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  • Why can't I save my model with a generic relation twice in Django?

    - by e-satis
    I got a model TrackedItem with a generic relation linking to any model it is supposed to track. If I do that: t = TrackedItem(content_object=MyModel) t.save() t.save() I get : IntegrityError: (1062, "Duplicate entry '1' for key 'PRIMARY'") Indeed, the first save has created an entry with "1" as a PK. But the second save should not insert, it should update. How am I suppose to update a model I can't save twice? With an ordinary model I can save as much as I want.

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  • Row selection based on subtable data in MySQL

    - by Felthragar
    I've been struggling with this selection for a while now, I've been searching around StackOverflow and tried a bunch of stuff but nothing that helps me with my particular issue. Maybe I'm just missing something obvious. I have two tables: Measurements, MeasurementFlags "Measurements" contain measurements from a device, and each measurement can have properties/attributes attached to them (commonly known as "flags") to signify that the measurement in question is special in some way or another (for instance, one flag may signify a test or calibration measurement). Note: One record per flag! Right, so a record from the "Measurements" table can theoreticly have an unlimited amount of MeasurementFlags attached to it, or it can have none. Now, I need to select records from "Measurements", that have an attached "MeasurementFlag" valued "X", but it must also NOT have a flag valued "Y" attached to it. We're talking about a fairly large database with hundreds of millions of rows, which is why I'm trying to keep all of this logic within one query. Splitting it up would create too many queries, however if it's not possible to do in one query I guess I don't have a choise. Thanks in advance.

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  • Calculating Length Based on Sensor Data

    - by BSchlinker
    I've got an IR sensor which writes its current information to a token which I then interpret in a C# application. That's all good -- no problems there, heres my code: SetLabelText(tokens [1],label_sensorValue); sensorreading = Int32.Parse(tokens[0]); sensordistance = (mathfunctionhere); Great. So the further away the IR sensor is from an object, the lower the sensor reading (as less light is reflected back and received by the sensor). My problem is in interpreting that length. I can go ahead and get lets say "110" as a value when an object is 5 inches away, and then "70" as a value when an object is 6 inches away. Now I want to be able to calculate the distance of an object using these constants for any length. Any ideas?

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  • MVC Application Design

    - by Paul Brown
    Hello I am about to create my first proper application in ASP.NET MVC3. It is basically a jobs site with 3 levels: 1) Users - No registration and can view all jobs posted on the website 2) Posters - Need to register and login to post adverts 3) Admin - Need to register and login to post adverts and review postings before they go live Would you suggest I use the same Jobs controller for the three levels I mention above? With a LIST action to show jobs to "Users" and a CREATE & EDIT action for the "Posters" & "Admin"? Thanks Paul

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  • Hibernate Communications Link Failure in Hibernate Based Java Servlet application powered by MySQL

    - by Vatsala
    Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?) edit - Here are the c3p0 parameters I tried out - select 1; 2

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  • Java paint speed relative to color model

    - by Jon
    I have a BufferedImage with an IndexColorModel. I need to paint that image onto the screen, but I've noticed that this is slow when using an IndexColorModel. However, if I run the BufferedImage through an identity affine transform it creates an image with a DirectColorModel and the painting is significantly faster. Here's the code I'm using AffineTransformOp identityOp = new AffineTransformOp(new AffineTransform(), AffineTransformOp.TYPE_BILINEAR); displayImage = identityOp.filter(displayImage, null); I have three questions 1. Why is painting the slower on an IndexColorModel? 2. Is there any way to speed up the painting of an IndexColorModel? 3. If the answer to 2. is no, is this the most efficient way to convert from an IndexColorModel to a DirectColorModel? I've noticed that this conversion is dependent on the size of the image, and I'd like to remove that dependency. Thanks for the help

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  • Is it a oop good design ?

    - by remi bourgarel
    Hi all, I'd like to know what you think about this part of our program is realized : We have in our database a list of campsite. Partners call us to get all the campsites near a GPS location or all the campsites which provide a bar (we call it a service). So how I realized it ? Here is our database : Campsite - ID - NAME - GPS_latitude - GPS_longitude CampsiteServices -Campsite_ID -Services_ID So my code (c# but it's not relevant, let say it's an OO language) looks like this public class SqlCodeCampsiteFilter{ public string SqlCode; public Dictionary<string, object> Parameters; } interface ISQLCampsiteFilter{ SqlCodeEngineCore CreateSQLCode(); } public class GpsLocationFilter : ISQLCampsiteFilter{ public float? GpsLatitude; public float? GpsLongitude; public SqlCodeEngineCore CreateSQLCode() { --return an sql code to filter on the gps location like dbo.getDistance(@gpsLat,@gpsLong,campsite.GPS_latitude,campsite.GPS_longitude) with the parameters } } public class ServiceFilter : : ISQLCampsiteFilter{ public int[] RequiredServicesID; public SqlCodeEngineCore CreateSQLCode() { --return an sql code to filter on the services "where ID IN (select CampsiteServices.Service_ID FROm CampsiteServices WHERE Service_ID in ...) } } So in my webservice code : List<ISQLFilterEngineCore> filters = new List<ISQLFilterEngineCore>(); if(gps_latitude.hasvalue && gps_longitude.hasvalue){ filters.Add (new GpsLocationFilter (gps_latitude.value,gps_longitude.value)); } if(required_services_id != null){ filters.Add (new ServiceFilter (required_services_id )); } string sql = "SELECT ID,NAME FROM campsite where 1=1" foreach(ISQLFilterEngineCore aFilter in filters){ SqlCodeCampsiteFilter code = aFilter.CreateSQLCode(); sql += code.SqlCode; mySqlCommand.AddParameters(code.Parameters);//add all the parameters to the sql command } return mySqlCommand.GetResults(); 1/ I don't use ORM for the simple reason that the system exists since 10 years and the only dev who is here since the beginning is starting to learn about difference between public and private. 2/ I don't like SP because : we can do override, and t-sql is not so funny to use :) So what do you think ? Is it clear ? Do you have any pattern that I should have a look to ? If something is not clear please ask

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  • Looping and recursion based on parameter passed

    - by contactkx
    I have an XML organized like below- <section name="Parent 1 Text here" ID="1" > <section name="Child 1 Text here" ID="11"> </section> <section name="Child 2 Text here" ID="12"> <section name="GrandChild Text here" ID="121" > </section> </section> </section> <section name="Parent 2 Text here" ID="2" > <section name="Child 1 Text here" ID="22"> </section> <section name="Child 2 Text here" ID="23"> <section name="GrandChild Text here" ID="232" > </section> </section> </section> I have to produce the below output XML - <section name="Parent 1 Text here" ID="1" > <section name="Child 2 Text here" ID="12"> <section name="GrandChild Text here" ID="121" > </section> </section> </section> <section name="Parent 2 Text here" ID="2" > <section name="Child 2 Text here" ID="23"> </section> </section> I have to achive above using XSLT 1.0 transformation. I was planning to pass a comma separated string as a parameter with value= "1,12,121,2,23" My question- How to loop the comma separated parameter in XSLT 1.0 ? Is there a simpler way to achieve the above. Please remember I have to do this in XSLT 1.0 Your help is appreciated.

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  • Identify machines behind a router uniquely based on ipaddress

    - by Amith George
    Some background first. I have a .net client agent installed on each of the machines in the lan. They are interacting with my central server [website] also on the same lan. It is important for my website to figure out which of the machines can talk to each other. For example, machines of one subnet cannot directly talk to machines of another subnet without configuring the routers and such. But machines in the same subnet should be able to talk to each other directly. The problem I am facing is when the lan setup is like in Figure 1. Because Comp1, Comp2 and Comp3 are behind a router, they have got the ipaddress 192.168.1.2 till 192.168.1.4. My client agent on these machines report the same ipaddress back to the server. However, machines Comp4, Comp5 also have the same ipaddresses. Thus, as far as my server is concerned, there are 2 machines with the same ipaddress. Not just that, because the subnet mask is 255.255.255.0 for all machines, my server is fooled into thinking that Comp1 can directly talk to Comp5, which is not possible. So, how do I solve this? What do I need to change in my client or in my server, so that I can support this scenario. These two are the only things in my control.

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  • web page design in html

    - by HIma
    hai I want to create a web page like left and right side image, middle portion content. My problem is that the content must be display under both images. I know the cell padding is not a good idea. Some thing like div is correct way. Does any one know this?

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  • How to get an object from a list based upon IEqualityComparer<T>

    - by Greg
    The Compare method in Linq lets you find by an IEqualityComparer, but I can't find a counterpart method that allows you retrieve an item by the same comparer. Is this really the best way to do it? MyItem myFinderItem = new MyItem(keyField1, keyField2); if (myList.Contains(myFinderItem, new MyEqualityComparer())) { MyItem myRealItem = myList.Single(item => new MyEqualityComparer().Equals(item , myFinderItem)); } (I'm sharing the usage of the IEqualityComaprer with a call to the Except Linq method and I'd like to maintain a single source for equality comparisons)

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  • Ruby is already using the class name of my model

    - by Octopus Inc
    I'm making a forum application with various levels of authorization, one of which is a Monitor. I am doing this by extending my User class, and I plan on fine tuning this with "-ship" classes (e.g. administratorship, authorship, moderatorship, etc.). Apparently the Monitor class is part of ruby mixin. How do I keep my resource name without the collisions?

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  • Conditional action based on whether any file in a directory has a ctime newer than X

    - by jberryman
    I would like to run a backup job on a directory tree from a bash script if any of the files have been modified in the last 30 minutes. I think I can hack together something using find with the -ctime flag, but I'm sure there is a standard way to examine a directory for changes. I know that I can inspect the ctime of the top level directory to see if files were added, but I need to be able to see changes also. FWIW, I am using duplicity to backup directories to S3.

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  • CakePHP based project is throwing error saying " return value of new by Reference is Deprecated"

    - by Bindas
    I have upgraded my Xampp to newer version(1.7.2).But right now when I run my project(done in CakePHP) it is throwing bug saying Deprecated: Assigning the return value of new by reference is deprecated in C:\xampp\htdocs\ebayn\cake\libs\debugger.php on line 99 Deprecated: Assigning the return value of new by reference is deprecated in C:\xampp\htdocs\ebayn\cake\libs\debugger.php on line 108 Deprecated: Assigning the return value of new by reference is deprecated in C:\xampp\htdocs\ebayn\cake\libs\file.php on line 96 Deprecated: Assigning the return value of new by reference is deprecated in C:\xampp\htdocs\ebayn\cake\libs\cache\file.php on line 89 Can anyone help me how can I rectify this stuff....??? Thanks In Advance

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  • Generate a list of file names based on month and year arithmetic

    - by MacUsers
    How can I list the numbers 01 to 12 (one for each of the 12 months) in such a way so that the current month always comes last where the oldest one is first. In other words, if the number is grater than the current month, it's from the previous year. e.g. 02 is Feb, 2011 (the current month right now), 03 is March, 2010 and 09 is Sep, 2010 but 01 is Jan, 2011. In this case, I'd like to have [09, 03, 01, 02]. This is what I'm doing to determine the year: for inFile in os.listdir('.'): if inFile.isdigit(): month = months[int(inFile)] if int(inFile) <= int(strftime("%m")): year = strftime("%Y") else: year = int(strftime("%Y"))-1 mnYear = month + ", " + str(year) I don't have a clue what to do next. What should I do here? Update: I think, I better upload the entire script for better understanding. #!/usr/bin/env python import os, sys from time import strftime from calendar import month_abbr vGroup = {} vo = "group_lhcb" SI00_fig = float(2.478) months = tuple(month_abbr) print "\n%-12s\t%10s\t%8s\t%10s" % ('VOs','CPU-time','CPU-time','kSI2K-hrs') print "%-12s\t%10s\t%8s\t%10s" % ('','(in Sec)','(in Hrs)','(*2.478)') print "=" * 58 for inFile in os.listdir('.'): if inFile.isdigit(): readFile = open(inFile, 'r') lines = readFile.readlines() readFile.close() month = months[int(inFile)] if int(inFile) <= int(strftime("%m")): year = strftime("%Y") else: year = int(strftime("%Y"))-1 mnYear = month + ", " + str(year) for line in lines[2:]: if line.find(vo)==0: g, i = line.split() s = vGroup.get(g, 0) vGroup[g] = s + int(i) sumHrs = ((vGroup[g]/60)/60) sumSi2k = sumHrs*SI00_fig print "%-12s\t%10s\t%8s\t%10.2f" % (mnYear,vGroup[g],sumHrs,sumSi2k) del vGroup[g] When I run the script, I get this: [root@serv07 usage]# ./test.py VOs CPU-time CPU-time kSI2K-hrs (in Sec) (in Hrs) (*2.478) ================================================== Jan, 2011 211201372 58667 145376.83 Dec, 2010 5064337 1406 3484.07 Feb, 2011 17506049 4862 12048.04 Sep, 2010 210874275 58576 145151.33 As I said in the original post, I like the result to be in this order instead: Sep, 2010 210874275 58576 145151.33 Dec, 2010 5064337 1406 3484.07 Jan, 2011 211201372 58667 145376.83 Feb, 2011 17506049 4862 12048.04 The files in the source directory reads like this: [root@serv07 usage]# ls -l total 3632 -rw-r--r-- 1 root root 1144972 Feb 9 19:23 01 -rw-r--r-- 1 root root 556630 Feb 13 09:11 02 -rw-r--r-- 1 root root 443782 Feb 11 17:23 02.bak -rw-r--r-- 1 root root 1144556 Feb 14 09:30 09 -rw-r--r-- 1 root root 370822 Feb 9 19:24 12 Did I give a better picture now? Sorry for not being very clear in the first place. Cheers!! Update @Mark Ransom This is the result from Mark's suggestion: [root@serv07 usage]# ./test.py VOs CPU-time CPU-time kSI2K-hrs (in Sec) (in Hrs) (*2.478) ========================================================== Dec, 2010 5064337 1406 3484.07 Sep, 2010 210874275 58576 145151.33 Feb, 2011 17506049 4862 12048.04 Jan, 2011 211201372 58667 145376.83 As I said before, I'm looking for the result to b printed in this order: Sep, 2010 - Dec, 2010 - Jan, 2011 - Feb, 2011 Cheers!!

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  • Discriminator based on joined property

    - by Andrew
    Suppose I have this relationship: abstract class Base { int Id; int JoinedId; ... } class Joined { int Id; int Discriminator; ... } class Sub1 : Base { ... } class Sub2 : Base { ... } for the following tables: table Base ( Id int, JoinedId int, ... ) table Joined ( Id int, Discriminator int, ... ) I would like to set up a table-per-hierarchy inheritance mapping for the Base, Sub1, Sub2 relationships, but using the Disciminator property from the Joined class as the discriminator. Here's the general idea for the mapping file: <class name="Base" table="Base"> <id name="Id"><generator class="identity"/></id> <discriminator /> <!-- ??? or <join> or <many-to-one>? --> <subclass name="Sub1" discriminator-value="1">...</subclass> <subclass name="Sub2" discriminator-value="2">...</subclass> </class> Is there any way of accomplishing something like this with the <discriminator>, <join>, or <many-to-one>? NHiberante seems to assume the discriminator is a column on the given table (which makes sense to me.. I know this is unorthodox). Thanks.

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  • 'e-Commerce' scalable database model

    - by Ruben Trancoso
    I would like to understand database scalability so I've just heard a talk about Habits of Highly Scalable Web Applications http://techportal.ibuildings.com/2010/03/02/habits-of-highly-scalable-web-applications/ On it, the presenter mainly talk about relational database scalability. I also have read something about MapReduce and Column oriented tables, big tables, hypertable etc... trying to understand which are the most up to date methods to scale web application data. But the second group, to me, is being hard to understand where it fits. It serves as transactional, reliable data store? or not, its just for large access and processing and to handle fine graned operations we will ever need to rely on RDBMSs? Could someone give a comprehensive landscape for those new technologies and how to use it?

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  • what's wrong with my producer-consumer queue design?

    - by toasteroven
    I'm starting with the C# code example here. I'm trying to adapt it for a couple reasons: 1) in my scenario, all tasks will be put in the queue up-front before consumers will start, and 2) I wanted to abstract the worker into a separate class instead of having raw Thread members within the WorkerQueue class. My queue doesn't seem to dispose of itself though, it just hangs, and when I break in Visual Studio it's stuck on the _th.Join() line for WorkerThread #1. Also, is there a better way to organize this? Something about exposing the WaitOne() and Join() methods seems wrong, but I couldn't think of an appropriate way to let the WorkerThread interact with the queue. Also, an aside - if I call q.Start(#) at the top of the using block, only some of the threads every kick in (e.g. threads 1, 2, and 8 process every task). Why is this? Is it a race condition of some sort, or am I doing something wrong? using System; using System.Collections.Generic; using System.Text; using System.Messaging; using System.Threading; using System.Linq; namespace QueueTest { class Program { static void Main(string[] args) { using (WorkQueue q = new WorkQueue()) { q.Finished += new Action(delegate { Console.WriteLine("All jobs finished"); }); Random r = new Random(); foreach (int i in Enumerable.Range(1, 10)) q.Enqueue(r.Next(100, 500)); Console.WriteLine("All jobs queued"); q.Start(8); } } } class WorkQueue : IDisposable { private Queue _jobs = new Queue(); private int _job_count; private EventWaitHandle _wh = new AutoResetEvent(false); private object _lock = new object(); private List _th; public event Action Finished; public WorkQueue() { } public void Start(int num_threads) { _job_count = _jobs.Count; _th = new List(num_threads); foreach (int i in Enumerable.Range(1, num_threads)) { _th.Add(new WorkerThread(i, this)); _th[_th.Count - 1].JobFinished += new Action(WorkQueue_JobFinished); } } void WorkQueue_JobFinished(int obj) { lock (_lock) { _job_count--; if (_job_count == 0 && Finished != null) Finished(); } } public void Enqueue(int job) { lock (_lock) _jobs.Enqueue(job); _wh.Set(); } public void Dispose() { Enqueue(Int32.MinValue); _th.ForEach(th = th.Join()); _wh.Close(); } public int GetNextJob() { lock (_lock) { if (_jobs.Count 0) return _jobs.Dequeue(); else return Int32.MinValue; } } public void WaitOne() { _wh.WaitOne(); } } class WorkerThread { private Thread _th; private WorkQueue _q; private int _i; public event Action JobFinished; public WorkerThread(int i, WorkQueue q) { _i = i; _q = q; _th = new Thread(DoWork); _th.Start(); } public void Join() { _th.Join(); } private void DoWork() { while (true) { int job = _q.GetNextJob(); if (job != Int32.MinValue) { Console.WriteLine("Thread {0} Got job {1}", _i, job); Thread.Sleep(job * 10); // in reality would to actual work here if (JobFinished != null) JobFinished(job); } else { Console.WriteLine("Thread {0} no job available", _i); _q.WaitOne(); } } } } }

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  • Forumotion profile customization using jQuery based on URL

    - by Harvengure
    The idea is have a jQuery snippet (I like Jquery...I can understand it better then regular javascript) that will detect that when it has been run on a profile with a url such as "http://customize.forum-motion.com/profile.forum?mode=viewprofile&u=1" (just as an example)...then upon detecting that it is a url of a profile...fetch data from a specific (and most likely hidden) element before wrapping that data in css tags and appending it to the heady of the current document. In short I'm trying to figure out how to make a sort of profile customization system where users can create their own css. The biggest problem I am having so far is figuring out how to make it so that the snippet can figure out what URL its being run on. Is there a function that can do this in jQuery at all?

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  • OO design for business logic

    - by hotyi
    I have one Sell Operation object and two Buy Operation objects, i want to implement such behavior that one Sell Operation discharges two Buy Operation, it looks like: sellOperation.Discharge(oneBuyOperation); sellOperation.Discharge(twoBuyOperation); so i want to ask whether i should call the repository function in the Discharge method, or i'd better call the repository save method outside Discharge method. like: opRepository.Save(sellOpertion); So anyone could give me some advise what are you going to implement in this scenario? using Service class or anything better way?

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  • C# Monitor Programs Periodically Based on PID

    - by ThaKidd
    Thank you in advance for you ideas and input. I would like to periodically check to see if a third party program is currently running on a user's system from my program. I am currently launching the program as follows in C#: String plinkConString = ""; // my connection string Process plink = Process.Start(utilityPath + @"\putty.exe", plinkConString); int plinkProcessId = plink.Id; I launch the program and grab its pid in a Windows environment. As Putty/PLink may disconnect from its SSH server at some point and close, what is the best way to monitor how this process is doing in code? Is there a better way to launch this program to monitor its success or failure?

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