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  • Automatic .NET code, nhibernate session, and LINQ datacontext clean-up?

    - by AverageJoe719
    Hi all, in my goal to adopt better coding practices I have a few questions in general about automatic handling of code. I have heard different answers both from online and talking with other developers/programmers at my work. I am not sure if I should have split them into 3 questions, but they all seem sort of related: 1) How does .NET handle instances of classes and other code things that take up memory? I recently found out about using the factory pattern for certain things like service classes so that they are only instantiated once in the entire application, but then I was told that '.NET handles a lot of that stuff automatically when mentioning it.' 2) How does Nhibernate's session handle automatic clean-up of un-used things? I've seen some say that it is great at handling things automatically and you should just use a session factory and that's it, no need to close it. But I have also read and seem many examples where people close the hibernate session. 3) How does LINQ's datacontext handle this? Most of the time I never .disposed my datacontext's and the app didn't see to take a performance hit (though I am not running anything super intensively), but it seems like most people recommend disposing of your datacontext after you are done with it. However, I have seen many many code examples where the dispose method is never called. Also in general I found it kind of annoying that you couldn't access even one-deep child related objects after disposing of the datacontext unless you explicity also grabbed them in the query. Thanks all. I am loving this site so far, I kind of get lost and spend hours just reading things on here. =)

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  • Inner join and outer join options in Entity Framework 4.0

    - by bigb
    I am using EF 4.0 and I need to implement query with one inner join and with N outer joins I started to implement this using different approaches but get into trouble at some point. Here is two examples how I started of doing this using ObjectQuery<'T' and Linq to Entity 1)Using ObjectQuery<'T' I implement flexible outer join but I don't know how to perform inner join with entity Rules in that case (by default Include("Rules") doing outer join, but i need to inner join by Id). public static IEnumerable<Race> GetRace(List<string> includes, DateTime date) { IRepository repository = new Repository(new BEntities()); ObjectQuery<Race> result = (ObjectQuery<Race>)repository.AsQueryable<Race>(); //perform outer joins with related entities if (includes != null) foreach (string include in includes) result = result.Include(include); //here i need inner join insteard of default outer join result = result.Include("Rules"); return result.ToList(); } 2)Using Linq To Entity I need to have kind of outer join(somethin like in GetRace()) where i may pass a List with entities to include) and also i need to perform correct inner join with entity Rules public static IEnumerable<Race> GetRace2(List<string> includes, DateTime date) { IRepository repository = new Repository(new BEntities()); IEnumerable<Race> result = from o in repository.AsQueryable<Race>() from b in o.RaceBetRules select new { o }); //I need here: // 1. to perform the same way inner joins with related entities like with ObjectQuery above //here i getting List<AnonymousType> which i cant cast to //IEnumerable<Race> when i did try to cast like //(IEnumerable<Race>)result.ToList(); i did get error: //Unable to cast object of type //'System.Collections.Generic.List`1[<>f__AnonymousType0`1[BetsTipster.Entity.Tip.Types.Race]]' //to type //'System.Collections.Generic.IEnumerable`1[BetsTipster.Entity.Tip.Types.Race]'. return result.ToList(); } May be someone have some ideas about that.

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  • What are the useful UNIX functions that MS doesn't implement? And why? [closed]

    - by prosseek
    When programming with Python, I came across some functions that are not implemented on Windows. os.fork() may be one of them. UNIX came before WinNT, so the WinNT developers (most notably Dave Cutler) must knew about the features and functions of the UNIX. But, to me, it seems that MS didn't like UNIX so much that they mistakenly/intentionally skipped or distorted some of the useful UNIX functions/features; i.e. /abc/def in UNIX, \abc\def in Windows as an easy example. And when I read the Windows System Programming book, I felt uncomfortable as the Windows system functions seem nothing more than a tweak from UNIX. (I might be wrong.) What are those functions/features that MS OSes don't have, but UNIX origninated? Is there any reason for this? Do they just want to differentiate from UNIX world? Or do they think some of the UNIX functions are unnecessary? Is Windows a tweak from UNIX? Or, is there any great OS features that were invented in MS to make Windows better than UNIX?

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  • Issue encondig java->xls

    - by Xerg
    This is not a pure java question and can also be related to HTML I've written a java servlet that queries a database table and shows the result as a html table. The user can also ask to receive the result as an Excel sheet. Im creating the Excel sheet by printing the same html table, but with the content-type of "application/vnd.ms-excel". The Excel file is created fine. The problem is that the tables may contain non-english data so I want to use a UTF-8 encoding. PrintWriter out = response.getWriter(); response.setContentType("application/vnd.ms-excel:ISO-8859-1"); //response.setContentType("application/vnd.ms-excel:UTF-8"); response.setHeader("cache-control", "no-cache"); response.setHeader("Content-Disposition", "attachment; filename=file.xls"); out.print(src); out.flush(); The non-english characters appear as garbage (áéíóú) Also I tried converting to bytes from String byte[] arrByte = src.getBytes("ISO-8859-1"); String result = new String(arrByte, "UTF-8"); But I Still getting garbage, What can I do?. Thanks

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  • background image shows up on right-click show image, but not on webpage

    - by William
    okay, so I'm trying to set up a webpage with a div wrapping two other divs, and the wrapper div has a background, and the other two are transparent. How come this isn't working? here is the CSS: .posttext{ float: left; width: 70%; text-align: left; padding: 5px; background-color: transparent !important; } .postavi{ float: left; width: 100px; height: 100%; text-align: left; background-color: transparent !important; padding: 5px; } .postwrapper{ background-image:url('images/post_bg.png'); background-position:left top; background-repeat:repeat-y; } and here is the HTML: <div class="postwrapper"> <div class="postavi"><img src="http://prime.programming-designs.com/test_forum/images/avatars/hacker.png" alt="hacker"/></div><div class="posttext"><p style="color: #ff0066">You will have bad luck today.</p>lol</div> </div> Edit: at request, here is a link to the site: http://prime.programming-designs.com/test_forum/viewthread.php?thread=33 Edit: edited css to be correct, still suffering same problem

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  • Reading numpy arrays outside of Python

    - by Abiel
    In a recent question I asked about the fastest way to convert a large numpy array to a delimited string. My reason for asking was because I wanted to take that plain text string and transmit it (over HTTP for instance) to clients written in other programming languages. A delimited string of numbers is obviously something that any client program can work with easily. However, it was suggested that because string conversion is slow, it would be faster on the Python side to do base64 encoding on the array and send it as binary. This is indeed faster. My question now is, (1) how can I make sure my encoded numpy array will travel well to clients on different operating systems and different hardware, and (2) how do I decode the binary data on the client side. For (1), my inclination is to do something like the following import numpy as np import base64 x = np.arange(100, dtype=np.float64) base64.b64encode(x.tostring()) Is there anything else I need to do? For (2), I would be happy to have an example in any programming language, where the goal is to take the numpy array of floats and turn them into a similar native data structure. Assume we have already done base64 decoding and have a byte array, and that we also know the numpy dtype, dimensions, and any other metadata which will be needed. Thanks.

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  • Why do programmers have to learn for their whole lives and aren't you afraid of that?

    - by serg555
    Programming technologies are evolving so fast that programmers constantly have to learn more and more to catch up whether you want it or not. Often it is not just learning more in the same direction but starting from a scratch. Lets say you were a topnotch programmer in 1999 who quit for 10 years and went to a job interview in 2009 (funny even to imagine) - how much of your knowledge is still needed? And if we take a carpenter, engineer, doctor or even mathematician - they all are still good specialists after 10 years. So why programming is so not stable? Is it because it is just relatively new or because something important is still missing after 50 years and we can't find it to settle in that direction? Do you think after some time situation will change? Learning something new all the time is exciting and all, but it is starting to worry me that as I become older it will be harder and harder. After all "you can't teach an old dog new tricks" and I'm afraid that at the end I just end up behind college students and become one of those "cobol dinosaurs", only it will be probably "java dinosaurs" by that time.

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  • Java (or possibly other languages) learning path

    - by bgo
    I am familiar (as a self-learner) with C, python and php such that i can solve some problems involving simple steps (for example, i easily do calculations for physics lab reports with python which normally would take 4x-5x times longer with a calculator). The point here is, as doing such things, i learnt the idea / concepts of programming language and problem solving along with oop or fuctional programming etc. Recently i have started Java and, with the familiarity of other languages, i am doing well for starters but i need guidence. -I am thinking of learning syntax from sun java tutorials and then practicing with codingbat.com or similar sites. I need a reference book that i can study deeper aspects of the topics i am learning. What do you suggest about these? -The problem is (and always have been) the lack of practice. I need coding and problem-solving practices sources. I stuck at the point where i can't figure out what to do next. Can you suggest any source (possibly like codingbat)? If i could plan a learning trail, i can progress faster and efficiently. So i need ideas, comments, suggestions. Thanks in advance.

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  • How to use SendMessage to another form in same app

    - by Robert Frank
    I've been trying to get this to work for some time now and can't figure it out. Probably obvious once you know it. I simply want a non-modal form (or perhaps an instantiated non-TForm class) to send a message to the application's main form. I can make the main form send a message to itself and receive (announcing with a beep) But, I can't seem to have other objects send messages to the main form. I'm using WM_MY_MESSAGE = WM_APP + 200; What should the first argument of the SendMessage be to send a message to the main form? Even sending it to Application.MainForm.Handle doesn't seem to work. The reason I need to do this is that the modal form has a slider that another form (#2) needs to know when it changes. Notifying the other form via a callback procedure was making it sluggish as form #2 did some work before returning from the call. Is having a modal form send a windows message to the main form a reasonable way to avoid this?

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  • Detecting Connection Speed / Bandwidth in .net/WCF

    - by Mystagogue
    I'm writing both client and server code using WCF, where I need to know the "perceived" bandwidth of traffic between the client and server. I could use ping statistics to gather this information separately, but I wonder if there is a way to configure the channel stack in WCF so that the same statistics can be gathered simultaneously while performing my web service invocations. This would be particularly useful in cases where ICMP is disabled (e.g. ping won't work). In short, while making my regular business-related web service calls (REST calls to be precise), is there a way to collect connection speed data implicitly? Certainly I could time the web service round trip, compared to the size of data used in the round-trip, to give me an idea of throughput - but I won't know how much of that perceived bandwidth was network related, or simply due to server-processing latency. I could perhaps solve that by having the server send back a time delta, representing server latency, so that the client can compute the actual network traffic time. If a more sophisticated approach is not available, that might be my answer...

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  • set a default saving data in a selection box in HABTM model

    - by vincent low
    here is my problem which in my system. my system allow user to add event, which include date, time, places. In the other hand, user are allow to choose the "Event sharing to" some of other user. So i successful to created and share to other user, when the user login which are being choose to share with the event, he is able to view for that particular event. But the problem is, when user add the event, he must choose for his own name also in the select box. If not he will be unable to read the event that he had created. So i need to save a default data to my model, which is whenever the user got choose the sharing event or not, it also will save the data to his user id. here is my code for select box, what can i edit and do to let it set a default saving value which is always save with the user own data?? input('User',array( 'label' = 'Select Related Potential', 'options' = $users, //'id'='user', 'style'='width:250px;height:100px', //'selected' = $ownUserId )); ? i try to solve by adding 1 more row to the add.ctp, but the permission just set to the own user who created it, the other user i choose is unable to read. $form-input('User',array( 'label' = 'Select Related Potential', 'options' = $users, //'id'='user', 'style'='width:250px;height:100px', 'selected' = $ownUserId )); $form-input('User',array('type'='hidden','value'=$ownUserId));

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  • Brackets matching using BIT

    - by amit.codename13
    edit: I was trying to solve a spoj problem. Here is the link to the problem : http://spoj.pl/problems/BRCKTS I can think of two possible data structures for solving the problem one using segment tree and the other using a BIT. I have already implemented the solution using a segment tree. I have read about BIT but i can't figure out how to do a particular thing with it(which i have mentioned below) I am trying to check if brackets are balanced in a given string containing only ('s or )'s. I am using a BIT(Binary indexed tree) for solving the problem. The procedure i am following is as follows: I am taking an array of size equal to the number of characters in the string. I am assigning -1 for ) and 1 for ( to the corresponding array elements. Brackets are balanced in the string only if the following two conditions are true. The cumulative sum of the whole array is zero. Minimum cumulative sum is non negative. i.e the minimum of cumulative sums of all the prefixes of the array is non-negative. Checking condition 1 using a BIT is trivial. I am facing problem in checking condition 2.

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  • Do you like Twisted?

    - by Luca
    I use Python Twisted for web development, and I don't like it? I know async programming is a great idea, I know there are may async web servers now, I know it's the only way to solve some problems you'd have with threads but I don't like. The problem is that, you're forced to program in a twisted way. So, the architecture you have in mind, very often have to be modified to fit the way twisted works. The architecture have to follow the technology, I don't think this is good. When we use callback in javascript, we don't have too many difficulties: things are usually simpler, we use a callback in response to an Ajax call. But in a server web app things are, very often, a bit more complex. Writing chain of callbacks don't seem to me a wonderful way of programming. The code is not simple, and so it is difficult to understand and to maintain. Writing twisted code we very often lost the linear intuitive idea of the algorithm we wanted to implement, especially when things grow in complexity. What's your point of view?

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  • Turning off antialiasing in Löve2D

    - by cjanssen
    I'm using Löve2D for writing a small game. Löve2D is an open source game engine for Lua. The problem I'm encountering is that some antialias filter is automatically applied to your sprites when you draw it at non-integer positions. love.graphics.draw( sprite, x, y ) So when x or y is not round (for example, x=100.24), the sprite appears blurred. The same happens when the sprite size is not even, because (x,y) points to the center of the sprite. For example, a sprite which is 31x30 big will appear blurred again, because its pixels are painted in non-integer positions. Since I am using pixel art, I want to avoid this all the way, otherwise the art is destroyed by this effect. The workaround I am using so far is to force the coordinates to be round by littering the code with calls to math.floor(), and forcing all the sprites to have even sizes by adding a row or column of transparent pixels with the paint program, if needed. Is there some command to deactivate the antialiasing I can call at program startup?

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  • How to use Data aware controls "correctly"?

    - by lyborko
    Hi, I would like to ask experienced users, if you prefer to use data aware controls to add, insert, delete and edit data in DB or you favor to do it manualy. I developed some DB applications, in which for the sake of "user friendly policy" I run into complicated web of table events (afterinsert, afteredit, after... and beforeedit, beforeinsert, before...). After that it was a quite nasty work to debug the application. Aware of this risk (later by another application) I tried to avoid this problem, so I paid increased attention to write code well, readable and comprehensive. It seemed everything all right from the beginning, but as I needed to handle some preprocessing stuff before sending and loading data etc, I run into the same problems again, "slowly and inevitably". Sometime I could not use dataaware controls anyway, and what seemed to be a "cool" feature of DAControl at the beginning it turned to an obstacle on the end. I "had to" write special routine for non-dataaware controls, in order to behave as dataaware. Then I asked myself, why on earth should I use dataaware controls? Is it better to found application architecture on non-dataaware controls? It requires more time to write bug-proof code, of course, but does it worth of it? I do not know... I happened to me several times, like jinxed : paradise on the beginning hell on the end... I do not know, if I use wrong method to write DB program, if there is some standard common practice how to proceed. Or if it is common problem to everybody? Thanx for advices and your experiences

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  • Does complex JOINs causes high coupling and maintenance problems ?

    - by ashkan.kh.nazary
    Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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  • Objective C loop logic

    - by Graham
    Hi guys, I'm really new to programming in Obj-C, my background is in labview which is a graphical programming language, I've worked with Visual Basic some and HTML/CSS a fair amount as well. I'm trying to figure out the logic to create an array of data for the pattern below. I need the pattern later to extract data from another 2 arrays in a specific order. I can do it by referencing a = 1, b = 2, c = 3 etc and then creating the array with a, b, c but I want to use a loop so that I don't have 8 references above the array. These references will be used to generate another generation of data so unless I can get help figuring out the logic I'll actually end up with 72 references above the array. // This is the first one which gives the pattern 0 0 0 0 (etc) // 1 1 1 1 // 2 2 2 2 NSMutableArray * expSecondRef_one = [NSMutableArray array]; int a1 = 0; while (a1 < 9) { int a2 = 0; while (a2 < 8) { NSNumber * a3 = [NSNumber numberWithInt:a1]; [expSecondRef_one addObject:a3]; a2++; } a1++; } // This is the second one which I'm stumbling over, I am looking for the pattern 1 2 3 4 5 6 7 8 // 0 2 3 4 5 6 7 8 // 0 1 3 4 5 6 7 8 // 0 1 2 4 5 6 7 8 // etc to -> // 0 1 2 3 4 5 6 7 If you run it in a line every 9th number is -1 but I don't know how to do that over a pattern of 8. Thanks in advance! Graham

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  • How can I create a properly sizing QWebView?

    - by chacham15
    I want to make a QWebView appear expanding to the width and height so that ideally it will have no scroll bars. Some websites may have fixed widths that wont allow this, but I am not concerned with those. In any case, I cannot do as I wish because QWebView implements sizeHint as follows: QSize QWebView::sizeHint() const { return QSize(800, 600); // ####... } This is incorrect on a number of levels. 1. It doesnt at all take into account the size of the actual web page. 2. It doesnt take into account that the height and width are related to each other. (To prove #2 think about text in web pages that wraps to the next line.) As a simple fix I tried to do (where QResizingWebView extends QWebView): QSize QResizingWebView::sizeHint() const{ return this-page()-mainFrame()-contentsSize(); } While this is closer to the result, it also has 2 flaws. 1. It doesnt take into account the relation between the displayed width/height. 2. this->page()->mainFrame()->contentsSize() is inaccurate from what I can tell from my preliminary testing (it has returned heights larger than it should under many cases, although this may be related to #1). Does anyone have any tips to fix this?

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  • Single Responsibility Principle vs Anemic Domain Model anti-pattern

    - by Niall Connaughton
    I'm in a project that takes the Single Responsibility Principle pretty seriously. We have a lot of small classes and things are quite simple. However, we have an anemic domain model - there is no behaviour in any of our model classes, they are just property bags. This isn't a complaint about our design - it actually seems to work quite well During design reviews, SRP is brought out whenever new behaviour is added to the system, and so new behaviour typically ends up in a new class. This keeps things very easily unit testable, but I am perplexed sometimes because it feels like pulling behaviour out of the place where it's relevant. I'm trying to improve my understanding of how to apply SRP properly. It seems to me that SRP is in opposition to adding business modelling behaviour that shares the same context to one object, because the object inevitably ends up either doing more than one related thing, or doing one thing but knowing multiple business rules that change the shape of its outputs. If that is so, then it feels like the end result is an Anemic Domain Model, which is certainly the case in our project. Yet the Anemic Domain Model is an anti-pattern. Can these two ideas coexist? EDIT: A couple of context related links: SRP - http://www.objectmentor.com/resources/articles/srp.pdf Anemic Domain Model - http://martinfowler.com/bliki/AnemicDomainModel.html I'm not the kind of developer who just likes to find a prophet and follow what they say as gospel. So I don't provide links to these as a way of stating "these are the rules", just as a source of definition of the two concepts.

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  • How would you mask data returned in a Dynamic Data for Entities website?

    - by David Stratton
    I'm doing this in Visual Studio 2008, not 2010, in case there is a relevant difference between the two versions of the Dynamic Data websites. How would I mask data in the automatically generated tables in a Dynamic Data for Entities website? The scenario is we have one table where we want to allow users to ENTER sensitive data, but not VIEW sensitive data, so... (In the list below, I'm using "template" to mean "The web page generated automatically based on the schema and action. I'm sure that's the wrong terminology, but the meaning should be clear.) The "Insert" template should have the field's textbox available for the user to type a value in. The "Edit" template should have the field's textbox blanked out (empty string) regardless of what was in the field in the database in the first place, but the user should be able to type in new data and have it save The "View" template should either have the data for this field masked, or non-visible. The auto-generated table showing the list of records should also have this field masked or non-visible. I can do this easily with standard Web Forms, but I'm having a hard time figuring this out in the Dynamic Data site I'm working on. Masking data is such a common task, I have to believe Microsoft thought of this and provided a way to do it...

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  • How can I improve this search usability?

    - by Craig Whitley
    This is the first real programming attempt of mine, and theres some major flaws. It's a learning project, and I'm currently re-writing the entire thing as my php is is really messy. I really want to get an idea on how I can improve the actual usability and accesibility of the site at the same time though - so I know how to implement it correctly. The website is basically a comparison website for gameserver hosting. As I mentioned, its a learning project and I don't actually expect any revenue from it. At the moment theres only test data in it, so in the game input box select either 'Battlefied Bad Company 2' or 'Call of Duty 4: Modern Warfare' and ignore the actual search results. http://www.laglessfrag.com I wasn't really sure how to work the search functionality. Basically when you click a game in the drop down box, it sends an ajax request and finds all the locations available to that specific game in the database. After selecting the country theres another ajax to find all the citys available to the game in that country - which gives me the two unique identifiers I need to create the search results. One major and fundamental flaw is that without javascript enabled, the site ceases to function. I'll overcome that in the next re-write, but without the ajax functionality stopping the user 'going wrong' - how can I implement a search that requires two fields without creating extra steps in new pages after form submissions? I'm also no designer so my whole layout and css is a bit rubbish, but this was mainly a learning project as I'm interested in applications / programming rather than design. It's also slow as its on shared hosting, but if I can get it to work correctly then I'm not impartial to chucking a bit of money at it for faster hosting and maybe a bit of advertising and seeing where it goes (if anywhere!). Any info appreciated.

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  • Nhibernate fires SQL commands

    - by Chris
    Hi all, when updating an entity A, NHibernate also send an SQL update command for some other entity B. A and B are not related. Just before saving entity A, the parent of entity B is loaded via a SQLQuery. Then, when accessed, B is lazy loaded (part of a collection). If I save entity A an update statement for entity B is generated as well. How can that be, that when saving an entity, another entity loaded before but is not related to the entity saved, is updated as well?! Can I somehow track where the update comes from? Btw. I am using an save event listener. Could it be that this is always triggered for entity loaded, even though they are not saved explicitly? public class EntitySaveEventListener : NHibernate.Event.Default.DefaultSaveEventListener { protected override object PerformSaveOrUpdate(SaveOrUpdateEvent e) { //auditing return base.PerformSaveOrUpdate(e); } } Update (sorry for providing not enough info): I tracked it down a bit. A select stateement on a entity called address is executed (is it lazy loaded by a parent). Then I create a new entity called Request. Right before saving this entity a session flush is called which updates the address, even though I did not call save or update on the address. Address is a collection within Request. <class name="Request" table="Request"> <bag name="addresses" access="field" cascade="all-delete-orphan" where="IsDeleted = 0"> <key column="RequestId"/> <one-to-many class="Address"/> </bag> ... // address is fetched only NHibernate.SQL: 2010-02-17 11:47:21,306 [21] DEBUG NHibernate.SQL [(null)] - SELECT addresses0_.RequestId as ServiceP8_3_, .... // session flushed here // address is updated NHibernate.SQL: 2010-02-17 11:47:34,306 [21] DEBUG NHibernate.SQL [(null)] - Batch commands: command 0:UPDATE Address SET Street = @p0, ..... Would the address be updated automatically when it is manipulated somehow even though it is not explicitly saved via it's parent (cascade)?

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  • Understanding Symbols In Ruby

    - by Kezzer
    Despite reading this article, I'm still confused as to the representation of the data in memory when it comes to using symbols. If a symbol, two of them contained in different objects, exist in the same memory location, then how is it that they contain different values? I'd have expected the same memory location to contain the same value. As a quote from the link: Unlike strings, symbols of the same name are initialized and exist in memory only once during a session of ruby I just don't understand how it manages to differentiate the values contained in the same memory location. EDIT So let's consider the example: patient1 = { :ruby => "red" } patient2 = { :ruby => "programming" } patient1.each_key {|key| puts key.object_id.to_s} 3918094 patient2.each_key {|key| puts key.object_id.to_s} 3918094 patient1 and patient2 are both hashes, that's fine. :ruby however is a symbol. If we were to output the following: patient1.each_key {|key| puts key.to_s} Then what will be output? "red", or "programming"? FURTHER EDIT I'm still really quite confused. I'm thinking a symbol is a pointer to a value. Let's forget hashes for a second. The questions I have are; can you assign a value to a symbol? Is a symbol just a pointer to a variable with a value in it? If symbols are global, does that mean a symbol always points to one thing?

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  • Web-app currency input/manipulation/calculation with javascript .. there has got to be a better (fra

    - by dreftymac
    BACKGROUND: I am of the "user-input-lockdown" school of thought. Whenever possible, I try to mistrust and sanitize user input, both client side and server side; and I try to take multiple opportunities to restrict possible inputs to a known subset of possibilities, usually this means providing a lot of checkboxes and select lists. (This is from the usability side of things, I know security-wise that malicious users can easily bypass fixed user input GUI controls). PROBLEM: Anyway, the problem always arises with non-fixed input of currency. Whenever I have to accept a freely-specified dollar amount as user input, I always have to confront these problems/annoyances and it is always painful: 1) Make sure to give the user two input boxes for each currency_datapoint, one for the whole_dollar_part and another for the fractional_pennies_part 2) Whenever the user changes a currency_datapoint, provide keystroke-by-keystroke GUI feedback to let them know whether the currency_datapoint is well-formed, with context-appropriate validation rules (e.g., no negatives?, nonzero only?, numeric only!, no non-numeric punctuation! no symbols!) 3) For display purposes, every user-provided currency_datapoint should be translated to human-readable currency formatting (dollar sign, period, commas provided by the app, where appropriate) 4) For calculation purposes, every user-provided currency_datapoint has to be converted to integer (all pennies, to avoid floating point errors) and summed into a grand total with zero or more subtotals. 5) Every user-provided currency_datapoint should be displayed or displayable in a nice "tabular" format, which auto-updates as the user enters each currency_datapoint, including a baloon that warns when one or more currency_datapoints is not well-formed. I seem to be re-inventing this wheel every time I have to work with currency in Javascript on the client side (server side is a bit more flexible since most programming languages have higher-level currency formatting logic). QUESTION: Has anyone out there solved the problem of dealing with the above issues, client side, in a way that is server-side-technology-stack agnostic, (preferrably plain javascript or jquery)? This is getting old, there has to be a better way.

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  • How do I [legally] get the current first responder on the screen on an iPhone?

    - by Anthony D
    I submitted my app a little over a week ago and got the dreaded rejection email today. It reads as follows: Dear -----------, Thank you for submitting --------- to the App Store. Unfortunately it cannot be added to the App Store because it is using a private API. Use of non-public APIs, which as outlined in the iPhone Developer Program License Agreement section 3.3.1 is prohibited: "3.3.1 Applications may only use Documented APIs in the manner prescribed by Apple and must not use or call any private APIs." The non-public API that is included in your application is firstResponder. Regards, iPhone Developer Program Now, the offending API call is actually a solution I found here on SO: UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow]; UIView *firstResponder = [keyWindow performSelector:@selector(firstResponder)]; So this is my question; How do I get the current first responder on the screen? I'm looking for a legal way that won't get my app rejected. Thanks. I figured this out based on the solution provided by Thomas below. Here is what the final code looks like: @implementation UIView (FindFirstResponder) - (UIView *)findFirstResonder { if (self.isFirstResponder) { return self; } for (UIView *subView in self.subviews) { UIView *firstResponder = [subView findFirstResonder]; if (firstResponder != nil) { return firstResponder; } } return nil; } @end

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