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  • Rails - Create if record doesn't exist or else update.....Whats Best way to do this?

    - by ChrisWesAllen
    Hi, I have a create statement for some models but its creating a record within a join table regardless if the record exist. Here is what my code looks like. @user = User.find(current_user) @event = Event.find(params[:id]) for interest in @event.interests @user.choices.create(:interest => interest, :score => 4) end The problem is it creates records no matter what. I would like it to create a record if it doesnt exist, if a record does exist I would just to it to take the attribute of the found record and add or subtract 1. So, I've been looking around and I see something called find_or_create_by. My question is what happens if it finds? Preferably if it finds,I would like to take the current :score attribute and +1. SO is it possible to find or create by id? I'm not sure what attribute I would find by since the model I'm looking at is a join model which only had id foreign keys and the score attribute. I tried @user.choices.find_or_create_by_user(:user => @user.id, :interest => interest, :score => 4) but got "undefined method `find_by_user'".....ANy ideas or help?

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  • What's the best way to return something like a collection of `std::auto_ptr`s in C++03?

    - by Billy ONeal
    std::auto_ptr is not allowed to be stored in an STL container, such as std::vector. However, occasionally there are cases where I need to return a collection of polymorphic objects, and therefore I can't return a vector of objects (due to the slicing problem). I can use std::tr1::shared_ptr and stick those in the vector, but then I have to pay a high price of maintaining separate reference counts, and object that owns the actual memory (the container) no longer logically "owns" the objects because they can be copied out of it without regard to ownership. C++0x offers a perfect solution to this problem in the form of std::vector<std::unique_ptr<t>>, but I don't have access to C++0x. Some other notes: I don't have access to C++0x, but I do have TR1 available. I would like to avoid use of Boost (though it is available if there is no other option) I am aware of boost::ptr_container containers (i.e. boost::ptr_vector), but I would like to avoid this because it breaks the debugger (innards are stored in void *s which means it's difficult to view the object actually stored inside the container in the debugger)

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  • What's the best editor/program for g++ in Linux?

    - by Phenom
    So far I've been using vi, but I'm wondering if there's something better to use in Linux. In Windows there's Visual C++, and I guess practically all C++ programmers in Windows use this these days. It has a lot of things in it to help the programmer. What about for Linux?

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  • Best way in Python to determine all possible intersections in a matrix?

    - by ssweens
    So if I have a matrix (list of lists) of unique words as my column headings, document ids as my row headings, and a 0 or 1 as the values if the word exists in that particular document. What I'd like to know is how to determine all the possible combinations of words and documents where more than one word is in common with more than one document. So something like: [[Docid_3, Docid_5], ['word1', 'word17', 'word23']], [[Docid_3, Docid_9, Docid_334], ['word2', 'word7', 'word23', 'word68', 'word982']], and so on for each possible combination. Would love a solution that provides the complete set of combinations and one that yields only the combinations that are not a subset of another, so from the example, not [[Docid_3, Docid_5], ['word1', 'word17']] since it's a complete subset of the first example. I feel like there is an elegant solution that just isn't coming to mind and the beer isn't helping. Thanks.

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  • What is the best approach in SQL to store multi-level descriptions?

    - by gime
    I need a new perspective on how to design a reliable and efficient SQL database to store multi-level arrays of data. This problem applies to many situations but I came up with this example: There are hundreds of products. Each product has an undefined number of parts. Each part is built from several elements. All products are described in the same way. All parts would require the same fields to describe them (let's say: price, weight, part name), all elements of all parts also have uniform design (for example: element code, manufacturer). Plain and simple. One element may be related to only part, and each part is related to one product only. I came up with idea of three tables: Products: -------------------------------------------- prod_id prod_name prod_price prod_desc 1 hoover 120 unused next Parts: ---------------------------------------------------- part_id part_name part_price part_weight prod_id 3 engine 10 20 1 and finally Elements: --------------------------------------- el_id el_code el_manufacturer part_id 1 BFG12 GE 3 Now, select a desired product, select all from PARTS where prod_id is the same, and then select all from ELEMENTS where part_id matches - after multiple queries you've got all data. I'm just not sure if this is the right approach. I've got also another idea, without ELEMENTS table. That would decrease queries but I'm a bit afraid it might be lame and bad practice. Instead of ELEMENTS table there are two more fields in the PARTS table, so it looks like this: part_id, part_name, part_price, part_weight, prod_id, part_el_code, part_el_manufacturer they would be text type, and for each part, information about elements would be stored as strings, this way: part_el_code | code_of_element1; code_of_element2; code_of_element3 part_el_manufacturer | manuf_of_element1; manuf_of_element2; manuf_of_element3 Then all we need is to explode() data from those fields, and we get arrays, easy to display. Of course this is not perfect and has some limitations, but is this idea ok? Or should I just go with the first idea? Or maybe there is a better approach to this problem? It's really hard to describe it in few words, and that means it's hard to search for answer. Also, understanding the principles of designing databases is not that easy as it seems.

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  • Best of both worlds: arrow keys for cursor movement or flipping through buffers.

    - by dreeves
    I really like this vim trick to use the left and right arrows to flip between buffers: "left/right arrows to switch buffers in normal mode map <right> :bn<cr> map <left> :bp<cr> (Put that in ~/.vimrc) But sometimes I'm munching on a sandwich or something when scrolling around a file and I really want the arrow keys to work normally. I think what would make most sense is for the arrow keys to have the above buffer-flipping functionality only if there are actually multiple buffers open. Is there a way to extend the above to accomplish that?

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  • In Python what's the best way to emulate Perl's __END__?

    - by FM
    Am I correct in thinking that that Python doesn't have a direct equivalent for Perl's __END__? print "Perl...\n"; __END__ End of code. I can put anything I want here. One thought that occurred to me was to use a triple-quoted string. Is there a better way to achieve this in Python? print "Python..." """ End of code. I can put anything I want here. """

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  • What is the best way to properly test object equality against an array of objects?

    - by radesix
    My objective is to abort the NSXMLParser when I parse an item that already exists in cache. The basic flow of the program works like this: 1) Program starts and downloads an XML feed. Each item in the feed is represented by a custom object (FeedItem). Each FeedItem gets added to an array. 2) When the parsing is complete the contents of the array (all FeedItem objects) are archived to the disk. The next time the program is executed or the feed is refreshed by the user I begin parsing again; however, since a cache (array) now exists as each item is parsed I want to see if the object exists in the cache. If it does then I know I have downloaded all the new items and no longer need to continue parsing. What I am learning, I think, is that I can't use indexOfObject or indexOfObjectIDenticalTo: because these really seem to be checking to see that the objects are using the same memory address (thus identical). What I want to do is see if the contents of the object are equal (or at least some of the contents). I've done some research and found that I can override the IsEqual method; however, I really don't want to iterate/enumerate through the entire cache contents table for every newly parsed XML FeedItem. Is iterating through the collection and testing each one for equality the only way to do this or is there a better technique I am not aware of? Currently I am using the following code though I know it needs to change: NSUInteger index = [self.feedListCache.feedList indexOfObject:self.currentFeedItem]; if (index == NSNotFound) { }

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  • What is the best way to sync multiple client SqlServers to one MS SqlServer 2005?

    - by user605055
    I have several client databases that use my windows application. I want to send this data for online web site. The client databases and server database structure is different because we need to add client ID column to some tables in server data base. I use this way to sync databases; use another application and use C# bulk copy with transaction to sync databases. My server database sql server is too busy and parallel task cannot be run. I work on this solution: I use triggers after update, delete, insert to save changes in one table and create sql query to send a web service to sync data. But I must send all data first! Huge data set (bigger than 16mg) I think can't use replication because the structure and primary keys are different.

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  • Doing a global count of an object type (like Users), best practice?

    - by user246114
    Hi, I know keeping global counters is frowned upon in app engine. I am interested in getting some stats though, like once every 24 hours. For example, I'd like to count the number of User objects in the system once every 24 hours. So how do we do this? Do we simply keep a set of admin tool functions which do something like: SELECT FROM com.me.project.server.User; and just see what the size of the returned List is? This is kind of a bummer because the datastore would have to deserialize every single User instance to create the returned list, right? I could optimize this possibly by asking for only the keys to be returned, so the whole User object doesn't have to be deserialized. Then again, a global counter for # of users probably would create too much contention, because there probably won't be hundreds of signups a minute for the service I'm creating. How should we go about doing this? Getting my total number of users once a day is probably a pretty typical operation? Thank you

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  • Best environment to port C/C++ code from Linux to Windows.

    - by Simone Margaritelli
    I'd like to make a big project of mine buildable on Windows platforms. The project itself it's written in C/C++ following POSIX standards, with some library dependencies such as libxml2, libcurl and so on. I'm more a Linux developer rather than a Windows developer, so i have no idea of which compiler suite i should use to port the code. Which one offers more compatibility with gcc 4.4.3 i'm using right now? My project needs flex and bison, is there any "ready to use" environment to port such projects to windows platforms? Thanks.

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  • I want to crop an image, draw a smaller size image without caching the images.... What is the best w

    - by rkbang
    Hello all, I am storing the images in database. I get the NSData and create an image from it. Now I want to crop or draw a smaller image of the existing image in database which I am getting from the querry. I dont want to cache the images since I am using them in bulk and want to release them as soon as the view being displayed where the images are used is popped up. Is there any efficient solution to make sure that images dont consume memory at the background once their use is over... I will appreciate the lines of code for this. Tnx in advance.

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  • What is the best businessmodel when using NHibernate to access the database?

    - by Sem Dendoncker
    Hi, I'm starting to use NHiberante as a dataaccess tier. I'm used to work with the repository model as a business model. This means, my domain model (not really a tier), my asp.net application tier, my repository tier which finally uses my dataaccess tier. But with what I've learned by now (on NHibernate) I know that many logic is done within an ISession so I was wondering if NHibernate could be used within the repository tier. Or perhaps there are even better ways to use NHibernate. Does anyone know where I could find a propriate example of how to use NHibernate in an webapplication? Cheers, M.

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  • What is the best instance type to use for hosting a website on ec2?

    - by Josh
    Amazon offers two instance types on EC2: 1) On-Demand and 2) Reserved. After reading the docs on these, I don't really understand the difference from an end-user perspective. More specifically, I'd like to know the answer to this question: is one or the other better for web applications? Based on their names and descriptions, it seems as though on-demand instances may get wiped away from the server altogether if they're not in use which means that they need to be restarted when a request finally does come in. That seems like a pretty bad thing for a website. Am I just misinterpreting the docs? Thanks!

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  • PHP: What's the best way to check equality of $_SERVER['HTTP_REFERER'] ?

    - by Hank
    I have a PHP script that checks the HTTP Referer. if ($_SERVER['HTTP_REFERER'] == 'http://www.example.com/') {...} However, this seems inherintly unsafe ... because what happens if the user goes to 'http://example.com/' or 'http://www.ExaMple.com' (both of which don't match the equality test). Question: what's a better equality test to ensure that the HTTP Referer is coming from 'example.com' ?

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