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• Ditching Django's models for Ajax/Web Services

  - by Igor Ganapolsky

  Recently I came across a problem at work that made me rethink Django's models. The app I am developing resides on a Linux server. Its a simple model/view/controller app that involves user interaction and updating data in the database. The problem is that this data resides in a MS SQL database on a Windows machine. So in order to use Django's models, I would have to leverage an ODBC driver on linux, and the use a python add-on like pyodbc. Well, let me tell you, setting up a reliable and functional ODBC connection on linux is no easy feat! So much so, that I spent several hours maneuvering this on my CentOS with no luck, and was left with frustration and lots of dumb system errors. In the meantime I have a deadline to meet, and suddenly the very agile and rapid Django application is a roadblock rather than a pleasure to work with. Someone on my team suggested writing this app in .NET. But there are a few problems with that: it won't be deployable on a linux machine, and I won't be able to work on it since I don't know ASP.net. Then a much better suggestion was made: keep the app in django, but instead of using models, do straight up ajax/web services calls in the template. And then it dawned on me - what a great idea. Django's models seem like a nuissance and hindrance in this case, and I can just have someone else write .Net services on their side, that I can call from my template. As a result my app will be leaner and more compact. So, I was wondering if you guys ever came across a similar dillema and what you decided to do about it.

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• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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• How to define a "complicated" ComputedColumn in SQL Server?

  - by Slauma

  SQL Server Beginner question: I'm trying to introduce a computed column in SQL Server (2008). In the table designer of SQL Server Management Studio I can do this, but the designer only offers me one single edit cell to define the expression for this column. Since my computed column will be rather complicated (depending on several database fields and with some case differentiations) I'd like to have a more comfortable and maintainable way to enter the column definition (including line breaks for formatting and so on). I've seen there is an option to define functions in SQL Server (scalar value or table value functions). Is it perhaps better to define such a function and use this function as the column specification? And what kind of function (scalar value, table value)? To make a simplified example: I have two database columns: DateTime1 (smalldatetime, NULL) DateTime2 (smalldatetime, NULL) Now I want to define a computed column "Status" which can have four possible values. In Dummy language: if (DateTime1 IS NULL and DateTime2 IS NULL) set Status = 0 else if (DateTime1 IS NULL and DateTime2 IS NOT NULL) set Status = 1 else if (DateTime1 IS NOT NULL and DateTime2 IS NULL) set Status = 2 else set Status = 3 Ideally I would like to have a function GetStatus() which can access the different column values of the table row which I want to compute the value of "Status" for, and then only define the computed column specification as GetStatus() without parameters. Is that possible at all? Or what is the best way to work with "complicated" computed column definitions? Thank you for tips in advance!

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• Where should I put contextual data related to an Object that is not really a property of the object?

  - by RenderIn

  I have a Car class. It has three properties: id, color and model. In a particular query I want to return all the cars and their properties, and I also want to return a true/false field called "searcherKnowsOwner" which is a field I calculate in my database query based on whether or not the individual conducting the search knows the owner. I have a database function that takes the ID of the searcher and the ID of the car and returns a boolean. My car class looks like this (pseudocode): class Car{ int id; Color color; Model model; } I have a screen where I want to display all the cars, but I also want to display a flag next to each car if the person viewing the page knows the owner of that car. Should I add a field to the Car class, a boolean searcherKnowsOwner? It's not a property of the car, but is actually a property of the user conducting the search. But this seems like the most efficient place to put this information.

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• How do I view the full content of a text or varchar(MAX) column in SQL Server 2008 Management Studio

  - by adamjford

  In this live SQL Server 2008 (build 10.0.1600) database, there's an Events table, which contains a text column named Details. (Yes, I realize this should actually be a varchar(MAX) column, but whoever set this database up did not do it that way.) This column contains very large logs of exceptions and associated JSON data that I'm trying to access through SQL Server Management Studio, but whenever I copy the results from the grid to a text editor, it truncates it at 43679 characters. I've read on various locations on the Internet that you can set your Maximum Characters Retrieved for XML Data in Tools > Options > Query Results > SQL Server > Results To Grid to Unlimited, and then perform a query such as this: select Convert(xml, Details) from Events where EventID = 13920 (Note that the data is column is not XML at all. CONVERTing the column to XML is merely a workaround I found from Googling that someone else has used to get around the limit SSMS has from retrieving data from a text or varchar(MAX) column.) However, after setting the option above, running the query, and clicking on the link in the result, I still get the following error: Unable to show XML. The following error happened: Unexpected end of file has occurred. Line 5, position 220160. One solution is to increase the number of characters retrieved from the server for XML data. To change this setting, on the Tools menu, click Options. So, any idea on how to access this data? Would converting the column to varchar(MAX) fix my woes?

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• Doctrine Default Primary Key Problem (Again)

  - by 01010011

  Hi, Should I change all of my uniquely-named MySQL database primary keys to 'id' to avoid getting errors related to Doctrine's default primary key set in the plugin 'doctrine_pi.php'? To further elaborate, I am getting the following reoccurring error, this time after trying to login to my login page: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'u.book_id' in 'field list'' in... I suspect the problem resides at a MySQL table used for my login, of which has a primary key called id Marc B originally solved an identical problem for me in this post http://stackoverflow.com/questions/2702229/doctrine-codeigniter-mysql-crud-errors when I had the same problem with a different table within the same database. Following his suggestion, I changed the default primary key located at system/application/plugins/doctrine_pi.php from 'id' to 'book_id': <?php // system/application/plugins/doctrine_pi.php ... // set the default primary key to be named 'id', integer, 4 bytes Doctrine_Manager::getInstance()->setAttribute( Doctrine::ATTR_DEFAULT_IDENTIFIER_OPTIONS, array('name' => 'book_id', 'type' => 'integer', 'length' => 4)); and that solved my previous problem. However, my login page stopped working. So what is the safe thing to do? Change all of my primary keys to 'id' (will that solve the problem without causing some other problem I am not aware of). Or should I add some lines of code in doctrine_pi.php?

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• SQL Server Express performance issue

  - by Developer IT

  Hi folks ! I know my questions will sound silly and probably nobody will have perfect answer but since I am in a complete dead-end with the situation it will make me feel better to post it here. So... I have a SQL Server Express database that's 500 Mb. It contains 5 tables and maybe 30 stored procedure. This database is use to store articles and is use for the Developer It web site. Normally the web pages load quickly, let's say 2 ou 3 sec. BUT, sqlserver process uses 100% of the processor for those 2 or 3 sec. I try to find which stored procedure was the problem and I could not find one. It seems like every read into the table dans contains the articles (there are about 155,000 of them and 20 or so gets added every 15 minutes). I added few index but without luck... It is because the table is full text indexed ? Should I have order with the primary key instead of date ? I never had any problems with ordering by dates.... Should I use dynamic SQL ? Should I add the primary key into the url of the articles ? Should I use mutiple indexes for seperate columns or one big index ? I you want more details or code bits, just ask for it. Basicly, every little hint is much apreciated. Thanks.

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• Good practice to create extension methods that apply to System.Object?

  - by Christian

  Hello, I'm wondering whether I should create extension methods that apply on the object level or whether they should be located at a lower point in the class hierarchy. What I mean is something along the lines of: public static string SafeToString(this Object o) { if (o == null || o is System.DBNull) return ""; else { if (o is string) return (string)o; else return ""; } } public static int SafeToInt(this Object o) { if (o == null || o is System.DBNull) return 0; else { if (o.IsNumeric()) return Convert.ToInt32(o); else return 0; } } //same for double.. etc I wrote those methods since I have to deal a lot with database data (From the OleDbDataReader) that can be null (shouldn't, though) since the underlying database is unfortunately very liberal with columns that may be null. And to make my life a little easier, I came up with those extension methods. What I'd like to know is whether this is good style, acceptable style or bad style. I kinda have my worries about it since it kinda "pollutes" the Object-class. Thank you in advance & Best Regards :) Christian P.S. I didn't tag it as "subjective" intentionally.

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• jQuery dynamically created table rows not responding to events

  - by mithunmo

  I have a table with one row in my HTML file. Now in jQuery I append lot of rows based on the data in the database. But the anchor tag which is created dynamically doesn't respond to events. How do I make this anchor tag respond to events? jQuery part //Appending rows from the Database $('<tr> <td> </td> <td id="log'+i+'"><a href="viewlog.php" target="_blank">log</a></td></tr> ').appendTo('#container'); Event part in jQuery Now when I write a line of code like this it does not respond. $('#container a ').click(function() { alert("Coming here "); }); //HTML <html> <table id="container"> <tr> <td> Name </td> <td> Link </td> </tr> </table> </html>

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• Why does a change of Session State provider lead to an ASPx page yielding garbage?

  - by Rory Becker

  I have an aspnet webapp which has worked very well up until now. I was recently asked to explore ways of making it scale better. I found that seperation of database and Webapp would help. Further I was told that if I changed my session providing mechanism to SQLServer, I would be able to duplicate the Web Stack to several machines which could each call back to the state server allowing the load to be distirbuted better. This sounds logical. So I created an ASPState database using ASPNet_RegSQL.exe as detailed in many locations across the web and changed the web.config on my app from: <sessionState mode="InProc" cookieless="false" timeout="20" /> To: <sessionState mode="SQLServer" sqlConnectionString="Server=SomeSQLServer;user=SomeUser;password=SomePassword" cookieless="false" timeout="20" /> Then I addressed my app, which presented me with its logon screen and I duly logged in. Once in I was presented, not with the page I was expecting, but with: I can change the sessionstate back and forth. This problem goes away and then comes back based on which set of configuration I use. Why is this happening?

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• Family Tree :- myheritage.com

  - by Nitesh Panchal

  Hello, The other day i just accidently visited the site myheritage.com. I was just wondering, how they must have created one? Can anybody tell me what can be their database design? and if possible, algorithm that we can use to generate such a tree? Generating simple binary tree is very easy using recursion. But if you have a look at the site(if you have time please make account on it and add few nodes to feel) when we add son to a father, it's mother is automatically added(if you don't add explicitly). Mother's family tree is also generated side by side and many such fancy things are happening. In a simple binary tree we have a root node and then many nodes below it. Thus we cannot show wife and husband in the tree and then show a line from wife and husband to child. In spare time, can anybody discuss what can be it's database design and the recursive algorithm that we can follow to generate it? I hope i am not asking too much from you :).

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• "NT AUTHORITY\ANONYMOUS LOGON" error in Windows 7 (ASP.NET & Web Service)

  - by Tony_Henrich

  I have an asp.net web app which works fine in Windows XP machine in a domain. I am porting it to a Windows 7 stand alone machine. The app uses a web service which makes a call to sql server. The web server (IIS 7.5) and SQL Server are on the same stand alone machine. I enabled Windows authentication for the website and web service. The web service uses a trusted connection connection string. The web service credentials uses System.Net.CredentialCache.DefaultCredentials. I noticed username, password and domainname are blank after the call! The webservice and web site use an application pool with identity "Network Service". I am getting an exception "NT AUTHORITY\ANONYMOUS LOGON" in the database call in the web service. I am assuming it's related to the blank credentials. I am expecting ASPNET user to be the security token to the database. Why is this not happening? (Usually this happens when sql server and web server are on two different machines in a domain, delegation & double hopping, but in my case everything is on a dev box)

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• Form (or Formset?) to handle multiple table rows in Django

  - by Ben

  Hi, I'm working on my first Django application. In short, what it needs to do is to display a list of film titles, and allow users to give a rating (out of 10) to each film. I've been able to use the {{ form }} and {{ formset }} syntax in a template to produce a form which lets you rate one film at a time, which corresponds to one row in a MySQL table, but how do I produce a form that iterates over all the movie titles in the database and produces a form that lets you rate lots of them at once? At first, I thought this was what formsets were for, but I can't see any way to automatically iterate over the contents of a database table to produce items to go in the form, if you see what I mean. Currently, my views.py has this code: def survey(request): ScoreFormSet = formset_factory(ScoreForm) if request.method == 'POST': formset = ScoreFormSet(request.POST, request.FILES) if formset.is_valid(): return HttpResponseRedirect('/') else: formset = ScoreFormSet() return render_to_response('cf/survey.html', { 'formset':formset, }) And my survey.html has this: <form action="/survey/" method="POST"> <table> {{ formset }} </table> <input type = "submit" value = "Submit"> </form> Oh, and the definition of ScoreForm and Score from models.py are: class Score(models.Model): movie = models.ForeignKey(Movie) score = models.IntegerField() user = models.ForeignKey(User) class ScoreForm(ModelForm): class Meta: model = Score So, in case the above is not clear, what I'm aiming to produce is a form which has one row per movie, and each row shows a title, and has a box to allow the user to enter their score. If anyone can point me at the right sort of approach to this, I'd be most grateful. Thanks, Ben

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• Should I Solve this with Multithreading in Ruby?

  - by viatropos

  I have a strange case, here's the sequence of actions: User edits a document and hits save Application sends GET request to service Service sends POST request back to application in the middle of responding to the GET request Application, in the same state as when it made the GET request, responds to the POST request (sends document data) to service. Service sends data back to Application (responding to original GET request) Application handles the rest... The use case is this: I was thinking how can I make Yahoo Pipes POST data? Specifically, I want it to be able to update Google Docs when a user makes a change locally (on a custom editor). So user edits doc, makes GET request to Yahoo Pipes, Pipes makes a POST request back to App to get the document (Pipes can only make this type of POST request), App sends doc, Pipes formats data according to the Google API, Pipes responds to GET request with Google API formatted XML, App makes the post request. Theoretically, how would I accomplish this? It seems that I need to create a separate ruby Process for the GET request, and when Pipes sends the POST request, I find that process and send its output, then I'm stuck. This would cut out the need for a database for this particular case (I could save the stuff temporarily in a database, but that doesn't seem right). Any ideas? This would make it so I don't have to format things to the Google API in ruby, I could leave that to Pipes.

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• How do I create a dynamic data transfer object dynamically from ADO.net model

  - by Richard

  I have a pretty simple database with 5 tables, PK's and relationships setup, etc. I also have an ASP.net MVC3 project I'm using to create simple web services to feed JSON/XML to a mobile app using post/get. To access my data I'm using an ADO.net entity model class to handle generation of the entities, etc. Due to issues with serialization/circular references created by the auto-generated relations from ADO.net entity model, I've been forced to create "Data transfer objects" to strip out the relations and data that doesn't need to be transferred. Question 1: is there an easier way to create DTOs using the entity framework itself? IE, specify only the entity properties I want to convert to Jsonresults? I don't wish to use any 3rd party frameworks if I can help it. Question 2: A side question for Entity Framework, say I create an ADO.net entity model in one project within a solution. Because that model relies on the connection to the database specified in project A, can project B somehow use that model with a similar connection? Both projects are in the same solution. Thanks!

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• The instruction at "0x7c910a19" referenced memory at "oxffffffff". The memory could not be "read"

  - by ClareBear

  Hello guys/girls The instruction at "0x7c910a19" referenced memory at "oxffffffff". The memory could not be "read" I have a small issue, I receive the error above before the .vbs terminates. I don't know why this error is thrown. Below is the process of the .vbs file: Call ImportTransactions() Call UpdateTransactions() Function ImportTransactions() Dim objConnection, objCommand, objRecordset, strOracle Dim strSQL, objRecordsetInsert Set objConnection = CreateObject("ADODB.Connection") objConnection.Open "DSN=*****;UID=*****;PWD==*****;" Set objCommand = CreateObject("ADODB.Command") Set objRecordset = CreateObject("ADODB.Recordset") strOracle = "SELECT query here from Oracle database" objCommand.CommandText = strOracle objCommand.CommandType = 1 objCommand.CommandTimeout = 0 Set objCommand.ActiveConnection = objConnection objRecordset.cursorType = 0 objRecordset.cursorlocation = 3 objRecordset.Open objCommand, , 1, 3 If objRecordset.EOF = False Then Do Until objRecordset.EOF = True strSQL = "INSERT query here into SQL database" strSQL = Query(strSQL) Call RunSQL(strSQL, objRecordsetInsert, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) objRecordset.MoveNext Loop End If objRecordset.Close() Set objRecordset = Nothing Set objRecordsetInsert = Nothing End Function Function UpdateTransactions() Dim strSQLUpdateVAT, strSQLUpdateCodes Dim objRecordsetVAT, objRecordsetUpdateCodes strSQLUpdateVAT = "UPDATE query here SET [value:costing output] = ([value:costing output] * -1)" Call RunSQL(strSQLUpdateVAT, objRecordsetVAT, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) strSQLUpdateCodes = "UPDATE query here SET [value:costing output] = ([value:costing output] * -1) different WHERE clause" Call RunSQL(strSQLUpdateCodes, objRecordsetUpdateCodes, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) Set objRecordsetVAT = Nothing Set objRecordsetUpdateCodes = Nothing End Function UDPATE: If I exit the function after I open the connection (see below) it still causes the same error. Function ImportTransactions() Dim objConnection, objCommand, objRecordset, strOracle Dim strSQL, objRecordsetInsert Set objConnection = CreateObject("ADODB.Connection") objConnection.Open "DSN=*****;UID=*****;PWD==*****;" Set objCommand = CreateObject("ADODB.Command") Set objRecordset = CreateObject("ADODB.Recordset") Exit Function End Function It does both the import and update and seems to throw this error after. Thanks in advance for any help, Clare

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• Recommend me an architecture for this Facebook application

  - by andybaird

  Firstly, this question is subjective. There is not a right answer for this question and it really depends on what works for you. I'm hoping to use this thread as a breeding ground for ideas. I hope this is acceptable in this medium. I'm working on building a Facebook app that will be replacing an already popular app that gets ~50k hits a day. The original app is using a very typical LAMP setup with help from some Zend libraries for database layer extraction. For the most part the app worked well, except to solve a lot of issues I ended up fragmenting tables to speed things up. As a result, I couldn't do a lot of things with the app that I wanted to (namely any processing using aggregate data that needed to be returned quickly) So I'm starting to design plans for the next version of this application, and I have a whole bunch of new and cool features that I know would choke my current setup. I'm looking for technological recommendations of data storage methods that scale well. The database does not necessarily need to be relational, simple key/value storage would suffice (although at present time I know little to nothing about KV stores) What's your recommendation? How would you tackle this? I'd like to take a completely free approach to this -- although I am most familiar and comfortable using PHP, I want to leave all technical options open.

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• MySql: Query multiple identical dynamic tables.

  - by JYelton

  I have a database with 500+ tables, each with identical structure, that contain historical data from sensors. I am trying to come up with a query that will locate, for example, all instances where sensor n exceeds x. The problem is that the tables are dynamic, the query must be able to dynamically obtain the list of tables. I can query information_schema.tables to get a list of the tables, like so: SELECT table_name FROM information_schema.tables WHERE table_schema = 'database_name'; I can use this to create a loop in the program and then query the database repeatedly, however it seems like there should be a way to have MySql do the multiple table search. I have not been able to make a stored procedure that works, but the examples I can find are generally for searching for a string in any column. I want to specifically find data in a specific column that exists in all tables. I admit I do not understand how to properly use stored procedures nor if they are the appropriate solution to this problem. An example query inside the loop would be: SELECT device_name, sensor_value FROM device_table WHERE sensor_value > 10; Trying the following does not work: SELECT device_name, sensor_value FROM ( SELECT table_name FROM information_schema.tables WHERE table_schema = 'database_name' ) WHERE sensor_value > 10; It results in an error: "Every derived table must have its own alias." The goal is to have a list of all devices that have had a given sensor value occur anywhere in their log (table). Ultimately, should I just loop in my program once I've obtained a list of tables, or is there a query structure that would be more efficient?

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• Global Temporary Table "On commit delete rows" functionality discrepancy.

  - by TomatoSandwich

  I have a global temporary table. I called my GTT, for that was it's initials. My GTT never hurt anyone, and did everything I bade of it. I asked my GTT to delete rows on commit. This is a valid function in the creation script of my GTT in oracle. I wanted to be able to have different users see GTT with their own data, and not the data of other people's sessions. 'Delete rows on commit' worked perfectly in our test environment. GTT and I were happy. But then, I deployed GTT as part of an update to functionality to a client's database. The database doesn't like to play well with GTT. GTT called me up all upset and worried, because it wasn't holding any data any more, and didn't know why. GTT told me that if someone did: insert into my_GTT (description) values ('Happy happy joy joy') he would sing-song back: 1 row inserted. However, if the same person tried select * from my_GTT; GTT didn't know what to do, and he replied 0 rows returned. GTT was upset that he didn't know what his playmate had inserted. Please, Stackoverflow, why would GTT forget what was placed into him? He can remember perfectly well at home, but out in the cold harsh world, he just gets so scared. :(

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• How do I sanitize a string in PHP that contains "; Echo"? (I have a solid reason)

  - by user337878

  I turned this case into a simple PHP page that submits to itself. My issue is that I am submitting track meet results and one of the girl's names is Echo...a lovely name. The problem text I'm submitting is: Pole vault - Rachel Simons, Tow, 8-6; Echo Wilson, Cit, 8-0; Molly Randall, Tow, 7-0; So you see a semicolon followed by white space followed by Echo... After submitting, it says: POST to /results/test.php not supported The end goal is to save it to a database along with some other info and have a search page to find it and simply print out the full result on the screen. I stripped out all my database stuff to get it down to this one error. I mean, I can intentionally mis-spell her name, but there's gotta be a way around this, right??? Here's the test PHP file. <html> <head> <title>title</title> </head> <body> <?php echo "<h3>Edit meet info below</h3>"; echo "<form action=\"test.php\" method=\"post\" id=\"submitForm\">"; echo "Full Results:<br/><textarea NAME=\"results\" id=\"results\" rows=\"20\" cols=\"80\" MAXLENGTH=\"8191\"></textarea><br/><br/>"; echo "<input type=\"submit\" name=\"submitMeet\" value=\"Submit\">"; echo "</form>"; ?> </body> </html>

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• Java CountDownLatch used to wait for JFrame to dispose

  - by Brian

  I have referenced this previous question as well as other sources, but cannot get CountDownLatch to work correctly. Background: mainFrame creates new Frame called dataEntryFrame. When dataEntryFrame "Submit" button is clicked, record added to database and dataEntryFrame disposed. At this point, mainFrame should clear and reload a jList that shows all records. Issue: When dataEntryFrame loads, java freezes, dataEntryFrame components never load. I cannot get past this part... then, in the DataEntryFrame, CountDownLatch should only decrements after the submit button is clicked, successfully adds a record to a database table, and disposes itself. Or when the user clicks cancel... Code: From MainFrame CountDownLatch dataEntryDone = new CountDownLatch(1); DataEntryFrame f = new DataEntryFrame(dataEntryDone); Thread newThread = new Thread(f); newThread.start(); dataEntryDone.await(); Code: From DataEntryFrame public void run(){ initComponents(); loadOtherData(); this.setVisible(true); } void submit(){ addRecord(); this.dispose() dataEntryDone.countDown(); }

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• How to create instances of a class from a static method?

  - by Pierre

  Hello. Here is my problem. I have created a pretty heavy readonly class making many database calls with a static "factory" method. The goal of this method is to avoid killing the database by looking in a pool of already-created objects if an identical instance of the same object (same type, same init parameters) already exists. If something was found, the method will just return it. No problem. But if not, how may I create an instance of the object, in a way that works with inheritance? >>> class A(Object): >>> @classmethod >>> def get_cached_obj(self, some_identifier): >>> # Should do something like `return A(idenfier)`, but in a way that works >>> class B(A): >>> pass >>> A.get_cached_obj('foo') # Should do the same as A('foo') >>> A().get_cached_obj('foo') # Should do the same as A('foo') >>> B.get_cached_obj('bar') # Should do the same as B('bar') >>> B().get_cached_obj('bar') # Should do the same as B('bar') Thanks.

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• Occasional weird Glassfish errors, resolved by a restart?

  - by Pooria

  I'm developing a web app using netbeans with GlassFishv3. Every once in a while when I add a new feature in my app, glassfish starts nagging with stupid errors, after a lot of time wasting and panicking, i restart glassfish and run my application again, then suddenly the errors all go away and my site starts acting correctly. (or in case I have made a real mistake, i receive a reasonable & descriptive error from GF.) [Edit: the rest of the question was revealed to have been my own mistake.] But the problems don't end there. Recently, i added the ability to write comments in a (JSF) page, after the user submits their comment, i add it to the database and redirect to the same page, so that hopefully the page refreshes with the new comment, but it wont! The underlying Mysql database shows that the new comment has been added, but the page just wont show the new comment! I've tried everything (e.g. deleting browser cache, using different browsers) but only after restarting GF is when the page shows the new comment! Do you have any idea what the problem could be? Could this be a Glassfish bug? What i am using: JSF2, EJB3.1, JPA, MySql

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• PHP: What is an efficient way to parse a text file containing very long lines?

  - by Shaun

  I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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• [MySQL/PHP] Avoid using RAND()

  - by Andrew Ellis

  So... I have never had a need to do a random SELECT on a MySQL DB until this project I'm working on. After researching it seems the general populous says that using RAND() is a bad idea. I found an article that explains how to do another type of random select. Basically, if I want to select 5 random elements, I should do the following (I'm using the Kohana framework here)? If not, what is a better solution? Thanks, Andrew <?php final class Offers extends Model { /** * Loads a random set of offers. * * @param integer $limit * @return array */ public function random_offers($limit = 5) { // Find the highest offer_id $sql = ' SELECT MAX(offer_id) AS max_offer_id FROM offers '; $max_offer_id = DB::query(Database::SELECT, $sql) ->execute($this->_db) ->get('max_offer_id'); // Check to make sure we're not trying to load more offers // than there really is... if ($max_offer_id < $limit) { $limit = $max_offer_id; } $used = array(); $ids = ''; for ($i = 0; $i < $limit; ) { $rand = mt_rand(1, $max_offer_id); if (!isset($used[$rand])) { // Flag the ID as used $used[$rand] = TRUE; // Set the ID if ($i > 0) $ids .= ','; $ids .= $rand; ++$i; } } $sql = ' SELECT offer_id, offer_name FROM offers WHERE offer_id IN(:ids) '; $offers = DB::query(Database::SELECT, $sql) ->param(':ids', $ids) ->as_object(); ->execute($this->_db); return $offers; } }

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