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• Use count or have a field that tallies?

  - by Dan LaManna

  Fairly simple concept, making an extremely basic message board system and I want users to have a post count. Now I was debating on whether or not to have a tally in their row that is added each time a post by them is created, or subtracted by one each time a post of theirs is deleted. However I'm sure that performing a count query when the post count is requested would be more accurate due to unforseen circumstances (say a thread gets deleted and it doesn't lower their tally properly), however this seems like it would be less efficient to run a query EVERY time their post count is loaded, especially in the case of them having 10 posts on the same page and it lists their post count each post. Thoughts/Advice? Thanks

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• Help in formulating sql query

  - by AJ

  Here is my scenario Table 1: GID || Info1 Table 2: GID || Tb1GID (refers to GID of Table1) || Info2 Table 3: GID || Info3 Table 4: GID || Tb2GID (refers to GID of Table2 || Tb3GID (refers to Table3 GID || Value Now I have to build an sql query to get the value, given a particular Info1, Info2, Info3. Essentially, I have to get the GID, of table 1 using info1, GID of table to , by mapping info2 and GID of table 1. And then get the GID of table 3 using info 3. And combine these to GIDs to get the value in table 4. What is the most optimal way of constructing an sql query for this one?

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• go up to 3 level dephth in hibernate criterion

  - by Satyajitsinh Raijada

  i am using hibernate criterion for fetching results. Here with i provided demo design of my persistence class. Class A{ private B b; } Class B{ private C c; } Class C{ private Long val; } assume these are the hibernate persistence classes i am not writing all annotations of mapping with database. now my problem is i want to retrieve results of Class A according to the value of Class C's val property. i tried to fetch it using, Criteria c = Restrictions.eq("b.c.val", value); List l = c.list; it shows could not resolve property. i searched and came to know criteria wont work up to this much depth. i don't want shift to HQL. any idea??

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• No difference between nullable:true and nullable:false in Grails 1.3.6?

  - by knorv

  The following domain model definition .. class Test { String a String b static mapping = { version(false) table("test_table") a(nullable: false) b(nullable: true) } } .. yields the following MySQL schema .. CREATE TABLE test_table ( id bigint(20) NOT NULL AUTO_INCREMENT, a varchar(255) NOT NULL, b varchar(255) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; Please note that a and b get identical MySQL column definitions despite the fact a is defined as non-nullable and b is nullable in the GORM mappings. What am I doing wrong? I'm running Grails 1.3.6.

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• What's the deal with all of the abstract stuff?

  - by JustVenting

  I see a lot of talk about MVVM, MVC, Design Patterns etc... You know, some guy has a blog, and he spent the last six months learning about one these things and desiging a program centered around that concept and then he goes on and on about it like its better than sliced bread. I read all of this crap and I wonder, whatever happened to simple logical programming? Not self-absorbed huge frameworks of design patterns and mvc and whatever else you can think of... just simple linear programming, perhaps a few classes to encapsulate things here and there.

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• How can I make an aggregated property support ActiveRecord::Dirty semantics?

  - by Eric

  I have an aggregated attribute which I want to be able ask about its _changed? ness, etc. composed_of :range, :class_name => 'Range', :mapping => [ %w(range_begin begin), %w(range_end end)], :allow_nil => true If I use the aggregation: foo.range = 1..10 This is what I get: foo.range # => 1..10 foo.range_changed? # NoMethodError foo.range_was # ditto foo.changed # ['range_begin', 'range_end'] So basically, I'm not getting ActiveRecord::Dirty semanitcs on aggregated attributes. Is there any way to do that? I'm not having a lot of luck with alias_attribute_with_dirty, etc.

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• Is it a good idea to apply some basic macros to simplify code in a large project?

  - by DoctorT

  I've been working on a foundational c++ library for some time now, and there are a variety of ideas I've had that could really simplify the code writing and managing process. One of these is the concept of introducing some macros to help simplify statements that appear very often, but are a bit more complicated than should be necessary. For example, I've come up with this basic macro to simplify the most common type of for loop: #define loop(v,n) for(unsigned long v=0; v<n; ++v) This would enable you to replace those clunky for loops you see so much of: for (int i = 0, i < max_things; i++) With something much easier to write, and even slightly more efficient: loop (i, max_things) Is it a good idea to use conventions like this? Are there any problems you might run into with different types of compilers? Would it just be too confusing for someone unfamiliar with the macro(s)?

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• What is the difference between the * and the & operators in c programming?

  - by Wesley

  I am just making sure I understand this concept correctly. With the * operator, I make a new variable, which is allocated a place in memory. So as to not unnecessarily duplicate variables and their values, the & operator is used in passing values to methods and such and it actually points to the original instance of the variable, as opposed to making new copies...Is that right? It is obviously a shallow understanding, but I just want to make sure I am not getting them mixed up. Thanks!

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• is there some lightweight tecnique for adding type safety to identifier properties?

  - by shoren

  After using C++ I got used to the concept of Identifier which can be used with a class for the type, provides type safety and has no runtime overhead (the actual size is the size of the primitive). I want to do something like that, so I will not make mistakes like: personDao.find(book.getId());//I want compilation to fail personDao.find(book.getOwnerId());//I want compilation to succeed Possible solutuions that I don't like: For every entity have an entity id class wrapping the id primitive. I don't like the code bloat. Create a generic Identifier class. Code like this will not compile: void foo(Identifier book); void foo(Identifier person); Does anyone know of a better way? Is there a library with a utility such as this? Is implementing this an overkill? And the best of all, can this be done in Java without the object overhead like in C++?

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• Routing fails when only category is supplied

  - by creativeincode

  My website uses categories and sub-categories. I'd like the follow mapping: /Category/Fruit /Category/Fruit/Apples But if I use the below: routes.MapRoute( "Category", // Route name "Category/{category}/{subcategory}", // URL with parameters new { controller = "Entity", action = "Category" } // Parameter defaults ); I get a 404 for /Category/Fruit however /Category/Fruit/Apples works ok. I'd like /Category/Fruit to work as well but I can't add another route with the same name. How do I get around this? Thanks in advance.

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• What features do you expect from a Java (Rich) Client Framework?

  - by Peter Walser

  I'm intending to design (and provide a reference implementation for) a new Swing Rich Client Framework. My job and personal experience covers many project-specific Swing client frameworks as well as the Eclipse RCP, and every one of them had some original and clever concepts, but also drawbacks and rigid realizations. My plan is to incorporate the best of those concepts and features into a new framework whose core is very open and extendable. For my must-have-features list, I'm counting on your input and hope you can share some concept pearls & diamonds you've encountered in other frameworks, or features you always wanted to have or have in a better way. The framework is intended for very simple to very complex and sophisticated projects for clients that need full i18n for richt clients that execute some or all of the non-presentation logic on the server to be very lightweight to be easy to learn and use Thanks in advance for sharing your insights :)

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• Interesting or unique types encountered?

  - by user318904

  What is the most strange or unique type you have seen in a programming language? I was thinking the other day about a "random variable", ie whenever it is evaluated it yields a random value from some domain. It would require some runtime trickery. Also I bet there can be some interesting mapping of regular expressions into a type system. It does not necessarily have to be a built in or primitive type, but some random class that implements a domain specific type won't really be interesting just unique.

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• How do I tell Entity Framework that a column in a view is nullable?

  - by Ryan ONeill

  I have a view which has an Int column which is nullable (let's call it StackOverflowCount). When generating an EF model from the database, the EF designer does not recognise it as nullable and creates the column as an Int. The issue I have is that on the EF designer I have set the column to Nullable and the following error then kills the compilation; Error 3031: Problem in mapping fragments starting at line 2327: Non-nullable column MyView.StackOverflowCount in table MyView is mapped to a nullable entity property. I can get round this by opening the .edmx file in XML mode and manually editing the SQL column definition, but there is no way to do this using the designer and it gets overwritten the next time I refresh from the model from the DB. Is this 'by design' or an example of something that slipped through into EF 4.0? I'm using .Net 4.0 with EF 4.0 under VS 2010.

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• Learning C++ from AS3

  - by grey

  I'm a decent AS3 programmer. I work in games, and that is my reason for programming. While there is much I can accomplish with Adobe AIR, my understanding at this point is that learning C++ is probably a good direction to take. I would learn a lot of valuable lower level programming if I needed it down the road, and I would have an easier time learning other C oriented languages. I see a lot of information for people looking to learn AS3 who know C++, but not the other way around. Why C++? Cross platform compatibility is important to me, so I'm not particularly interested in C# or Objective-C at this junction. I'm also aware of HaXe, and while I love the concept, after doing some research I'm worried about investing a lot of time into something so recent with limited learning resources and documentation. I'm looking for advice and resources (books, articles) related to this topic. Thanks in advance!

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• Fitting place names into map shapes

  - by Old Man

  I'm drawing shapes using GDI+ using a list of lat/lon floats, and I need to place the name of the place within the borders of the polygon. Simply centering the text in the bounding rectangle doesn't work for irregular shapes. I have the text and the font so I can get the size of the rectangle that the text will need to fit in, but at that point I'm stuck. This seems like a common problem that all mapping software solves, as well as the kind of thing you would find in an algorithm or computer graphics textbook. So, given a list of floats for a polygon and a rectangle, is there a way to get the best possible point to place the text, using: 1) GDI+; 2) SQL Server Geospatial; or 3) c# code (or c, pseudocode, etc)

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• In DirectShow, what determines the graph source?

  - by Seva Alekseyev

  Hi all, I have two machines - A (XP SP2) and B (Win7). Machine B has trouble playing OGM files - enabling subtitles causes a crash in the player. Investigation shows that the DirectShow graphs are quite different. On A, the source is a file source, which produces a stream of subtype OGG, which goes into "Ogg Splitter". On B, the source is an instance of Haali Media Splitter, which produces video, audio, and subtitles as separate streams. Machine A has Haali splitter installed as well, but it is not invoked somehow. Question - what determines the source filter? Is there a file type to preferred source mapping, or does the system load and ask all suitable filters if they would take this file? On machine A, the merit of Haali splitter is higher than that of File source, so it's probably not about relative merits.

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• How do I use a custom select statement in Hibernate using the HibernateDaoSupport class

  - by Bill Leeper

  I am trying to write a custom select statement in Hibernate using the getHibernateTemplate() method. I am having problems with the resulting mapping. Example Code: List<User> users = getHibernateTemplate().find("Select user, sysdate as latestPost from User as user"); for (User user : users) { assertNotNull(users.name); } The goal of the above line is to eventually have a join where I get the max(date) of posts made by the user. The problem I am having is that the resulting users list is not a list of User objects and I get a class cast exception. Hopefully that is enough code. It is a greatly simplified version of my problem and a combination of snippets from various parts of my application.

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• Query with multiple IN-statements but without the cartesian product

  - by Janne

  How could I make this kind of query e.g. in MySQL SELECT * FROM Table t WHERE t.a IN (1,2,3) AND t.b IN (4,5,6) AND t.c IN (7,8,9) ... so that the result would contain only the three rows: t.a|t.b|t.c ---+---+--- 1 | 4 | 7 2 | 5 | 8 3 | 6 | 9 The above query of course returns all the combinations of the values in the IN clauses but I would like to get just the ones where the first elements of each tuple match, second elements of each tuple match and so on. Is there any efficient way to do this? By the way is there some common term for this kind of query or concept? I'm having hard time coming up with the question's title because I can't put this into words..

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• Confusion between JPA and Hibernate cascading

  - by Jay

  I'm using Hibernate 3.6 and have my code annotated (versus using hibernate mapping files). I ran into the known "problem" of using JPA cascading options that are not compatible with Hibernate's CascadeType (see this link for more info http://www.mkyong.com/hibernate/cascade-jpa-hibernate-annotation-common-mistake/). I was hoping to get a bit more clarification on the problem. I have some particular questions: 1) So @Cascade({CascadeType.SAVE_UPDATE}) works for saveOrUpdate(), but does it apply also if I use merge() or persist()? or do I have to use all three Hibernate CascadeTypes? 2) How do I decide whether to use JPA cascade options or the Hibernate @Cascade annotation instead? 2) There is a "bug" filed against this in Hibernate, but the developers apparently see this as a documentation issue, (I'm completely disagree with them), and I'm not seeing that it was addressed in said documentation. Anyone know why this is "working as designed" and not a bug in Hibernate's JPA implementation? Many thanks in advance.

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• What's the most simple way to retrieve all data from a table and save it back in .NET 3.5?

  - by zoman

  I have a number of tables containing some basic (business related) mapping data. What's the most simple way to load the data from those tables, then save the modified values back. (all data should be replaced in the tables) An ORM is out of question as I would like to avoid creating domain objects for each table. The actual editing of the data is not an issue. (it is exported into Excel where the data is edited, then the file is uploaded with the modified data) The technology is .NET 3.5 (ASP.NET MVC) and SQL Server 2005. Thanks.

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• Are there any Visual Studio add-ins for true 'smart tabs'?

  - by Eye of Hell

  Hello. 'Smart Tabs' concept allows to automatically insert tab character for block indentation and space characters for in-block formatting. It's described here. Unfortunately, Visual Studio's 'smart tabs' option in text editor settings just indents text on enter press. Same name, completely different and near useless thing :). So, maybe someone knows of a visual studio addin that can change how 'tab' key work so it will insert tab characters and space characters according to rules mentioned above? Any hints are welcome. Update: I need it for C++. According to comments, ReSharper can do something like this, but only for Basic and C#.

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• Hibernate - Persisting polymorphic joins

  - by Marty Pitt

  Hi I'm trying to understand how to best implement a polymorphic one-to-many in hibernate. Eg: @MappedSuperclass public class BaseEntity { Integer id; // etc... } @Entity public class Author extends BaseEntity {} @Entity public class Post extends BaseEntity {} @Entity public class Comment extends BaseEntity {} And now, I'd like to also persist audit information, with the following class: @Entity public class AuditEvent { @ManyToOne // ? BaseEntity entity; } What is the appropriate mapping for auditEvent.entity? Also, how will Hibernate actually persist this? Would a series of join tables be generated (AuditEvent_Author , AuditEvent_Post, AuditEvent_Comment), or is there a better way? Note, I'd rather not have my other entity classes expose the other side of the join (eg., List<AuditEvent> events on BaseEntity) - but if that's the cleanest way to implement, then it will suffice.

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• Overriding Magento Admin Controller, for Beginners

  - by Knowledge Craving

  In the Magento Admin section, I want to override the "Sales/Order/ShipmentController.php" controller file of the core Mage. I have tried rewriting the URL, using the "from" & "to" tags, but in vain. I don't know what is the actual & correct way of doing this, as I'm a newbie in Magento. Please anybody provide some good fundamental & correct answer, so that at least the concept gets clear. Also, if possible, please tell me, what is the actual purpose of the controller, for both the frontend & the back-end? Any help is greatly appreciated.

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• How secure is encryption?

  - by Stomped

  Let me preface this by saying I know nothing about encryption. I understand the basic concept of public key / private key encryption but I don't how easily it can be broken, if at all. If one were to believe the movies, encrypted data can be broken by a teenager with a decent computer in a few hours. I have a client who wants credit card information sent via email - encrypted of course, but I'm still not feeling terribly good about the idea. I feel it would be safer to store the info on the VPS, but even then its an unmanaged server and there's nobody watching it who knows much about security. So can anyone tell me if there's a safe way to store and/or send this data out? Thanks

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• How would you code this: Grid-breaking shapes

  - by BeachRunnerJoe

  I'm a person that learns best from example. Currently, I'm diving into the field of Web Development after fifteen years of developing desktop apps. I'm still getting used to all the web technologies used for developing modern web sites and everywhere I look, I see cool little UI elements and question how they're implemented. So I thought I'd ask you, the web experts...the wexperts :) What are some straight forward or creative ways you could code this grid-breaking arrow... The basic layout for this page looks like... What would the html/css code look like? Would you split the image into multiple images or could you use a single image? I'm sure this is a really simple concept and it completely boggles me. I'm sorry if this is a strange question, remember I'm a noob! :) Thanks in advance for all your help! Here's a link to the original tutorial where I found these images

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