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• ViewModel updates after Model server roundtrip

  - by Pavel Savara

  I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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• Object created in Interface Builder getting dealloc'ed too soon

  - by Collin Allen

  The Project I'm working on a relatively simple iPhone OS project that's navigation controller based, with a root table view and a detail table view. Tap an item in the main list to see its details in a pushed table view. The Setup I broke out the data source for both views into their own objects so as not to muddy the purpose of a view controller. Having done this, the table views no longer have data sources since those methods are now in separate files, so I created an instance of each data source class in the appropriate XIB files with the Object item (dragged it in, then set its class). Then, to actually connect the tableviews to their data sources, I set the dataSource outlet of each tableview to the yellow data source object in Interface Builder. The table view delegates are still set to their view controllers. The Problem The root table view works just fine, but when you tap a row to push to the detail view, the data source object gets instantiated as expected, then immediately dealloc'ed, causing a crash (numberOfSectionsInTableView: gets called on the freed object). I can't figure out why the data source is getting automatically dealloc-ed when I need it right then and there for the detail view, as indicated by my data source object creation and tableview connection in Interface Builder. What's more perplexing is that the very approach works fine for the root tableview! The Question Is there anything obvious I'm missing that would cause this to happen? Or, is this even the right way to instantiate a data source for a table view controller? It seems like poor object oriented programming to do it from within the view controller, which should only be concerned with the view. I could cram everything in two table view controller classes and it would probably work, but it would not be as modular as I'd like. Thanks!

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• DDD: Persisting aggregates

  - by Mosh

  Hello, Let's consider the typical Order and OrderItem example. Assuming that OrderItem is part of the Order Aggregate, it an only be added via Order. So, to add a new OrderItem to an Order, we have to load the entire Aggregate via Repository, add a new item to the Order object and persist the entire Aggregate again. This seems to have a lot of overhead. What if our Order has 10 OrderItems? This way, just to add a new OrderItem, not only do we have to read 10 OrderItems, but we should also re-insert all these 10 OrderItems again. (This is the approach that Jimmy Nillson has taken in his DDD book. Everytime he wants to persists an Aggregate, he clears all the child objects, and then re-inserts them again. This can cause other issues as the ID of the children are changed everytime because of the IDENTITY column in database.) I know some people may suggest to apply Unit of Work pattern at the Aggregate Root so it keeps track of what has been changed and only commit those changes. But this violates Persistence Ignorance (PI) principle because persistence logic is leaking into the Domain Model. Has anyone thought about this before? Mosh

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• How can I use nested Async (WCF) calls within foreach loops in Silverlight ?

  - by Peter St Angelo

  The following code contains a few nested async calls within some foreach loops. I know the silverlight/wcf calls are called asyncrously -but how can I ensure that my wcfPhotographers, wcfCategories and wcfCategories objects are ready before the foreach loop start? I'm sure I am going about this all the wrong way -and would appreciate an help you could give. private void PopulateControl() { List<CustomPhotographer> PhotographerList = new List<CustomPhotographer>(); proxy.GetPhotographerNamesCompleted += proxy_GetPhotographerNamesCompleted; proxy.GetPhotographerNamesAsync(); //for each photographer foreach (var eachPhotographer in wcfPhotographers) { CustomPhotographer thisPhotographer = new CustomPhotographer(); thisPhotographer.PhotographerName = eachPhotographer.ContactName; thisPhotographer.PhotographerId = eachPhotographer.PhotographerID; thisPhotographer.Categories = new List<CustomCategory>(); proxy.GetCategoryNamesFilteredByPhotographerCompleted += proxy_GetCategoryNamesFilteredByPhotographerCompleted; proxy.GetCategoryNamesFilteredByPhotographerAsync(thisPhotographer.PhotographerId); // for each category foreach (var eachCatergory in wcfCategories) { CustomCategory thisCategory = new CustomCategory(); thisCategory.CategoryName = eachCatergory.CategoryName; thisCategory.CategoryId = eachCatergory.CategoryID; thisCategory.SubCategories = new List<CustomSubCategory>(); proxy.GetSubCategoryNamesFilteredByCategoryCompleted += proxy_GetSubCategoryNamesFilteredByCategoryCompleted; proxy.GetSubCategoryNamesFilteredByCategoryAsync(thisPhotographer.PhotographerId,thisCategory.CategoryId); // for each subcategory foreach(var eachSubCatergory in wcfSubCategories) { CustomSubCategory thisSubCatergory = new CustomSubCategory(); thisSubCatergory.SubCategoryName = eachSubCatergory.SubCategoryName; thisSubCatergory.SubCategoryId = eachSubCatergory.SubCategoryID; } thisPhotographer.Categories.Add(thisCategory); } PhotographerList.Add(thisPhotographer); } PhotographerNames.ItemsSource = PhotographerList; } void proxy_GetPhotographerNamesCompleted(object sender, GetPhotographerNamesCompletedEventArgs e) { wcfPhotographers = e.Result.ToList(); } void proxy_GetCategoryNamesFilteredByPhotographerCompleted(object sender, GetCategoryNamesFilteredByPhotographerCompletedEventArgs e) { wcfCategories = e.Result.ToList(); } void proxy_GetSubCategoryNamesFilteredByCategoryCompleted(object sender, GetSubCategoryNamesFilteredByCategoryCompletedEventArgs e) { wcfSubCategories = e.Result.ToList(); }

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• Automation Error when exporting Excel data to SQL Server

  - by brohjoe

  I'm getting an Automation error upon running VBA code in Excel 2007. I'm attempting to connect to a remote SQL Server DB and load data to from Excel to SQL Server. The error I get is, "Run-time error '-2147217843(80040e4d)': Automation error". I checked out the MSDN site and it suggested that this may be due to a bug associated with the sqloledb provider and one way to mitigate this is to use ODBC. Well I changed the connection string to reflect ODBC provider and associated parameters and I'm still getting the same error. Here is the code with ODBC as the provider: Dim cnt As ADODB.Connection Dim rst As ADODB.Recordset Dim stSQL As String Dim wbBook As Workbook Dim wsSheet As Worksheet Dim rnStart As Range Public Sub loadData() 'This was set up using Microsoft ActiveX Data Components version 6.0. 'Create ADODB connection object, open connection and construct the connection string object. Set cnt = New ADODB.Connection cnt.ConnectionString = "Driver={SQL Server}; Server=onlineSQLServer2010.foo.com; Database=fooDB;Uid=logonalready;Pwd='helpmeOB1';" cnt.Open On Error GoTo ErrorHandler 'Open Excel and run query to export data to SQL Server. strSQL = "SELECT * INTO SalesOrders FROM OPENDATASOURCE('Microsoft.ACE.OLEDB.12.0'," & _ "'Data Source=C:\Database.xlsx; Extended Properties=Excel 12.0')...[SalesOrders$]" cnt.Execute (strSQL) 'Error handling. ErrorExit: 'Reclaim memory from the connection objects Set rst = Nothing Set cnt = Nothing Exit Sub ErrorHandler: MsgBox Err.Description, vbCritical Resume ErrorExit 'clean up and reclaim memory resources. If CBool(cnt.State And adStateOpen) Then Set rst = Nothing Set cnt = Nothing cnt.Close End If End Sub

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• instantiate python object within a c function called via ctypes

  - by gwk

  My embedded Python 3.3 program segfaults when I instantiate python objects from a c function called by ctypes. After setting up the interpreter, I can successfully instantiate a python Int (as well as a custom c extension type) from c main: #import <Python/Python.h> #define LOGPY(x) \ { fprintf(stderr, "%s: ", #x); PyObject_Print((PyObject*)(x), stderr, 0); fputc('\n', stderr); } // c function to be called from python script via ctypes. void instantiate() { PyObject* instance = PyObject_CallObject((PyObject*)&PyLong_Type, NULL); LOGPY(instance); } int main(int argc, char* argv[]) { Py_Initialize(); instantiate(); // works fine // run a script that calls instantiate() via ctypes. FILE* scriptFile = fopen("emb.py", "r"); if (!scriptFile) { fprintf(stderr, "ERROR: cannot open script file\n"); return 1; } PyRun_SimpleFileEx(scriptFile, scriptPath, 1); // close on completion return 0; } I then run a python script using PyRun_SimpleFileEx. It appears to run just fine, but when it calls instantiate() via ctypes, the program segfaults inside PyObject_CallObject: import ctypes as ct dy = ct.CDLL('./emb') dy.instantiate() # segfaults lldb output: instance: 0 Process 52068 stopped * thread #1: tid = 0x1c03, 0x000000010000d3f5 Python`PyObject_Call + 69, stop reason = EXC_BAD_ACCESS (code=1, address=0x18) frame #0: 0x000000010000d3f5 Python`PyObject_Call + 69 Python`PyObject_Call + 69: -> 0x10000d3f5: movl 24(%rax), %edx 0x10000d3f8: incl %edx 0x10000d3fa: movl %edx, 24(%rax) 0x10000d3fd: leaq 2069148(%rip), %rax ; _Py_CheckRecursionLimit (lldb) bt * thread #1: tid = 0x1c03, 0x000000010000d3f5 Python`PyObject_Call + 69, stop reason = EXC_BAD_ACCESS (code=1, address=0x18) frame #0: 0x000000010000d3f5 Python`PyObject_Call + 69 frame #1: 0x00000001000d5197 Python`PyEval_CallObjectWithKeywords + 87 frame #2: 0x0000000201100d8e emb`instantiate + 30 at emb.c:9 Why does the call to instantiate() fail from ctypes only? The function only crashes when it calls into the python lib, so perhaps some interpreter state is getting munged by the ctypes FFI call?

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• video calling (center)

  - by rrejc

  We are starting to develop a new application and I'm searching for information/tips/guides on application architecture. Application should: read the data from an external (USB) device send the data to the remote server (through internet) receive the data from the remote server perform a video call with to the calling (support) center receive a video call call from the calling (support) center support touch screens In addition: some of the data should also be visible through the web page. So I was thinking about: On the server side: use the database (probably MS SQL) use ORM (nHibernate) to map the data from the DB to the domain objects create a layer with business logic in C# create a web (WCF) services (for client application) create an asp.net mvc application (for item 7.) to enable data view through the browser On the client side I would use WPF 4 application which will communicate with external device and the wcf services on the server. So far so good. Now the problem begins. I have no idea how to create a video call (outgoing or incoming) part of the application. I believe that there is no problem to communicate with microphone, speaker, camera with WPF/C#. But how to communicate with the call center? What protocol and encoding should be used? I think that I will need to create some kind of server which will: have a list of operators in the calling center and track which operator is occupied and which operator is free have a list of connected end users receive incoming calls from end users and delegate call to free operator delegate calls from calling center to the end user Any info, link, anything on where to start would be much appreciated. Many thanks!

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• Printing an invisible NSView

  - by Rodger Wilson

  Initially I created a simple program with a custom NSView. I drew a picture (certificate) and printed it! beautiful! Everything worked great! I them moved my custom NSView to an existing application. My hope was that when a user hit print it would print this certificate. Simple enough. I figured a could have a NSView pointer in my controller code. Then at initialization I would populate the pointer. Then when someone wanted to print the certificate it would print. The problem is that all of my drawing code is in the "drawRect" method. This method doesn't get called because this view is never displayed in a window. I have heart that others use non-visible NSView objects just for printing. What do I need to do. I really don't want to show this view to the screen. Rodger

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• using R.zoo to plot multiple series with error bars

  - by dnagirl

  I have data that looks like this: > head(data) groupname ob_time dist.mean dist.sd dur.mean dur.sd ct.mean ct.sd 1 rowA 0.3 61.67500 39.76515 43.67500 26.35027 8.666667 11.29226 2 rowA 60.0 45.49167 38.30301 37.58333 27.98207 8.750000 12.46176 3 rowA 120.0 50.22500 35.89708 40.40000 24.93399 8.000000 10.23363 4 rowA 180.0 54.05000 41.43919 37.98333 28.03562 8.750000 11.97061 5 rowA 240.0 51.97500 41.75498 35.60000 25.68243 28.583333 46.14692 6 rowA 300.0 45.50833 43.10160 32.20833 27.37990 12.833333 14.21800 Each groupname is a data series. Since I want to plot each series separately, I've separated them like this: > A <- zoo(data[which(groupname=='rowA'),3:8],data[which(groupname=='rowA'),2]) > B <- zoo(data[which(groupname=='rowB'),3:8],data[which(groupname=='rowB'),2]) > C <- zoo(data[which(groupname=='rowC'),3:8],data[which(groupname=='rowC'),2]) ETA: Thanks to gd047: Now I'm using this: z <- dlply(data,.(groupname),function(x) zoo(x[,3:8],x[,2])) The resulting zoo objects look like this: > head(z$rowA) dist.mean dist.sd dur.mean dur.sd ct.mean ct.sd 0.3 61.67500 39.76515 43.67500 26.35027 8.666667 11.29226 60 45.49167 38.30301 37.58333 27.98207 8.750000 12.46176 120 50.22500 35.89708 40.40000 24.93399 8.000000 10.23363 180 54.05000 41.43919 37.98333 28.03562 8.750000 11.97061 240 51.97500 41.75498 35.60000 25.68243 28.583333 46.14692 300 45.50833 43.10160 32.20833 27.37990 12.833333 14.21800 So if I want to plot dist.mean against time and include error bars equal to +/- dist.sd for each series: how do I combine A,B,C dist.mean and dist.sd? how do I make a bar plot, or perhaps better, a line graph of the resulting object?

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• Are lambda expressions/delegates in C# "pure", or can they be?

  - by Bob

  I recently asked about functional programs having no side effects, and learned what this means for making parallelized tasks trivial. Specifically, that "pure" functions make this trivial as they have no side effects. I've also recently been looking into LINQ and lambda expressions as I've run across examples many times here on StackOverflow involving enumeration. That got me to wondering if parallelizing an enumeration or loop can be "easier" in C# now. Are lambda expressions "pure" enough to pull off trivial parallelizing? Maybe it depends on what you're doing with the expression, but can they be pure enough? Would something like this be theoretically possible/trivial in C#?: Break the loop into chunks Run a thread to loop through each chunk Run a function that does something with the value from the current loop position of each thread For instance, say I had a bunch of objects in a game loop (as I am developing a game and was thinking about the possibility of multiple threads) and had to do something with each of them every frame, would the above be trivial to pull off? Looking at IEnumerable it seems it only keeps track of the current position, so I'm not sure I could use the normal generic collections to break the enumeration into "chunks". Sorry about this question. I used bullets above instead of pseudo-code because I don't even know enough to write pseudo-code off the top of my head. My .NET knowledge has been purely simple business stuff and I'm new to delegates and threads, etc. I mainly want to know if the above approach is good for pursuing, and if delegates/lambdas don't have to be worried about when it comes to their parallelization.

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• Filter a date property between a begin and end Dates with JDOQL

  - by Sergio del Amo

  I want to code a function to get a list of Entry objects whose date field is between a beginPeriod and endPeriod I post below a code snippet which works with a HACK. I have to substract a day from the begin period date. It seems the condition great or equal does not work. Any idea why I have this issue? public static List<Entry> getEntries(Date beginPeriod, Date endPeriod) { /* TODO * The great or equal condition does not seem to work in the filter below * Substract a day and it seems to work */ Calendar calendar = Calendar.getInstance(); calendar.set(beginPeriod.getYear(), beginPeriod.getMonth(), beginPeriod.getDate() - 1); beginPeriod = calendar.getTime(); PersistenceManager pm = JdoUtil.getPm(); Query q = pm.newQuery(Entry.class); q.setFilter("this.date >= beginPeriodParam && this.date <= endPeriodParam"); q.declareParameters("java.util.Date beginPeriodParam, java.util.Date endPeriodParam"); List<Entry> entries = (List<Entry>) q.execute(beginPeriod,endPeriod); return entries; }

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• Qt Jambi: Accessing the content of QNetworkReply

  - by Richard

  Hi All, I'm having trouble accessing the content of QNetworkReply objects. Content appears to be empty or zero. According to the docs (translating from c++ to java) I think I've got this set up correctly, but to no avail. Additionally an "Unknown error" is being reported. Any ideas much appreciated. Code: public class Test extends QObject { private QWebPage page; public Test() { page = new QWebPage(); QNetworkAccessManager nac = new QNetworkAccessManager(); nac.finished.connect(this, "requestFinished(QNetworkReply)"); page.setNetworkAccessManager(nac); page.loadProgress.connect(this, "loadProgress(int)"); page.loadFinished.connect(this, "loadFinished()"); } public void requestFinished(QNetworkReply reply) { reply.reset(); reply.open(OpenModeFlag.ReadOnly); reply.readyRead.connect(this, "ready()"); // never gets called System.out.println("bytes: " + reply.url().toString()); // writes out asset uri no problem System.out.println("bytes: " + reply.bytesToWrite()); // 0 System.out.println("At end: " + reply.atEnd()); // true System.out.println("Error: " + reply.errorString()); // "Unknown error" } public void loadProgress(int progress) { System.out.println("Loaded " + progress + "%"); } public void loadFinished() { System.out.println("Done"); } public void ready() { System.out.println("Ready"); } public void open(String url) { page.mainFrame().load(new QUrl(url)); } public static void main(String[] args) { QApplication.initialize(new String[] { }); Test t = new Test(); t.open("http://news.bbc.co.uk"); QApplication.exec(); } }

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• How do I send an XML document to an ASP.NET MVC page for manipuation

  - by Decker

  I have some hierarchical data stored as an multiple XML files on the server according to a vendor's schema. In my ASP.NET MVC (2!) application, I'd like the user to choose one of these hierarchies (i.e. file -- I provide a list in my controller's Index action). When the user selects one to "edit" my edit action should return a page that presents the XML hierarchy (it's a representation of a folder tree). So my thoughts are that the view would return HTML that contained a JQuery on load ajax call back to the server for the XML data -- at which point I would present the tree using one of the many JQuery tree controls. On the client side I'd like the user to manipulate the tree and when done, I'd like to post back the new hierarchy where I would replace the original XML file that represents that hierarchy. So my questions are: What form should I use to send the data down? XML or JSON?. If I send down XML then I would have to not only read the XML -- which JQuery can do -- but I would also have to be able to modify that XML and then send it back. Can I use JQuery to modify this XML DOM? And will all the namespace declarations be preserved? What form should I send the data back? If I originally sent the client the hierarchy as JSON (using JsonResult), then presumably I would have a hierarchy of javascript objects. What options would I have to post that back? Would I have to recreate the XML reprentation on the client and post that back? Or should I serialize back to JSON, post that to the server, and then have the server do the work of recreating the XML according to the schema. Thanks for any advice.

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• WCF Service instead of ASMX Web Service?

  - by wchrisjohnson

  I'm writing a SOAP Server that will act as an endpoint for an external client. The external client expects SOAP 1.1. I'll be taking embedded business objects in the SOAP messages and passing them to an internal application, getting responses back and responding with SOAP messages to the eternal client. I did the traditional ASMX based web services several years ago. Now, I've been exploring WCF Services and wondering the best approach to take. 1) Should WCF be considered a superset of ASMX web services? 2) Is there any reason to still write new web services using ASMX instead of WCF? 3) Does WCF provide better facilities for working with SOAP messages, as opposed to SOAP Extensions? 4) Can I restrict communication to SOAP 1.1 using WCF, the way I can with a web.config change in ASMX? 5) Does WCF have an easy way to log or review the requests that hit the service without resorting to something like SOAP extensions? Sorry my questions are not very specific; still trying to get handle on what I need to know... Using VS2008, Windows Server 2008. Chris

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• Dependency Injection and decoupling of software layers

  - by cs31415

  I am trying to implement Dependency Injection to make my app tester friendly. I have a rather basic doubt. Data layer uses SqlConnection object to connect to a SQL server database. SqlConnection object is a dependency for data access layer. In accordance with the laws of dependency injection, we must not new() dependent objects, but rather accept them through constructor arguments. Not wanting to upset the DI gods, I dutifully create a constructor in my DAL that takes in SqlConnection. Business layer calls DAL. Business layer must therefore, pass in SqlConnection. Presentation layer calls Business layer. Hence it too, must pass in SqlConnection to business layer. This is great for class isolation and testability. But didn't we just couple the UI and Business layers to a specific implementation of the data layer which happens to use a relational database? Why do the Presentation and Business layers need to know that the underlying data store is SQL? What if the app needs to support multiple data sources other than SQL server (such as XML files, Comma delimited files etc.) Furthermore, what if I add another object upon which my data layer is dependent on (say, a second database). Now, I have to modify the upper layers to pass in this new object. How can I avoid this merry-go-round and reap all the benefits of DI without the pain?

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• Name Values in Excel Object model

  - by mcoolbeth

  I am using VSTO to create an Excel add-in. My plan is to persist objects inside of excel workbooks by serializing them to strings and assigning those strings to be the values of names in the workbook. However, when I call the API function to add the new name, I get a mysterious exception from the COM library. More precisely, I am calling _app.ActiveWorkbook.Names.Add(name, value, true, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing); where name = "an_object" and value = "TestTemplate|'Sheet1'!$A$1| 1Cube=(0,1):(1,2)| 2EntryNumber=(1,1):(2,2)| 3Description=(2,1):(3,2)| 4Group=(4,1):(5,2)| 5Repost=(3,1):(4,2)| 6Debit=(13,3):(16,4)| 7Credit=(13,2):(16,3)|Company=(6,1):(7,2)|Company Partner=(7,1):(8,2)|Time Monthly=(8,1):(9,2)|Currency=(9,1):(10,2)|Version=(10,1):(11,2)|Department=(13,0):(16,1)|Account=(13,1):(16,2)|" A hypothesis is that the value string does not qualify as a string that can be stored in a name (illegal characters, too long, etc) but I cannot find any documentation about what the restrictions are. Does anyone know what is going wrong here? The error message, in case anyone wants it, is Exception from HRESULT: 0x800A03EC Thanks alot.

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• How to route tree-structured URLs with ASP.NET Routing?

  - by Venemo

  Hello Everyone, I would like to achieve something very similar to this question, with some enhancements. There is an ASP.NET MVC web application. I have a tree of entities. For example, a Page class which has a property called Children, which is of type IList<Page>. (An instance of the Page class corresponds to a row in a database.) I would like to assign a unique URL to every Page in the database. I handle Page objects with a Controller called PageController. Example URLs: http://mysite.com/Page1/ http://mysite.com/Page1/SubPage/ http://mysite.com/Page/ChildPage/GrandChildPage/ You get the picture. So, I'd like every single Page object to have its own URL that is equal to its parent's URL plus its own name. In addition to that, I also would like the ability to map a single Page to the / (root) URL. I would like to apply these rules: If a URL can be handled with any other route, or a file exists in the filesystem in the specified URL, let the default URL mapping happen If a URL can be handled by the virtual path provider, let that handle it If there is no other, map the other URLs to the PageController class I also found this question, and also this one and this one, but they weren't of much help, since they don't provide an explanation about my first two points. I see the following possible soutions: Map a route for each page invidually. This requires me to go over the entire tree when the application starts, and adding an exact match route to the end of the route table. I could add a route with {*path} and write a custom IRouteHandler that handles it, but I can't see how could I deal with the first two rules then, since this handler would get to handle everything. So far, the first solution seems to be the right one, because it is also the simplest. I would really appreciate your thoughts on this. Thank you in advance!

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• Appending data to NSFetchedResultsController during find or create loop

  - by Justin Williams

  I have a table view that is managed by an NSFetchedResultsController. I am having an issue with a find-or-create operation, however. When the user hits the bottom of my table view, I am querying my server for another batch of content. If it doesn't exist in the local cache, we create it and store it. If it does exist, however, I want to append that data to the fetched results controller and display it. I can't quite figure that part out. Here's what I'm doing thus far: Passing the returned array of values from my server to an NSOperation to process. In the operation, create a new managed object context to work with. In the operation, I iterate through the array and execute a fetch request to see if the object exists (based on its server id). If the object doesn't exist, we create it and insert it into the operations' managed object context. After the iteration completes, we save the managed object context, which triggers a merge notification on my main thread. At this point, any objects that weren't locally cached in my Core Data store before will appear, but the ones that previously existed do not come along for the ride. I feel like it's something simple I'm missing, and could use a nudge in the right direction.

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• List.Sort in C#: comparer being called with null object

  - by cbp

  I am getting strange behaviour using the built-in C# List.Sort function with a custom comparer. For some reason it sometimes calls the comparer class's Compare method with a null object as one of the parameters. But if I check the list with the debugger there are no null objects in the collection. My comparer class looks like this: public class DelegateToComparer<T> : IComparer<T> { private readonly Func<T,T,int> _comparer; public int Compare(T x, T y) { return _comparer(x, y); } public DelegateToComparer(Func<T, T, int> comparer) { _comparer = comparer; } } This allows a delegate to be passed to the List.Sort method, like this: mylist.Sort(new DelegateToComparer<MyClass>( (x, y) => { return x.SomeProp.CompareTo(y.SomeProp); }); So the above delegate will throw a null reference exception for the x parameter, even though no elements of mylist are null. UPDATE: Yes I am absolutely sure that it is parameter x throwing the null reference exception! UPDATE: Instead of using the framework's List.Sort method, I tried a custom sort method (i.e. new BubbleSort().Sort(mylist)) and the problem went away. As I suspected, the List.Sort method passes null to the comparer for some reason.

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• Generic list typecasting problem

  - by AJ

  Hello, I'm new to C# and am stuck on the following. I have a Silverlight web service that uses LINQ to query a ADO.NET entity object. e.g.: [OperationContract] public List<Customer> GetData() { using (TestEntities ctx = new TestEntities()) { var data = from rec in ctx.Customer select rec; return data.ToList(); } } This works fine, but what I want to do is to make this more abstract. The first step would be to return a List<EntityObject> but this gives a compiler error, e.g.: [OperationContract] public List<EntityObject> GetData() { using (TestEntities ctx = new TestEntities()) { var data = from rec in ctx.Customer select rec; return data.ToList(); } } The error is: Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<SilverlightTest.Web.Customer>' to 'System.Collections.Generic.IEnumerable<System.Data.Objects.DataClasses.EntityObject>'. An explicit conversion exists (are you missing a cast?) What am i doing wrong? Thanks, AJ

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• Using perl to split a line that may contain whitespace

  - by Tommy Fisk

  Okay, so I'm using perl to read in a file that contains some general configuration data. This data is organized into headers based on what they mean. An example follows: [vars] # This is how we define a variable! $var = 10; $str = "Hello thar!"; # This section contains flags which can be used to modify module behavior # All modules read this file and if they understand any of the flags, use them [flags] Verbose = true; # Notice the errant whitespace! [path] WinPath = default; # Keyword which loads the standard PATH as defined by the operating system. Append with additonal values. LinuxPath = default; Goal: Using the first line as an example "$var = 10;", I'd like to use the split function in perl to create an array that contains the characters "$var" and "10" as elements. Using another line as an example: Verbose = true; # Should become [Verbose, true] aka no whitespace is present This is needed because I will be outputting these values to a new file (which a different piece of C++ code will read) to instantiate dictionary objects. Just to give you a little taste of what it might look like (just making it up as I go along): define new dictionary name: [flags] # Start defining keys => values new key name: Verbose new value val: 10 # End dictionary Oh, and here is the code I currently have along with what it is doing (incorrectly): sub makeref($) { my @line = (split (/=/)); # Produces ["Verbose", " true"]; }

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• how to manage a "resource" array efficiently

  - by Haiyuan Zhang

  The senario of my question is that one need to use a fixed size of array to keep track of certain number of "objects" . The object here can be as simply as a integer or as complex as very fancy data structure. And "keep track" here means to allocate one object when other part of the app need one instance of object and recyle it for future allocation when one instance of the object is returned .Finally ,let me use c++ to put my problme in a more descriptive way . #define MAX 65535 /* 65535 just indicate that many items should be handled . performance demanding! */ typedef struct { int item ; }Item_t; Item_t items[MAX] ; class itemManager { private : /* up to you.... */ public : int get() ; /* get one index to a free Item_t in items */ bool put(int index) ; /* recyle one Item_t indicate by one index in items */ } how will you implement the two public functions of itemManager ? it's up to you to add any private member .

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• A simple WCF Service (POX) without complex serialization

  - by jammer59

  I'm a complete WCF novice. I'm trying to build a deploy a very, very simple IIS 7.0 hosted web service. For reasons outside of my control it must be WCF and not ASMX. It's a wrapper service for a pre-existing web application that simply does the following: 1) Receives a POST request with the request body XML-encapsulated form elements. Something like valuevalue. This is untyped XML and the XML is atomic (a form) and not a list of records/objects. 2) Add a couple of tags to the request XML and the invoke another HTTP-based service with a simple POST + bare XML -- this will actually be added by some internal SQL ops but that isn't the issue. 3) Receive the XML response from the 3rd party service and relay it as the response to the original calling client in Step 1. The clients (step 1) will be some sort of web-based scripting but could be anything .aspx, python, php, etc. I can't have SOAP and the usual WCF-based REST examples with their contracts and serialization have me confused. This seems like a very common and very simple problem conceptually. It would be easy to implement in code but IIS-hosted WCF is a requirement. Any pointers?

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• Need some help/advice on WCF Per-Call Service and NServiceBus interop.

  - by Alexey

  I have WCF Per-Call service wich provides data for clients and at the same time is integrated with NServiceBus. All statefull objects are stored in UnityContainer wich is integrated into custom service host. NServiceBus is configured in service host and uses same container as service instances. Every client has its own instance context(described by Juval Lowy in his book in chapter about Durable Services). If i need to send request over bus I just use some kind of dispatcher and wait response using Thread.Sleep().Since services are per-call this is ok afaik. But I am confused a bit about messages from bus, that service must handle and provide them to clients. For some data like stock quotes I just update some kind of statefull object and and then, when clients invoke GetQuotesData() just provide data from this object. But there are numerous service messages like new quote added and etc. At this moment I have an idea to implement something like "Postman daemon" =)) and store this type of messages in instance context. Then client will invoke "GetMail()",recieve those messages and parse them. Problem is that NServiceBus messages are "Interface based" and I cant pass them over WCF, so I need to convert them to types derieved from some abstract class. Dunno what is best way to handle this situation. Will be very gratefull for any advice on this. Thanks in advance.

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• Use Objective-C without NSObject?

  - by Alex I

  I am testing some simple Objective-C code on Windows (cygwin, gcc). This code already works in Xcode on Mac. I would like to convert my objects to not subclass NSObject (or anything else, lol). Is this possible, and how? What I have so far: // MyObject.h @interface MyObject - (void)myMethod:(int) param; @end and // MyObject.m #include "MyObject.h" @interface MyObject() { // this line is a syntax error, why? int _field; } @end @implementation MyObject - (id)init { // what goes in here? return self; } - (void)myMethod:(int) param { _field = param; } @end What happens when I try compiling it: gcc -o test MyObject.m -lobjc MyObject.m:4:1: error: expected identifier or ‘(’ before ‘{’ token MyObject.m: In function ‘-[MyObject myMethod:]’: MyObject.m:17:3: error: ‘_field’ undeclared (first use in this function) EDIT My compiler is cygwin's gcc, also has cygwin gcc-objc package: gcc --version gcc (GCC) 4.7.3 I have tried looking for this online and in a couple of Objective-C tutorials, but every example of a class I have found inherits from NSObject. Is it really impossible to write Objective-C without Cocoa or some kind of Cocoa replacement that provides NSObject? (Yes, I know about GNUstep. I would really rather avoid that if possible...)

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