "line1", "line2", "line3", "line4" }; int index = 0; foreach (var line in lines) { if (index == 0) sb.Append(">>> "); sb.Append("[" + line + "]"); if (index < lines.Count - 1) sb.Append(", "); else sb.Append(" <<<"); index++; } Console.WriteLine(sb.ToString()); Console.ReadLine(); } } }

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• How to read a parameter passed to a facelet from a backing bean

  - by Antonio

  Hi, I've written a facelet, and a corresponding backing bean, that implements user management (addition, deletion and so on). I'd want to be able to perform some custom processing when, for instance, a new user is added. There is a "create" button in the facelet, whose click event is handled by its backing bean. At the end of the event handler, I'd want to be able to call a method of another backing bean, which is not known because ideally the facelet can be used in several pages, with different custom processing. I thought to implement this feature by providing to the facelet a backing bean name and a method name, like this: <myfacelet:subaccounts backingBean="myBackingBean" createListener="createListener" /> and at the end of the event handler call #{myBackingBean.createListener} someway. I'm using this method (along with some overloads) to obtain a MethodExpression: protected MethodExpression getMethodExpression(String beanName, String methodName, Class<?> expectedReturnType, Class<?>[] expectedParamTypes) { ExpressionFactory expressionFactory; MethodExpression method; ELContext elContext; String el; el = String.format("#{%s['%s']}", beanName, methodName); expressionFactory = getApplication().getExpressionFactory(); elContext = getFacesContext().getELContext(); method = expressionFactory.createMethodExpression(elContext, el, expectedReturnType, expectedParamTypes); return method; } and the click event handler should look like: public void saveSubaccountListener(ActionEvent event) { MethodExpression method; ... method = getMethodExpression( "backingBean", "createSubaccountListener", SubuserBean.class); if (method != null) method.invoke( getFacesContext().getELContext(), new Object[] { _editedSubuser }); } That works fine as long as I provide an existing bean name (myBackingBean), but if I use backingBean the invoke() doesn't work due to the following error: javax.el.PropertyNotFoundException: Target Unreachable, identifier 'backingBean' resolved to null Is there a way I can retrieve from the facelet backing bean the value of a parameter that has been passed to the facelet? In my case, the value of backingBean, which should be myBackingBean? I've searched for and tried different solutions, but with no luck yet.

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• Binding value for NSTableView, but tooltip gets set as well

  - by Mark

  I've set up an NSTableView in Interface Builder to be populated from an NSArray. Each value of the array represents one row in the table. The value is bound correctly, but as a side effect, the table cell's tooltip is set to the string representation of the bound object. In my case, the NSArray contains NSDictiorany objects and the tooltip looks like it could be the [... description] output of that dictionary. Very ugly... I don't want the tooltip to be set at all. I have other tables that have plain NSString values bound to them and they don't have a tooltip set automatically. Is there some Interface Builder magic going on? I tried to start with a blank project - same problem. I should add that the table cell is a custom implementation of NSTextFieldCell that uses an NSButtonCell instance to draw an image and a label into the table. The values are retrieved from the dictionary bound as value. Why is the tooltip set when I only bind the "value" attribute? Thanks in advance!

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• Using entity framework to connect to multiple similar tables in .net MVC.

  - by Dite

  A relative newcomer to .net MVC2 and the entity framework, I am working on a project which requires a single web application, (C# .net 4), to connect to multiple different databases depending on the route of access, (ie subdomain). No problem with this in principle and all the logic is written to transform the subdomain into an entity connection and pass this through to the Entity Model. The problem comes with the fact that the different database whilst being largely similar in structure contain 3 or 4 unique tables bespoke to that instance. To my mind there are two ways to solve this issue, neither of which i am sure will be possible. 1/ Use a separate entity model for each database. -Attempts down this route have through up conflicts where table/sp names are the same across differnt db's, or implicit conversion errors when I try and put the different models in different namespaces. or 2/ Overwrite the classes which refer to the changeable database objects based on the value of a base controller property. -I have found nothing to suggest i can even do this. My question is if either of theser routes can ever work in principle or if i should just give up on the EF and connect to the dtabases directlky using ADO. Perhaps there is another way to solve this problem i haven't thought of? Thanks for any help...

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• Wrapper class that creates objects at runtime and stores data in an array.

  - by scriptingalias

  I tried making a wrapper class that encapsulates an object, a string (for naming and differentiating the object instance), and an array to store data. The problem I'm having now is accessing this class using methods that determine the "name" of the object and also reading the array containing some random variables. import java.util.Arrays; import java.util.Random; public class WrapperClass { String varName; Object varData; int[] array = new int[10]; public WrapperClass(String name, Object data, int[] ARRAY) { varName = name; varData = data; array = ARRAY; } public static void getvalues() { } public static void main(String[] args) { int[] array = new int[10]; Random random = new Random(3134234); for(int i = 0; i < 10; i++) { for (int c = 0; c < 10; c++) { array[c] = random.nextInt();//randomly creates data } WrapperClass w = new WrapperClass("c" + i, new Object(),array); } } }

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