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• How to have NHibernate persist a String.Empty property value as NULL

  - by Todd

  I have a fairly simple class that I want to save to SQL Server via NHibernate (w/ Fluent mappings). The class is made up mostly of optional string fields. My problem is I default the class fields to string.empty to avoid NullRefExceptions and when NHibernate saves the row to the database each column contains an empty string instead of null. Question: Is there a way for me to get NHibernate to automatically save null when the string property is an empty string? Or do I need to litter my code with if (string.empty) checks?

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• database row/ record pointers

  - by David

  Hi I don't know the correct words for what I'm trying to find out about and as such having a hard time googling. I want to know whether its possible with databases (technology independent but would be interested to hear whether its possible with Oracle, MySQL and Postgres) to point to specific rows instead of executing my query again. So I might initially execute a query find some rows of interest and then wish to avoid searching for them again by having a list of pointers or some other metadata which indicates the location on a database which I can go to straight away the next time I want those results. I realise there is caching on databases, but I want to keep these "pointers" else where and as such caching doesn't ultimately solve this problem. Is this just an index and I store the index and look up by this? most of my current tables don't have indexes and I don't want the speed decrease that sometimes comes with indexes. So whats the magic term I've been trying to put into google? Cheers

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• Passing message over network

  - by Sylvestre Equy

  Hi, I'm currently trying to develop a message-oriented networking framework and I'm a bit stuck on the internal mechanism. Here are the problematic interfaces : public interface IMessage { } public class Connection { public void Subscribe<TMessage>(Action<TMessage> messageCallback); public void Send<TMessage>(TMessage message); } The Send method does not seem complicated, though the mechanism behind Subscribe seems a bit more painful. Obviously when receiving a message on one end of the connection, I'll have to invoke the appropriate delegate. Do you have any advice on how to read messages and easily detect their types ? By the way, I'd like to avoid to use MSMQ.

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• What's the easiest way to implement background downloading in Wicket?

  - by David Moles

  I've got a simple Wicket form that lets users select some data and then download a ZIP file (generated on the fly) containing what they asked for. Currently the form button's onSubmit() method looks something like this: public void onSubmit() { IResourceStream stream = /* assemble the data they asked for ... */ ; ResourceStreamRequestTarget target = new ResourceStreamRequestTarget(stream); target.setFileName("download.zip"); RequestCycle.get().setRequestTarget(target); } This works, but of course the request stops there and it's impossible to display any other feedback to the user. What I'd like to have is something like the typical "Your requested download [NAME] should begin automatically. If not, click this link." Ideally, still displaying the same page, so the user can immediately select some different data and download that as well. I imagine it's possible to do this using Wicket's Ajax classes, but I've managed to avoid having to use them so far, and it's not immediately obvious to me how. What's my quickest way out, here?

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• Creating and releasing objects in the same method, while using self as delegate

  - by user200341

  In objective-c you are responsible for releasing objects you allocate, but what happens when you allocate an object in a method, assign self as the objects delegate, and then release the object. The callbacks from the newly created (and released) object fails at this point, or rather, doesn't happen. - (void)doSomething { MyObj *myObj = [[MyObj alloc] init]; myObj.delegate = self; [myObj performOperation]; [myObj release]; } - (void)callbackMethodFromMyObj:(NSString *)message { NSLog(message); } I can't release the object until the callback has occurred, and I can't avoid releasing the object in the same method that creates it (because it exists outside the scope). One way of doing it would be to pass the object along in the call-back and release it in the callback, but is this the right way to go about this?

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• Hibernate Unit tests - Reset schema

  - by Marco

  Hi, I'm testing the CRUD operations of my DAOs in JUnit tests. When i execute the single test, Hibernate always resets the schema and populates the DB in a known state. But when i execute multiple tests in a row, Hibernate resets the schema once, and then the data is accumulated during the execution of the tests. This is an unexpected behavior, so I'd like to add in the @Before method of the tests a function that explicitly resets the schema to avoid the pesistence of side data created by previous tests during the execution chain. Any tips? Thanks

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• What happens to an instance of ServerSocket blocked inside accept(), when I drop all references to i

  - by Hanno Fietz

  In a multithreaded Java application, I just tracked down a strange-looking bug, realizing that what seemed to be happening was this: one of my objects was storing a reference to an instance of ServerSocket on startup, one thread would, in its main loop in run(), call accept() on the socket while the socket was still waiting for a connection, another thread would try to restart the component under some conditions, the restart process missed the cleanup sequence before it reached the initialization sequence as a result, the reference to the socket was overwritten with a new instance, which then wasn't able to bind() anymore the socket which was blocking inside the accept() wasn't accessible anymore, leaving a complete shutdown and restart of the application as the only way to get rid of it. Which leaves me wondering: with no references left to the ServerSocket instance, what would free the socket for a new connection? At what point would the ServerSocket become garbage collected? In general, what are good practices I can follow to avoid this type of bug?

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• IntelliJ Split Window Navigation

  - by jmquigley

  If I split the editor window (horizontal or vertical) into N tab groups, how do I switch/toggle from one tab group to another via the keyboard? If all of the tabs are in the same group you can switch from each tab easily (CTRL + right/left arrow), but when they're in separate tab groups I can't. I've searched through the key mappings and have not found one that seems to accomplish this. I know I can use the mouse, but I'm trying to find ways to avoid the mouse and stay with the keyboard. TIA for any help on this.

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• Raphael how to get last path and last circle, if i have 2 elements in the paper?

  - by 3gwebtrain

  I need to find the last path or circle in a paper, in order to perform further calculations to draw more elements, and calling 'paper.bottom' only gets the last element. Is there any way to get shapes of specific types, e.g. bottom.path, bottom.circle or traverse for the n'th child? I want to avoid using jQuery selectors, as i can't retrieve any properties from those. An example of a paper populated with shapes: var paper = Raphael('paper',500,500); var c1 = paper.circle(100,100,50) var p1 = paper.path("M10 20l70 0") var c2 = paper.circle(200,100,50)

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• Is it a good practice to create a reference to application context and use it anywhere?

  - by kknight

  I have to use context in many places of my code such as database operations, preference operations, etc. I don't want to pass in context for every method. Is it a good practice to create a reference to application context at the main Activity and use it anywhere such as database operations? So, I don't need some many context in method parameters, and the code can avoid position memory leak due to use of Activity Context. public class MainActivity extends Activity { public static Context s_appContext; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); s_appContext = this.getApplicationContext();

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• Accessing php $_SESSION from python (wsgi) - is it possible?

  - by Bill Zimmerman

  Hi, I've got a python/WSGI app which needs to check to see if a user has logged on to a PHP web app. The problem is that the PHP app checks if a user has logged on by comparing a value in the $_SESSION variable to a value in the cookie from the user's browser. I would prefer to avoid changing the behavior of the php app if at all possible. My questions: Is there anyway I can access the session variables from within python? Where should I start to look? Are there any obvious security/performance issues I should be aware of when taking this approach?

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• Refresh combo box in Windows Form VB.NET

  - by fireBand

  Following is the code to populate combobox using DataSource Dim CountryList As Array = MyCtrl.GetAllCountries With cbCountyList .DataSource = CountryList .DisplayMember = "CountryName" .ValueMember = "CountryID" End With After adding a new COuntry Name to Database I want to reflect the changes in combobox. Repeating this code is not an option becasue it triggers SelectIndexChange event and had to do some crappy work around to avoid that. So I was wondering if there is way to refresh the combobox list. I actually thought binding with the DataSource property supposed to do it automatically. I also tried cbCountyList.Refresh() Thanks in advance.

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• UITableView with contact image problems.

  - by prathumca

  As par my app requirement, I'm showing the contact images in a UITableView as shown below. ABRecordRef contact = [self getContact]; if(contact && ABPersonHasImageData(contact)) { UIImage *contactImage = [UIImage imageWithData:(NSData*)ABPersonCopyImageData(contact)]; callImage.image = contactImage; } I've two problems if I use the above code segment. Table Scrolling is too slow. If comment the above code, then UITable responds very fast. Memory Management. My app started using 25 - 30 MB of RAM. Is there any better way to avoid the above two problems?

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• Cakephp ajax Autocomplete not working

  - by Vijay Kumbhar

  Hello All, I am using ajax autocomplete in my application, but it is not giving the output. Ajax request to the desired function goes but it is not giving back any response, it is blank. I am also using jquery but it is used for other effects. i added jquery no conflict to avoid the prototype & jquery conflicts. I have tried other ajax helper methods like obeserverfield, it is working fine & returning the proper response, but when i use autocomplete it fails Can anybody help me ..........

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• [C#] How to create a constructor of a class that return a collection of instances of that class?

  - by codemonkie

  My program has the following class definition: public sealed class Subscriber { private subscription; public Subscriber(int id) { using (DataContext dc = new DataContext()) { this.subscription = dc._GetSubscription(id).SingleOrDefault(); } } } ,where _GetSubscription() is a sproc which returns a value of type ISingleResult<_GetSubscriptionResult> Say, I have a list of type List<int> full of 1000 ids and I want to create a collection of subscribers of type List<Subscriber>. How can I do that without calling the constructor in a loop for 1000 times? Since I am trying to avoid switching the DataContext on/off so frequently that may stress the database. TIA.

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• Can I have fixed typed ArrayList in C#, just like C++?

  - by Kazoom

  I have an ArrayList which contains fixed type of objects. However everytime I need to extract an object a particular index, I need to typecast it to my user defined type from object type. Is there a way in C# to declare ArrayList of fixed types just like Java and C++, or is there a work around to avoid the typecasting everytime? Edit: I apologize I forgot mentioning that I require the datastructure to be thread-safe, which List is not. Otherwise I would have just used a normal Array. But I want to save myself from the effort of explicitly locking and unlocking while writing the array. So I thought of using ArrayList, synchronize it, but it requires typecasting every time.

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• How to assess the risk of a java version upgrade?

  - by Roy Tang

  I'm being asked to assess whether we can safely upgrade the java version on one of our production-deployed webapps. The codebase is fairly large and we want to avoid having to regression test everything (no automated tests sadly), but we've already encountered at least one problem during some manual testing (XmlStringReader.getLocalName now throws an IllegalStateExeption when it just used to return null) and higher-ups are pretty nervous about the upgrade. The current suggested approach is to do a source compare of the JDK sources for each version and assess those changes to see which ones might have impact, but it seems there's a lot of changes to go through (and as mentioned the codebase is kinda large). Is it safe and easier to just review the java version changes for each version? Or is there an easier way to conduct this assessment? Edit: I forgot to mention the version upgrade being considered is a minor version upgrade, i.e. 1.6.10 to 1.6.33

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• How to enforce lazy loading of entities on certain conditions

  - by Samuel

  We have an JPA @Entity class (say User) which has a @ManyToOne reference (say Address) loaded using the EAGER option which in turn loads it's own @ManyToOne fields (say Country) in a EAGER fashion. We use the EntityQuery interface to count the list of User's based on a search criteria, during such a load all the @ManyToOne fields which have been marked as EAGER get loaded. But in order to perform a EntityQuery.resultCount(), I actually don't need to load the @ManyToOne fields. Is there a way to prevent loading of the EAGER fields in such cases so that we can avoid the unnecessary joins?

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• how to call a C++ dll from C# windows application project

  - by chathuradd

  I have created a dll in C++ using a Class Library project in Visual Studio. I need to call a method in the dll from a C# application. I got to know there are 2 approches. One is to add the dll project reference to C# project or use DllExport to export method. However when I tried in both ways it always gives the following error when the dll method is called in runtime. An unhandled exception of type 'System.BadImageFormatException' occurred in TestClient.exe Additional information: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B) Can i know how to avoid this problem ? Thanks in advance!

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• Is the "message" of an exception culturally independent?

  - by Ray Hayes

  In an application I'm developing, I have the need to handle a socket-timeout differently from a general socket exception. The problem is that many different issues result in a SocketException and I need to know what the cause was. There is no inner exception reported, so the only information I have to work with is the message: "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond" This question has a general and specific part: is it acceptable to write conditional logic based upon the textual representation of an exception? Is there a way to avoid needing exception handling? Example code below... try { IPEndPoint endPoint = null; client.Client.ReceiveTimeout = 1000; bytes = client.Receive(ref endPoint); } catch( SocketException se ) { if ( se.Message.Contains("did not properly respond after a period of time") ) { // Handle timeout differently.. } }

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• website is very slow on IE

  - by Bhupi

  Hi, I need to know what can be the main reasons (apart from the basics like grouping CSS selectors, reducing image size, using image sprite etc.) which makes a website slow on Internet Explorer, because my website works fine on the others like FF, chrome etc. Is it the huge use of Javascript framework (ie. jQuery, extjs, prototype)? Is it because of the use of plugins based on JS framework? Should I use core javascript and remove the use of any js framework? Should I try to avoid using jQuery(document).ready()? in case of jQuery framework? Above some of the questions which I know and please answer the questions which I couldn't ask because of lesser knowledge about these. I need to make my website perform well on IE (6,7,8) also please suggest. Thanks

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• Is shortening properties names worth it?

  - by raam86

  in how to node Blog rolling with node.js and mongoDB the author mentions it's a good idea to shorten proprieties names: ....oft-reported issue with mongoDB is the size of the data on the disk... each and every record stores all the field-names .... This means that it can often be more space-efficient to have properties such as 't', or 'b' rather than 'title' or 'body', however for fear of confusion I would avoid this unless truly required! I am aware of solutions of how to do it I am more intrested in when is it truly required?

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• Hashing a python function to regenerate output when the function is modified

  - by Seth Johnson

  I have a python function that has a deterministic result. It takes a long time to run and generates a large output: def time_consuming_function(): # lots_of_computing_time to come up with the_result return the_result I modify time_consuming_function from time to time, but I would like to avoid having it run again while it's unchanged. [time_consuming_function only depends on functions that are immutable for the purposes considered here; i.e. it might have functions from Python libraries but not from other pieces of my code that I'd change.] The solution that suggests itself to me is to cache the output and also cache some "hash" of the function. If the hash changes, the function will have been modified, and we have to re-generate the output. Is this possible or ridiculous? Updated: based on the answers, it looks like what I want to do is to "memoize" time_consuming_function, except instead of (or in addition to) arguments passed into an invariant function, I want to account for a function that itself will change.

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• Preprocessor directive to test if this is C or C++

  - by Collin

  I'm trying to find a standard macro which will test whether a header file is being compiled as C or as C++. The purpose of this is that the header may be included by either C or C++ code, and must behave slightly differently depending on which. Specifically: In C, I need this to be the code: extern size_t insert (const char*); In C++, I need this to be the code: extern "C" size_t insert (const char*); Additionally, is there a way to avoid putting #ifdef's around every declaration in the header?

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• Multivalue parametres in SSRS- display in the report

  - by pfeffer

  I just started working with SSRS, so this question might seem silly. Anyway, for now I'm trying to avoid multi-valued parameters, because I want my parameters to be able to be NULL. So I'm just passing a comma-separated string of ID values to my stored procedure, and everything works. The problem I encountered is that I want to display the actual values, not IDs, in the report, so that users can see, what filter was used. If that were a multi-valued parameter, I would simply use JOIN function, but now I am out of ideas and would really appreciate some help. Thanks!

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