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  • Django model class and custom property

    - by dArignac
    Howdy - today a weird problem occured to me: I have a modle class in Django and added a custom property to it that shall not be saved into the database and therefore is not represent in the models structure: class Category(models.Model): groups = models.ManyToManyField(Group) title = defaultdict() Now, when I'm within the shell or writing a test and I do the following: c1 = Category.objects.create() c1.title['de'] = 'german title' print c1.title['de'] # prints "german title" c2 = Category.objects.create() print c2.title['de'] # prints "german title" <-- WTF? It seems that 'title' is kind of global. If I change title to a simple string it works as expected, so it has to do something with the dict? I also tried setting title as a property: title = property(_title) But that did not work, too. So, how can I solve this? Thank you in advance! enter code here

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  • Using my ISerializable implementation instead of DataContractSerializer

    - by mpm
    My WCF client and server exchange objects whose types are defined on a class library shared by both, the server and the client. These objects implement custom serialization via ISerializable. However, my custom serialization is not being used. DataContractSerializer is being used, instead. How do I force my custom serialization to be used? The reason why I need to use my own serialization is because I do trasfer some big object graphs and my serialization algorithm does a good job in compressing/speeding up things.

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  • Does allocation speed depend on the garbage collector being used?

    - by jkff
    My app is allocating a ton of objects (1mln per second; most objects are byte arrays of size ~80-100 and strings of the same size) and I think it might be the source of its poor performance. The app's working set is only tens of megabytes. Profiling the app shows that GC time is negligibly small. However, I suspect that perhaps the allocation procedure depends on which GC is being used, and some settings might make allocation faster or perhaps make a positive influence on cache hit rate, etc. Is that so? Or is allocation performance independent on GC settings under the assumption that garbage collection itself takes little time?

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  • Teacher confused about MVC?

    - by Gideon
    I have an assignment to create a game in java using MVC as a pattern. The thing is that stuff I read about MVC aren't really what the teacher is telling me. What I read is that the Model are the information objects, they are manipulated by the controllers. So in a game the controller mutates the placement of the objects and check if there is any collision etc. What my teacher told me is that I should put everything that is universal to the platform in the models and the controllers should only tell the model which input is given. That means the game loop will be in a model class, but also collision checks etc. So what I get from his story is that the View is the screen, the Controller is the unput handeler, and the Model is the rest. Can someone point me in the right direction?

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  • Django populate select field based on model query

    - by Mike
    I have the following model class DNS(models.Model): domain = models.ForeignKey(Domain) host_start = models.CharField(max_length=150, blank=True, null=True) type = models.SmallIntegerField(max_length=1, default=0, choices=DNS_CHOICE) value = models.SmallIntegerField(max_length=3, default=0, blank=True, null=True) ip = models.IPAddressField(blank=True, null=True) host_end = models.ForeignKey("DNS", blank=True, null=True) other_end = HostnameField(max_length=150, blank=True, null=True) created = models.DateTimeField(auto_now_add=True) sticky = models.BooleanField(default=0) other = models.BooleanField(default=0) When I try to init a form with just foreignkeys on host_end.. it always shows all entries in the DNS table domain = Domain.objects.get(id=request.GET['domain'], user=request.user, active=1) form = DNSFormCNAME(initial={'ip': settings.MAIN_IP, 'type': request.GET['type'], 'host_end': DNS.objects.filter(domain=domain)}) I just want the zones that match that domain.. not all domains.

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  • using arrays to get best memory alignment and cache use, is it necessary?

    - by Alberto Toglia
    I'm all about performance these days cause I'm developing my first game engine. I'm no c++ expert but after some research I discovered the importance of the cache and the memory alignment. Basically what I found is that it is recommended to have memory well aligned specially if you need to access them together, for example in a loop. Now, In my project I'm doing my Game Object Manager, and I was thinking to have an array of GameObjects references. meaning I would have the actual memory of my objects one after the other. static const size_t MaxNumberGameObjects = 20; GameObject mGameObjects[MaxNumberGameObjects]; But, as I will be having a list of components per object -Component based design- (Mesh, RigidBody, Transformation, etc), will I be gaining something with the array at all? Anyway, I have seen some people just using a simple std::map for storing game objects. So what do you guys think? Am I better off using a pure component model?

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  • Show a django relationship in a template

    - by kevin_82
    I have a django model as follows: class Person(models.Model): name = models.CharField(max_length=255) class Relationship(models.Model): parent = models.ForeignKey(Person) child = models.ForeignKey(Person) description = models.TextField(blank=True) In my view, I pass a certain person, and the relationships in which he/she is parent: person = Person.objects.filter(name ='some name') descendant_relationships = Relationship.objects.filter(parent = person) An I want to show this person's descendants in a list in a template: <ul> {% for item in descendant_relationships%} <li> {{item.child.name}} - {{item.description}} </li> {% endfor %} </ul> But this template code will not show the children of children (i.e. grandchildren, great-grandchildren etc.). How can I get these lower level descendants to show up? I imagine recursion is necessary somewhere, but where?

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  • iOS UITableViewCell UIImageView setting on different conditions

    - by chis54
    I have an app that has a UITableView and in my Cells I have UIImageViews and UILabels that change images/textColors for a day theme and a night theme (trying to be automatically set). My issue is that I set the images and colors when the table is populated with cellForRowAtIndexPath and its during the day "theme", then if I reopen the app hours later in the night "theme" and the app is still in the "background" and not needing to be reloaded (ie viewDidLoad doesn't fire), the day "theme" shows until I scroll the UITableView and then the night "theme" shows when new cells are brought into view by scrolling. How should I set the objects in my cells when changing around time of the day? I was thinking to use an NSTimer, but I'm not sure how to update the objects in my cells. I was also thinking about using the appropriate methods in the AppDelagate to set things in motion, but is there a way to force reloading the TableView? Any suggestions?

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  • How can I write faster JavaScript?

    - by a paid nerd
    I'm writing an HTML5 canvas visualization. According to the Chrome Developer Tools profiler, 90% of the work is being done in (program), which I assume is the V8 interpreter at work calling functions and switching contexts and whatnot. Other than logic optimizations (e.g., only redrawing parts of the visualization that have changed), what can I do to optimize the CPU usage of my JavaScript? I'm willing to sacrifice some amount of readability and extensibility for performance. Is there a big list I'm missing because my Google skills suck? I have some ideas but I'm not sure if they're worth it: Limit function calls When possible, use arrays instead of objects and properties Use variables for math operation results as much as possible Cache common math operations such as Math.PI / 180 Use sin and cos approximation functions instead of Math.sin() and Math.cos() Reuse objects when passing around data instead of creating new ones Replace Math.abs() with ~~ Study jsperf.com until my eyes bleed Use a preprocessor on my JavaScript to do some of the above operations

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  • What is the accepted way to replace java.util.Date(year,month,day)

    - by dagw
    I'm trying to do something really simple, but starting to realize that dates in Java are a bit of minefield. All I want is to get passed groups of three ints ( a year, a month and a date) create some Date objects, do some simple test on them (along the lines of as date A before date B and after January 1 1990), convert them to java.sql.Date objects and pass them off to the database via JDBC. All very simple and works fine using the java.util.Date(int year,int month,int day) constructor. Of course that constructor is depreciated, and I'd like to avoid using depreciated calls in new code I'm writing. However all the other options to solve this simple problem seem stupidly complicated. Is there really no simple way to do what I want without using depreciated constructors? I know the standard answer to all Java date related questions is "use joda time", but I really don't want to start pulling in third party libraries for such a seemingly trivial problem.

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  • Need recommendation for object serialization library in c++

    - by michael
    Hi, I am looking for recommendation for object serialization/deserialization library in c++? Which one are the most advanced and open-sourced? Can it handle Any class that users defined? Object hierarchy (parent and child classes)? A Tree of objects? Class A has an attribute of Class B which has an attribute of Class C? STL containers? Class A has a vector of Class B? A cyclic of objects? Class A has a pointer pointing to B which has a pointer to A? I find boost serialization library. I am not sure what is its limitation from http://www.boost.org/doc/libs/1_42_0/libs/serialization/doc/tutorial.html

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  • Information Modeling

    - by Betamoo
    The sensor module in my project consists of a rotating camera, that collects noisy information about moving objects in the surrounding environment. The information consists of distance, angle and relative change of the moving objects.. The limiting view range of the camera makes it essential to rotate the camera periodically to update environment information... I was looking for algorithms / ways to model these information, in order to be able to guess / predict / learn motion properties of these object.. My current proposed idea is to store last n snapshots of each object in a queue. I take weighted average of positions and velocities of moving object, but I think it is a poor method... Can you state some titles that suit this case? Thanks

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  • Aggregation over a few models - Django

    - by RadiantHex
    Hi folks, I'm trying to compute the average of a field over various subsets of a queryset. Player.objects.order_by('-score').filter(sex='male').aggregate(Avg('level')) This works perfectly! But... if I try to compute it for the top 50 players it does not work. Player.objects.order_by('-score').filter(sex='male')[:50].aggregate(Avg('level')) This last one returns the exact same result as the query above it, which is wrong. What am I doing wrong? Help would be very much appreciated!

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  • How to declare and use the name of a function from a json object?

    - by Sebastian
    Hello, I have a json object collection of geo locations that I build in the server. Each of those objects has two properties: "marker" and "onClick". Marker is for storing a Google Maps marker object and the onClick stores the name of the function to be called when that marker is clicked on the map. When I'm pushing the location objects into an array using javascript in the client side, I create the markers and assign them to each location object within the array. My problem is that when I bind the marker with the onClick property, the function won't be found in the DOM and get an error. Is there a way to declare a property in a json object for using it on an event binding? Hope I could explain it clearly, if not, please let me know. Thanks!

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  • How should flushing be handled in a doctrine EntityManager instance shared across different services in symfony2?

    - by Jbm
    I have defined several services in symfony 2 which persist changes to the database. These services have the doctrine instance as one of their dependencies: a.given.service: class: Acme\TestBundle\Service\AGivenService arguments: [@doctrine] If I have two different services and both of them persist objects through the EntityManager, which is obtained like this from the doctrine instance: $em = $doctrine->getEntityManager(); Would all services always share the same EntityManager? If so, how should I handle flushing if I wanted to handle all the changes in a single transaction? I have checked this: http://docs.doctrine-project.org/projects/doctrine-orm/en/2.0.x/reference/transactions-and-concurrency.html and it explains how to handle different transactions in a request, but I want to achieve the opposite, which is having different changes in different services handled as a single transaction. Is there a better approach to handle multiple changes in different services? For now my best bet is having a front-end service in charge of calling the other services and doing the flushing afterwards. Backend services would persist objects but would not do any flushing.

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  • C# Dataset usage necessary before passing to GridView datasource?

    - by Goober
    Scenario Lets say for example I have a series of events that fire continually every half second presenting me with an object containing some bits of information. There are always between 10 and 15 objects that are being updated constantly. Since these bits of information are changing continually I want to display them in a GridView. When I do so, I want the user to see the data displayed in the gridview and actually be updated as opposed to just a continually extending list being printed and incrementing (like writeline on the console). Question Is the best way to achieve this to map my objects to a dataset and have the dataset mapped to the gridview? Thoughts Will this allow the gridview to just be "UPDATED" as opposed to being added to? Any implementation suggestions would be greatly appreciated. EDIT: it MUST be windows forms (I use DevExpress too)

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  • When can we mock an object and its methods?

    - by Shailendra
    I am novice to the Moq and unit testing. I have to write unit tests to a lot of classes which has the objects of other classes. can i mock the methods of the class objects. Here is the exact scenerio- I have a class two classes A and B and A has a private object of B and in a method of A i am internally calling the method of B and then doing some calculation and returning the result. Can i mock the method of B in this scenerio? Please try to give me full detail about the conditions where i can mock the methods and functions of the class. Thanx

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  • PHP: How do I access child properties from a method in a base object?

    - by Nick
    I'd like for all of my objects to be able to return a JSON string of themselves. So I created a base class for all of my objects to extend, with an AsJSON() method: class BaseObject { public function AsJSON() { $JSON=array(); foreach ($this as $key = $value) { if(is_null($value)) continue; $JSON[$key] = $value; } return json_encode($JSON); } } And then extend my child classes from that: class Package extends BaseObject { ... } So in my code, I expect to do this: $Box = new Package; $Box-SetID('123'); $Box-SetName('12x8x6'); $Box-SetBoxX('12'); $Box-SetBoxY('8'); $Box-SetBoxZ('6'); echo $Box-AsJSON(); But the JSON string it returns only contains the BaseClass's properties, not the child properties. How do I modify my AsJSON() function so that $this refers to the child's properties, not the parent's?

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  • C#, Generic Lists and Inheritance

    - by Andy
    I have a class called Foo that defines a list of objects of type A: class Foo { List<A> Items = new List<A>(); } I have a class called Bar that can save and load lists of objects of type B: class Bar { void Save(List<B> ComplexItems); List<B> Load(); } B is a child of A. Foo, Bar, A and B are in a library and the user can create children of any of the classes. What I would like to do is something like the following: Foo MyFoo = new Foo(); Bar MyBar = new Bar(); MyFoo.Items = MyBar.Load(); MyBar.Save(MyFoo.Items); Obviously this won't work. Is there a clever way to do this that avoids creating intermediate lists? thanks, Andy

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  • Can Django flush its database(s) between every unit test

    - by mikem
    Django (1.2 beta) will reset the database(s) between every test that runs, meaning each test runs on an empty DB. However, the database(s) are not flushed. One of the effects of flushing the database is the auto_increment counters are reset. Consider a test which pulls data out of the database by primary key: class ChangeLogTest(django.test.TestCase): def test_one(self): do_something_which_creates_two_log_entries() log = LogEntry.objects.get(id=1) assert_log_entry_correct(log) log = LogEntry.objects.get(id=2) assert_log_entry_correct(log) This will pass because only two log entries were ever created. However, if another test is added to ChangeLogTest and it happens to run before test_one, the primary keys of the log entries are no longer 1 and 2, they might be 2 and 3. Now test_one fails. This is actually a two part question: Is it possible to force ./manage.py test to flush the database between each test case? Since Django doesn't flush the DB between each test by default, maybe there is a good reason. Does anyone know?

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  • Download multiple files in background in Android

    - by Addev
    Basically I'm trying to make a little app for watching offline content. So there's a moment where the user selects to download the contents (and the app should download about 300 small files and images). I'd like to show the user how does the process go if he enters the proper activity. Showing a list of all the files, telling what has been already downloaded, in progress or waiting for download. My problem is that I really don't know what approach to take for achieve this. Since the download should last until finished I imagine the solution is an Service, but whats best? an IntentService, a Bound Service or an Standard Service calling a startService() for each download? And how can I keep my objects updated for displaying them later? should I use a database or objects in memory? Thanks

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  • Django : looking for a good LDAP manipulation library

    - by sebpiq
    Hi ! I am looking for a good ldap library on Django, that would allow me to manage my ldap server : adding, modifying, deleting entries for groups, users, and all kind of objects The library django-ldapdb looked promising, it offers a Model base class that can be used to declare ldap objects in a Django fashion (which is what we ideally want), however we've had some bugs with it, and furthermore it seems like it is not maintained any more. Does somebody know a good library that could do the trick ? Otherwise I guess I'll just try to improve and debug django-ldapdb ... Thanks !

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  • WPF Converter to look up in generic list

    - by user310046
    I have a list of data where I keep e.g. countries with code, name and some other data. List<Country> countries = <deserialized objects from file> which consist of objects like this: public class Country { public string Code { get; set;} public string Name { get; set;} } The object which use as a DataContext may look like this: public class Address { public string StreetName{ get; set;} public string CountryCode { get; set;} } Then in my XAML I want to do something like this to show the name of the country <TextBlock Text="{Binding Path=CountryCode, Converter={StaticResource CountryNameLookupConverter}}"/> But how can I make the CountryNameLookupConverter use the countries list I read from the xml file?

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