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  • EJB3 Transaction Propogation

    - by Matt S.
    I have a stateless bean something like: @Stateless public class MyStatelessBean implements MyStatelessLocal, MyStatelessRemote { @PersistenceContext(unitName="myPC") private EntityManager mgr; @TransationAttribute(TransactionAttributeType.SUPPORTED) public void processObjects(List<Object> objs) { // this method just processes the data; no need for a transaction for(Object obj : objs) { this.process(obj); } } @TransationAttribute(TransactionAttributeType.REQUIRES_NEW) public void process(Object obj) { // do some work with obj that must be in the scope of a transaction this.mgr.merge(obj); // ... this.mgr.merge(obj); // ... this.mgr.flush(); } } The typically usage then is the client would call processObjects(...), which doesn't actually interact with the entity manager. It does what it needs to do and calls process(...) individually for each object to process. The duration of process(...) is relatively short, but processObjects(...) could take a very long time to run through everything. Therefore I don't want it to maintain an open transaction. I do need the individual process(...) operations to operate within their own transaction. This should be a new transaction for every call. Lastly I'd like to keep the option open for the client to call process(...) directly. I've tried a number of different transaction types: never, not supported, supported (on processObjects) and required, requires new (on process) but I get TransactionRequiredException every time merge() is called. I've been able to make it work by splitting up the methods into two different beans: @Stateless @TransationAttribute(TransactionAttributeType.NOT_SUPPORTED) public class MyStatelessBean1 implements MyStatelessLocal1, MyStatelessRemote1 { @EJB private MyStatelessBean2 myBean2; public void processObjects(List<Object> objs) { // this method just processes the data; no need for a transaction for(Object obj : objs) { this.myBean2.process(obj); } } } @Stateless public class MyStatelessBean2 implements MyStatelessLocal2, MyStatelessRemote2 { @PersistenceContext(unitName="myPC") private EntityManager mgr; @TransationAttribute(TransactionAttributeType.REQUIRES_NEW) public void process(Object obj) { // do some work with obj that must be in the scope of a transaction this.mgr.merge(obj); // ... this.mgr.merge(obj); // ... this.mgr.flush(); } } but I'm still curious if it's possible to accomplish this in one class. It looks to me like the transaction manager only operates at the bean level, even when individual methods are given more specific annotations. So if I mark one method in a way to prevent the transaction from starting calling other methods within that same instance will also not create a transaction, no matter how they're marked? I'm using JBoss Application Server 4.2.1.GA, but non-specific answers are welcome / preferred.

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  • Can't Set Crystal Report Selection Formula Programatically

    - by eidylon
    Hello all, first, I can't stand Crystal! Okay, that's off my chest... Now, we have an old VB6 app we maintain for a client, which uses the Crystal Automation library to programatically change the record selection formulas in a bunch of Crystal Reports 8.5 reports. There are two reports which are ALMOST identical. I had to change them recently to add another field from another table. When I added the table in to the reports though, while it added it in the visual designer, it did not add it in the FROM clause of the SQL statement. So, I manually edited the SQL statement to add in the additional join. KO, works great. If i run the reports in Crystal preview mode, they work exactly as expected. Now, the users went to test the changes from within the VB app. One of the reports works fine and dandy. The other report however, is failing to set the selection formula as expected. The code sets the selection formulas using the function PESetSelectionFormula. I verified that the string being passed in to the function as the new selection formula is correct via a step-through examination of the variables. The call to PESetSelectionFormula seems to be working okay, and is returning a value of 1, which as near as I can find anywhere indicates success. (The other report, which is working fine from code is also returning 1.) However, the report is failing with an error: Error Code: 534 - Error detected by database DLL. The code, for debugging purposes dumps out the SQL string currently being used by the report. The SQL coming out of the report is: SELECT ... FROM ... WHERE ORDER BY ... As you can see, the WHERE clause is blank, which I would imagine is why the database DLL is upchucking on this statement. I don't understand why the automation library is not setting the WHERE clause even though the call to PESetSelectionFormula is being passed a valid string and is returning success. I thought perhaps it was because I had manually edited the SQL in the report to add the table it wasn't adding, but I did the same thing in the other nearly identical report, and that one is working fine. Anyone have any ideas why PESetSelectionFormula might report success but not actually do anything? P.S. I have already tried doing a Database Verify Database from the menus, and that said the report was all up to date and did not help at all.

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  • Lucene.NET search index approach

    - by Tim Peel
    Hi, I am trying to put together a test case for using Lucene.NET on one of our websites. I'd like to do the following: Index in a single unique id. Index across a comma delimitered string of terms or tags. For example. Item 1: Id = 1 Tags = Something,Separated-Term I will then be structuring the search so I can look for documents against tag i.e. tags:something OR tags:separate-term I need to maintain the exact term value in order to search against it. I have something running, and the search query is being parsed as expected, but I am not seeing any results. Here's some code. My parser (_luceneAnalyzer is passed into my indexing service): var parser = new QueryParser(Lucene.Net.Util.Version.LUCENE_CURRENT, "Tags", _luceneAnalyzer); parser.SetDefaultOperator(QueryParser.Operator.AND); return parser; My Lucene.NET document creation: var doc = new Document(); var id = new Field( "Id", NumericUtils.IntToPrefixCoded(indexObject.id), Field.Store.YES, Field.Index.NOT_ANALYZED, Field.TermVector.NO); var tags = new Field( "Tags", string.Join(",", indexObject.Tags.ToArray()), Field.Store.NO, Field.Index.ANALYZED, Field.TermVector.YES); doc.Add(id); doc.Add(tags); return doc; My search: var parser = BuildQueryParser(); var query = parser.Parse(searchQuery); var searcher = Searcher; TopDocs hits = searcher.Search(query, null, max); IList<SearchResult> result = new List<SearchResult>(); float scoreNorm = 1.0f / hits.GetMaxScore(); for (int i = 0; i < hits.scoreDocs.Length; i++) { float score = hits.scoreDocs[i].score * scoreNorm; result.Add(CreateSearchResult(searcher.Doc(hits.scoreDocs[i].doc), score)); } return result; I have two documents in my index, one with the tag "Something" and one with the tags "Something" and "Separated-Term". It's important for the - to remain in the terms as I want an exact match on the full value. When I search with "tags:Something" I do not get any results. Question What Analyzer should I be using to achieve the search index I am after? Are there any pointers for putting together a search such as this? Why is my current search not returning any results? Many thanks

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  • Contract developer trying to get outsourcing contract with current client.

    - by Mike
    I work for a major bank as a contract software developer. I've been there a few months, and without exception this place has the worst software practices I've ever seen. The software my team makes has no formal testing, terrible code (not reusable, hard to read, etc), minimal documentation, no defined development process and an absolutely sickening amount of waste due to bureaucratic overhead. Part of my contract is to maintain a group of thousands of very poorly written batch jobs. When one of the jobs fails (read: crashes), it's a developers job to look at the source, figure out what's wrong, fix it, and check it in. There is no quality assurance process or auditing of the results whatsoever. Once the developer says "it works" a manager signs off and it goes into production. What's disturbing is that these jobs essentially grab market data and put it into a third-party risk management system, which provides the bank with critical intelligence. I've discovered the disturbing truth that this has been happening since the 90s and nobody really has evidence the system is getting the correct data! Without going into details, an issue arose on Friday that was so horrible I actually stormed out of the place. I was ready to quit, but I decided to just get out to calm my nerves and possibly go back Monday. I've been reflecting today on how to handle this. I have realized that, in probably less than 6 months, I could (with 2 other developers) remake a large component of this system. The new system would provide them with, as primary benefits, a maintainable codebase less prone to error and a solid QA framework. To do it properly I would have to be outside the bank, the internal bureaucracy is just too much. And moreover, I think a bank is fundamentally not a place that can make good software. This is my plan. Write a report explaining in depth all the problems with their current system Explain why their software practices fail and generate a tremendous amount of error and waste. Use this as the basis for claiming the project must be developed externally. Write a high level development plan, including what resources I will require Hand 1,2,3 to my manager, hopefully he passes it up the chain. Worst case he fires me, but this isn't so bad. Convinced Executive decides to award my company a contract for the new system I have 8 years experience as a software contractor and have delivered my share of successful software products, but all working in-house for small/medium sized companies. When I read this over, I think I have a dynamite plan. But since this is the first time doing something this bold so I have my doubts. My question is, is this a good idea? If you think not, please spare no detail.

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  • Java: error handling with try-catch, empty-try-catch, dummy-return

    - by HH
    A searh uses recursively defined function that easily throws exceptions. I have tried 3 ways to handle exeptions: to ignore with an empty-try-catch() add-dummy-return stop err-propagation due to exeption throw a specific except. (this part I don't really understand. If I throw except, can I force it to continue elsewhere, not continuing the old except-thrown-path?) Some exceptions I do not realy care like during execution removed files -exception (NullPointer) but some I really do like unknown things. Possible exceptions: // 1. if a temp-file or some other file removed during execution -> except. // 2. if no permiss. -> except. // 3. ? --> except. The code is Very import for the whole program. I earlier added clittered-checks, try-catches, avoided-empty-try-catches but it really blurred the logic. Some stoned result here would make the code later much easier to maintain. It was annoying to track random exeptions due to some random temp-file removal! How would you handle exceptions for the critical part? Code public class Find { private Stack<File> fs=new Stack<File>(); private Stack<File> ds=new Stack<File>(); public Stack<File> getD(){ return ds;} public Stack<File> getF(){ return fs;} public Find(String path) { // setting this type of special checks due to errs // propagation makes the code clittered if(path==null) { System.out.println("NULL in Find(path)"); System.exit(9); } this.walk(path); } private void walk( String path ) { File root = new File( path ); File[] list = root.listFiles(); //TODO: dangerous with empty try-catch?! try{ for ( File f : list ) { if ( f.isDirectory() ) { walk( f.getAbsolutePath() ); ds.push(f); } else { fs.push(f); } } }catch(Exception e){e.printStackTrace();} } } Code refactored from here.

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  • Asp.net hosting equivalent of Dreamhost (pricing, features and support)

    - by Cherian
    Disclaimer: I have browsed http://stackoverflow.com/questions/tagged/asp.net+hosting and didn’t find anything quite similar in value to Dreamhost. One of the biggest impediments IMHO for developing web applications on asp.net is the cost of deployment. I am not talking about building sites like Stackoverflow.com or plentyoffish.com. This is about sites that are bigger than brochureware and smaller than ones that require dedicated servers. Let me give you an example. xmec.org is an asp.net site I maintain for my college alumni. On an average it’s slated to hit around 1000-1100 views per day. At present it’s hosted on godaddy. The service is so damn pathetic; I am using it only because of the lack of options. The site doesn’t scale (no, it’s not the code) and the web control panels are extremely slow. The money I pay doesn’t justify the service or the performance. Every deployment push is a visit to the infuriating web control panel to set the permissions and the root directories. Had I developed it in python, this would have been deployed on Dreamhost.com with $10/year hosting fees (they have offers running all throughout) 50 GB space 5 MySQL Databases Shell / FTP Users POP / SMTP Access Unlimited Domains hosting Unlimited Sub domains hosting Unlimited Domains Forwarded/Mirrored Custom DNS (These are the only ones I could think of. More at the feature page) With a dream host shell, I even have a svn checked-out version of wordpress for my blog. Now, that’s control! To my question: Is there any asp.net (preferably .net 3.5. Dreamhost keeps on updating versions every fortnight) hosting company providing remotely similar feature-sets and pricing like Dreamhost. My requirements are: Less than $15-25/ year Typical WISP minus PHP .net 3.5 SP1 Full Trust mode(I can live with medium trust, if not for the IL emitting libraries) Isolated Application Pool 5 – 10 MySQL db’s Unlimited domain hosting MsSql 2005 or 2008 FTP support At Least 5 GB space SMTP IIS 7 Log files Accessibility Moderately good control panel Scripting, shell support Nominal bandwidth Another case in point: Recently I’ve been contemplating building a tool-website to find duplicates and weird characters in my Google contacts and fix them. With asp.net, the best part is that I can do this with LINQ to XML in less than 100 lines of code. What’s bad is the hosting part. I don’t think I stand to make any money out of this and therefore can’t afford to host it on GoGrid or DiscountAsp.net. Godaddy is not an option either. If I do this in python, I can push to this my existing $10 Dreamhost account with another domain pointed. No extra cost. Svn exported with scripts (capability) to change the connection string! Looking at the problem holistically, I think I represent a large breed of programmers playing it cheap and experimenting different things on a regular basis, one of which will become the next twitter/digg.

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  • How to represent different entities that have identical behavior?

    - by Dominik
    I have several different entities in my domain model (animal species, let's say), which have a few properties each. The entities are readonly (they do not change state during the application lifetime) and they have identical behavior (the differ only by the values of properties). How to implement such entities in code? Unsuccessful attempts: Enums I tried an enum like this: enum Animals { Frog, Duck, Otter, Fish } And other pieces of code would switch on the enum. However, this leads to ugly switching code, scattering the logic around and problems with comboboxes. There's no pretty way to list all possible Animals. Serialization works great though. Subclasses I also thought about where each animal type is a subclass of a common base abstract class. The implementation of Swim() is the same for all Animals, though, so it makes little sense and serializability is a big issue now. Since we represent an animal type (species, if you will), there should be one instance of the subclass per application, which is hard and weird to maintain when we use serialization. public abstract class AnimalBase { string Name { get; set; } // user-readable double Weight { get; set; } Habitat Habitat { get; set; } public void Swim(); { /* swim implementation; the same for all animals but depends uses the value of Weight */ } } public class Otter: AnimalBase{ public Otter() { Name = "Otter"; Weight = 10; Habitat = "North America"; } } // ... and so on Just plain awful. Static fields This blog post gave me and idea for a solution where each option is a statically defined field inside the type, like this: public class Animal { public static readonly Animal Otter = new Animal { Name="Otter", Weight = 10, Habitat = "North America"} // the rest of the animals... public string Name { get; set; } // user-readable public double Weight { get; set; } public Habitat Habitat { get; set; } public void Swim(); } That would be great: you can use it like enums (AnimalType = Animal.Otter), you can easily add a static list of all defined animals, you have a sensible place where to implement Swim(). Immutability can be achieved by making property setters protected. There is a major problem, though: it breaks serializability. A serialized Animal would have to save all its properties and upon deserialization it would create a new instance of Animal, which is something I'd like to avoid. Is there an easy way to make the third attempt work? Any more suggestions for implementing such a model?

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  • Suggestions for designing large-scale Java webapp from the group up

    - by Chris Thompson
    Hi all, I'm about to start developing a large-scale system and I'm struggling with which direction to proceed. I've done plenty of Java web apps before and I have plenty of experience with servlet containers and GWT and some experience with Spring. The problem is most of my webapps have been thrown together just to be a proof of concept and what I'm struggling with is what set of frameworks to use. I need to have both a browser based application as well as a web service designed to support access from mobile devices (Android and iPhone for now). Ideally, I'd like to design this system in such a way that I don't end up rewriting all of my servlets for each client (browser and phone) although I don't mind having some small checks in there to properly format the data. In addition, although I'm the only developer now, that won't necessarily be the case down the road and I'd like to design something that scales well both with regards to traffic and number of developers (isn't just a nightmare to maintain). So where I am now is planning on using GWT to design the browser-based interface but I'm struggling with how to reuse that code with to present the interface (most likely xml) for the mobile devices. Using GWT RPC would, I think, make it relatively easy to do all of the AJAX in the browser, but might make generating xml for the mobile phones difficult. In addition, I like the idea of using something like Hibernate for persistence and Spring Security to secure the whole thing. Again, I'm not sure how well those will cooperate with GWT (I think Hibernate should be fine...) There's obviously a lot more to this than I've presented here, but I've tried to give you the 5-minute overview. I'm a bit stumped and was wondering if anybody in the community had any experience starting from this place. Does what I'm trying to do make sense? Is it realistic? I have no doubt I can make all of these frameworks speak the same language, I'm just wondering if it's worth my time to fight with them. Also, am I missing a framework that would be really beneficial? Thanks in advance and sorry for the relatively broad question... Chris

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  • Best practices for developing simple ASP.NET sites (built in controls or JQuery + scripts)

    - by Nix
    I was recently reviewing some code written by two different contractors, both were basic ASP.NET management sites. The sites allowed the user to view and edit data. Pretty much simple CRUD gateways. One group did their best to use built in ASP + AJAX Toolkit controls and did their best to use as many built in controls as possible. I found the code much easier to read and maintain. The other used jQuery and the code is heavily marked up with script blocks which are then used to build pages from javascript files. Which one is more common? The one that basically leveraged embedded HTML markup in scripts controled by javascript files screams readability and maintenance issues? Is this just the way of doing asp dev with jQuery? Assuming the second example happens a lot, are there tools that help facilitate jQuery development with visual studio? Do you think they generated the html somewhere else and just copied it in? Example Script block: <script id="HRPanel" type="text/html"> <table cellpadding='0' cellspacing='0' class="atable"><thead class="mHeader"><tr><th>Name</th><th>Description</th><th>Other</th></thead><tbody> <# for(var i=0; i < hrRows.length; i++) { var r = HRRows[i]; #> <tr><td><#=r.Name#></td><td><#=r.Description#></td><td class="taRight"><#=r.Other#></td></tr> <#}#> </tbody><tfoot><th></th><th></th><th></th></tfoot></table> </script> Then in a separate location (js file) you would see something like this. $("#HRPanel").html($("#HRPanel").parseTemplate({ HRRows: response.something.bah.bah }));

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  • Experienced developer trying to get outsourcing contract with current client.

    - by Mike
    I work for a major bank as a contract software developer. I've been there a few months, and without exception this place has the worst software practices I've ever seen. The software my team makes has no formal testing, terrible code (not reusable, hard to read, etc), minimal documentation, no defined development process and an absolutely sickening amount of waste due to bureaucratic overhead. Part of my contract is to maintain a group of thousands of very poorly written batch jobs. When one of the jobs fails (read: crashes), it's a developers job to look at the source, figure out what's wrong, fix it, and check it in. There is no quality assurance process or auditing of the results whatsoever. Once the developer says "it works" a manager signs off and it goes into production. What's disturbing is that these jobs essentially grab market data and put it into a third-party risk management system, which provides the bank with critical intelligence. I've discovered the disturbing truth that this has been happening since the 90s and nobody really has evidence the system is getting the correct data! Without going into details, an issue arose on Friday that was so horrible I actually stormed out of the place. I was ready to quit, but I decided to just get out to calm my nerves and possibly go back Monday. I've been reflecting today on how to handle this. I have realized that, in probably less than 6 months, I could (with 2 other developers) remake a large component of this system. The new system would provide them with, as primary benefits, a maintainable codebase less prone to error and a solid QA framework. To do it properly I would have to be outside the bank, the internal bureaucracy is just too much. And moreover, I think a bank is fundamentally not a place that can make good software. This is my plan. Write a report explaining in depth all the problems with their current system Explain why their software practices fail and generate a tremendous amount of error and waste. Use this as the basis for claiming the project must be developed externally. Write a high level development plan, including what resources I will require Hand 1,2,3 to my manager, hopefully he passes it up the chain. Worst case he fires me, but this isn't so bad. Convinced Executive decides to award my company a contract for the new system I have 8 years experience as a software contractor and have delivered my share of successful software products, but all working in-house for small/medium sized companies. When I read this over, I think I have a dynamite plan. But since this is the first time doing something this bold so I have my doubts. My question is, is this a good idea? If you think not, please spare no detail.

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  • Alternatives to requiring users to register for an account?

    - by jamieb
    I'm working on a side project to build a new web app idea of mine. For the sake of discussion, let's say this app displays a random photograph of a famous work of art. On a scale of 1 to 5, users are asked to rate how well they like each piece of art, and then are shown the next photo. Eventually, the app is able to get an sense of the person's style and is able to recommend artwork that he/she may find pleasing. The whole concept is similar to Netflix. I understand how to do all the preference matching logic (although not as sophisticated as Netflix). But I'd like to find a way to do this without requiring that users create an account first. This is a novelty website that a typical user might use only a handful of times. Requiring registration is overkill and will likely drastically reduce it's utility. I'd like to allow people to begin rating artwork within five seconds of their initial pageview, yet maintain the integrity of the voting (since recommendations are predicated on how other people have rated the various pieces of artwork). Can it be done? Some ideas: OpenID. The perfect solution except for the fact that it's not wildly used and my target audience isn't the most technically adept demographic. Text message. User inputs phone number and is texted a four digit code to key into the web app. Quick, easy, and great way to limit abuse. However, privacy concerns abound... people are probably even less likely to give me their phone number than their email address. Facebook login. I personally don't have a Facebook account due to privacy concerns. And I'd really hate to support such a proprietary platform. Hash code/Bookmark. Vistor's initial pageview generates a 5 or 6 digit alphanumeric code that is embedded in each subsequent URL. They can bookmark any page to save their state. Good: Very simple system that doesn't require any user action. Bad: Very easy to stuff the ballot box, might be difficult to account for users sharing the link containing their ID code via email or social networking sites.

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  • Override variables while testing a standalone Perl script

    - by BrianH
    There is a Perl script in our environment that I now need to maintain. It is full of bad practices, including using (and re-using) global variables throughout the script. Before I start making changes to the script, I was going to try to write some test scripts so I can have a good regression base. To do this, I was going to use a method described on this page. I was starting by writing tests for a single subroutine. I put this line somewhat near the top of the script I am testing: return 1 if ( caller() ); That way, in my test script, I can require 'script_to_test.pl'; and it won't execute the whole script. The first subroutine I was going to test makes a lot of use of global variables that are set throughout the script. My thought was to try to override these variables in my test script, something like this: require_ok('script_to_test.pl'); $var_from_other_script = 'Override Value'; ok( sub_from_other_script() ); Unfortunately (for me), the script I am testing has a massive "my" block at the top, where it declares all variables used in the script. This prevents my test script from seeing/changing the variables in the script I'm running tests against. I've played with Exporter, Test::Mock..., and some other modules, but it looks like if I want to be able to change any variables I am going to have to modify the other script in some fashion. My goal is to not change the other script, but to get some good tests running so when I do start changing the other script, I can make sure I didn't break anything. The script is about 10,000 lines (3,000 of them in the main block), so I'm afraid that if I start changing things, I will affect other parts of the code, so having a good test suite would help. Is this possible? Can a calling script modify variables in another script declared with "my"? And please don't jump in with answers like, "Just re-write the script from scratch", etc. That may be the best solution, but it doesn't answer my question, and we don't have the time/resources for a re-write.

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  • Asynchronous vs Synchronous vs Threading in an iPhone App

    - by Coocoo4Cocoa
    I'm in the design stage for an app which will utilize a REST web service and sort of have a dilemma in as far as using asynchronous vs synchronous vs threading. Here's the scenario. Say you have three options to drill down into, each one having its own REST-based resource. I can either lazily load each one with a synchronous request, but that'll block the UI and prevent the user from hitting a back navigation button while data is retrieved. This case applies almost anywhere except for when your application requires a login screen. I can't see any reason to use synchronous HTTP requests vs asynchronous because of that reason alone. The only time it makes sense is to have a worker thread make your synchronous request, and notify the main thread when the request is done. This will prevent the block. The question then is bench marking your code and seeing which has more overhead, a threaded synchronous request or an asynchronous request. The problem with asynchronous requests is you need to either setup a smart notification or delegate system as you can have multiple requests for multiple resources happening at any given time. The other problem with them is if I have a class, say a singleton which is handling all of my data, I can't use asynchronous requests in a getter method. Meaning the following won't go: - (NSArray *)users { if(users == nil) users = do_async_request // NO GOOD return users; } whereas the following: - (NSArray *)users { if(users == nil) users == do_sync_request // OK. return users; } You also might have priority. What I mean by priority is if you look at Apple's Mail application on the iPhone, you'll notice they first suck down your entire POP/IMAP tree before making a second request to retrieve the first 2 lines (the default) of your message. I suppose my question to you experts is this. When are you using asynchronous, synchronous, threads -- and when are you using either async/sync in a thread? What kind of delegation system do you have setup to know what to do when a async request completes? Are you prioritizing your async requests? There's a gamut of solutions to this all too common problem. It's simple to hack something out. The problem is, I don't want to hack and I want to have something that's simple and easy to maintain.

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  • Debugging site written mainly in JScript with AJAX code injection

    - by blumidoo
    Hello, I have a legacy code to maintain and while trying to understand the logic behind the code, I have run into lots of annoying issues. The application is written mainly in Java Script, with extensive usage of jQuery + different plugins, especially Accordion. It creates a wizard-like flow, where client code for the next step is downloaded in the background by injecting a result of a remote AJAX request. It also uses callbacks a lot and pretty complicated "by convention" programming style (lots of events handlers are created on the fly based on certain object names - e.g. current page name, current step name). Adding to that, the code is very messy and there is no obvious inner structure - the functions are scattered in the code, file names do not reflect the business role of the code, lots of functions and code snippets are most likely not used at all etc. PROBLEM: How to approach this code base, so that the inner flow of the code can be sort-of "reverse engineered" using a suite of smart debugging tools. Ideally, I would like to be able to attach to the running application and step through the code, breaking on each new function call. Also, it would be nice to be able to create a "diagram of calls" in the application (i.e. in order to run a particular page logic, this particular flow of function calls was executed in a particular order). Not to mention to be able to run a coverage analysis, identifying potentially orphaned code fragments. I would like to stress out once more, that it is impossible to understand the inner logic of the application just by looking at the code itself, unless you have LOTS of spare time and beer crates, which I unfortunately do not have :/ (shame...) An IDE of some sort that would aid in extending that code would be also great, but I am currently looking into possibility to use Visual Studio 2010 to do the job, as the site itself is a mix of Classic ASP and ASP.NET (I'd say - 70% Java Script with jQuery, 30% ASP). I have obviously tried FireBug, but I was unable to find a way to define a breakpoint or step into the code, which is "injected" into the client JS using AJAX calls (i.e. the application retrieves the code by invoking an URL and injects it to the client local code). Venkman debugger had similar issues. Any hints would be welcome. Feel free to ask additional questions.

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  • Strange error inserting new relationship data in core-data

    - by michael
    My app will allow users to create a personalised list of events from a large list of events. I have a table view which simply displays these events, tapping on one of them takes the user to the event details view, which has a button "add to my events". In this detailed view I own the original event object, retrieved via an NSFetchedResultsController and passed to the detailed view (via a table cell, the same as the core data recipes sample). I have no trouble retrieving/displaying information from this "event". I am then trying to add it to the list of MyEvents represented by a one to many (inverse) relationship: This code: NSManagedObjectContext *context = [event managedObjectContext]; MyEvents *myEvents = (MyEvents *)[NSEntityDescription insertNewObjectForEntityForName:@"MyEvents" inManagedObjectContext:context]; [myEvents addEventObject:event];//ERROR And this code (suggested below): //would this add to or overwrite the "list" i am attempting to maintain NSManagedObjectContext *context = [event managedObjectContext]; MyEvents *myEvents = (MyEvents *)[NSEntityDescription insertNewObjectForEntityForName:@"MyEvents" inManagedObjectContext:context]; NSMutableSet *myEvent = [myEvents mutableSetValueForKey:@"event"]; [myEvent addObject:event]; //ERROR Bot produce (at the line indicated by //ERROR): *** -[NSComparisonPredicate evaluateWithObject:]: message sent to deallocated instance Seems I may have missed something fundamental. I cant glean any more information through the use of debugging tools, with my knowledge of them. 1) Is this a valid way to compile and store an editable list like this? 2) Is there a better way? 3) What could possibly be the deallocated instance in error? -- I have now modified the Event entity to have a to-many relationship called "myEvents" which referrers to itself. I can add Events to this fine, and logging the object shows the correct memory addresses appearing for the relationship after a [event addMyEventObject:event];. The same failure happens right after this however. I am still at a loss to understand what is going wrong. This is the backtrace #0 0x01f753a7 in ___forwarding___ () #1 0x01f516c2 in __forwarding_prep_0___ () #2 0x01c5aa8f in -[NSFetchedResultsController(PrivateMethods) _preprocessUpdatedObjects:insertsInfo:deletesInfo:updatesInfo:sectionsWithDeletes:newSectionNames:treatAsRefreshes:] () #3 0x01c5d63b in -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] () #4 0x0002e63a in _nsnote_callback () #5 0x01f40005 in _CFXNotificationPostNotification () #6 0x0002bef0 in -[NSNotificationCenter postNotificationName:object:userInfo:] () #7 0x01bbe17d in -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] () #8 0x01c1d763 in -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] () #9 0x01ba25ea in -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] () #10 0x01bdfb3a in -[NSManagedObjectContext processPendingChanges] () #11 0x01bd0957 in _performRunLoopAction () #12 0x01f4d252 in __CFRunLoopDoObservers () #13 0x01f4c65f in CFRunLoopRunSpecific () #14 0x01f4bc48 in CFRunLoopRunInMode () #15 0x0273878d in GSEventRunModal () #16 0x02738852 in GSEventRun () #17 0x002ba003 in UIApplicationMain () Cheers.

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  • Temporarily impersonate and enable privileges?

    - by Luke
    We maintain a DLL that does a lot of system-related things; traversing the file system, registry, etc. The callers of this DLL may or may not be using impersonation. In order to better support all possible scenarios I'm trying to modify it to be smarter. I'll use the example of deleting a file. Currently we just call DeleteFile(), and if that fails that's the end of that. I've come up with the following: BOOL TryReallyHardToDeleteFile(LPCTSTR lpFileName) { // 1. caller without privilege BOOL bSuccess = DeleteFile(lpFileName); DWORD dwError = GetLastError(); if(!bSuccess && dwError == ERROR_ACCESS_DENIED) { // failed with access denied; try with privilege DWORD dwOldRestorePrivilege = 0; BOOL bHasRestorePrivilege = SetPrivilege(SE_RESTORE_NAME, SE_PRIVILEGE_ENABLED, &dwOldRestorePrivilege); if(bHasRestorePrivilege) { // 2. caller with privilege bSuccess = DeleteFile(lpFileName); dwError = GetLastError(); SetPrivilege(SE_RESTORE_NAME, dwOldRestorePrivilege, NULL); } if(!bSuccess && dwError == ERROR_ACCESS_DENIED) { // failed with access denied; if caller is impersonating then try as process HANDLE hToken = NULL; if(OpenThreadToken(GetCurrentThread(), TOKEN_QUERY | TOKEN_IMPERSONATE, TRUE, &hToken)) { if(RevertToSelf()) { // 3. process without privilege bSuccess = DeleteFile(lpFileName); dwError = GetLastError(); if(!bSuccess && dwError == ERROR_ACCESS_DENIED) { // failed with access denied; try with privilege bHasRestorePrivilege = SetPrivilege(SE_RESTORE_NAME, SE_PRIVILEGE_ENABLED, &dwOldRestorePrivilege); if(bHasRestorePrivilege) { // 4. process with privilege bSuccess = DeleteFile(lpFileName); dwError = GetLastError(); SetPrivilege(SE_RESTORE_NAME, dwOldRestorePrivilege, NULL); } } SetThreadToken(NULL, hToken); } CloseHandle(hToken); hToken = NULL; } } } if(!bSuccess) { SetLastError(dwError); } return bSuccess; } So first it tries as the caller. If that fails with access denied, it temporarily enables privileges in the caller's token and tries again. If that fails with access denied and the caller is impersonating, it temporarily unimpersonates and tries again. If that fails with access denied, it temporarily enables privileges in the process token and tries again. I think this should handle pretty much any situation, but I was wondering if there was a better way to achieve this? There are a lot of operations that we would potentially want to use this method (i.e. pretty much any operation that accesses securable objects).

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  • Suggestions for designing large-scale Java webapp from the ground up

    - by Chris Thompson
    Hi all, I'm about to start developing a large-scale system and I'm struggling with which direction to proceed. I've done plenty of Java web apps before and I have plenty of experience with servlet containers and GWT and some experience with Spring. The problem is most of my webapps have been thrown together just to be a proof of concept and what I'm struggling with is what set of frameworks to use. I need to have both a browser based application as well as a web service designed to support access from mobile devices (Android and iPhone for now). Ideally, I'd like to design this system in such a way that I don't end up rewriting all of my servlets for each client (browser and phone) although I don't mind having some small checks in there to properly format the data. In addition, although I'm the only developer now, that won't necessarily be the case down the road and I'd like to design something that scales well both with regards to traffic and number of developers (isn't just a nightmare to maintain). So where I am now is planning on using GWT to design the browser-based interface but I'm struggling with how to reuse that code with to present the interface (most likely xml) for the mobile devices. Using GWT RPC would, I think, make it relatively easy to do all of the AJAX in the browser, but might make generating xml for the mobile phones difficult. In addition, I like the idea of using something like Hibernate for persistence and Spring Security to secure the whole thing. Again, I'm not sure how well those will cooperate with GWT (I think Hibernate should be fine...) There's obviously a lot more to this than I've presented here, but I've tried to give you the 5-minute overview. I'm a bit stumped and was wondering if anybody in the community had any experience starting from this place. Does what I'm trying to do make sense? Is it realistic? I have no doubt I can make all of these frameworks speak the same language, I'm just wondering if it's worth my time to fight with them. Also, am I missing a framework that would be really beneficial? Thanks in advance and sorry for the relatively broad question... Chris

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  • How to create Query syntax for multiple DataTable for implementing IN operator of Sql Server

    - by Shantanu Gupta
    I have fetched 3-4 tables by executing my stored procedure. Now they resides on my dataset. I have to maintain this dataset for multiple forms and I am not doing any DML operation on this dataset. Now this dataset contains 4 tables out of which i have to fetch some records to display data. Data stored in tables are in form of one to many relationship. i.e. In case of transactions. N records per record. Then these N records are further mapped to M records of 3rd table. Table 1 MAP_ID GUEST_ID DEPARTMENT_ID PARENT_ID PREFERENCE_ID -------------------- -------------------- -------------------- -------------------- -------------------- 19 61 1 1 5 14 61 1 5 15 15 61 2 4 10 18 61 2 13 23 17 61 2 20 26 16 61 40 40 41 20 62 1 5 14 21 62 1 5 15 22 62 1 6 16 24 62 2 3 4 23 62 2 4 9 27 62 2 13 23 25 62 2 20 24 26 62 2 20 25 28 63 1 1 5 29 63 1 1 8 34 63 1 5 15 30 63 2 4 10 33 63 2 4 11 31 63 2 13 23 32 63 40 40 41 35 65 1 NULL 1 36 65 1 NULL 1 38 68 2 13 22 37 68 2 20 25 39 68 2 23 27 40 92 1 NULL 1 Table 2 Department_ID Department_Name Parent_Id Parent_Name -------------------- ----------------------- --------------- ---------------------------------------------------------------------------------- 1 Food 1, 5, 6 Food, North Indian, South Indian 2 Lodging 3, 4, 13, 20, 23 Room, Floor, Non Air Conditioned, With Balcony, Without Balcony 40 New 40 SubNew TABLE 3 Parent_Id Parent_Name Preference_ID Preference_Name -------------------- ----------------------------------------------- ----------------------- ------------------- NULL NULL NULL NULL 1 Food 5, 8 North Indian, Italian 3 Room 4 Floor 4 Floor 9, 10, 11 First, Second, Third 5 North Indian 14, 15 X, Y 6 South Indian 16 Dosa 13 Non Air Conditioned 22, 23 With Balcony, Without Balcony 20 With Balcony 24, 25, 26 Mountain View, Ocean View, Garden View 23 Without Balcony 27 Mountain View 40 New 41 SubNew I have these 3 tables that are related in some fashion like this. Table 1 will be the master for these 2 tables i.e. table 2 and table 3. I need to query on them as SELECT Department_Id, Department_Name, Parent_Name FROM Table2 WHERE Department_Id in ( SELECT Department_Id FROM Table1 WHERE guest_id=65 ) SELECT Parent_Id, Parent_Name, Preference_Name FROM Table3 WHERE PARENT_ID in ( SELECT parent_id FROM Table1 WHERE guest_id=65 ) Now I need to use these queries on DataTables. So I am using Query Syntax for this and reached up to this point. var dept_list= from dept in DtMapGuestDepartment.AsEnumerable() where dept.Field<long>("PK_GUEST_ID")==long.Parse(63) select dept; This should give me the list of all departments that has guest id =63 Now I want to select all departments_name and parent_name from Table 2 where guest_id=63 i.e. departments that i fetched above. This same case will be followed for Table3. Please suggest how to do this. Thanks for keeping up patience for reading my question.

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  • How to make freelance clients understand the costs of developing and maintaining mature products?

    - by John
    I have a freelance web application project where the client requests new features every two weeks or so. I am unable to anticipate the requirements of upcoming features. So when the client requests a new feature, one of several things may happen: I implement the feature with ease because it is compatible with the existing platform I implement the feature with difficulty because I have to rewrite a significant portion of the platform's foundation Client withdraws request because it costs too much to implement against existing platform At the beginning of the project, for about six months, all feature requests fell under category 1) because the system was small and agile. But for the past six months, most feature implementation fell under category 2). The system is mature, forcing me to refactor and test everytime I want to add new modules. Additionally, I find myself breaking things that use to work, and fixing it (I don't get paid for this). The client is starting to express frustration at the time and cost for me to implement new features. To them, many of the feature requests are of the same scale as the features they requested six months ago. For example, a client would ask, "If it took you 1 week to build a ticketing system last year, why does it take you 1 month to build an event registration system today? An event registration system is much simpler than a ticketing system. It should only take you 1 week!" Because of this scenario, I fear feature requests will soon land in category 3). In fact, I'm already eating a lot of the cost myself because I volunteer many hours to support the project. The client is often shocked when I tell him honestly the time it takes to do something. The client always compares my estimates against the early months of a project. I don't think they're prepared for what it really costs to develop, maintain and support a mature web application. When working on a salary for a full time company, managers were more receptive of my estimates and even encouraged me to pad my numbers to prepare for the unexpected. Is there a way to condition my clients to think the same way? Can anyone offer advice on how I can continue to work on this web project without eating too much of the cost myself? Additional info - I've only been freelancing full time for 1 year. I don't yet have the high end clients, but I'm slowly getting there. I'm getting better quality clients as time goes by.

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  • Why is my file being cleared if I don't save it?

    - by Kat
    My program is suppose to maintain a collection of Photos in a PhotoAlbum. It begins by reading a folder of photos and adds them to my PhotoAlbum. It then prints a menu that allows the user to list all the photos, add a photo, find a photo, save, and quit the program. Right now if I run my program it will add the 100 photos to the PhotoAlbum, but if I quit the program without saving, it clears the file I am reading from even if I haven't added a photo or done anything to the PhotoAlbum and I'm not sure why. Here is my method for printing to a file: private static void saveFile(PrintWriter writer) { String result; ArrayList<Photo> temp = album.getPhotoAlbum(); for (int i = 0; i < temp.size(); i++){ result = temp.get(i).toString() + "\n"; writer.println(result); } writer.close(); } And where the PrintWriter is instantiated: File file = new File(args[0] + File.separator + "album.dat"); try { PrintWriter fout = new PrintWriter(new FileWriter(file)); fileWriter = fout; } catch (IOException e){ System.out.println("ReadFromFile: Folder " + args[0] + " is not found."); System.exit(0); } And where it is called in my runMenu Method: private static void runMainMenu(Scanner scan) { String input; do { showMainMenu(); input = scan.nextLine().toLowerCase(); switch (input.charAt(0)) { case 'p': System.out.println(album.toString()); break; case 'a': album.addPhoto(readPhoto(scan, t)); break; case 'f': findMenu(scan); break; case 's': saveFile(fileWriter); System.exit(0); break; case 'q': break; default: System.out.println("Invalid entry: " + input.charAt(0)); break; } } while (!input.equalsIgnoreCase("q")); }

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  • Prevent SQL Injection in Dynamic column names

    - by Mr Shoubs
    I can't get away without writing some dynamic sql conditions in a part of my system (using Postgres). My question is how best to avoid SQL Injection with the method I am currently using. EDIT (Reasoning): There are many of columns in a number of tables (a number which grows (only) and is maintained elsewhere). I need a method of allowing the user to decide which (predefined) column they want to query (and if necessary apply string functions to). The query itself is far too complex for the user to write themselves, nor do they have access to the db. There are 1000's of users with varying requirements and I need to remain as flexible as possible - I shouldn't have to revisit the code unless the main query needs to change - Also, there is no way of knowing what conditions the user will need to use. I have objects (received via web service) that generates a condition (the generation method is below - it isn't perfect yet) for some large sql queries. The _FieldName is user editable (parameter name was, but it didn't need to be) and I am worried it could be an attack vector. I put double quotes (see quoted identifier) around the field name in an attempt to sanitize the string, this way it can never be a key word. I could also look up the field name against a list of fields, but it would be difficult to maintain on a timely basis. Unfortunately the user must enter the condition criteria, I am sure there must be more I can add to the sanatize method? and does quoting the column name make it safe? (my limited testing seems to think so). an example built condition would be "AND upper(brandloaded.make) like 'O%' and upper(brandloaded.make) not like 'OTHERBRAND'" ... Any help or suggestions are appreciated. Public Function GetCondition() As String Dim sb As New Text.StringBuilder 'put quote around the table name in an attempt to prevent some sql injection 'http://www.postgresql.org/docs/8.2/static/sql-syntax-lexical.html sb.AppendFormat(" {0} ""{1}"" ", _LogicOperator.ToString, _FieldName) Select Case _ConditionOperator Case ConditionOperatorOptions.Equals sb.Append(" = ") ... End Select sb.AppendFormat(" {0} ", Me.UniqueParameterName) 'for parameter Return Me.Sanitize(sb) End Function Private Function Sanitize(ByVal sb As Text.StringBuilder) As String 'compare against a similar blacklist mentioned here: http://forums.asp.net/t/1254125.aspx sb.Replace(";", "") sb.Replace("'", "") sb.Replace("\", "") sb.Replace(Chr(8), "") Return sb.ToString End Function Public ReadOnly Property UniqueParameterName() As String Get Return String.Concat(":" _UniqueIdentifier) End Get End Property

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  • How does this Singleton-like web class persists session data, even though session is not updated in

    - by Micah Burnett
    Ok, I've got this singleton-like web class which uses session to maintain state. I initially thought I was going to have to manipulate the session variables on each "set" so that the new values were updated in the session. However I tried using it as-is, and somehow, it remembers state. For example, if run this code on one page: UserContext.Current.User.FirstName = "Micah"; And run this code in a different browser tab, FirstName is displayed correctly: Response.Write(UserContext.Current.User.FirstName); Can someone tell me (prove) how this data is getting persisted in the session? Here is the class: using System; using System.Collections.Generic; using System.Linq; using System.Web; public class UserContext { private UserContext() { } public static UserContext Current { get { if (System.Web.HttpContext.Current.Session["UserContext"] == null) { UserContext uc = new UserContext(); uc.User = new User(); System.Web.HttpContext.Current.Session["UserContext"] = uc; } return (UserContext)System.Web.HttpContext.Current.Session["UserContext"]; } } private string HospitalField; public string Hospital { get { return HospitalField; } set { HospitalField = value; ContractField = null; ModelType = null; } } private string ContractField; public string Contract { get { return ContractField; } set { ContractField = value; ModelType = string.Empty; } } private string ModelTypeField; public string ModelType { get { return ModelTypeField; } set { ModelTypeField = value; } } private User UserField; public User User { get { return UserField; } set { UserField = value; } } public void DoSomething() { } } public class User { public int UserId { get; set; } public string FirstName { get; set; } } I added this to a watch, and can see that the session variable is definitely being set somewhere: (UserContext)System.Web.HttpContext.Current.Session["UserContext"]; As soon as a setter is called the Session var is immediately updated: set { HospitalField = value; //<--- here ContractField = null; ModelType = null; }

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  • Executing a .NET Managed Assembly from SQL Server 2008 - Pro's, Con's & Recommendations

    - by RPM1984
    Hi guys, looking for opinions/recommendations/links for the following scenario im currently facing. The Platform: .NET 4.0 Web Application SQL Server 2008 The Task: Overhaul a component of the system that performs (fairly) complex mathematical operations based on a specific user activity, and updates numerous tables in the database. A common user activity might be "Bob" decides to post a forum topic. This results in (the end-solution) needing to look at various factors (about the post he did), then after doing some math based on lookup values/ratios as well as other data in the database, inserting some other data as a result of these operations. The Options: Ok - so here's what im thinking. Although it would be much easier to do this in C# (LINQ-SQL) it doesnt make much sense as the majority of the computations are based on values in the db, and it will get difficult to control/optimize/debug the LINQ over time. Hence, im leaning towards created a managed assembly (C# Class Library) that contains the lookup values (constants) as well as leveraging the math classes in the existing .NET BCL. Basically i'd expose a few methods that can be called by the T-SQL Stored Procedures. This to me has the following advantages: Simplicity of math. Do complex math in .NET vs complex math in T-SQL. No brainer. =) Abstraction of computatations, configurable "lookup" values and business logic from raw T-SQL. T-SQL only needs to care about the data, simplifying the stored procedures and making it easier to maintain. When it needs to do math it delegates off to the managed assembly. So, having said that - ive never done this before (call .NET assmembly from T-SQL), and after some googling the best site i could come up with is here, which is useful but outdated. So - what am i asking? Well, firstly - i need some better references on how to actually do this. "This" being how to call a C# .NET 4 Assembly from within T-SQL Stored Procedures in SQL Server 2008. Secondly, who out there has done this, what problems (if any) did you face? Realize this may be difficult to provide a "correct answer", so ill try to give it to whoever gives me the answer with a combination of good links and a list of pro's/con's/problems with this implementation. Cheers!

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  • Problem with GwtUpload on GAE

    - by weesilmania
    I'm using GwtUpload to upload images on GAE. The problem is that the images seem to get much bigger when I move them into a blob. I've noticed the same for simple text fields and in that case I've realised that some weirdo characters are being appended to the end of the field values (encoding right?). Can anyone help? public class ImageUploadServlet extends AppEngineUploadAction { /** * Maintain a list with received files and their content types */ Hashtable<String, File> receivedFiles = new Hashtable<String, File>(); Hashtable<String, String> receivedContentTypes = new Hashtable<String, String>(); private Objectify objfy; public ImageUploadServlet() { ObjectifyService.register(Thumbnail.class); objfy = ObjectifyService.begin(); System.out.println("ImageUploadServlet init"); } /** * Override executeAction to save the received files in a custom place and * delete this items from session. */ @Override public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException { Thumbnail t = new Thumbnail(); for (FileItem item : sessionFiles) { //CacheableFileItem item = (CacheableFileItem)fItem; if (false == item.isFormField()) { System.out.println("the name 1st:" + item.getFieldName()); try { // You can also specify the temporary folder InputStream imgStream = item.getInputStream(); Blob imageBlob = new Blob(IOUtils.toByteArray(imgStream)); t.setMainImage(imageBlob); System.out.println("blob: " + t.getMainImage()); } catch (Exception e) { throw new UploadActionException(e.getMessage()); } } else { System.out.println("the name 2nd:" + item.getFieldName()); String name = item.getFieldName(); String value; try { InputStream is = item.getInputStream(); StringWriter writer = new StringWriter(); IOUtils.copy(is, writer,"UTF-8"); value = writer.toString(); writer.close(); System.out.println("parm name: " + name); System.out.println("parm value: " + value + " **" + value.length()); System.out.println(item.getContentType()); if (name.equals("thumb-name")) { t.setName(value); } } catch (IOException e) { // TODO Auto-generated catch block System.out.println("Error"); e.printStackTrace(); } } removeSessionFileItems(request); } objfy.put(t); return null; } As an example the size of the image is 20kb, and the lib has some debugging that confirms that this is the case when it's uploading the file but the blob ends up being over 1 MB. Wes

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  • SQLAlchemy unsupported type error - and table design issues?

    - by Az
    Hi there, back again with some more SQLAlchemy shenanigans. Let me step through this. My table is now set up as so: engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('sid', Integer, primary_key=True), Column('name', String), Column('preferences', Integer), Column('allocated_rank', Integer), Column('allocated_project', Integer) ) metadata.create_all(engine) mapper(Student, students_table) Fairly simple, and for the most part I've been enjoying the ability to query almost any bit of information I want provided I avoid the error cases below. The class it is mapped from is: class Student(object): def __init__(self, sid, name): self.sid = sid self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.sid, self.name) Explanation: preferences is basically a set of all the projects the student would prefer to be assigned. When the allocation algorithm kicks in, a student's allocated_project emerges from this preference set. Now if I try to do this: for student in students.itervalues(): session.add(student) session.commit() It throws two errors, one for the allocated_project column (seen below) and a similar error for the preferences column: sqlalchemy.exc.InterfaceError: (InterfaceError) Error binding parameter 4 - probably unsupported type. u'INSERT INTO studs (sid, name, allocated_rank, allocated_project) VALUES (?, ?, ?, ?, ?, ?, ?)' [1101, 'Muffett,M.', 1, 888 Human-spider relationships (Supervisor id: 123)] If I go back into my code I find that, when I'm copying the preferences from the given text files, it actually refers to the Project class which is mapped to a dictionary, using the unique project id's (pid) as keys. Thus, as I iterate through each student via their rank and to the preferences set, it adds not a project id, but the reference to the project id from the projects dictionary. students[sid].preferences[int(rank)].add(projects[int(pid)]) Now this is very useful to me since I can find out all I want to about a student's preferred projects without having to run another check to pull up information about the project id. The form you see in the error has the object print information passed as: return "%s %s (Supervisor id: %s)" %(self.proj_id, self.proj_name, self.proj_sup) My questions are: I'm trying to store an object in a database field aren't I? Would the correct way then, be copying the project information (project id, name, etc) into its own table, referenced by the unique project id? That way I can just have the project id field for one of the student tables just be an integer id and when I need more information, just join the tables? So and so forth for other tables? If the above makes sense, then how does one maintain the relationship with a column of information in one table which is a key index on another table? Does this boil down into a database design problem? Are there any other elegant ways of accomplishing this? Apologies if this is a very long-winded question. It's rather crucial for me to solve this, so I've tried to explain as much as I can, whilst attempting to show that I'm trying (key word here sadly) to understand what could be going wrong.

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