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  • Edit form not being instantiated

    - by 47
    I have two models like this: class OptionsAndFeatures(models.Model): options = models.TextField(blank=True, null=True) entertainment = models.TextField(blank=True, null=True) seats_trim = models.TextField(blank=True, null=True) convenience = models.TextField(blank=True, null=True) body_exterior = models.TextField(blank=True, null=True) lighting = models.TextField(blank=True, null=True) safety = models.TextField(blank=True, null=True) powertrain = models.TextField(blank=True, null=True) suspension_handling = models.TextField(blank=True, null=True) specs_dimensions = models.TextField(blank=True, null=True) offroad_capability = models.TextField(blank=True, null=True) class Vehicle(models.Model): ... options_and_features = models.ForeignKey(OptionsAndFeatures, blank=True, null=True) I have a model form for the OptionsAndFeaturesclass that I'm using in both the add and edit views. In the add view it works just fine. But the edit view renders the OptionsAndFeatures as blank. The code for the edit view is as follows: def edit_vehicle(request, stock_number=None): vehicle = get_object_or_404(Vehicle, stock_number=stock_number) if request.method == 'POST': # save info else: vehicle_form = VehicleForm(instance=vehicle) photos = PhotosFormSet(instance=vehicle) options = OptionsForm(instance=vehicle) #render_to_reponse What could be the problem here?

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  • Python utf-8 decoding issue with hashlib.digest() method

    - by Sorw
    Hello StackOverflow community, Using Google App Engine, I wrote a keyToSha256() method within a model class (extending db.Model) : class Car(db.Model): def keyToSha256(self): keyhash = hashlib.sha256(str(self.key())).digest() return keyhash When displaying the output (ultimately within a Django template), I get garbled text, for example : ?????_??!`?I?!?;?QeqN??Al?'2 I was expecting something more in line with this : 9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08 Am I missing something important ? Despite reading several guides on ASCII, Unicode, utf-8 and the like, I think I'm still far from mastering the secrets of string encoding/decoding. After browsing StackOverflow and searching for insights via Google, I figured out I should ask the question here. Any idea ? Thanks !

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  • Custom Sorting on Custom Field in Django

    - by RotaJota
    In my app, I have defined a custom field to represent a physical quantity using the quantities package. class AmountField(models.CharField): def __init__(self, *args, **kwargs): ... def to_python(self, value): create_quantities_value(value) Essentially the way it works is it extends CharField to store the value as a string in the database "12 min" and represents it as a quantities object when using the field in a model array(12) * min Then in a model it is used as such: class MyModel(models.Model): group = models.CharField() amount = AmountField() class Meta: ordering = ['group', 'amount'] My issue is that these fields do not seem to sort by the quantity, but instead by the string. So if I have some objects that contain something like {"group":"A", "amount":"12 min"} {"group":"A", "amount":"20 min"} {"group":"A", "amount":"2 min"} {"group":"B", "amount":"20 min"} {"group":"B", "amount":"1 hr"} they end up sorted something like this: >>> MyModel.objects.all() [{A, 12 min}, {A, 2 min}, {A, 20 min}, {B, 1 hr}, {B, 20 min}] essentially alphabetical order. Can I give my custom AmountField a comparison function so that it will compare by the python value instead of the DB value?

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  • Singleton pattern and broken double checked locking in real world java application

    - by saugata
    I was reading the article Double-checked locking and the Singleton pattern, on how double checked locking is broken, and some related questions here on stackoverflow. I have used this pattern/idiom several times without any issues. Since I have been using Java 5, my first thought was that this has been rectified in Java 5 memory model. However the article says This article refers to the Java Memory Model before it was revised for Java 5.0; statements about memory ordering may no longer be correct. However, the double-checked locking idiom is still broken under the new memory model. I'm wondering if anyone has actually run into this problem in any application and under what conditions.

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  • jQuery - google chrome won't get updated textarea value

    - by Phil Jackson
    Hi, I have a textarea with default text 'write comment...'. when a user updates the textarea and clicks 'add comment' Google chrome does not get the new text. heres my code; function add_comment( token, loader ){ $('textarea.n-c-i').focus(function(){ if( $(this).html() == 'write a comment...' ) { $(this).html(''); } }); $('textarea.n-c-i').blur(function(){ if( $(this).html() == '' ) { $(this).html('write a comment...'); } }); $(".add-comment").bind("click", function() { try{ var but = $(this); var parent = but.parents('.n-w'); var ref = parent.attr("ref"); var comment_box = parent.find('textarea'); var comment = comment_box.val(); alert(comment); var con_wrap = parent.find('ul.com-box'); var contents = con_wrap .html(); var outa_wrap = parent.find('.n-c-b'); var outa = outa_wrap.html(); var com_box = parent.find('ul.com-box'); var results = parent.find('p.com-result'); results.html(loader); comment_box.attr("disabled", "disabled"); but.attr("disabled", "disabled"); $.ajax({ type: 'POST', url: './', data: 'add-comment=true&ref=' + encodeURIComponent(ref) + '&com=' + encodeURIComponent(comment) + '&token=' + token + '&aj=true', cache: false, timeout: 7000, error: function(){ $.fancybox(internal_error, internal_error_fbs); results.html(''); comment_box.removeAttr("disabled"); but.removeAttr("disabled"); }, success: function(html){ auth(html); if( html != '<span class="error-msg">Error, message could not be posted at this time</span>' ) { if( con_wrap.length == 0 ) { outa_wrap.html('<ul class="com-box">' + html + '</ul>' + outa); outa_wrap.find('li:last').fadeIn(); add_comment( token, loader ); }else{ com_box.html(contents + html); com_box.find('li:last').fadeIn(); } } results.html(''); comment_box.removeAttr("disabled"); but.removeAttr("disabled"); } }); }catch(err){alert(err);} return false; }); } any help much appreciated.

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  • Java MVC - How to divide a done text game into MVC?

    - by Zopyrus
    Been sitting here for hours now trying to figure this out, so a bit sympathy for this large question. :) The Goal: I simply want to divide my done code into MVC (Model View Controller) parts. I have the game logics done and text based - the code works fine. The Problem: Well, I want to implement this code into MVC, but where do explain for the MODEL that it should use text-based? Because the VIEW is only for the layout (graphically) correct? I am having a REALLY hard time figuring out where to begin at all. Any pointers would be so nice! Here is my game logics code: import mind.*; import javax.swing.*; import java.util.*; import java.lang.*; import java.awt.*; public class Drive { String[] mellan; boolean gameEnd, checkempty, checkempty2, enemy, enemy2; String gr,rd,tom; int digits; public Drive() { // Gamepieces in textform gr="G"; rd="R"; tom=" "; mellan = new String[7]; String[] begin = {gr,gr,gr,tom,rd,rd,rd}; String[] end = {rd,rd,rd,tom,gr,gr,gr}; //input Scanner in = new Scanner(System.in); mellan=begin; gameEnd=false; while (gameEnd == false) { for(int i=0; i<mellan.length; i++) { System.out.print(mellan[i]); } System.out.print(" Choose 0-6: "); digits = in.nextInt(); move(); checkWin(); } } void move() { //BOOLEAN for gameruls!!! checkempty = digits<6 && mellan[digits+1]==tom; checkempty2 = digits>0 && mellan[digits-1]==tom; enemy = (mellan[digits]==gr && mellan[digits+1]==rd && mellan[digits+2]==tom); enemy2 = (mellan[digits]==rd && mellan[digits-1]==gr && mellan[digits-2]==tom); if(checkempty) { mellan[digits+1]=mellan[digits]; mellan[digits]=tom; } else if (checkempty2) { mellan[digits-1]=mellan[digits]; mellan[digits]=tom; } else if (enemy) { mellan[digits+2]=mellan[digits]; mellan[digits]=tom; } else if (enemy2) { mellan[digits-2]=mellan[digits]; mellan[digits]=tom; } } void checkWin() { String[] end = {rd,rd,rd,tom,gr,gr,gr}; for (int i=0; i<mellan.length; i++){ } if (Arrays.equals(mellan,end)) { for (int j=0; j<mellan.length; j++) { System.out.print(mellan[j]); } displayWin(); } } void displayWin() { gameEnd = true; System.out.println("\nNicely Done!"); return; } // Kör Drive! public static void main(String args[]) { new Drive(); } } Here is how I defined my DriveView thus far: (just trying to make one button to work) import mind.*; import javax.swing.*; import java.util.*; import java.lang.*; import java.awt.*; import java.awt.event.*; public class DriveView extends JFrame { JButton ruta1 = new JButton("Green"); JButton ruta2 = new JButton("Green"); JButton rutatom = new JButton(""); JButton ruta6 = new JButton("Red"); private DriveModel m_model; public DriveView(DriveModel model) { m_model = model; //Layout for View JPanel myPanel = new JPanel(); myPanel.setLayout(new FlowLayout()); myPanel.add(ruta1); myPanel.add(ruta2); myPanel.add(rutatom); myPanel.add(ruta6); this.setContentPane(myPanel); this.pack(); this.setTitle("Drive"); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } void addMouseListener(ActionListener mol) { ruta2.addActionListener(mol); } } And DriveController which gives me error at compile import mind.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.lang.*; public class DriveController { private DriveModel m_model; private DriveView m_view; public DriveController(DriveModel model, DriveView view) { m_model = model; m_view = view; view.addMouseListener(new MouseListener()); } class MouseListener implements ActionListener { public void actionPerformed(ActionEvent e) { String mening; mening = e.getActionCommand(); if (mening.equals("Green")) { setForeground(Color.red); } } } }

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  • Scala/Erlang use something like greenThread or not ?

    - by CHAPa
    Hi all, Im reading a lot about how scala/Erlang does lightweight threads and your concurrency model ( Actor Model ). Off course, some doubts appear in my head. Scala/Erlang use a approach similar to the old thread model used by java (greenThread) ? for example, suppose that there is a machine with 2 cores, so the scala/erlang environment will fork one thread per processor ? The other threads will be scheduled by user-space( scala VM / erlang vm ) environment. is it correct ? how under the hood that really work ? thanks a lot.

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  • GDB says that a KVO observer is registered even though it is not (or is it?).

    - by Paperflyer
    When my application is closed, the main controller class removes itself as Observer from the model and then releases the model. Like this: - (void)dealloc { [theModel removeObserver:self forKeyPath:@"myValue"]; [theModel release]; [super dealloc]; } And right after that, the debugger says: 2010-04-29 14:07:40.294 MyProgram[13678:a0f] An instance 0x116f2e880 of class TheModel was deallocated while key value observers were still registered with it. Observation info was leaked, and may even become mistakenly attached to some other object. Set a breakpoint on NSKVODeallocateBreak to stop here in the debugger. Here's the current observation info: <NSKeyValueObservationInfo 0x100288450> ( <NSKeyValueObservance 0x1002aca90: Observer: 0x116f40ec0, Key path: myValue, Options: <New: YES, Old: NO, Prior: NO> Context: 0x0, Property: 0x116f80430> ) where 0x116f2e880 is indeed the model and 0x116f40ec0 is indeed the controller. How can the controller still be an observer when it just removed itself as an observer?

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  • Empty list in appengine datastore: java vs python

    - by lOranger
    I have the following java model class in AppEngine: public class Xyz ... { @Persistent private Set<Long> uvw; } When saving an object Xyz with an empty set uvw in Java, I get a "null" field (as listed in the appengine datastore viewer). When I try to load the same object in python (through remote_api), as defined by the following python model class: class Xys(db.Model): uvw = db.ListProperty(int) I get a "BadValueError: Property uvw is required". When saving another object of the same class in python with an empty uvw list, the datastore viewer print a "missing" field. Apparently empty lists storage handling differs between Java and python and lead to "incompatible" objects. Thus my question: Is there a way to, either: force Java to store an empty list as a "missing" field, force Python to gracefully accept a "null" list as an empty list when loading the object? Or any other suggestion on how to handle empty list field in both languages. Thanks for your answers!

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  • Re-using unit tests for models using STI

    - by TenJack
    I have a number of models that use STI and I would like to use the same unit test to test each model. For example, I have: class RegularList < List class OtherList < List class ListTest < ActiveSupport::TestCase fixtures :lists def test_word_count list = lists(:regular_list) assert_equal(0, list.count) end end How would I go about using the test_word_count test for the OtherList model. The test is much longer so I would rather not have to retype it for each model. Thanks.

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  • Java to Qt code convert

    - by user289175
    Hello, I'm teaching my self Qt; in the same time I don't want to lose my Java skills in Qt. I stacked in some codes to do it in Qt, I tried many times as well as search in the net. Code # 1 Object[] names = jList1.getSelectedValues(); String msg = ""; for (Object o : names) msg += o; Code # 2 DefaultListModel model; model = new DefaultListModel(); jList1.setModel(model); Code # 3 if(!jList1.isSelectionEmpty()) I didn't find Empty method :-( I'm going to do some Qt's video tutorials on youtube, but before that I need to solve the above codes. If any programmer can help I will be thankful; Thanks in advance At the end I would like to thanks the experts who are spent thier value times to help others

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  • Show different sub-sets in edit view

    - by Martin R-L
    In the context of C# 4, ASP.NET MVC 2, and NHibernate; I've got the following scenario: Let's assume an entity Product that have an association to ProductType. In a product edit view; how do I implement that only a sub-set of the product's properties are shown in an elegant and DRY way? Use a product view model builder, and from different view models automagically generate the view with my own Html.EditorForModel() (including drop-downs and other stuff not out-of-the-box)? Attribute the properties of one view model and use the Html.EditorForModel() way aforementioned? Use one model, but implement different web controls (view strategies) (can it be done DRY?)? Something else entirely?

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  • Design Layout/Patterns

    - by wpfwannabe
    I am still fairly new to C# and I am trying to decide the best way to structure a new program. Here is what I want to do and I would like feed back on my idea. Presentation Layer Business Layer (Separate Class Library) Data Layer (Separate Class Library) Model Layer (Separate Class Library) What I am struggling with is if it is ok to have the classes in the Data Layer and Business Layer inherit from the types I define in Model Layer. This way I can extended the types as needed in my Business Layer with any new properties I see fit. I might not use every property from the Model type in my Business Layer class but is that really a big deal? If this isn't clear enough I can try and put together an example.

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  • DataBinding a DropDownList in ASP.NET MVC 2

    - by Daniel Coffman
    I'm extremely frustrated trying to switch to MVC after a couple years of webforms development. Here's my extremely simple problem that I can't manage to solve: I have a list of States in a table called StateProvince. I have a DropDownList. I want the DropDownList to display all of the States in the StateProvince table and post the selected state back on HTTP PUT. This is what I'm doing: <%: Html.DropDownListFor(model = model.StateProvinceId, new SelectList(Model.StateProvinces, "StateProvinceId", "Name") )% I'm getting an Object reference not set to an instance of an object. Why? How can I make this work? Keep it simple, I know nothing about MVC.

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  • How to smooth an image loaded with FileReference?

    - by Lost_in_code
    Been trying to smooth images loaded with FileReferece with no luck. Below is the code I'm using: fileRef = new FileReference(); fileRef.addEventListener(Event.COMPLETE, fileLoaded); private function fileLoaded(e:Event):void{ var ldr:Loader = new Loader(); ldr.contentLoaderInfo.addEventListener(Event.COMPLETE, function(e:Event):void{ var bm:Bitmap = Bitmap(e.target.content as Bitmap); bm.smoothing = true; img.load(bm) }); ldr.loadBytes(fileRef.data); } <custom:SWFLoaderAdvanced id="img"/> bm.smoothing should've smoothened the loaded image, but for some reason it doesn't. Am I missing something here? Note: SWFLoaderAdvanced automatically smoothens any image that's loaded inside it. It works perfectly with loaded images other than the ones loaded with FileReference.

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  • Django foreign keys cascade deleting and "related_name" parameter (bug?)

    - by Wiseman
    In this topic I found a good way to prevent cascade deleting of relating objects, when it's not neccessary. class Factures(models.Model): idFacture = models.IntegerField(primary_key=True) idLettrage = models.ForeignKey('Lettrage', db_column='idLettrage', null=True, blank=True) class Paiements(models.Model): idPaiement = models.IntegerField(primary_key=True) idLettrage = models.ForeignKey('Lettrage', db_column='idLettrage', null=True, blank=True) class Lettrage(models.Model): idLettrage = models.IntegerField(primary_key=True) def delete(self): """Dettaches factures and paiements from current lettre before deleting""" self.factures_set.clear() self.paiements_set.clear() super(Lettrage, self).delete() But this method seems to fail when we are using ForeignKey field with "related_name" parameter. As it seems to me, "clear()" method works fine and saves the instance of "deassociated" object. But then, while deleting, django uses another memorized copy of this very object and since it's still associated with object we are trying to delete - whooooosh! ...bye-bye to relatives :) Database was arcitectured before me, and in somewhat odd way, so I can't escape these "related_names" in reasonable amount of time. Anybody heard about workaround for such a trouble?

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  • How does Fluent NHibernate support the Import Entity

    - by Bender
    I want to create a strongly type object from a fluent NHibernate query. If I were using HQL and NHibernate I belive I would need: the class for the output Namespace Model Public Class namecount Public Overridable Property lastname() as string ... Public Overridable Property lastnamecount() as integer ... Public Sub New(lastname as string, count as integer) ... End Class End Namespace an .hbm.xml file <?xml ...> <hibernate-mapping ...> <import class="model.namecount,model"> </hibernate-mapping> and of course the query _session.createquery("select new namecount(lastname, count(lastname)) ...") (The above is a paraphrased example taken from one of the 2008 SummerofNHibernate videos) I cannot find any examples of how to do this with fluent (even in C#), is it possible? If it isn't is there a VB example of how to mix Fluent and .hbm.xml

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  • Why is Django reverse() failing with unicode?

    - by JeffS
    Here is a django models file that is not working as I would expect. I would expect the to_url method to do the reverse lookup in the urls.py file, and get a url that would correspond to calling that view with arguments supplied by the Arguments model. from django.db import models class Element(models.Model): viewname = models.CharField(max_length = 200) arguments = models.ManyToManyField('Argument', null = True, blank = True ) @models.permalink def to_url(self): d = dict( self.arguments.values_list('key', 'value') ) return (self.viewname, (), d) class Argument(models.Model): key = models.CharField(max_length=200) value = models.CharField(max_length=200) The value d ends up as a dictionary from a unicode string to another unicode string, which I believe, should work fine with the reverse() method that would be called by the permalink decorator, however, it results in: TypeError: reverse() keywords must be strings

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  • Visual Studio C++ multi-project solution

    - by Lucas
    I have created an C++ solution in VS2008. The first project contains the model. The second projects is the view. The problem is that i don't get make references to my model classes defined in the first project. The message error is : Error 1 fatal error C1083: Cannot open include file: 'utils/GeradorSistematicoDeAlturaDoPlanoDeCorteStrategy.h': No such file or directory c:\Users\user\Programação em C++\Simulacao\Simulacao_Testes\src\Teste1.cpp 3 Simulacao_Testes Is there any configuration in VS2008 that makes to be made in order to, from the my view (second project) project, i do make references to the first project, the model?

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  • Django syncdb not making tables for my app

    - by Rosarch
    It used to work, and now it doesn't. python manage.py syncdb no longer makes tables for my app. From settings.py: INSTALLED_APPS = ( 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'mysite.myapp', 'django.contrib.admin', ) What could I be doing wrong? The break appeared to coincide with editing this model in models.py, but that could be total coincidence. I commented out the lines I changed, and it still doesn't work. class MyUser(models.Model): user = models.ForeignKey(User, unique=True) takingReqSets = models.ManyToManyField(RequirementSet, blank=True) takingTerms = models.ManyToManyField(Term, blank=True) takingCourses = models.ManyToManyField(Course, through=TakingCourse, blank=True) school = models.ForeignKey(School) # minCreditsPerTerm = models.IntegerField(blank=True) # maxCreditsPerTerm = models.IntegerField(blank=True) # optimalCreditsPerTerm = models.IntegerField(blank=True) UPDATE: When I run python manage.py loadddata initial_data, it gives an error: DeserializationError: Invalid model identifier: myapp.SomeModel Loading this data had worked fine before. This error is thrown on the very first data object in the data file.

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  • Actionscript 2.0, load images into array

    - by incrediman
    I need to load an external image into an array. Let's say the image is http://sstatic.net/so/img/logo.png I'm using AS2 - I do not have the option of using AS3. Any idea what to do? I'm able to load the image just fine into a movieclip in _root (below), but not into an array. var loader:MovieClipLoader = new MovieClipLoader(); loader.loadClip("http://sstatic.net/so/img/logo.png",_root.mcOnTheStage); Like is there some way to make an array ov MC's that I can load the images into?

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  • django admin gives warning "Field 'X' doesn't have a default value"

    - by noam
    I have created two models out of an existing legacy DB , one for articles and one for tags that one can associate with articles: class Article(models.Model): article_id = models.AutoField(primary_key=True) text = models.CharField(max_length=400) class Meta: db_table = u'articles' class Tag(models.Model): tag_id = models.AutoField(primary_key=True) tag = models.CharField(max_length=20) article=models.ForeignKey(Article) class Meta: db_table = u'article_tags' I want to enable adding tags for an article from the admin interface, so my admin.py file looks like this: from models import Article,Tag from django.contrib import admin class TagInline(admin.StackedInline): model = Tag class ArticleAdmin(admin.ModelAdmin): inlines = [TagInline] admin.site.register(Article,ArticleAdmin) The interface looks fine, but when I try to save, I get: Warning at /admin/webserver/article/382/ Field 'tag_id' doesn't have a default value

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  • Search over multiple fields

    - by schneck
    Hi there, I think I don't unterstand django-haystack properly: I have a data model containing several fields, and I would to have two of them searched: class UserProfile(models.Model): user = models.ForeignKey(User, unique=True, default=None) twitter_account = models.CharField(max_length=50, blank=False) My search index settings: class UserProfileIndex(SearchIndex): text = CharField(document=True, model_attr='user') twitter_account = CharField(model_attr='twitter_account') def get_queryset(self): """Used when the entire index for model is updated.""" return UserProfile.objects.all() But when I perform a search, only the field "username" is searched; "twitter_account" is ignored. When I select the Searchresults via dbshell, the objects contain the correct values for "user" and "twitter_account", but the result page shows a "no results": {% if query %} <h3>Results</h3> {% for result in page.object_list %} <p> <a href="{{ result.object.get_absolute_url }}">{{ result.object.id }}</a> </p> {% empty %} <p>No results</p> {% endfor %} {% endif %} Any ideas?

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  • Approaches for generic, compile-time safe lazy-load methods

    - by Aaronaught
    Suppose I have created a wrapper class like the following: public class Foo : IFoo { private readonly IFoo innerFoo; public Foo(IFoo innerFoo) { this.innerFoo = innerFoo; } public int? Bar { get; set; } public int? Baz { get; set; } } The idea here is that the innerFoo might wrap data-access methods or something similarly expensive, and I only want its GetBar and GetBaz methods to be invoked once. So I want to create another wrapper around it, which will save the values obtained on the first run. It's simple enough to do this, of course: int IFoo.GetBar() { if ((Bar == null) && (innerFoo != null)) Bar = innerFoo.GetBar(); return Bar ?? 0; } int IFoo.GetBaz() { if ((Baz == null) && (innerFoo != null)) Baz = innerFoo.GetBaz(); return Baz ?? 0; } But it gets pretty repetitive if I'm doing this with 10 different properties and 30 different wrappers. So I figured, hey, let's make this generic: T LazyLoad<T>(ref T prop, Func<IFoo, T> loader) { if ((prop == null) && (innerFoo != null)) prop = loader(innerFoo); return prop; } Which almost gets me where I want, but not quite, because you can't ref an auto-property (or any property at all). In other words, I can't write this: int IFoo.GetBar() { return LazyLoad(ref Bar, f => f.GetBar()); // <--- Won't compile } Instead, I'd have to change Bar to have an explicit backing field and write explicit getters and setters. Which is fine, except for the fact that I end up writing even more redundant code than I was writing in the first place. Then I considered the possibility of using expression trees: T LazyLoad<T>(Expression<Func<T>> propExpr, Func<IFoo, T> loader) { var memberExpression = propExpr.Body as MemberExpression; if (memberExpression != null) { // Use Reflection to inspect/set the property } } This plays nice with refactoring - it'll work great if I do this: return LazyLoad(f => f.Bar, f => f.GetBar()); But it's not actually safe, because someone less clever (i.e. myself in 3 days from now when I inevitably forget how this is implemented internally) could decide to write this instead: return LazyLoad(f => 3, f => f.GetBar()); Which is either going to crash or result in unexpected/undefined behaviour, depending on how defensively I write the LazyLoad method. So I don't really like this approach either, because it leads to the possibility of runtime errors which would have been prevented in the first attempt. It also relies on Reflection, which feels a little dirty here, even though this code is admittedly not performance-sensitive. Now I could also decide to go all-out and use DynamicProxy to do method interception and not have to write any code, and in fact I already do this in some applications. But this code is residing in a core library which many other assemblies depend on, and it seems horribly wrong to be introducing this kind of complexity at such a low level. Separating the interceptor-based implementation from the IFoo interface by putting it into its own assembly doesn't really help; the fact is that this very class is still going to be used all over the place, must be used, so this isn't one of those problems that could be trivially solved with a little DI magic. The last option I've already thought of would be to have a method like: T LazyLoad<T>(Func<T> getter, Action<T> setter, Func<IFoo, T> loader) { ... } This option is very "meh" as well - it avoids Reflection but is still error-prone, and it doesn't really reduce the repetition that much. It's almost as bad as having to write explicit getters and setters for each property. Maybe I'm just being incredibly nit-picky, but this application is still in its early stages, and it's going to grow substantially over time, and I really want to keep the code squeaky-clean. Bottom line: I'm at an impasse, looking for other ideas. Question: Is there any way to clean up the lazy-loading code at the top, such that the implementation will: Guarantee compile-time safety, like the ref version; Actually reduce the amount of code repetition, like the Expression version; and Not take on any significant additional dependencies? In other words, is there a way to do this just using regular C# language features and possibly a few small helper classes? Or am I just going to have to accept that there's a trade-off here and strike one of the above requirements from the list?

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  • deploying gwt web application on jetty

    - by Azhar
    Hi I am deploying my web application created in Gwt on the jetty. I have used mongodb as my database.After starting the server it starts deploying the weapp.war and gives following error - 694 [main] INFO org.mortbay.log - Extract /usr/share/jetty/webapps/myapp.war to /tmp/Jetty_0_0_0_0_8090_myapp.war__myapp__n6yltk/webapp 3567 [main] WARN org.mortbay.log - failed Startup: java.lang.LinkageError: loader constraint violation: loader (instance of org/mortbay/jetty/webapp/WebAppClassLoader) previously initiated loading for a different type with name "javax/management/MBeanServer" at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:634) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) at java.net.URLClassLoader.access$000(URLClassLoader.java:73) at java.net.URLClassLoader$1.run(URLClassLoader.java:212) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:392) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:363) at com.mongodb.DBPortPool$Holder.get(DBPortPool.java:58) at com.mongodb.DBTCPConnector._set(DBTCPConnector.java:458) at com.mongodb.DBTCPConnector.<init>(DBTCPConnector.java:46) at com.mongodb.Mongo.<init>(Mongo.java:137) at com.mongodb.Mongo.<init>(Mongo.java:123)

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