stackoverflow podcast - Page 198

Finding good heuristic for A* search

- by Martin

I'm trying to find the optimal solution for a little puzzle game called Twiddle (an applet with the game can be found here). The game has a 3x3 matrix with the number from 1 to 9. The goal is to bring the numbers in the correct order using the minimum amount of moves. In each move you can rotate a 2x2 square either clockwise or counterclockwise. I.e. if you have this state 6 3 9 8 7 5 1 2 4 and you rotate the upper left 2x2 square clockwise you get 8 6 9 7 3 5 1 2 4 I'm using a A* search to find the optimal solution. My f() is simply the number of rotations need. My heuristic function already leads to the optimal solution but I don't think it's the best one you can find. My current heuristic takes each corner, looks at the number at the corner and calculates the manhatten distance to the position this number will have in the solved state (which gives me the number of rotation needed to bring the number to this postion) and sums all these values. I.e. You take the above example: 6 3 9 8 7 5 1 2 4 and this end state 1 2 3 4 5 6 7 8 9 then the heuristic does the following 6 is currently at index 0 and should by at index 5: 3 rotations needed 9 is currently at index 2 and should by at index 8: 2 rotations needed 1 is currently at index 6 and should by at index 0: 2 rotations needed 4 is currently at index 8 and should by at index 3: 3 rotations needed h = 3 + 2 + 2 + 3 = 10 But there is the problem, that you rotate 4 elements at once. So there a rare cases where you can do two (ore more) of theses estimated rotations in one move. This means theses heuristic overestimates the distance to the solution. My current workaround is, to simply excluded one of the corners from the calculation which solves this problem at least for my test-cases. I've done no research if really solves the problem or if this heuristic still overestimates in same edge-cases. So my question is: What is the best heuristic you can come up with? (Disclaimer: This is for a university project, so this is a bit of homework. But I'm free to use any resource if can come up with, so it's okay to ask you guys. Also I will credit Stackoverflow for helping me ;) )

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MySQL Query to find consecutive available times of variable lenth

- by Armaconn

I have an events table that has user_id, date ('2013-10-01'), time ('04:15:00'), and status_id; What I am looking to find is a solution similar to http://stackoverflow.com/questions/2665574/find-consecutive-rows-calculate-duration but I need I need two additional components: 1) Take date into consideration, so 10/1/2013 at 11:00 PM - 10/2/2013 at 3:00AM. Feel free to just put in a fake date range (like '2013-10-01' to '2013-10-31') 2) Limit output to only include when there are 4+ consecutive times (each event is 15 minutes and I want it to display minimum blocks of an hour, but would also like to be able to switch this restriction to 1.5 hours or some other duration if possible). SUMMARY - Looking for a query that provides the start and end times for a set of events that have the same user_id, status_id, and are in a continuous series based on date and time. For which I can restrict results based on date range and minimum series duration. So the output should have: user_id, date_start, time_start, date_end, time_end, status_id, duration CREATE TABLE `events` ( `event_id` int(11) NOT NULL auto_increment COMMENT 'ID', `user_id` int(11) NOT NULL, `date` date NOT NULL, `time` time NOT NULL, `status_id` int(11) default NULL, PRIMARY KEY (`event_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1568 ; INSERT INTO `events` VALUES(1, 101, '2013-08-14', '23:00:00', 2); INSERT INTO `events` VALUES(2, 101, '2013-08-14', '23:15:00', 2); INSERT INTO `events` VALUES(3, 101, '2013-08-14', '23:30:00', 2); INSERT INTO `events` VALUES(4, 101, '2013-08-14', '23:45:00', 2); INSERT INTO `events` VALUES(5, 101, '2013-08-15', '00:00:00', 2); INSERT INTO `events` VALUES(6, 101, '2013-08-15', '00:15:00', 1); INSERT INTO `events` VALUES(7, 500, '2013-08-14', '23:45:00', 1); INSERT INTO `events` VALUES(8, 500, '2013-08-15', '00:00:00', 1); INSERT INTO `events` VALUES(9, 500, '2013-08-15', '00:15:00', 2); INSERT INTO `events` VALUES(10, 500, '2013-08-15', '00:30:00', 2); INSERT INTO `events` VALUES(11, 500, '2013-08-15', '00:45:00', 1); Desired output row |user_id | date_start | time_start | date_end | time_end | status_id | duration 1 |101 |'2013-08-14'| '23:00:00' |'2013-08-15'|'00:15:00'| 2 | 5 2 |101 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:30:00'| 1 | 1 3 |500 |'2013-08-14'| '00:23:45' |'2013-08-15'|'00:15:00'| 1 | 2 4 |500 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:45:00'| 2 | 2 5 |500 |'2013-08-15'| '00:00:45' |'2013-08-15'|'01:00:00'| 2 | 1 *except that rows 2 and 5 wouldn't appear if duration had to be greater than 30 minutes Thanks for any help that you can provide! And please let me know if there is anything I can further clarify!!

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Need MYSQL query for finding lowest score per game player

- by Chris Barnhill

I have a game on Facebook called Rails Across Europe. I have a Best Scores page where I show the players with the best 20 scores, which in game terms refers to the lowest winning turn. The problem is that there are a small number of players who play frequently, and their scores dominate the page. I'd like to make the scores page open to more players. So I thought that I could display the single lowest winning turn for each player instead of displaying all of the lowest winning turns for all players. The problem is that the query for this eludes me. So I hope that one of you brilliant StackOverflow folks can help me with this. I have included the relevant MYSQL table schemas below. Here are the the table relationships: player_stats contains statistics for either a game in progress or a completed game. If a game is in progress, winning_turn is zero (which means that games with a winning_turn of zero should not be included in the query). player_stats has a game_player table id reference. game_player contains data describing games currently in progress. game_player has a player table id reference. player contains data describing a person who plays the game. Here's the query I'm currently using: 'SELECT p.fb_user_id, ps.winning_turn, gp.difficulty_level, c.name as city_name, g.name as goods_name, d.cost FROM game_player as gp, player as p, player_stats as ps, demand as d, city as c, goods as g WHERE p.status = "ACTIVE" AND gp.player_id = p.id AND ps.game_player_id = gp.id AND d.id = ps.highest_demand_id AND c.id = d.city_id AND g.id = d.goods_id AND ps.winning_turn > 0 ORDER BY ps.winning_turn ASC, d.cost DESC LIMIT '.$limit.';'; Here are the relevant table schemas: -- -- Table structure for table `player_stats` -- CREATE TABLE IF NOT EXISTS `player_stats` ( `id` int(11) NOT NULL auto_increment, `game_player_id` int(11) NOT NULL, `winning_turn` int(11) NOT NULL, `highest_demand_id` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `game_player_id` (`game_player_id`,`highest_demand_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `game_player` -- CREATE TABLE IF NOT EXISTS `game_player` ( `id` int(10) unsigned NOT NULL auto_increment, `game_id` int(10) unsigned NOT NULL, `player_id` int(10) unsigned NOT NULL, `player_number` int(11) NOT NULL, `funds` int(10) unsigned NOT NULL, `turn` int(10) unsigned NOT NULL, `difficulty_level` enum('STANDARD','ADVANCED','MASTER','ULTIMATE') NOT NULL, `date_last_used` datetime NOT NULL, PRIMARY KEY (`id`), KEY `game_id` (`game_id`,`player_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `player` -- CREATE TABLE IF NOT EXISTS `player` ( `id` int(11) NOT NULL auto_increment, `fb_user_id` char(255) NOT NULL, `fb_proxied_email` text NOT NULL, `first_name` char(255) NOT NULL, `last_name` char(255) NOT NULL, `birthdate` date NOT NULL, `date_registered` datetime NOT NULL, `date_last_logged_in` datetime NOT NULL, `status` enum('ACTIVE','SUSPENDED','CLOSED') NOT NULL, PRIMARY KEY (`id`), KEY `fb_user_id` (`fb_user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1646 ;

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c++ multithread array

- by user1731972

i'm doing something for fun, trying to learn multithreading Problems passing array by reference to threads but Arno pointed out that my threading via process.h wasn't going to be multi-threaded. What I'm hoping to do is something where I have an array of 100 (or 10,000, doesn't really matter I don't think), and split up the assignment of values to each thread. Example, 4 threads = 250 values per thread to be assigned. Then I can use this filled array for further calculations. Here's some code I was working on (which doesn't work) #include <process.h> #include <windows.h> #include <iostream> #include <fstream> #include <time.h> //#include <thread> using namespace std; void myThread (void *dummy ); CRITICAL_SECTION cs1,cs2; // global int main() { ofstream myfile; myfile.open ("coinToss.csv"); int rNum; long numRuns; long count = 0; int divisor = 1; float holder = 0; int counter = 0; float percent = 0.0; HANDLE hThread[1000]; int array[10000]; srand ( time(NULL) ); printf ("Runs (use multiple of 10)? "); cin >> numRuns; for (int i = 0; i < numRuns; i++) { //_beginthread( myThread, 0, (void *) (array1) ); //??? //hThread[i * 2] = _beginthread( myThread, 0, (void *) (array1) ); hThread[i*2] = _beginthread( myThread, 0, (void *) (array) ); } //WaitForMultipleObjects(numRuns * 2, hThread, TRUE, INFINITE); WaitForMultipleObjects(numRuns, hThread, TRUE, INFINITE); } void myThread (void *param ) { //thanks goes to stockoverflow //http://stackoverflow.com/questions/12801862/problems-passing-array-by-reference-to-threads int *i = (int *)param; for (int x = 0; x < 1000000; x++) { //param[x] = rand() % 2 + 1; i[x] = rand() % 2 + 1; } } Can anyone explain why it isn't working?

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GKSession sendDataToAllPeers getting invalid parameter

- by cb4

This is my first post and I wanted to start it by thanking the many stackoverflow contributors who will never know how much they helped me out these past several days as I worked to complete my first iOS app. I am indebted to them and to this site for giving them a place to post. To 'pay off' some of that debt, I hope this will help others as I have been helped... So, my app uses the GKPeerPickerController to make a connection to a 2nd device. Once connected, the devices can send text messages to each other. The receiving peer has the message displayed in a UIAlertView. Everything was working fine. Then I decided to experiment with locations and added code to get the current location. I convert it into latitude & longitude in degrees, minutes, and seconds and put them into one NSString. I added a button to my storyboard called 'Send Location' which, when tapped, sends the location to the connected peer. This is where I ran into the problem. Both the send text and send location methods call the sendPacket method with a NSString. sendPacket converts the string to NSData and calls sendDataToAllPeers. When I learned how to capture the error, it was "Invalid parameter for - sendDataToAllPeers:withDataMode:error:". [.....pause.....] Well, this was going to be a question but in writing all this to explain the problem, the answer just dawned on me. Did a few tests and verified it now works. The issue was not in sendDataToAllPeers, it was in the conversion of the NSString (strToSend) to NSData: packet = [strToSend dataUsingEncoding:NSASCIIStringEncoding]; Specifically, it was the degree sign character (little circle, ASCII 176). NSASCIIStringEncoding only includes ASCII characters up to 127 so don't use any above that. I'm sure there was a quicker way to find the problem, but I don't know Objective-C or Xcode's debugging facility well enough yet. Whew! Several hours to discover that little tidbit. I did learn a lot, though, and that's always a good thing!

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Should an object be fully complete before injected as a dependency?

- by Hans

This is an extension of this question: http://stackoverflow.com/questions/3027082/understanding-how-to-inject-object-dependencies. Since it is a bit different, I wanted to separate them, to make it, hopefully, easier to answer. Also, this is not a real system, just a simplified example that I thought we'd all be familiar with. TIA. : DB threads: thread_id, thread_name, etc posts: post_id, thread_id, post_name, post_contents, post_date, post_user_id, etc Overview Basically I'm looking at the most maintainable way to load $post_id and have it cascade and load the other things I want to know about and I'm trying to keep the controller skinny. BUT: I'm ending up with too many dependencies to inject I'm passing in initialized but empty objects I want to limit how many parameters I am passing around I could inject $post(-many) into $thread(one<-), but on that page I'm not looking at a thread, I'm looking at a post I could combine/inject them into a new object Detail If I am injecting an object into another, is it best to have it fully created first? I'm trying to limit how many parameters I have to pass in to a page, but I end up with a circle. // 1, empty object injected via constructor $thread = new Thread; $post = new Post($thread); // $thread is just an empty object $post->load($post_id); // I could now do something like $post->get('thread_id') to get everything I want in $post // 2, complete object injected via constructor $thread = new Thread; $thread->load($thread_id); // this page would have to have passed in a $thread_id, too $post = new Post($thread); // thread is a complete object, with the data I need, like thread name $post->load($post_id); // 3, inject $post into $thread, but this makes less sense to me, since I'm looking at a post page, not a thread page $post = new Post(); $post->load($post_id); $thread = new Thread($post); $thread->load(); // would load based on the $post->get('post_id') and combine. Now I have all the data I want, but it's non-intuitive to be heirarchially Thread->Post instead of Post-with-thread-info // Or, I could inject $post into $thread, but if I'm on a post page, // having an object with a top level of Thread instead of // Post-which-contains-thread-info, makes less sense to me. // to go with example 1 class post { public function __construct(&$thread) { $this->thread=$thread; } public function load($id) { // ... here I would load all the post data based on $id // now include the thread data $this->thread->load($this->get('thread_id')); return $this; } } // I don't want to do $thread = new Thread; $post = new Post; $post->load($post_id); $thread->load($post->get('post_id')); Or, I could create a new object and inject both $post and $thread into it, but then I have object with an increasing number of dependencies.

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Bulk update & occasional insert (coredata) - Too slow

- by Andrew

Update: Currently looking into NSSET's minusSet links: http://stackoverflow.com/questions/1475636/comparing-two-arrays Hi guys, Could benefit from your wisdom here.. I'm using Coredata in my app, on first launch I download a data file and insert over 500 objects (each with 60 attributes) - fast, no problem. Each subsequent launch I download an updated version of the file, from which I need to update all existing objects' attributes (except maybe 5 attributes) and create new ones for items which have been added to the downloaded file. So, first launch I get 500 objects.. say a week later my file now contains 507 items.. I create two arrays, one for existing and one for downloaded. NSArray *peopleArrayDownloaded = [CoreDataHelper getObjectsFromContext:@"person" :@"person_id" :YES :managedObjectContextPeopleTemp]; NSArray *peopleArrayExisting = [CoreDataHelper getObjectsFromContext:@"person" :@"person_id" :YES :managedObjectContextPeople]; If the count of each array is equal then I just do this: NSUInteger index = 0; if ([peopleArrayExisting count] == [peopleArrayDownloaded count]) { NSLog(@"Number of people downloaded is same as the number of people existing"); for (person *existingPerson in peopleArrayExisting) { person *tempPerson = [peopleArrayDownloaded objectAtIndex:index]; // NSLog(@"Updating id: %@ with id: %@",existingPerson.person_id,tempPerson.person_id); // I have 60 attributes which I to update on each object, is there a quicker way other than overwriting existing? index++; } } else { NSLog(@"Number of people downloaded is different to number of players existing"); So now comes the slow part. I end up using this (which is tooooo slow): NSLog(@"Need people added to the league"); for (person *tempPerson in peopeArrayDownloaded) { NSPredicate *predicate = [NSPredicate predicateWithFormat:@"person_id = %@",tempPerson.person_id]; // NSLog(@"Searching for existing person, person_id: %@",existingPerson.person_id); NSArray *filteredArray = [peopleArrayExisting filteredArrayUsingPredicate:predicate]; if ([filteredArray count] == 0) { NSLog(@"Couldn't find an existing person in the downloaded file. Adding.."); person *newPerson = [NSEntityDescription insertNewObjectForEntityForName:@"person" inManagedObjectContext:managedObjectContextPeople]; Is there a way to generate a new array of index items referring to the additional items in my downloaded file? Incidentally, on my tableViews I'm using NSFetchedResultsController so updating attributes will call [cell setNeedsDisplay]; .. about 60 times per cell, not a good thing and it can crash the app. Thanks for reading :)

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How to find an specific key/value (property list)

- by Bob Rivers

Hi, I'm learning cocoa/objective-c. Right now I'm dealing with key/value coding. After reading Aaron's book and other sources, I thought that I was able to left the simple examples and try a complex one... I'm trying read iTunes property list (iTunes Music Library.xml). I would like to retrieve the tracks held by an specific playlist. Probably everybody knows it, but bellow I put a piece of the xml: <plist version="1.0"> <dict> <key>Major Version</key><integer>1</integer> ... <key>Playlists</key> <array> <dict> <key>Name</key><string>Library</string> ... <key>Playlist Items</key> <array> <dict> <key>Track ID</key><integer>10281</integer> </dict> ... </array> </dict> <dict> ... </dict> </array> </dict> </plist> As you can see, the playlists are stored as dictionaries inside an array, and the key that identifies it is inside it, not as a <key> preceding it. The problem is that I'm not able to figure out how to search for a key that is inside another one. With the following code I can find the the array in which the playlists are stored, but how to find an specific <dict>? NSDictionary *rootDict = [[NSDictionary alloc] initWithContentsOfFile:file]; NSArray *playlists = [rootDict objectForKey:@"Playlists"]; Here at Stackoverflow I found this post, but I'm not sure if iterate over the array and test it is a good idea. I'm quite sure that I could use valueForKeyPath, but I'm unable to figure out how to do it. Any help is welcome. TIA, Bob

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Is it OK to put a standard, pure C header #include directive inside a namespace?

- by mic_e

I've got a project with a class log in the global namespace (::log). So, naturally, after #include <cmath>, the compiler gives an error message each time I try to instantiate an object of my log class, because <cmath> pollutes the global namespace with lots of three-letter methods, one of them being the logarithm function log(). So there are three possible solutions, each having their unique ugly side-effects. Move the log class to it's own namespace and always access it with it's fully qualified name. I really want to avoid this because the logger should be as convenient as possible to use. Write a mathwrapper.cpp file which is the only file in the project that includes <cmath>, and makes all the required <cmath> functions available through wrappers in a namespace math. I don't want to use this approach because I have to write a wrapper for every single required math function, and it would add additional call penalty (cancelled out partially by the -flto compiler flag) The solution I'm currently considering: Replace #include <cmath> by namespace math { #include "math.h" } and then calculating the logarithm function via math::log(). I have tried it out and it does, indeed, compile, link and run as expected. It does, however, have multiple downsides: It's (obviously) impossible to use <cmath>, because the <cmath> code accesses the functions by their fully qualified names, and it's deprecated to use in C++. I've got a really, really bad feeling about it, like I'm gonna get attacked and eaten alive by raptors. So my question is: Is there any recommendation/convention/etc that forbid putting include directives in namespaces? Could anything go wrong with diferent C standard library implementations (I use glibc), different compilers (I use g++ 4.7, -std=c++11), linking? Have you ever tried doing this? Are there any alternate ways to banish the math functions from the global namespace? I've found several similar questions on stackoverflow, but most were about including other C++ headers, which obviously is a bad idea, and those that weren't made contradictory statements about linking behaviour for C libraries. Also, would it be beneficial to additionally put the #include <math.h> inside extern "C" {}?

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template; operator (int)

- by Oops

Hi, regarding my Point struct already mentioned here: http://stackoverflow.com/questions/2794369/template-class-ctor-against-function-new-c-standard is there a chance to replace the function toint() with a cast-operator (int)? namespace point { template < unsigned int dims, typename T > struct Point { T X[ dims ]; //umm??? template < typename U > Point< dims, U > operator U() const { Point< dims, U > ret; std::copy( X, X + dims, ret.X ); return ret; } //umm??? Point< dims, int > operator int() const { Point<dims, int> ret; std::copy( X, X + dims, ret.X ); return ret; } //OK Point<dims, int> toint() { Point<dims, int> ret; std::copy( X, X + dims, ret.X ); return ret; } }; //struct Point template < typename T > Point< 2, T > Create( T X0, T X1 ) { Point< 2, T > ret; ret.X[ 0 ] = X0; ret.X[ 1 ] = X1; return ret; } }; //namespace point int main(void) { using namespace point; Point< 2, double > p2d = point::Create( 12.3, 34.5 ); Point< 2, int > p2i = (int)p2d; //äähhm??? std::cout << p2d.str() << std::endl; char c; std::cin >> c; return 0; } I think the problem is here that C++ cannot distinguish between different return types? many thanks in advance. regards Oops

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rake db:create not working for legacy rails app (2.3.5) using MySQL (5.5.28)

- by ridicter

I'm a new Rails Developer, and I'm working on a legacy Rails app. Whenever I run the rake db:create command, I get an error that the database couldn't be created. I have found many StackOverflow questions related to this, but in troubleshooting nearly all permutations of solutions, I couldn't resolve the issue. I created the three Dbs (dev, prod, test), created the user with all access privileges to these dbs, and ran rake db:create. I'm running Mac OS X Lion, MySQL 5.5.28, Rails 2.3.5, Ruby 1.8.7. Here are my settings development: adapter: mysql encoding: utf8 database: adva_development username: adva password: **** host: localhost socket: /tmp/mysql.sock Here's the error: Couldn't create database for {"adapter"=>"mysql", "username"=>"adva", "host"=>"localhost", "encoding"=>"utf8", "database"=>"adva_development", "socket"=>"/tmp/mysql.sock", "password"=>"****"}, charset: utf8, collation: utf8_unicode_ci (if you set the charset manually, make sure you have a matching collation) I have done the following troubleshooting: Verified user and password are correct, and the user has access to the DB. (Double checked user access with SELECT * FROM mysql.db WHERE Db = 'adva_development' \G; User has all privileges.) Verify the socket is correct. I don't really understand sockets, but I can plainly see it at /tmp/mysql.sock. Checked collation and character set. I found out I had created the DB in latin charset and collation, so I recreated them. I ran show variables like "collation_database"; and show variables like "character_set_database"; and came back with utf8 and utf8_unicode_ci respectively. I followed the instructions in this question. After uninstalling mysql gem, I ran the following but came up with the same error: gem install --no-rdoc --no-ri mysql -- --with-mysql-dir=/usr/local/mysql-5.5.28-osx10.6-x86_64/bin --with-mysql-config=/usr/local/mysql-5.5.28-osx10.6-x86_64/bin/mysql_config Following Matt's suggestion, here's what a rake --trace db:create reveals: ** Invoke db:create (first_time) ** Invoke db:load_config (first_time) ** Invoke rails_env (first_time) ** Execute rails_env ** Execute db:load_config ** Execute db:create Couldn't create database for {"database"=>"adva_development", "adapter"=>"mysql", "host"=>"127.0.0.1", "password"=>"woof2adva", "username"=>"adva", "encoding"=>"utf8"}, charset: utf8, collation: utf8_unicode_ci (if you set the charset manually, make sure you have a matching collation) After 3 days and six or seven hours, I have pretty much run out of options. I tried various random things, like replacing localhost with 127.0.0.1 to no avail. Could there be something wrong related to my specific environment? Mac OS X Lion + MySQL 5.5.28? I plan on trying on setting up everything in a Linux environment. Thanks!

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Magento - How to select mysql rows by max value?

- by Damodar Bashyal

mysql> SELECT * FROM `log_customer` WHERE `customer_id` = 224 LIMIT 0, 30; +--------+------------+-------------+---------------------+-----------+----------+ | log_id | visitor_id | customer_id | login_at | logout_at | store_id | +--------+------------+-------------+---------------------+-----------+----------+ | 817 | 50139 | 224 | 2011-03-21 23:56:56 | NULL | 1 | | 830 | 52317 | 224 | 2011-03-27 23:43:54 | NULL | 1 | | 1371 | 136549 | 224 | 2011-11-16 04:33:51 | NULL | 1 | | 1495 | 164024 | 224 | 2012-02-08 01:05:48 | NULL | 1 | | 2130 | 281854 | 224 | 2012-11-13 23:44:13 | NULL | 1 | +--------+------------+-------------+---------------------+-----------+----------+ 5 rows in set (0.00 sec) mysql> SELECT * FROM `customer_entity` WHERE `entity_id` = 224; +-----------+----------------+---------------------------+----------+---------------------+---------------------+ | entity_id | entity_type_id | email | group_id | created_at | updated_at | +-----------+----------------+---------------------------+----------+---------------------+---------------------+ | 224 | 1 | [email protected] | 3 | 2011-03-21 04:59:17 | 2012-11-13 23:46:23 | +-----------+----------------+---------------------------+----------+--------------+----------+-----------------+ 1 row in set (0.00 sec) How can i search for customers who hasn't logged in for last 10 months and their account has not been updated for last 10 months. I tried below but failed. $collection = Mage::getModel('customer/customer')->getCollection(); $collection->getSelect()->joinRight(array('l'=>'log_customer'), "customer_id=entity_id AND MAX(l.login_at) <= '" . date('Y-m-d H:i:s', strtotime('10 months ago')) . "'")->group('e.entity_id'); $collection->addAttributeToSelect('*'); $collection->addFieldToFilter('updated_at', array( 'lt' => date('Y-m-d H:i:s', strtotime('10 months ago')), 'datetime'=>true, )); $collection->addAttributeToFilter('group_id', array( 'neq' => 5, )); Above tables have one customer for reference. I have no idea how to use MAX() on joins. Thanks UPDATE: This seems returning correct data, but I would like to do magento way using resource collection, so i don't need to do load customer again on for loop. $read = Mage::getSingleton('core/resource')->getConnection('core_read'); $sql = "select * from ( select e.*,l.login_at from customer_entity as e left join log_customer as l on l.customer_id=e.entity_id group by e.entity_id order by l.login_at desc ) as l where ( l.login_at <= '".date('Y-m-d H:i:s', strtotime('10 months ago'))."' or ( l.created_at <= '".date('Y-m-d H:i:s', strtotime('10 months ago'))."' and l.login_at is NULL ) ) and group_id != 5"; $result = $read->fetchAll($sql); I have loaded full shell script to github https://github.com/dbashyal/Magento-ecommerce-Shell-Scripts/blob/master/shell/suspendCustomers.php

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Delete duplicate rows, do not preserve one row

- by Radley

I need a query that goes through each entry in a database, checks if a single value is duplicated elsewhere in the database, and if it is - deletes both entries (or all, if more than two). Problem is the entries are URLs, up to 255 characters, with no way of identifying the row. Some existing answers on Stackoverflow do not work for me due to performance limitations, or they use uniqueid which obviously won't work when dealing with a string. Long Version: I have two databases containing URLs (and only URLs). One database has around 3,000 urls and the other around 1,000. However, a large majority of the 1,000 urls were taken from the 3,000 url database. I need to merge the 1,000 into the 3,000 as new entries only. For this, I made a third database with combined URLs from both tables, about 4,000 entries. I need to find all duplicate entries in this database and delete them (Both of them, without leaving either). I have followed the query of a few examples on this site, but whenever I try to delete both entries it ends up deleting all the entries, or giving sql errors. Alternatively: I have two databases, each containing the separate database. I need to check each row from one database against the other to find any that aren't duplicates, and then add those to a third database. Edit: I've got my own PHP solution which is pretty hacky, but works. I cannot answer my own question for 8 hours because I'm new, so here it is for now: I went with a PHP script to accomplish this, as I'm more familiar with PHP than MySQL. This generates a simple list of urls that only exist in the target database, but not both. If you have more than 7,000 entries to parse this may take awhile, and you will need to copy/paste the results into a text file or expand the script to store them back into a database. I'm just doing it manually to save time. Note: Uses MeekroDB <pre> <?php require('meekrodb.2.1.class.php'); DB::$user = 'root'; DB::$password = ''; DB::$dbName = 'testdb'; $all = DB::query('SELECT * FROM old_urls LIMIT 7000'); foreach($all as $row) { $test = DB::query('SELECT url FROM new_urls WHERE url=%s', $row['url']); if (!is_array($test)) { echo $row['url'] . "\n"; }else{ if (count($test) == 0) { echo $row['url'] . "\n"; } } } ?> </pre>

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Database advantages? Access, MySQL, msSQL, or any others?

- by JimZ

Dear all Stackoverflowers, I just started to learn programming and now I'm putting this question online based on a quote: no question is silly My work needs to develop a order system based on web, which wants a database system. Since using Excel for years as a general office user, I naturally turn this to Access. However, most people say Access is very limited comparing to MySQL or MSSQL, or any other more professional database system. But after developing some functions for my company's order system, I really find Access can fulfill my request. And I also tried MSSQL to develop, which I found it not quite convenient to use. I have searched in stackoverflow and find no general answer about my doubt. Now I am sincerely hoping some experienced and professional developers could clear my doubts. Now I'm listing some Access advantages, which I don't think other database system have. I hope you could help me also find these advantages in others. 1. Access is portable, I can just copy a xxx.accdb file to my company and continue with development. 2. Access is easy to generate helpful table, for example, it will automatically generate a field that can automatically count, could be used as primary key value. 3. it is more compatable with Excel, to display and filter data. 4. importantly, it nerely needs no environment to setup, just needs MS Office to be installed. ............others However, I also find some points that MSSQL is advantaged: 1. security reasons 2. easy to backup, ( just use BACKUP..... sql statement to do it) 3. can edit stored procedure to save some functions to database ...............others specifically, I wish some friends could tell me how to make other database portable? since I usually work both at home and in office. It's a headache to move MSSQL work to my office, since the version of MSSQL is not the same. Thank you all and best regards, :)

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The big last_insert_id() problem, again.

- by wretrOvian

Note - this follows my question here: http://stackoverflow.com/questions/2983685/jdbc-does-the-connection-break-if-i-lose-reference-to-the-connection-object Now i have a created a class so i can deal with JDBC easily for the rest of my code - public class Functions { private String DB_SERVER = ""; private String DB_NAME = "test"; private String DB_USERNAME = "root"; private String DB_PASSWORD = "password"; public Connection con; public PreparedStatement ps; public ResultSet rs; public ResultSetMetaData rsmd; public void connect() throws java.io.FileNotFoundException, java.io.IOException, SQLException, Exception { String[] dbParms = Parameters.load(); DB_SERVER = dbParms[0]; DB_NAME = dbParms[1]; DB_USERNAME = dbParms[2]; DB_PASSWORD = dbParms[3]; // Connect. Class.forName("com.mysql.jdbc.Driver").newInstance(); con = DriverManager.getConnection("jdbc:mysql://" + DB_SERVER + "/" + DB_NAME, DB_USERNAME, DB_PASSWORD); } public void disconnect() throws SQLException { // Close. con.close(); } } As seen Parameters.load() refreshes the connection parameters from a file every-time, so that any changes to the same may be applied on the next immediate connection. An example of this class in action - public static void add(String NAME) throws java.io.FileNotFoundException, java.io.IOException, SQLException, Exception { Functions dbf = new Functions(); dbf.connect(); String query = "INSERT INTO " + TABLE_NAME + "(" + "NAME" + ") VALUES(?)"; PreparedStatement ps = dbf.con.prepareStatement(query); ps.setString(1, NAME); ps.executeUpdate(); dbf.disconnect(); } Now here is the problem - for adding a record to the table above, the add() method will open a connection, add the record - and then call disconnect() . What if i want to get the ID of the inserted record after i call add() -like this : Department.add("new dept"); int ID = getlastID(); Isn't it possible that another add() was called between those two statements?

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curl problems in c++ class

- by Danilo

I read a few articles on c++ / curl here on stackoverflow and assembled the following. The main goal is to handle the whole request in an instance of a class -- and maybe later in a secondary thread. My problem is: "content_" seems to stay empty though its the same addr and HttpFetch.h: class HttpFetch { private: CURL *curl; static size_t handle(char * data, size_t size, size_t nmemb, void * p); size_t handle_impl(char * data, size_t size, size_t nmemb); public: std::string content_; static std::string url_; HttpFetch(std::string url); void start(); std::string data(); }; HttpFetch.cpp: HttpFetch::HttpFetch(std::string url) { curl_global_init(CURL_GLOBAL_ALL); //pretty obvious curl = curl_easy_init(); content_.append("Test"); std::cout << &content_ << "\n"; curl_easy_setopt(curl, CURLOPT_URL, &url); curl_easy_setopt(curl, CURLOPT_WRITEDATA, &content_); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &HttpFetch::handle); //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); //tell curl to output its progress curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); //std::cout << &content_ << "\n"; } void HttpFetch::start() { curl_easy_perform(curl); curl_easy_cleanup(curl); } size_t HttpFetch::handle(char * data, size_t size, size_t nmemb, void * p) { std::string *stuff = reinterpret_cast<std::string*>(p); stuff->append(data, size * nmemb); std::cout << stuff << "\n"; // has content from data in it! return size * nmemb; } main.cpp: #include "HttpFetch.h" int main(int argc, const char * argv[]) { HttpFetch call = *new HttpFetch("http://www.example.com"); call.start(); ::std::cout << call.content_ << "\n" } Thanks in advance

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NullPointerException while trying to bind at SimpleCursorAdapter

- by hrskrs

I have asked a question before where i found my mistake. However now i am facing with another problem. I have checked all the similar errors asked on StackOverflow but without success.Any help is appriciated. The idea here is that i am getting image names from DB so depending on those names images from Drawable folder will be shown in a listView together with a description but im getting an error of NullPointException at setViewValue. Here is the code snippet: private void populateListView() { ListView customListView = (ListView)findViewById(R.id.lvCustom); Cursor cursor = DBhelper.getAllimages(); startManagingCursor(cursor); String[] from = { DBhelper.COLUMN_PIC_URL, DBhelper.COLUMN_PIC_DESC}; int[] to = {R.id.ivImg, R.id.tvTitle}; SimpleCursorAdapter cursorAdapter = new SimpleCursorAdapter(this, R.layout.custom_listview_row, cursor, from, to, 0); cursorAdapter.setViewBinder(new ViewBinder() { @Override public boolean setViewValue(View view, Cursor cursor, int columnIndex) { ImageView imageImageView = (ImageView)findViewById(R.id.ivImg); String[] imgNames = new String[cursor.getCount()]; int[] imgResourceIds = new int[cursor.getCount()]; for(int i=0; i<cursor.getCount(); i++){ imgNames[i] = cursor.getString(cursor.getColumnIndex(DBhelper.COLUMN_PIC_URL)); imgResourceIds[i] = getResources().getIdentifier(imgNames[i], "drawable", getPackageName()); imageImageView.setImageResource(imgResourceIds[i]); cursor.moveToNext(); } return true; } }); customListView.setAdapter(cursorAdapter); } Here is the Error from LogCat: I have tried to log the output of imgNames[i] where it returns the url pic from the DB correctly and imgResourceIds[i] where it return the image resource id correctly also(it does not return NULL but something like: 295731). But it stops at imageImageView.setImageResource(imgResourceIds[i]); To see from where that NullPointerException is coming, i commented out imageImageView.setImageResource(imgResourceIds[i]);. This time imageNames(those with a TAG) and imgResourceIds(those system printed out) came correctly but doubled, when i removed cursor.MoveToNext() last row were doubled. Here is the screen shot of that: I have tried all the suggestions on stack about gettin a NullException but without success. Any idea where i am doing mistake?

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PHP array performance

- by dfo

Hi, this is my first question on Stackoverflow, please bear with me. I'm testing an algorithm for 2d bin packing and I've chosen PHP to mock it up as it's my bread-and-butter language nowadays. As you can see on http://themworks.com/pack_v0.2/oopack.php?ol=1 it works pretty well, but you need to wait around 10-20 seconds for 100 rectangles to pack. For some hard to handle sets it would hit the php's 30s runtime limit. I did some profiling and it shows that most of the time my script goes through different parts of a small 2d array with 0's and 1's in it. It either checks if certain cell equals to 0/1 or sets it to 0/1. It can do such operations million times and each times it takes few microseconds. I guess I could use an array of booleans in a statically typed language and things would be faster. Or even make an array of 1 bit values. I'm thinking of converting the whole thing to some compiled language. Is PHP just not good for it? If I do need to convert it to let's say C++, how good are the automatic converters? My script is just a lot of for loops with basic arrays and objects manipulations. Thank you! Edit. This function gets called more than any other. It reads few properties of a very simple object, and goes through a very small part of a smallish array to check if there's any element not equal to 0. function fits($bin, $file, $x, $y) { $flag = true; $xw = $x + $file->get_width();; $yh = $y + $file->get_height(); for ($i = $x; $i < $xw; $i++) { for ($j = $y; $j < $yh; $j++) { if ($bin[$i][$j] !== 0) { $flag = false; break; } } if (!$flag) break; } return $flag; }

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Compiling examples for consuming the REST Endpoints for WCF Service using Agatha

- by REA_ANDREW

I recently made two contributions to the Agatha Project by Davy Brion over on Google Code, and one of the things I wanted to follow up with was a post showing examples and some, seemingly required tid bits. The contributions which I made where: To support StructureMap To include REST (JSON and XML) support for the service contract The examples which I have made, I want to format them so they fit in with the current format of examples over on Agatha and hopefully create and submit a third patch which will include these examples to help others who wish to use these additions. Whilst building these examples for both XML and JSON I have learnt a couple of things which I feel are not really well documented, but are extremely good practice and once known make perfect sense. I have chosen a real basic e-commerce context for my example Requests and Responses, and have also made use of the excellent tool AutoMapper, again on Google Code. Setting the scene I have followed the Pipes and Filters Pattern with the IQueryable interface on my Repository and exposed the following methods to query Products: IQueryable<Product> GetProducts(); IQueryable<Product> ByCategoryName(this IQueryable<Product> products, string categoryName) Product ByProductCode(this IQueryable<Product> products, String productCode) I have an interface for the IProductRepository but for the concrete implementation I have simply created a protected getter which populates a private List<Product> with 100 test products with random data. Another good reason for following an interface based approach is that it will demonstrate usage of my first contribution which is the StructureMap support. Finally the two Domain Objects I have made are Product and Category as shown below: public class Product { public String ProductCode { get; set; } public String Name { get; set; } public Decimal Price { get; set; } public Decimal Rrp { get; set; } public Category Category { get; set; } } public class Category { public String Name { get; set; } } Requirements for the REST Support One of the things which you will notice with Agatha is that you do not have to decorate your Request and Response objects with the WCF Service Model Attributes like DataContract, DataMember etc… Unfortunately from what I have seen, these are required if you want the same types to work with your REST endpoint. I have not tried but I assume the same result can be achieved by simply decorating the same classes with the Serializable Attribute. Without this the operation will fail. Another surprising thing I have found is that it did not work until I used the following Attribute parameters: Name Namespace e.g. [DataContract(Name = "GetProductsRequest", Namespace = "AgathaRestExample.Service.Requests")] public class GetProductsRequest : Request { } Although I was surprised by this, things kind of explained themselves when I got round to figuring out the exact construct required for both the XML and the REST. One of the things which you already know and are then reminded of is that each of your Requests and Responses ultimately inherit from an abstract base class respectively. This information needs to be represented in a way native to the format being used. I have seen this in XML but I have not seen the format which is required for the JSON. JSON Consumer Example I have used JQuery to create the example and I simply want to make two requests to the server which as you will know with Agatha are transmitted inside an array to reduce the service calls. I have also used a tool called json2 which is again over at Google Code simply to convert my JSON expression into its string format for transmission. You will notice that I specify the type of Request I am using and the relevant Namespace it belongs to. Also notice that the second request has a parameter so each of these two object are representing an abstract Request and the parameters of the object describe it. <script type="text/javascript"> var bodyContent = $.ajax({ url: "http://localhost:50348/service.svc/json/processjsonrequests", global: false, contentType: "application/json; charset=utf-8", type: "POST", processData: true, data: JSON.stringify([ { __type: "GetProductsRequest:AgathaRestExample.Service.Requests" }, { __type: "GetProductsByCategoryRequest:AgathaRestExample.Service.Requests", CategoryName: "Category1" } ]), dataType: "json", success: function(msg) { alert(msg); } }).responseText; </script> XML Consumer Example For the XML Consumer example I have chosen to use a simple Console Application and make a WebRequest to the service using the XML as a request. I have made a crude static method which simply reads from an XML File, replaces some value with a parameter and returns the formatted XML. I say crude but it simply shows how XML Templates for each type of Request could be made and then have a wrapper utility in whatever language you use to combine the requests which are required. The following XML is the same Request array as shown above but simply in the XML Format. <?xml version="1.0" encoding="utf-8" ?> <ArrayOfRequest xmlns="http://schemas.datacontract.org/2004/07/Agatha.Common" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> <Request i:type="a:GetProductsRequest" xmlns:a="AgathaRestExample.Service.Requests"/> <Request i:type="a:GetProductsByCategoryRequest" xmlns:a="AgathaRestExample.Service.Requests"> <a:CategoryName>{CategoryName}</a:CategoryName> </Request> </ArrayOfRequest> It is funny because I remember submitting a question to StackOverflow asking whether there was a REST Client Generation tool similar to what Microsoft used for their RestStarterKit but which could be applied to existing services which have REST endpoints attached. I could not find any but this is now definitely something which I am going to build, as I think it is extremely useful to have but also it should not be too difficult based on the information I now know about the above. Finally I thought that the Strategy Pattern would lend itself really well to this type of thing so it can accommodate for different languages. I think that is about it, I have included the code for the example Console app which I made below incase anyone wants to have a mooch at the code. As I said above I want to reformat these to fit in with the current examples over on the Agatha project, but also now thinking about it, make a Documentation Web method…{brain ticking} :-) Cheers for now and here is the final bit of code: static void Main(string[] args) { var request = WebRequest.Create("http://localhost:50348/service.svc/xml/processxmlrequests"); request.Method = "POST"; request.ContentType = "text/xml"; using(var writer = new StreamWriter(request.GetRequestStream())) { writer.WriteLine(GetExampleRequestsString("Category1")); } var response = request.GetResponse(); using(var reader = new StreamReader(response.GetResponseStream())) { Console.WriteLine(reader.ReadToEnd()); } Console.ReadLine(); } static string GetExampleRequestsString(string categoryName) { var data = File.ReadAllText(Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "ExampleRequests.xml")); data = data.Replace("{CategoryName}", categoryName); return data; } }

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CodePlex Daily Summary for Monday, June 14, 2010

CodePlex Daily Summary for Monday, June 14, 2010New ProjectsBD File Hash: BD File Hash is a convenient file hash and hash compare tool for Windows which currently works with MD5, SHA-1, and SHA-256 algorithms. FileScan: This is an application that searches through a drive or directory structure for files matching a filter. This project was converted from VB to ...genesis9: genesis9HeinanOS: HeinanOS is an operating system developed mainly in C++. HeinanOS is a light OS (1.44 MB image) with a lot of capabilites and many more are being ...MediaBrowserWS - Creates a Web Service for the popular MediaBrowser plugin: Creates a web service in Media Center for accessing your MediaBrowser collection. Allows for external devices (Tablets/phones/laptops) to access a ...MME: New Edition of Managed Menu Extensions for Visual Studio 2010 The Main goal of "MME" is to provide easy access to adding Right Click menus in the ...MVMMapper: Generate the ViewModel and its mapping to the Model when implementing MVVM in .NET. Developed using T4 templates. Current version supports Silver...ProjectArDotNet: Si te agarro te parto! Si te agarro te emperno no me importa que seas menor de edad!Scriptagility for DotNetNuke: Scriptagility is a DotNetNuke module for Javascript developers. This module provides dynamic client scripting infrastructure for developing javascr...simpleLinux Distro: SimpleLinux. is a Linux distributions that is easy to use. Simple Linux website: http://simplelinux.tkTag Cloud Control for asp.net: Tag Cloud Control for asp.net allows the user to display the most important keywords to display in tag cloud. Each Tag has it own navigation url to...thefreeimdb: fsadie qwUppityUp: UppityUp is a simple and light-weight tray application which monitors a remote server and shows a notification when it comes online. This is usefu...Vivid3D 2 - DirectX 10 3D ToolKit: The sequel to my first ever engine wrote several years ago. It is not based on it in anyway. VSIDev: VSI DevXTQXK_WORK: Actionscript 3.0东坡博客: 这是一个ASP。net mvc 2博客。New Releases.NET Extensions - Extension Methods Library: Release 2010.08: Added extension methods for Bitmap manipulation (scaling for now): - Bitmap.ScaleToSize() - Bitmap.ScaleToSizeProportional() - Bitmap.ScaleProport...Black Falcon Software's Database Data-Access-Layers: “SQLHELPER”, “ORAHELPER” - Handling Binary Data: See attached document...BTech Networking Library: BTech Networking Library: Same as pervious just new namespace, extended networking coming soon!!!Community Forums NNTP bridge: Community Forums NNTP Bridge V37: Release of the Community Forums NNTP Bridge to access the social and anwsers MS forums with a single, open source NNTP bridge. This release has ad...Generic Entity Model 2: GEM2 build 54383: This is second BETA release of GEM2! Please see source code change sets for updates! Following implementation is not included in this release: My...Hades: Projet Hadès - Official Demo - Version 0.1.0 Beta: ---------------------------------------------------------------------------- - Projet Hadès - Official Demo - Version 0.1.0 Beta ------------------...HeinanOS: HeinanOS M1 Source Code: You can download HeinanOS M1 Source Code and contribute to HeinanOS development! Be aware that you should not use this code for your own systems! ...HeinanOS: Milestone 1: This is the first major release for HeinanOS 1.0 Please note this is a PRE-RELEASE! This release includes the following features: -Bootable DOS-...HKGolden Express: HKGoldenExpress (Build 201006131900): New features: (None) Bug fix: Incorrect message submit date of message/ replies. (Note: Showing message submit date is enabled since Build 20100...HKGolden Express: HKGoldenExpress (Build 201006140110): New features: (None) Bug fix: (None) Improvements: (None) Other changes: Set time zone of message date as Hong Kong. Adjusted the format of messa...MediaCoder.NET: MediaCoder.NET v1.0 Beta 1.5: Installer file for MediaCoder.NET v1.0 beta 1.5. Now converts multiple files.MME: First release: Features of this release 1. One installer MME.msi. However you can also install MMEMenuManagerSetup.vsix which installs a project template that e...MSBuild Launch Pad (mPad): 1.1 Beta 1: Platform selection box is added.MVMMapper: MVMMapper Release v 1.0.1: This release has no downloadable documentation. Please use the Documentation section to get started.NginxTray: NginxTray 0.7 RC2: NginxTray 0.7 RC2PowerAuras: PowerAuras-3.0.0K-beta3: New Auras: Item Name Equipment Slot Tracking Changes from beta1 5 new aura textures Fixed Tracking bug Added graphical equipment slot sele...PowerAuras: PowerAuras-3.0.0K-beta4: New Auras: Item Name Equipment Slot Tracking Changes from beta1 5 new aura textures Fixed Tracking bug Added graphical equipment slot sele...Scriptagility for DotNetNuke: Scriptagility 1.0 (Beta): Initial public release please evaluate and feedbackSharpDevelop: SharpDevelop 4.0 Beta 1: Release notes: http://community.sharpdevelop.net/forums/t/11388.aspxsimpleLinux Distro: Project X3: This is an example of download for simpleLinuxSOAPI - StackOverflow API Parser/Wrapper Generator: SOAPI Beta 3: The SOAPI Beta 3 download will be made availabe later today when the initial documentation is complete. The previously available Beta 1 download h...Sofa: Initial release V1.0: This is the first release of Sofa. As it is made of code being previously used, as we tested it is a stable release. But bugs are always possible,...Tag Cloud Control for asp.net: Tag Cloud Control for asp.net: Tag Cloud Control for asp.net allows the user to display the most important keywords to display in tag cloud. Each Tag has it own navigation url to...UppityUp: UppityUp v0.1: First functional version, supports monitoring availability by ping (ICMP) requests. Fit for general use. Consists of one standalone .exe file - no...VCC: Latest build, v2.1.30613.0: Automatic drop of latest buildWindStyle ExifInfo for Windows Live Writer: 1.1.0.0: Add: Multiple Language(English and Simplified Chinese); Add: Insert multiple files; Fix: Error when insert pictures without Exif info; Update: Icon...Work Recorder - Hold on own time!: WorkRecorder 1.2: +Add a whole day chartXsltDb - DotNetNuke Module Builder: 01.01.24: Syntax highlighting delivered!New samples for RadControls. On single page you can find RadTreeView, RadRating, RadChart, RadFormDecorator, RadEdito...xUnit.net Contrib: xunitcontrib 0.4 (ReSharper 5.0 RTM + dotCover): xunitcontrib release 0.4 (ReSharper runner) This release provides a test runner plugin for Resharper 5.0, 4.5 and 4.1, targetting all versions of x...Most Popular ProjectsCommunity Forums NNTP bridgeRIA Services EssentialsNeatUploadBxf (Basic XAML Framework)Agile Personal Development Methodology.NET Transactional File ManagerSOLID by exampleASP.NET MVC Time PlannerWEI ShareSiverlight ProjectMost Active ProjectsjQuery Library for SharePoint Web Servicespatterns & practices – Enterprise LibraryNB_Store - Free DotNetNuke Ecommerce Catalog ModuleRhyduino - Arduino and Managed CodeCommunity Forums NNTP bridgeCassandraemonBlogEngine.NETLightweight Fluent WorkflowMediaCoder.NETAndrew's XNA Helpers

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ASP.NET MVC–How to show asterisk after required field label

- by DigiMortal

Usually we have some required fields on our forms and it would be nice if ASP.NET MVC views can detect those fields automatically and display nice red asterisk after field label. As this functionality is not built in I built my own solution based on data annotations. In this posting I will show you how to show red asterisk after label of required fields. Here are the main information sources I used when working out my own solution: How can I modify LabelFor to display an asterisk on required fields? (stackoverflow) ASP.NET MVC – Display visual hints for the required fields in your model (Radu Enuca) Although my code was first written for completely different situation I needed it later and I modified it to work with models that use data annotations. If data member of model has Required attribute set then asterisk is rendered after field. If Required attribute is missing then there will be no asterisk. Here’s my code. You can take just LabelForRequired() methods and paste them to your own HTML extension class. public static class HtmlExtensions { [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")] public static MvcHtmlString LabelForRequired<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, string labelText = "") { return LabelHelper(html, ModelMetadata.FromLambdaExpression(expression, html.ViewData), ExpressionHelper.GetExpressionText(expression), labelText); } private static MvcHtmlString LabelHelper(HtmlHelper html, ModelMetadata metadata, string htmlFieldName, string labelText) { if (string.IsNullOrEmpty(labelText)) { labelText = metadata.DisplayName ?? metadata.PropertyName ?? htmlFieldName.Split('.').Last(); } if (string.IsNullOrEmpty(labelText)) { return MvcHtmlString.Empty; } bool isRequired = false; if (metadata.ContainerType != null) { isRequired = metadata.ContainerType.GetProperty(metadata.PropertyName) .GetCustomAttributes(typeof(RequiredAttribute), false) .Length == 1; } TagBuilder tag = new TagBuilder("label"); tag.Attributes.Add( "for", TagBuilder.CreateSanitizedId( html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName) ) ); if (isRequired) tag.Attributes.Add("class", "label-required"); tag.SetInnerText(labelText); var output = tag.ToString(TagRenderMode.Normal); if (isRequired) { var asteriskTag = new TagBuilder("span"); asteriskTag.Attributes.Add("class", "required"); asteriskTag.SetInnerText("*"); output += asteriskTag.ToString(TagRenderMode.Normal); } return MvcHtmlString.Create(output); } } And here’s how to use LabelForRequired extension method in your view: <div class="field"> @Html.LabelForRequired(m => m.Name) @Html.TextBoxFor(m => m.Name) @Html.ValidationMessageFor(m => m.Name) </div> After playing with CSS style called .required my example form looks like this: These red asterisks are not part of original view mark-up. LabelForRequired method detected that these properties have Required attribute set and rendered out asterisks after field names. NB! By default asterisks are not red. You have to define CSS class called “required” to modify how asterisk looks like and how it is positioned.

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How accurate is "Business logic should be in a service, not in a model"?

- by Jeroen Vannevel

Situation Earlier this evening I gave an answer to a question on StackOverflow. The question: Editing of an existing object should be done in repository layer or in service? For example if I have a User that has debt. I want to change his debt. Should I do it in UserRepository or in service for example BuyingService by getting an object, editing it and saving it ? My answer: You should leave the responsibility of mutating an object to that same object and use the repository to retrieve this object. Example situation: class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } A comment I received: Business logic should really be in a service. Not in a model. What does the internet say? So, this got me searching since I've never really (consciously) used a service layer. I started reading up on the Service Layer pattern and the Unit Of Work pattern but so far I can't say I'm convinced a service layer has to be used. Take for example this article by Martin Fowler on the anti-pattern of an Anemic Domain Model: There are objects, many named after the nouns in the domain space, and these objects are connected with the rich relationships and structure that true domain models have. The catch comes when you look at the behavior, and you realize that there is hardly any behavior on these objects, making them little more than bags of getters and setters. Indeed often these models come with design rules that say that you are not to put any domain logic in the the domain objects. Instead there are a set of service objects which capture all the domain logic. These services live on top of the domain model and use the domain model for data. (...) The logic that should be in a domain object is domain logic - validations, calculations, business rules - whatever you like to call it. To me, this seemed exactly what the situation was about: I advocated the manipulation of an object's data by introducing methods inside that class that do just that. However I realize that this should be a given either way, and it probably has more to do with how these methods are invoked (using a repository). I also had the feeling that in that article (see below), a Service Layer is more considered as a façade that delegates work to the underlying model, than an actual work-intensive layer. Application Layer [his name for Service Layer]: Defines the jobs the software is supposed to do and directs the expressive domain objects to work out problems. The tasks this layer is responsible for are meaningful to the business or necessary for interaction with the application layers of other systems. This layer is kept thin. It does not contain business rules or knowledge, but only coordinates tasks and delegates work to collaborations of domain objects in the next layer down. It does not have state reflecting the business situation, but it can have state that reflects the progress of a task for the user or the program. Which is reinforced here: Service interfaces. Services expose a service interface to which all inbound messages are sent. You can think of a service interface as a façade that exposes the business logic implemented in the application (typically, logic in the business layer) to potential consumers. And here: The service layer should be devoid of any application or business logic and should focus primarily on a few concerns. It should wrap Business Layer calls, translate your Domain in a common language that your clients can understand, and handle the communication medium between server and requesting client. This is a serious contrast to other resources that talk about the Service Layer: The service layer should consist of classes with methods that are units of work with actions that belong in the same transaction. Or the second answer to a question I've already linked: At some point, your application will want some business logic. Also, you might want to validate the input to make sure that there isn't something evil or nonperforming being requested. This logic belongs in your service layer. "Solution"? Following the guidelines in this answer, I came up with the following approach that uses a Service Layer: class UserController : Controller { private UserService _userService; public UserController(UserService userService){ _userService = userService; } public ActionResult MakeHimPay(string username, int amount) { _userService.MakeHimPay(username, amount); return RedirectToAction("ShowUserOverview"); } public ActionResult ShowUserOverview() { return View(); } } class UserService { private IUserRepository _userRepository; public UserService(IUserRepository userRepository) { _userRepository = userRepository; } public void MakeHimPay(username, amount) { _userRepository.GetUserByName(username).makePayment(amount); } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } Conclusion All together not much has changed here: code from the controller has moved to the service layer (which is a good thing, so there is an upside to this approach). However this doesn't look like it had anything to do with my original answer. I realize design patterns are guidelines, not rules set in stone to be implemented whenever possible. Yet I have not found a definitive explanation of the service layer and how it should be regarded. Is it a means to simply extract logic from the controller and put it inside a service instead? Is it supposed to form a contract between the controller and the domain? Should there be a layer between the domain and the service layer? And, last but not least: following the original comment Business logic should really be in a service. Not in a model. Is this correct? How would I introduce my business logic in a service instead of the model?

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3D picking lwjgl

- by Wirde

I have written some code to preform 3D picking that for some reason dosn't work entirely correct! (Im using LWJGL just so you know.) I posted this at stackoverflow at first but after researching some more in to my problem i found this neat site and tought that you guys might be more qualified to answer this question. This is how the code looks like: if(Mouse.getEventButton() == 1) { if (!Mouse.getEventButtonState()) { Camera.get().generateViewMatrix(); float screenSpaceX = ((Mouse.getX()/800f/2f)-1.0f)*Camera.get().getAspectRatio(); float screenSpaceY = 1.0f-(2*((600-Mouse.getY())/600f)); float displacementRate = (float)Math.tan(Camera.get().getFovy()/2); screenSpaceX *= displacementRate; screenSpaceY *= displacementRate; Vector4f cameraSpaceNear = new Vector4f((float) (screenSpaceX * Camera.get().getNear()), (float) (screenSpaceY * Camera.get().getNear()), (float) (-Camera.get().getNear()), 1); Vector4f cameraSpaceFar = new Vector4f((float) (screenSpaceX * Camera.get().getFar()), (float) (screenSpaceY * Camera.get().getFar()), (float) (-Camera.get().getFar()), 1); Matrix4f tmpView = new Matrix4f(); Camera.get().getViewMatrix().transpose(tmpView); Matrix4f invertedViewMatrix = (Matrix4f)tmpView.invert(); Vector4f worldSpaceNear = new Vector4f(); Matrix4f.transform(invertedViewMatrix, cameraSpaceNear, worldSpaceNear); Vector4f worldSpaceFar = new Vector4f(); Matrix4f.transform(invertedViewMatrix, cameraSpaceFar, worldSpaceFar); Vector3f rayPosition = new Vector3f(worldSpaceNear.x, worldSpaceNear.y, worldSpaceNear.z); Vector3f rayDirection = new Vector3f(worldSpaceFar.x - worldSpaceNear.x, worldSpaceFar.y - worldSpaceNear.y, worldSpaceFar.z - worldSpaceNear.z); rayDirection.normalise(); Ray clickRay = new Ray(rayPosition, rayDirection); Vector tMin = new Vector(), tMax = new Vector(), tempPoint; float largestEnteringValue, smallestExitingValue, temp, closestEnteringValue = Camera.get().getFar()+0.1f; Drawable closestDrawableHit = null; for(Drawable d : this.worldModel.getDrawableThings()) { // Calcualte AABB for each object... needs to be moved later... firstVertex = true; for(Surface surface : d.getSurfaces()) { for(Vertex v : surface.getVertices()) { worldPosition.x = (v.x+d.getPosition().x)*d.getScale().x; worldPosition.y = (v.y+d.getPosition().y)*d.getScale().y; worldPosition.z = (v.z+d.getPosition().z)*d.getScale().z; worldPosition = worldPosition.rotate(d.getRotation()); if (firstVertex) { maxX = worldPosition.x; maxY = worldPosition.y; maxZ = worldPosition.z; minX = worldPosition.x; minY = worldPosition.y; minZ = worldPosition.z; firstVertex = false; } else { if (worldPosition.x > maxX) { maxX = worldPosition.x; } if (worldPosition.x < minX) { minX = worldPosition.x; } if (worldPosition.y > maxY) { maxY = worldPosition.y; } if (worldPosition.y < minY) { minY = worldPosition.y; } if (worldPosition.z > maxZ) { maxZ = worldPosition.z; } if (worldPosition.z < minZ) { minZ = worldPosition.z; } } } } // ray/slabs intersection test... // clickRay.getOrigin().x + clickRay.getDirection().x * f = minX // clickRay.getOrigin().x - minX = -clickRay.getDirection().x * f // clickRay.getOrigin().x/-clickRay.getDirection().x - minX/-clickRay.getDirection().x = f // -clickRay.getOrigin().x/clickRay.getDirection().x + minX/clickRay.getDirection().x = f largestEnteringValue = -clickRay.getOrigin().x/clickRay.getDirection().x + minX/clickRay.getDirection().x; temp = -clickRay.getOrigin().y/clickRay.getDirection().y + minY/clickRay.getDirection().y; if(largestEnteringValue < temp) { largestEnteringValue = temp; } temp = -clickRay.getOrigin().z/clickRay.getDirection().z + minZ/clickRay.getDirection().z; if(largestEnteringValue < temp) { largestEnteringValue = temp; } smallestExitingValue = -clickRay.getOrigin().x/clickRay.getDirection().x + maxX/clickRay.getDirection().x; temp = -clickRay.getOrigin().y/clickRay.getDirection().y + maxY/clickRay.getDirection().y; if(smallestExitingValue > temp) { smallestExitingValue = temp; } temp = -clickRay.getOrigin().z/clickRay.getDirection().z + maxZ/clickRay.getDirection().z; if(smallestExitingValue < temp) { smallestExitingValue = temp; } if(largestEnteringValue > smallestExitingValue) { //System.out.println("Miss!"); } else { if (largestEnteringValue < closestEnteringValue) { closestEnteringValue = largestEnteringValue; closestDrawableHit = d; } } } if(closestDrawableHit != null) { System.out.println("Hit at: (" + clickRay.setDistance(closestEnteringValue).x + ", " + clickRay.getCurrentPosition().y + ", " + clickRay.getCurrentPosition().z); this.worldModel.removeDrawableThing(closestDrawableHit); } } } I just don't understand what's wrong, the ray are shooting and i do hit stuff that gets removed but the result of the ray are verry strange it sometimes removes the thing im clicking at, sometimes it removes things thats not even close to what im clicking at, and sometimes it removes nothing at all. Edit: Okay so i have continued searching for errors and by debugging the ray (by painting smal dots where it travles) i can now se that there is something oviously wrong with the ray that im sending out... it has its origin near the world center (nearer or further away depending on where on the screen im clicking) and always shots to the same position no matter where I direct my camera... My initial toughts is that there might be some error in the way i calculate my viewMatrix (since it's not possible to get the viewmatrix from the gluLookAt method in lwjgl; I have to build it my self and I guess thats where the problem is at)... Edit2: This is how i calculate it currently: private double[][] viewMatrixDouble = {{0,0,0,0}, {0,0,0,0}, {0,0,0,0}, {0,0,0,1}}; public Vector getCameraDirectionVector() { Vector actualEye = this.getActualEyePosition(); return new Vector(lookAt.x-actualEye.x, lookAt.y-actualEye.y, lookAt.z-actualEye.z); } public Vector getActualEyePosition() { return eye.rotate(this.getRotation()); } public void generateViewMatrix() { Vector cameraDirectionVector = getCameraDirectionVector().normalize(); Vector side = Vector.cross(cameraDirectionVector, this.upVector).normalize(); Vector up = Vector.cross(side, cameraDirectionVector); viewMatrixDouble[0][0] = side.x; viewMatrixDouble[0][1] = up.x; viewMatrixDouble[0][2] = -cameraDirectionVector.x; viewMatrixDouble[1][0] = side.y; viewMatrixDouble[1][1] = up.y; viewMatrixDouble[1][2] = -cameraDirectionVector.y; viewMatrixDouble[2][0] = side.z; viewMatrixDouble[2][1] = up.z; viewMatrixDouble[2][2] = -cameraDirectionVector.z; /* Vector actualEyePosition = this.getActualEyePosition(); Vector zaxis = new Vector(this.lookAt.x - actualEyePosition.x, this.lookAt.y - actualEyePosition.y, this.lookAt.z - actualEyePosition.z).normalize(); Vector xaxis = Vector.cross(upVector, zaxis).normalize(); Vector yaxis = Vector.cross(zaxis, xaxis); viewMatrixDouble[0][0] = xaxis.x; viewMatrixDouble[0][1] = yaxis.x; viewMatrixDouble[0][2] = zaxis.x; viewMatrixDouble[1][0] = xaxis.y; viewMatrixDouble[1][1] = yaxis.y; viewMatrixDouble[1][2] = zaxis.y; viewMatrixDouble[2][0] = xaxis.z; viewMatrixDouble[2][1] = yaxis.z; viewMatrixDouble[2][2] = zaxis.z; viewMatrixDouble[3][0] = -Vector.dot(xaxis, actualEyePosition); viewMatrixDouble[3][1] =-Vector.dot(yaxis, actualEyePosition); viewMatrixDouble[3][2] = -Vector.dot(zaxis, actualEyePosition); */ viewMatrix = new Matrix4f(); viewMatrix.load(getViewMatrixAsFloatBuffer()); } Would be verry greatfull if anyone could verify if this is wrong or right, and if it's wrong; supply me with the right way of doing it... I have read alot of threads and documentations about this but i can't seam to wrapp my head around it... Edit3: Okay with the help of Byte56 (thanks alot for the help) i have now concluded that it's not the viewMatrix that is the problem... I still get the same messedup result; anyone that think that they can find the error in my code, i certenly can't, have bean working on this for 3 days now :(

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Portable class libraries and fetching JSON

- by Jeff

After much delay, we finally have the Windows Phone 8 SDK to go along with the Windows 8 Store SDK, or whatever ridiculous name they’re giving it these days. (Seriously… that no one could come up with a suitable replacement for “metro” is disappointing in an otherwise exciting set of product launches.) One of the neat-o things is the potential for code reuse, particularly across Windows 8 and Windows Phone 8 apps. This is accomplished in part with portable class libraries, which allow you to share code between different types of projects. With some other techniques and quasi-hacks, you can share some amount of code, and I saw it mentioned in one of the Build videos that they’re seeing as much as 70% code reuse. Not bad. However, I’ve already hit a super annoying snag. It appears that the HttpClient class, with its idiot-proof async goodness, is not included in the Windows Phone 8 class libraries. Shock, gasp, horror, disappointment, etc. The delay in releasing it already caused dismay among developers, and I’m sure this won’t help. So I started refactoring some code I already had for a Windows 8 Store app (ugh) to accommodate the use of HttpWebRequest instead. I haven’t tried it in a Windows Phone 8 project beyond compiling, but it appears to work. I used this StackOverflow answer as a starting point since it’s been a long time since I used HttpWebRequest, and keep in mind that it has no exception handling. It needs refinement. The goal here is to new up the client, and call a method that returns some deserialized JSON objects from the Intertubes. Adding facilities for headers or cookies is probably a good next step. You need to use NuGet for a Json.NET reference. So here’s the start: using System.Net; using System.Threading.Tasks; using Newtonsoft.Json; using System.IO; namespace MahProject { public class ServiceClient<T> where T : class { public ServiceClient(string url) { _url = url; } private readonly string _url; public async Task<T> GetResult() { var response = await MakeAsyncRequest(_url); var result = JsonConvert.DeserializeObject<T>(response); return result; } public static Task<string> MakeAsyncRequest(string url) { var request = (HttpWebRequest)WebRequest.Create(url); request.ContentType = "application/json"; Task<WebResponse> task = Task.Factory.FromAsync( request.BeginGetResponse, asyncResult => request.EndGetResponse(asyncResult), null); return task.ContinueWith(t => ReadStreamFromResponse(t.Result)); } private static string ReadStreamFromResponse(WebResponse response) { using (var responseStream = response.GetResponseStream()) using (var reader = new StreamReader(responseStream)) { var content = reader.ReadToEnd(); return content; } } } } Calling it in some kind of repository class may look like this, if you wanted to return an array of Park objects (Park model class omitted because it doesn’t matter): public class ParkRepo { public async Task<Park[]> GetAllParks() { var client = new ServiceClient<Park[]>(http://superfoo/endpoint); return await client.GetResult(); } } And then from inside your WP8 or W8S app (see what I did there?), when you load state or do some kind of UI event handler (making sure the method uses the async keyword): var parkRepo = new ParkRepo(); var results = await parkRepo.GetAllParks(); // bind results to some UI or observable collection or something Hopefully this saves you a little time.

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How to decrypt an encrypted Apple iTunes iPhone backup?

- by afit

I've been asked by a number of unfortunate iPhone users to help them restore data from their iTunes backups. This is easy when they are unencrypted, but not when they are encrypted, whether or not the password is known. As such, I'm trying to figure out the encryption scheme used on mddata and mdinfo files when encrypted. I have no problems reading these files otherwise, and have built some robust C# libraries for doing so. (If you're able to help, I don't care which language you use. It's the principle I'm after here!) The Apple "iPhone OS Enterprise Deployment Guide" states that "Device backups can be stored in encrypted format by selecting the Encrypt iPhone Backup option in the device summary pane of iTunes. Files are encrypted using AES128 with a 256-bit key. The key is stored securely in the iPhone keychain." That's a pretty good clue, and there's some good info here on Stackoverflow on iPhone AES/Rijndael interoperability suggesting a keysize of 128 and CBC mode may be used. Aside from any other obfuscation, a key and initialisation vector (IV)/salt are required. One might assume that the key is a manipulation of the "backup password" that users are prompted to enter by iTunes and passed to "AppleMobileBackup.exe", padded in a fashion dictated by CBC. However, given the reference to the iPhone keychain, I wonder whether the "backup password" might not be used as a password on an X509 certificate or symmetric private key, and that the certificate or private key itself might be used as the key. (AES and the iTunes encrypt/decrypt process is symmetric.) The IV is another matter, and it could be a few things. Perhaps it's one of the keys hard-coded into iTunes, or into the devices themselves. Although Apple's comment above suggests the key is present on the device's keychain, I think this isn't that important. One can restore an encrypted backup to a different device, which suggests all information relevant to the decryption is present in the backup and iTunes configuration, and that anything solely on the device is irrelevant and replacable in this context. So where might be the key be? I've listed paths below from a Windows machine but it's much of a muchness whichever OS we use. The "\appdata\Roaming\Apple Computer\iTunes\itunesprefs.xml" contains a PList with a "Keychain" dict entry in it. The "\programdata\apple\Lockdown\09037027da8f4bdefdea97d706703ca034c88bab.plist" contains a PList with "DeviceCertificate", "HostCertificate", and "RootCertificate", all of which appear to be valid X509 certs. The same file also appears to contain asymmetric keys "RootPrivateKey" and "HostPrivateKey" (my reading suggests these might be PKCS #7-enveloped). Also, within each backup there are "AuthSignature" and "AuthData" values in the Manifest.plist file, although these appear to be rotated as each file gets incrementally backed up, suggested they're not that useful as a key, unless something really quite involved is being done. There's a lot of misleading stuff out there suggesting getting data from encrypted backups is easy. It's not, and to my knowledge it hasn't been done. Bypassing or disabling the backup encryption is another matter entirely, and is not what I'm looking to do. This isn't about hacking apart the iPhone or anything like that. All I'm after here is a means to extract data (photos, contacts, etc.) from encrypted iTunes backups as I can unencrypted ones. I've tried all sorts of permutations with the information I've put down above but got nowhere. I'd appreciate any thoughts or techniques I might have missed.

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