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  • i read that for RESTful websites. it is not good to use $_SESSION. Why is it not good? how then do i

    - by keisimone
    I read that it is not good to use $_SESSION. http://www.recessframework.org/page/towards-restful-php-5-basic-tips I am creating a WEBSITE, not web service in PHP. and i am trying to make it more RESTful. at least in spirit. right now i am rewriting all the action to use Form tags POST and add in a hidden value called _method which would be "delete" for deleting action and "put" for updating action. however, i am not sure why it is recommended NOT to use $_SESSION. i would like to know why and what can i do to improve. To allow easy authorization checking, what i did was to after logging in the user, the username is stored in the $_SESSION. Everytime the user navigates to a page, the page would check if the username is stored inside $_SESSION and then based on the $_SESSION retrieves all the info including privileges from the database and then evaluates the authorization to access the page based on the info retrieved. Is the way I am implementing bad? not RESTful? how do i improve performance and security? Thank you.

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  • Creating collaborative whiteboard drawing application

    - by Steven Sproat
    I have my own drawing program in place, with a variety of "drawing tools" such as Pen, Eraser, Rectangle, Circle, Select, Text etc. It's made with Python and wxPython. Each tool mentioned above is a class, which all have polymorphic methods, such as left_down(), mouse_motion(), hit_test() etc. The program manages a list of all drawn shapes -- when a user has drawn a shape, it's added to the list. This is used to manage undo/redo operations too. So, I have a decent codebase that I can hook collaborative drawing into. Each shape could be changed to know its owner -- the user who drew it, and to only allow delete/move/rescale operations to be performed on shapes owned by one person. I'm just wondering the best way to develop this. One person in the "session" will have to act as the server, I have no money to offer free central servers. Somehow users will need a way to connect to servers, meaning some kind of "discover servers" browser...or something. How do I broadcast changes made to the application? Drawing in realtime and broadcasting a message on each mouse motion event would be costly in terms of performance and things get worse the more users there are at a given time. Any ideas are welcome, I'm not too sure where to begin with developing this (or even how to test it)

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  • How to optimize a postgreSQL server for a "write once, read many"-type infrastructure ?

    - by mhu
    Greetings, I am working on a piece of software that logs entries (and related tagging) in a PostgreSQL database for storage and retrieval. We never update any data once it has been inserted; we might remove it when the entry gets too old, but this is done at most once a day. Stored entries can be retrieved by users. The insertion of new entries can happen rather fast and regularly, thus the database will commonly hold several millions elements. The tables used are pretty simple : one table for ids, raw content and insertion date; and one table storing tags and their values associated to an id. User search mostly concern tags values, so SELECTs usually consist of JOIN queries on ids on the two tables. To sum it up : 2 tables Lots of INSERT no UPDATE some DELETE, once a day at most some user-generated SELECT with JOIN huge data set What would an optimal server configuration (software and hardware, I assume for example that RAID10 could help) be for my PostgreSQL server, given these requirements ? By optimal, I mean one that allows SELECT queries taking a reasonably little amount of time. I can provide more information about the current setup (like tables, indexes ...) if needed.

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  • compare two text files using linq?

    - by bala3569
    I have 4 text files in one folder and a pattern.txt to compare these text files..In pattern.txt i have insert update delete drop I need to compare this text file with those four text files and if these patterns matches any line in that text files i have to write those lines in another log file...i had read those files using linq..i need to compare those files and write in a text file with line number..here is my code var foldercontent = Directory.GetFiles(pathA) .Select(filename => File.ReadAllText(filename)) .Aggregate(new StringBuilder(), (sb, s) => sb.Append(s).Append(Environment.NewLine), sb => sb.ToString()); var pattern = File.ReadAllLines(pathB).Aggregate(new StringBuilder(), (sb, s) => sb.Append(s).Append(Environment.NewLine), sb => sb.ToString()); using (var dest = File.AppendText(Path.Combine(_logFolderPath, "log.txt"))) { //dest.WriteLine("LineNo : " + counter.ToString() + " : " + "" + line); } EDIT I have already used c# to compare two text files but i need this in linq while ((line = file.ReadLine()) != null) { if (line.IndexOf(line2, StringComparison.CurrentCultureIgnoreCase) != -1) { dest.WriteLine("LineNo : " + counter.ToString() + " : " + " " + line.TrimStart()); } counter++; } file.BaseStream.Seek(0, SeekOrigin.Begin); counter = 1;

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  • Managing Many to Many relationships in asp.net Wizard Control

    - by Luis
    Say I have this entity with a lot of attributes. In the input form I have decided to implement a wizard control so I can collect information about this entity in several steps. The problem is that I need to collect information that has been modeled has many to many relationships. I am planning to use a telerik gridview to manage this (add/edit/delete), the problem is where do I store that data since the entity in a insert form is not created on the database yet. OK so I can store all that info in temporary lists residing in the viewstate, waiting for the final submit where I dump all that in the DB, but one of the steps I am collecting files...now storing files in the viewstate is out of the question, same as as storing them in the session... I have been thinking of implementing in a way that the user has to submit some info first (say first 3 steps), commit the data to the database creating the parent entity and then start inserting all the childs entities...but this will get weird as it's confusing since on the first steps you not saving the data to the DB and on the next ones you are commiting directly... Anyone has any thoughts on this? Thanks

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  • MySQL - What is wrong with this query or my database? Terrible performance.

    - by Moss
    SELECT * from `employees` a LEFT JOIN (SELECT phone1 p1, count(*) c, FROM `employees` GROUP BY phone1) b ON a.phone1 = b.p1; I'm not sure if it is this query in particular that has the problem. I have been getting terrible performance in general with this database. The table in question has 120,000 rows. I have tried this particular query remotely and locally with the MyISAM and InnoDB engines, with different types of joins, and with and without an index on phone1. I can get this to complete in about 4 minutes on a 10,000 row table successfully but performance drops exponentially with larger tables. Remotely it will lose connection to the server and locally it brings my system to its knees and seems to go on forever. This query is only a smaller step I was trying to do when a larger query couldn't complete. Maybe I should explain the whole scenario. I have one big flat ugly table that lists a bunch of people and their contact info and the info of the companies they work for. I'm trying to normalize the database and intelligently determine which phone numbers apply to individual people and which apply to an office location. My reasoning is that if a phone number occurs multiple times and the number of occurrence equals the number of times that the street address it is attached to occurs then it must be an office number. So the first step is to count each phone number grouping by phone number. Normally if you just use COUNT()...GROUP BY it will only list the first record it finds in that group so I figured I have to join the full table to the count table where the phone number matches. This does work but as I said I can't successfully complete it on any table much larger than 10,000 rows. This seems pathetic and this doesn't seem like a crazy query to do. Is there a better way to achieve what I want or do I have to break my large table into 12 pieces or is there something wrong with the table or db?

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  • File.Replace throwing IOException

    - by WebDevHobo
    I have an app that can make modify images. In some cases, this makes the filesize smaller, in some cases bigger. The program doesn't have an option to "not replace the file if result has a bigger filesize". So I wrote a little C# app to try and solve this. Instead of overwriting the files, I make the app write the result to a folder under the current one and name that folder Test. The C# app I wrote compares grabs the contents of both folders and puts the full path to the file(s) in two List objects. I then compare and replace. The replacing isn't working however. I get the following IOException: Unable to remove the file to be replaced The location is on an external hard-drive, on which I have full rights. Now, I know I can just do File.Delete and File.Move in that order, but this exception has gotten me interested in why this particular setup wont work. Here's the source code: http://pastebin.com/4Vq82Umu And yes, the file specified as last argument of the Replace function does exist.

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  • Deleting an option in a <select> list

    - by Tyzak
    hello, i have following function: function delete_auswahl() { var anzahl =document.getElementById ("warenkorbfeld").length ; for (var i =0; i<=anzahl; i++) { if (document.getElementById ("warenkorbfeld").options[i].selected==true) { if (document.getElementById ("warenkorbfeld").options[i].id == "Margherita" ) gesamtbetrag = gesamtbetrag - 4; if (document.getElementById ("warenkorbfeld").options[i].id=="Salami" ) gesamtbetrag = gesamtbetrag - 4.50; if (document.getElementById ("warenkorbfeld").options[i].id=="Hawaii" ) gesamtbetrag = gesamtbetrag - 5.50; document.getElementById ("warenkorbfeld").options[i]=null; i--;// auf der gleichen stelle bleiben, da dass nächste feld nachrückt } } document.getElementById('gesamtbetrag').innerHTML=gesamtbetrag ; } before i added values with function hinzu (pizza) { NeuerEintrag = new Option(pizza, pizza, false, false); document.getElementById("warenkorbfeld").options[document.getElementById("warenkorbfeld").length] = NeuerEintrag ; if (pizza=="Margherita") { gesamtbetrag = gesamtbetrag + 4; } if (pizza=="Salami") { gesamtbetrag = gesamtbetrag + 4.50; } if (pizza=="Hawaii") { gesamtbetrag = gesamtbetrag + 5.50; } document.getElementById('gesamtbetrag').innerHTML=gesamtbetrag ; } now, in the delete function doesn't substract the price. despite this, all works. what's wrong with this term? if (document.getElementById ("warenkorbfeld").options[i].id == "Margherita" ) gesamtbetrag = gesamtbetrag - 4; thanks in advance

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  • Getting a table cell to become a different color on mouseover

    - by Andrei Korchagin
    Currently, when I create a table, and I mouseover a cell, that entire row is highlighted. I'm trying to make it so that it is only the immediate cell. Here's all the CSS code that pertains to tables in my stylesheet: table{margin:.5em 0 1em;} table td,table th{text-align:center;border-right:1px solid #fff;padding:.4em .8em;} table th{background-color:#5e5e5e;color:#fff;text-transform:uppercase;font-weight:bold;border- bottom:1px solid #e8e1c8;} table td{background-color:#eee;} table th a{color:#d6f325;} table th a:hover{color:#fff;} table tr.even td{background-color:#ddd;} table tr:hover td{background-color:#fff;} table.nostyle td,table.nostyle th,table.nostyle tr.even td,table.nostyle tr:hover td{border:0;background:none;background-color:transparent;} I know it's probably a simple fix but I can't find where to make it work. Everything I try just kills the mouseover effect entirely rather than making it the way I want it. Thanks in advance!

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  • Hadoop File Read

    - by user3684584
    Hadoop Distributed Cache Wordcount example in hadoop 2.2.0. Copied file into hdfs filesystem to be used inside setup of mapper class. protected void setup(Context context) throws IOException,InterruptedException { Path[] uris = DistributedCache.getLocalCacheFiles(context.getConfiguration()); cacheData=new HashMap(); for(Path urifile: uris) { try { BufferedReader readBuffer1 = new BufferedReader(new FileReader(urifile.toString())); String line; while ((line=readBuffer1.readLine())!=null) { System.out.println("**************"+line); cacheData.put(line,line); } readBuffer1.close(); } catch (Exception e) { System.out.println(e.toString()); } } } Inside Driver Main class Configuration conf = new Configuration(); String[] otherArgs = new GenericOptionsParser(conf,args).getRemainingArgs(); if (otherArgs.length != 3) { System.err.println("Usage: wordcount <in> <out>"); System.exit(2); } Job job = new Job(conf, "word_count"); job.setJarByClass(WordCount.class); job.setMapperClass(Map.class); job.setReducerClass(Reduce.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); FileInputFormat.addInputPath(job, new Path(otherArgs[0])); Path outputpath=new Path(otherArgs[1]); outputpath.getFileSystem(conf).delete(outputpath,true); FileOutputFormat.setOutputPath(job,outputpath); System.out.println("CachePath****************"+otherArgs[2]); DistributedCache.addCacheFile(new URI(otherArgs[2]),job.getConfiguration()); System.exit(job.waitForCompletion(true) ? 0 : 1); But getting exception java.io.FileNotFoundException: file:/home/user12/tmp/mapred/local/1408960542382/cache (No such file or directory) So Cache functionality not working properly. Any Idea ?

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  • Conversion failed when converting datetime from character string

    - by salvationishere
    I am developing a C# VS 2008 / SQL Server 2005 Express website application. I have tried some of the fixes for this problem but my call stack differs from others. And these fixes did not fix my problem. What steps can I take to troubleshoot this? Here is my error: System.Data.SqlClient.SqlException was caught Message="Conversion failed when converting datetime from character string." Source=".Net SqlClient Data Provider" ErrorCode=-2146232060 LineNumber=10 Number=241 Procedure="AppendDataCT" Server="\\\\.\\pipe\\772EF469-84F1-43\\tsql\\query" State=1 StackTrace: at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe) at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() at ADONET_namespace.ADONET_methods.AppendDataCT(DataTable dt, Dictionary`2 dic) in c:\Documents and Settings\Admin\My Documents\Visual Studio 2008\WebSites\Jerry\App_Code\ADONET methods.cs:line 102 And here is the related code. When I debugged this code, "dic" only looped through the 3 column names, but did not look into row values which are stored in "dt", the Data Table. public static string AppendDataCT(DataTable dt, Dictionary<string, string> dic) { if (dic.Count != 3) throw new ArgumentOutOfRangeException("dic can only have 3 parameters"); string connString = ConfigurationManager.ConnectionStrings["AW3_string"].ConnectionString; string errorMsg; try { using (SqlConnection conn2 = new SqlConnection(connString)) { using (SqlCommand cmd = conn2.CreateCommand()) { cmd.CommandText = "dbo.AppendDataCT"; cmd.CommandType = CommandType.StoredProcedure; cmd.Connection = conn2; foreach (string s in dic.Keys) { SqlParameter p = cmd.Parameters.AddWithValue(s, dic[s]); p.SqlDbType = SqlDbType.VarChar; } conn2.Open(); cmd.ExecuteNonQuery(); conn2.Close(); errorMsg = "The Person.ContactType table was successfully updated!"; } } }

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  • perl multithreading issue for autoincrement

    - by user3446683
    I'm writing a multi threaded perl script and storing the output in a csv file. I'm trying to insert a field called sl.no. in the csv file for each row entered but as I'm using threads, the sl. no. overlaps in most. Below is an idea of my code snippet. for ( my $count = 1 ; $count <= 10 ; $count++ ) { my $t = threads->new( \&sub1, $count ); push( @threads, $t ); } foreach (@threads) { my $num = $_->join; } sub sub1 { my $num = shift; my $start = '...'; #distributing data based on an internal logic my $end = '...'; #distributing data based on an internal logic my $next; for ( my $x = $start ; $x <= $end ; $x++ ) { my $count = $x + 1; #part of code from which I get @data which has name and age my $j = 0; if ( $x != 0 ) { $count = $next; } foreach (@data) { #j is required here for some extra code flock( OUTPUT, LOCK_EX ); print OUTPUT $count . "," . $name . "," . $age . "\n"; flock( OUTPUT, LOCK_UN ); $j++; $count++; } $next = $count; } return $num; } I need the count to be incremented which is the serial number for the rows that would be inserted in the csv file. Any help would be appreciated.

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  • Gridview column right click issue

    - by peter
    I have grid named 'GridView1' and displaying columns like this <asp:GridView ID="GridView1" OnRowCommand="ScheduleGridView_RowCommand" runat="server" AutoGenerateColumns="False" Height="60px" Style="text-align: center" Width="869px" EnableViewState="False"> <Columns> <asp:BoundField HeaderText="Topic" DataField="Topic" /> <asp:BoundField DataField="Moderator" HeaderText="Moderator" /> <asp:BoundField DataField="Expert" HeaderText="Expert" /> <asp:BoundField DataField="StartTime" HeaderText="Start" > <HeaderStyle Width="175px" /> </asp:BoundField> <asp:BoundField DataField="EndTime" HeaderText="End" > <HeaderStyle Width="175px" /> </asp:BoundField> <asp:TemplateField HeaderText="Join" ShowHeader="False"> <ItemTemplate> <asp:Button ID="JoinBT" runat="server" CommandArgument="<%# Container.DataItemIndex %>" CommandName="Join" Text="Join" Width="52px" /> </ItemTemplate> <HeaderStyle Height="15px" /> </asp:TemplateField> </Columns> </asp:GridView> Here what is my requirement is whenever we right click on each row in gridview ,it should display three option join meeting(if we click it will go to meeting.aspx),,view details(will go to detail.aspx),,Subscribe(subscribe.aspx) just like when we click right any where we can see view,sortby,refresh like that..Do we need to implement javascript here

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  • NHibernate: What are child sessions and why and when should I use them?

    - by stefando
    In the comments for the ayende's blog about the auditing in NHibernate there is a mention about the need to use a child session:session.GetSession(EntityMode.Poco). As far as I understand it, it has something to do with the order of the SQL operation which session.Flush will emit. (For example: If I wanted to perform some delete operation in the pre-insert event but the session was already done with deleting operations, I would need some way to inject them in.) However I did not find documentation about this feature and behavior. Questions: Is my understanding of child sessions correct? How and in which scenarios should I use them? Are they documented somewhere? Could they be used for session "scoping"? (For example: I open the master session which will hold some data and then I create 2 child-sessions from the master one. I'd expect that the two child-scopes will be separated but the will share objects from the master session cache. Is this the case?) Are they first class citizens in NHibernate or are they just hack to support some edge-case scenarios? Thanks in advance for any info.

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  • CSS: 100% of container height without modifying the container

    - by Rena
    Yeah, this ugly question again. I'm writing some HTML that gets inserted into a page. I have no control over the rest of the page. The structure is something like: <table <tr <td rowspan="2"left column</td <td height="1"top row above content</td </tr <tr<td height="220"my content here</td</tr </table I can write whatever I want into that table cell (including style tags to pack in my CSS), but I can't touch anything outside of it, which means I can't set the height of any parent element (including html and body), add a doctype (it has none), etc - that already kills just about every solution I can find (all seem to be "add a doctype" and/or "give the parent container a fixed height"). What I want to do is simply have a <div fill the entire cell. Width is no problem but unsurprisingly height is being a massive pain. Writing "height: 100%" doesn't do anything unless the container has a fixed height (the height="220" attribute apparently doesn't count) or the div uses absolute positioning - and then it seems to want to use 100% of the window's height (and width even) instead of the cell's. The root of the problem is the left column varies in height, as does the content, and when the left column cell is larger than the content, it won't expand to fill the cell it's in. If I set a fixed height for the content, it'll be much larger than necessary most of the time, and if I don't, it doesn't take up all of the cell and leaves an ugly gap at the bottom.

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  • Get the src part of a string [duplicate]

    - by Kay Lakeman
    This question already has an answer here: Grabbing the href attribute of an A element 7 answers First post ever here, and i really hope you can help. I use a database where a large piece of html is stored, now i just need the src part of the image tag. I already found a thread, but i just doesn't do the trick. My code: Original string: <p><img alt=\"\" src=\"http://domain.nl/cms/ckeditor/filemanager/userfiles/background.png\" style=\"width: 80px; height: 160px;\" /></p> How i start: $image = strip_tags($row['information'], '<img>'); echo stripslashes($image); This returns: <img alt="" src="http://domain.nl/cms/ckeditor/filemanager/userfiles/background.png" style="width: 80px; height: 160px;" /> Next step: extract the src part: preg_match('/< *img[^>]*src *= *["\']?([^"\']*)/i', $image, $matches); echo $matches ; This last echo returns: Array What is going wrong? Thanks in advance for your anwser.

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  • Visual Studio 2008 closes unexpectedly

    - by Jose
    I don't know if I can really get an answer to this question, but it really irks me and I would like to know if someone has an idea how to arrive to an answer. I have a pretty large solution in VS 2008 that maybe every week/every other week whenever I click properties to get to the project properties the IDE closes without warning. After that happens it will close EVERY time I try and view the properties. At that point I try and delete the .suo file, I resize the IDE, I close the tabs within the project, I restore default VS Settings(when I'm desperate). Eventually 20-30 minutes later I can actually view the properties. I haven't figured out exactly what fixes it, seems to be different every time. Once it's "fixed" I can't break it again so I can figure out what "fixed" it. This seems to be project specific, because I can view properties of other projects while this project is misbehaving. I guess my first question is, does VS log reasons for closing unexpectedly? Can I find out what the offending reason behind this is? The main frustration is I don't know that cause, nor the cure. Any ideas?

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  • Issue with GCD and too many threads

    - by dariaa
    I have an image loader class which provided with NSURL loads and image from the web and executes completion block. Code is actually quite simple - (void)downloadImageWithURL:(NSString *)URLString completion:(BELoadImageCompletionBlock)completion { dispatch_async(_queue, ^{ // dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{ UIImage *image = nil; NSURL *URL = [NSURL URLWithString:URLString]; if (URL) { image = [UIImage imageWithData:[NSData dataWithContentsOfURL:URL]]; } dispatch_async(dispatch_get_main_queue(), ^{ completion(image, URLString); }); }); } When I replace dispatch_async(_queue, ^{ with commented out dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{ Images are loading much faster, wich is quite logical (before that images would be loaded one at a time, now a bunch of them are loading simultaneously). My issue is that I have perhaps 50 images and I call downloadImageWithURL:completion: method for all of them and when I use global queue instead of _queue my app eventually crashes and I see there are 85+ threads. Can the problem be that my calling dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0) 50 times in a row makes GCD create too many threads? I thought that gcd handles all the treading and makes sure the number of threads is not huge, but if it's not the case is there any way I can influence number of threads?

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  • How can I introduce a regex action to match the first element in a Catalyst URI ?

    - by RET
    Background: I'm using a CRUD framework in Catalyst that auto-generates forms and lists for all tables in a given database. For example: /admin/list/person or /admin/add/person or /admin/edit/person/3 all dynamically generate pages or forms as appropriate for the table 'person'. (In other words, Admin.pm has actions edit, list, add, delete and so on that expect a table argument and possibly a row-identifying argument.) Question: In the particular application I'm building, the database will be used by multiple customers, so I want to introduce a URI scheme where the first element is the customer's identifier, followed by the administrative action/table etc: /cust1/admin/list/person /cust2/admin/add/person /cust2/admin/edit/person/3 This is for "branding" purposes, and also to ensure that bookmarks or URLs passed from one user to another do the expected thing. But I'm having a lot of trouble getting this to work. I would prefer not to have to modify the subs in the existing framework, so I've been trying variations on the following: sub customer : Regex('^(\w+)/(admin)$') { my ($self, $c, @args) = @_; #validation of captured arg snipped.. my $path = join('/', 'admin', @args); $c->request->path($path); $c->dispatcher->prepare_action($c); $c->forward($c->action, $c->req->args); } But it just will not behave. I've used regex matching actions many times, but putting one in the very first 'barrel' of a URI seems unusually traumatic. Any suggestions gratefully received.

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  • Is there any function in Matlab for changing the form of matrix?

    - by niko
    Hi, I have to get the unknown matrix by changing the form of known matrix considering the following rules: H = [-P'|I] G = [I|P] where H is known matrix G is unknown matrix which has to be calculated I is identity matrix So for example if we had a matrix H = [1 1 1 1 0 0; 0 0 1 1 0 1; 1 0 0 1 1 0] its form has to be changed to H = [1 1 1 1 0 0; 0 1 1 0 1 0; 1 1 0 0 0 1] so -P' = [1 1 1; 0 1 0; 1 1 0] and in case of binary matrices -P = P therefore G = [1 0 0 1 1 1; 0 1 0 0 1 0; 0 0 1 1 1 0] I know how to solve it on the paper by performing basic row operations but don't know how if there is any function already written in Matlab to calculate G from H or H from G by considering the above rules. I would be very thankful if anyone of you could suggest any method for solving the given problem. Thank you.

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  • What, if any, printable character did a user type based on the values in a given System.Windows.Form

    - by Corey Trager
    As a workaround for a problem, I think I have to handle KeyDown events to get the printable character the user actually typed. KeyDown supplies me with a KeyEventArgs object with the properities KeyCode, KeyData, KeyValue, Modifiers, Alt, Shift, Control. My first attempt was just to consider the KeyCode to be the ascii code, but KeyCode on my keyboard is 46, a period ("."), so I end up printing a period when the user types the delete key. So, I know my logic is inadequate. (For those who are curious, the problem is that I have my own combobox in a DataGridView's control collection and somehow SOME characters I type don't produce the KeyPress and TextChanged ComboBox events. These letters include Q, $, %.... This code will reproduce the problem. Generate a Form App and replace the ctor with this code. Run it, and try typing the letter Q into the two comboxes. public partial class Form1 : Form { ComboBox cmbInGrid; ComboBox cmbNotInGrid; DataGridView grid; public Form1() { InitializeComponent(); grid = new DataGridView(); cmbInGrid = new ComboBox(); cmbNotInGrid = new ComboBox(); cmbInGrid.Items.Add("a"); cmbInGrid.Items.Add("b"); cmbNotInGrid.Items.Add("c"); cmbNotInGrid.Items.Add("d"); this.Controls.Add(cmbNotInGrid); this.Controls.Add(grid); grid.Location = new Point(0, 100); this.grid.Controls.Add(cmbInGrid); }

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  • How to debug memory allocation issues?

    - by amitabh
    Hi I am writing an iPhone app that that is trying to create a second a view when the user clicks on an element in UITableView. The code looks like ReplyToViewController *reply = [[ReplyToViewController alloc] initWithNibName:@"ReplyTo" bundle:nil]; reply.delegate = self; Message *message = [resultData objectAtIndex:indexPath.row]; int dbid = [message.bizid intValue]; NSLog(@"dbid=%d",dbid); reply.currentMessage = message; reply.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:reply animated:YES]; The reply object gets created properly and the view is proper. Last line in above code segment calls some framework code which eventually calls the viewDidLoad method of the ReplyToViewController. Address of the reply object in the above code and the address of the object in viewDidLoad is not same. Any idea where this new object is coming from? How do I debug? I also added init method the following method in ReplyToViewController hoping that it will get called and I can find who is creating this new object. But it does not stop in this method. Any help will be greatly appreciated. - (id) init { /* first initialize the base class */ self = [super init]; return self; } // Following gets called from the 1st code segment. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Custom initialization } return self; } - (void)viewDidLoad { [super viewDidLoad]; NSLog(currentMessage.text]; // THIS returns nil and the program fails later in the code. }

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  • Use SQL to clone a tree structure represented in a database

    - by AmoebaMan17
    Given a table that represents a hierarchical tree structure and has three columns ID (Primary Key, not-autoincrementing) ParentGroupID SomeValue I know the lowest most node of that branch, and I want to copy that to a new branch with the same number of parents that also need to be cloned. I am trying to write a single SQL INSERT INTO statement that will make a copy of every row that is of the same main has is part one GroupID into a new GroupID. Example beginning table: ID | ParentGroupID | SomeValue ------------------------ 1 | -1 | a 2 | 1 | b 3 | 2 | c Goal after I run a simple INSERT INTO statement: ID | ParentGroupID | SomeValue ------------------------ 1 | -1 | a 2 | 1 | b 3 | 2 | c 4 | -1 | a-cloned 5 | 4 | b-cloned 6 | 5 | c-cloned Final tree structure +--a (1) | +--b (2) | +--c (3) | +--a-cloned (4) | +--b-cloned (5) | +--c-cloned (6) The IDs aren't always nicely spaced out as this demo data is showing, so I can't always assume that the Parent's ID is 1 less than the current ID for rows that have parents. Also, I am trying to do this in T-SQL (for Microsoft SQL Server 2005 and greater). This feels like a classic exercise that should have a pure-SQL answer, but I'm too used to programming that my mind doesn't think in relational SQL.

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  • Uncommitted reads in SSIS

    - by OldBoy
    I'm trying to debug some legacy Integration Services code, and really want some confirmation on what I think the problem is: We have a very large data task inside a control flow container. This control flow container is set up with TransactionOption = supported - i.e. it will 'inherit' transactions from parent containers, but none are set up here. Inside the data flow there is a call to a stored proc that writes to a table with pseudo code something like: "If a record doesn't exist that matches these parameters then write it" Now, the issue is that there are three records being passed into this proc all with the same parameters, so logically the first record doesn't find a match and a record is created. The second record (with the same parameters) also doesn't find a match and another record is created. My understanding is that the first 'record' passed to the proc in the dataflow is uncommitted and therefore can't be 'read' by the second call. The upshot being that all three records create a row, when logically only the first should. In this scenario am I right in thinking that it is the uncommitted transaction that stops the second call from seeing the first? Even setting the isolation level on the container doesn't help because it's not being wrapped in a transaction anyway.... Hope that makes sense, and any advice gratefully received. Work-arounds confer god-like status on you.

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  • avoiding code duplication in Rails 3 models

    - by Dustin Frazier
    I'm working on a Rails 3.1 application where there are a number of different enum-like models that are stored in the database. There is a lot of identical code in these models, as well as in the associated controllers and views. I've solved the code duplication for the controllers and views via a shared parent controller class and the new view/layout inheritance that's part of Rails 3. Now I'm trying to solve the code duplication in the models, and I'm stuck. An example of one of my enum models is as follows: class Format < ActiveRecord::Base has_and_belongs_to_many :videos attr_accessible :name validates :name, presence: true, length: { maximum: 20 } before_destroy :verify_no_linked_videos def verify_no_linked_videos unless self.videos.empty? self.errors[:base] << "Couldn't delete format with associated videos." raise ActiveRecord::RecordInvalid.new self end end end I have four or five other classes with nearly identical code (the association declaration being the only difference). I've tried creating a module with the shared code that they all include (which seems like the Ruby Way), but much of the duplicate code relies on ActiveRecord, so the methods I'm trying to use in the module (validate, attr_accessible, etc.) aren't available. I know about ActiveModel, but that doesn't get me all the way there. I've also tried creating a common, non-persistent parent class that subclasses ActiveRecord::Base, but all of the code I've seen to accomplish this assumes that you won't have subclasses of your non-persistent class that do persist. Any suggestions for how best to avoid duplicating these identical lines of code across many different enum models?

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