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  • Django: optimizing queries

    - by Josh
    I want to list the number of items for each list. How can I find this number in a single query, rather than a query for each list? Here is a simplified version of my current template code: {% for list in lists %} <li> {{ listname }}: {% with list.num_items as item_count %} {{ item_count }} item{{ item_count|pluralize }} {% endwith %} </li> {% endfor %} lists is passed as: List.objects.filter(user=user) and num_items is a property of the List model: def _get_num_items(self): return self.item_set.filter(archived=False).count() num_items = property(_get_num_items) This queries SELECT COUNT(*) FROM "my_app_item" WHERE... n times, where n is the number of lists. Is it possible to make a single query here?

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  • SQL Profiles showing high activity

    - by Wong Chi
    I am running my application locally -- ie. No external traffic and very low number of queries, fully under my control. I see tons of 'Audit Login' and 'Audit Logout' events. What are these and where are they actually stored (ie. Where is this audit log)? Are these a hint of a problem with connections, because I have only a simple connection string within my app and thought that connections would remain active throughout the operation of my app (ie. a single login at launch, and then a single logout when terminating).

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  • C++: is it safe to read an integer variable that's being concurrently modified without locking?

    - by Hongli
    Suppose that I have an integer variable in a class, and this variable may be concurrently modified by other threads. Writes are protected by a mutex. Do I need to protect reads too? I've heard that there are some hardware architectures on which, if one thread modifies a variable, and another thread reads it, then the read result will be garbage; in this case I do need to protect reads. I've never seen such architectures though. This question assumes that a single transaction only consists of updating a single integer variable so I'm not worried about the states of any other variables that might also be involved in a transaction.

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  • Your favorite LiveCD

    - by sova
    Perhaps this is a question better suited for linux.se but since I have servers on all environments I was wondering what your favorite LiveCD is. Wiki defines this, for those unfamiliar, as a CD or DVD containing a bootable computer operating system. Live CDs are unique in that they have the ability to run a complete, modern operating system on a computer lacking mutable secondary storage, such as a hard disk drive. Live USB flash drives are similar to live CDs, but often have the added functionality of automatically and transparently writing changes back to their bootable medium. I tend to stick with Knoppix, and today I have to register the machine on the network before I can get any of my utilities running via IP. Any suggestions?

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  • NSTableview objectAtIndex error

    - by Matt S.
    I followed the guide here, but for some reason, the table view shows this in the console when I attempt to scroll through it: -[NSCFString objectAtIndex:]: unrecognized selector sent to instance 0x100227710

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  • How to instantiate a Singleton multiple times?

    - by Sebi
    I need a singleton in my code. I implemented it in Java and it works well. The reason I did it, is to ensure that in a mulitple environment, there is only one instance of this class. But now I want to test my Singleton object locally with a Unit test. For this reason I need to simulate another instance of this Singleton (the object that would be from another device). So is there a possiblity to instantiate a Singleton a second time for testing purpose or do I have to mock it? I'm not sure, but I think it could be possible by using a different class loader?

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  • Is the php method md5() secure? Can it be used for passwords? [migrated]

    - by awiebe
    So executing a php script causes the form values to be sent to the server, and then they are processed. If you want to store a password in your db than you want it to be a cryptographic hash(so your client side is secure, can you generate an md5 using php securely( without submitting the user:password pair in the clear), or is there an alternative standard method of doing this, without having the unecrypted pasword leaving the clients machine? Sorry if this is a stupid question I'm kind of new at this. I think this can be done somehow using https, and on that note if a site's login page does not use https, does that mean that while the databse storage is secure, the transportation is not?

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  • Building an array of arrays

    - by iFloh
    I am trying to get the following loop working to fill an array of arrays: while (condition) { [itemsArray fillFromDB]; if (! [checkArray containsObject:checkFlag]) { // Add existing itemsArray to myArray if (itemsArray.count) { // add the itemsArray to myArray and create a new instance of itemsArray [myArray addObject:itemsArray]; [itemsArray release]; NSMutableArray *itemsArray = [[NSMutableArray alloc] init]; } [itemsArray addObject:myObject]; [checkArray addObject:checkFlag]; } else { [itemsArray addObject:tmpEvent]; } } However I try to shape this loop it falls over the release of itemsArray when I use release (as above), the array does not re-initialise as a new instance with alloc. Whilst expecting emptyness, the next Object is added to the old array. when I use removeAllObjects, my Array is emptied and so is the array attached to myArray. Where am I going in the wrong direction?

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  • How to test that invalid arguments raise an ArgumentError exception using RSpec?

    - by John Topley
    I'm writing a RubyGem that can raise an ArgumentError if the arguments supplied to its single method are invalid. How can I write a test for this using RSpec? The example below shows the sort of implementation I have in mind. The bar method expects a single boolean argument (:baz), the type of which is checked to make sure that it actually is a boolean: module Foo def self.bar(options = {}) baz = options.fetch(:baz, true) validate_arguments(baz) end def self.validate_arguments(baz) raise(ArgumentError, ":baz must be a boolean") unless valid_baz?(baz) end def self.valid_baz?(baz) baz.is_a?(TrueClass) || baz.is_a?(FalseClass) end end

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  • iPhone xcode - Best way to control audio from several view controllers

    - by Are Refsdal
    Hi, I am pretty new to iPhone programming. I have a navBar with three views. I need to control audio from all of the views. I only want one audio stream to play at a time. I was thinking that it would be smart to let my AppDelegate have an instance of my audioplaying class and let the three other views use that instance to control the audio. My problem is that I don´t know how my views can use the audioplaying class in my AppDelegate. Is this the best approach and if so, how? Is there a better way?

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  • Will I use HtmlDocument even I want to parse the HTML string using HtmlAglityPack ?

    - by skhan
    Hi everyone, I'm working in C#. I'm trying to extract the first instance of img tag from a HTML string (which is actually a post data). This is my code: private string GrabImage(string htmlContent) { String firstImage; HtmlAgilityPack.HtmlDocument htmlDoc = new HtmlAgilityPack.HtmlDocument(); htmlDoc.LoadHtml(htmlContent); HtmlAgilityPack.HtmlNode imageNode = htmlDoc.DocumentNode.SelectSingleNode("//img"); if (imageNode != null) { return firstImage = imageNode.ToString(); } else return firstImage=" "; } But it gets null in htmlDoc, will I use the HtmlDocument type even if I'm trying to parse the HTML from a string ? P.S btw is it the correct way of grabbing the first instance of image tag from my HTML string?

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  • Synchronize Azure SQL (cloud) with Azure SQL Emulator (local)?

    - by Sid
    We have an Azure service (web role) that heavily depends on the database. For offline development/testing, we'd like to have the app+db run offline within the emulators. Running the webrole itself within the emulator is straightforward but doing so for the Azure SQL storage isn't so. What is the simplest way to ensure that the cloud Azure SQL database and the emulator/local Azure SQL database are in sync? We can afford some level of staleness for simplicity of sync operation (meaning it's ok for the local copy to be a few hours stale versus mirroring every write as soon as it happens) Thanks

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  • Quality web hosts not using c panel [closed]

    - by J4G
    Possible Duplicate: How to find web hosting that meets my requirements? I was an iPower web hosting user before I encountered major problems with their MySQL databases. I recently tried A Small Orange, whose GUI was not compelling, and I quickly learned to loathe c panel. I looked into using GoDaddy, but reviews of their service have been very negative. I was satisfied with iPower's control panel, so something similar would be appropriate. Can anyone recommend a quality web host that includes the following features? *Unlimited bandwidth (200gb or higher) *Unlimited storage (10gb or higher) *High up-time (preferably 95% or higher) *Does not use C panel or other difficult-to-use control panels *Supports multiple MySQL databases *Uses a recent version of PHPmyAdmin

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  • IMAGE REQUIRED for Project

    - by soniya
    Do anybody have an animated image tat contains all emotion(happy,sad,love) a single gif file that exhibits different smileys representing all emotions like happy,angry pls help me out SONIYA

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  • sql server 2008 express. cannot create mdf databse.

    - by yair
    Hi, I'm working with visual studio 2008 express and sql 2008 express. I'm trying to create mdf database (Add new Item ...)and I recieve the following error message: "a network-related or instance-specific error occured while establishing a connection to SQL Server. The server was not found or was not accessible. Verfy that instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named pipes Provider:40 - could not open connection to SQL)" Why ? Is it possible to create mdf database with SQL 2008 Express ? If it is then what to do ?

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  • How to restrict the range of elements of C++ STL vector?

    - by cambr
    vector<int> l; for(int i=0;i<10;i++){ l.push_back(i); } I want the vector to only be able to store numbers from a specified range (or set). How can that be done, in general? In particular, I want to restrict the vector to beonly be able to store single digits. So, if I do a l[9]++, it should give me an error or warn me. (because 10 is not a single digit number). Similarly, l[0]-- should warn me. Is there a way to do this using C++ STL vector?

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  • Making a Wrapper class for ActiveMQ

    - by DarthVader
    I want to make a Wrapper class for ActiveMQ which will have only send and get functions. I want to wrap them in a static class. Users can use this client and send, get messages to the activemq instance. I want this process to be transparent. There are two classes in this link My only handicap is, i need to this in c++ and not sure where to start. I havent used c++ for ages and now not sure how I can create this wrapper class. I m giving it a try as follows: // .h file #include <stdlib.h> #include <iostream> using namespace std; class ActiveMQWrapper { public: static void send(std::string message); static std::string get(); }; // .cpp file #include<string> #include<iostream> #include "ActiveMQWrapper.h" void ActiveMQWrapper::send(std::string message){ std::cout<<message; } std::string ActiveMQWrapper::get(){ return "test"; } // test file #include <string> #include <iostream> #include "ActiveMQWrapper.h" int main() { std::string foo ="test"; ActiveMQWrapper::send(foo); std::cout<<ActiveMQWrapper::get(); return 1; } When I added the following to .h file, hell breaks loose. Do you think I should seperate this impl to a factory and initialize and instance and return to the wrapper above? How do i deal with all the dependencies? private: Connection* connection; Session* session; Destination* destination; MessageProducer* producer; int numMessages; bool useTopic; bool sessionTransacted; std::string brokerURI; and the header files, i get several messages as errors, which complains about the path. How can i get this correct? I eventually want to build a Factory, get an instance and send or get the messages to the queue. is there a code sample i can look into to get this right? essential i want to use the functionality of only this producer and consumer. Edit: I understand there is no such thing as static class in C++ . This is my reference.

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  • [iOS] How to catch cancallation of UIScrollView or others?

    - by kyu
    Sometimes, interruptions such as phone call occur and disturb a regular behavior of an app in iPhone or iPad. For example, I created one UIScrollView instance and implemented UIScrollView delegate methods: scrollViewWillBeginDragging and scrollViewDidEndDragging(and scrollViewDidEndDecelerating). A scrollViewWillBeginDragging method deactivated all custom buttons in my app. Then scrollViewDidEndDragging and scrollViewDidEndDecelerating methods activated these custom buttons. That is, while the user scrolled, all custom buttons became deactivated for a while. The problem was that while the user started to drag and just held an UIScrollView instance, if I took a screenshot by pressing a home button and a power button, then any of scrollViewDidEndDragging and scrollViewDidEndDecelerating didn't get called. So the app became messed up. I implemented a UIApplicationWillResignActiveNotification method in my UIViewController, but it didn't get called after taking a screenshot. How can I catch any kind of interruption that disturbs a regular flow of events? Sometimes, touchesEnd and touchesCanceled didn't get called too due to an interruption. Thank you.

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  • Cannot add App_Data SQL Server database

    - by Interfector
    Hello, Using Visual Studio 2010 10.0.20319.1 RTMRel and SQL Server Express 10.50.1600.1 I'm trying to add a new SQL Server Database .mdf, however, I receive the following error: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 25 – Connection string is not valid) I have enabled TCP/IP and Named Pipelines, added Firewall Exceptions for Sql Server, I am successfully connecting from VS in the Server Explorer window. I would appreciate if someone can pint me to a solution to my problem. Thank you.

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  • Click Listener not invoked within ListFragment

    - by membersound
    I'm extending a SherlockListFragment, but it should not matter as my question seems to be more general related to Fragments. Now, I implement a simple click listener for my list, but it does not get called. public class MyListFragment extends SherlockListFragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.list, container, false); v.setOnClickListener(new OnClickListener() { public void onClick(View view) { Log.i("debug", "single click"); } }); return v; } } Is anything wrong with this? //Solution: listView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Log.i("debug", "single click"); } });

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  • NSInvalidArgumentException when updating WebView from AppDelegate

    - by H.Protagonist
    I had to do an update in my WebView from the Appdelegate.m I try it like this: [self performSelectorOnMainThread:@selector(loadWebViewWithContent:) withObject:requestObj waitUntilDone:NO]; The loadWebViewWithContent Method works great from ViewController.m, but not from the Appdelegate. I allready wrote this in my Appdelegate.h: -(void)loadWebViewWithContent:(NSURLRequest *)requestObj; Whats wrong? Please help me. I´m still a big Noob in IOS. Error: -[AppDelegate loadWebViewWithContent]: unrecognized selector sent to instance 0x1f86a5e0*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[AppDelegate loadWebViewWithContent]: unrecognized selector sent to instance 0x1f86a5e0'

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  • In PLT scheme, can I export functions after another function has been called?

    - by Jason Baker
    I'm trying to create a binding to libpython using scheme's FFI. To do this, I have to get the location of python, create the ffi-lib, and then create functions from it. So for instance I could do this: (module pyscheme scheme (require foreign) (unsafe!) (define (link-python [lib "/usr/lib/libpython2.6.so"]) (ffi-lib lib)) This is all well and good, but I can't think of a way to export functions. For instance, I could do something like this: (define Py_Initialize (get-ffi-obj "Py_Initialize" libpython (_fun -> _void))) ...but then I'd have to store a reference to libpython (created by link-python) globally somehow. Is there any way to export these functions once link-python is called? In other words, I'd like someone using the module to be able to do this: (require pyscheme) (link-python) (Py_Initialize) ...or this: (require pyscheme) (link-python "/weird/location/for/libpython.so") (Py_Initialize) ...but have this give an error: (require pyscheme) (Py_Initialize) How can I do this?

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  • Displaying same icon in 2 different sizes on c#

    - by ET
    My goal is to display the same icon twice, but each time in different size. I tried the following: FileStream fs = new FileStream("name_of_the_icon_file.ico", FileMode.Open); Icon ico = new Icon(fs, 32, 32); //create an in-memory instance of the icon, size 32x32 Icon ico2 = new Icon(fs, 16, 16); //create an in-memory instance of the icon, size 16x16 ... Graphics.DrawIcon(ico, /*some point*/); Graphics.DrawIcon(ico2, /*some other point*/); The last line throws an ArgumentException: Value does not fall within the expected range. Can some one explain me whats wrong and whats the way to do this right?

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  • Whats the most useful programming language?

    - by Sebi
    I know this question was here a lot of times and can't be answered at all, but im not looking for a single name, but rather for an advice in my situation. I learned programming with Java and now I'm developing in Java for more or less 5 years (at the university) and I thinks my programming skills their are really ok/average. I have also small experience in C/C++ and C#. Now I have some spare time and I'd like to learn a new language or deepen the knowledge of Java/C/C++. But how to choose the right language to learn? I'd like to learn a language which will be usefull in the future concerning working in a software development business? I know there is no single answer, but I'm sure you could mention some languages that are more usefull than others.

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