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  • ROR accepts_nested_attributes_for one to many relationship with selection

    - by bilash.saha
    I have two models Doctors and Questions like the follwong: Doctor Model class Doctor < ActiveRecord::Base has_many :questions has_many :brands accepts_nested_attributes_for :questions end Question model class Question < ActiveRecord::Base belongs_to :discipline belongs_to :doctor belongs_to :brand end Now you can clearly see that Doctor has many questions and brands and question belongs to doctor and brand.I want to add previously saved question to a doctor from doctors edit page. I want to remove them as well.How can I proceed ? I tried like : <%= form.fields_for :questions, question,:child_index => (question.new_record? ? "index_to_replace_with_js" : nil) do |question_form| %> <table> <tr> <td> <div class="label">Select Question</div> <%= question_form.collection_select :id, Question.all, :id, :title ,{:include_blank => true } %> </td> </tr> </table> but this doesnot works for me.Can you give me a solution with proper example ?

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  • Assign C++ instance method to a global-function-pointer ?

    - by umanga
    Greetings, My project structure is as follows: \- base (C static library) callbacks.h callbacks.c paint_node.c . . * libBase.a \-app (C++ application) main.cpp In C library 'base' , I have declared global-function-pointer as: in singleheader file callbacks.h #ifndef CALLBACKS_H_ #define CALLBACKS_H_ extern void (*putPixelCallBack)(); extern void (*putImageCallBack)(); #endif /* CALLBACKS_H_ */ in single C file they are initialized as callbacks.c #include "callbacks.h" void (*putPixelCallBack)(); void (*putImageCallBack)(); Other C files access this callback-functions as: paint_node.c #include "callbacks.h" void paint_node(node *node,int index){ //Call callbackfunction . . putPixelCallBack(node->x,node->y,index); } I compile these C files and generate a static library 'libBase.a' Then in C++ application, I want to assign C++ instance method to this global function-pointer: I did something like follows : in Sacm.cpp file #include "Sacm.h" extern void (*putPixelCallBack)(); extern void (*putImageCallBack)(); void Sacm::doDetection() { putPixelCallBack=(void(*)())&paintPixel; //call somefunctions in 'libBase' C library } void Sacm::paintPixel(int x,int y,int index) { qpainter.begin(this); qpainter.drawPoint(x,y); qpainter.end(); } But when compiling it gives the error: sacmtest.cpp: In member function ‘void Sacm::doDetection()’: sacmtest.cpp:113: error: ISO C++ forbids taking the address of an unqualified or parenthesized non-static member function to form a pointer to member function. Say ‘&Sacm::paintPixel’ sacmtest.cpp:113: error: converting from ‘void (Sacm::)(int, int, int)’ to ‘void ()()’ Any tips?

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  • Setting acquired location to a text view: How to maintain?

    - by Mark
    Hi, I have built an app for the Motorola Droid which should automatically update a server with the phone's location. After the user performs a particular task on the main activity screen, an alarm is set to update the user's location periodically, using a service. The alarm is explicitly stopped when the user completes another task. Thing is, I have set up a location manager within the main activity's onCreate() method which is supposed to place the first acquired lat/long into two textview fields. Even though the manifest is set up for acquiring coarse and fine coords and I'm using requestLocationUpdates (String provider, long minTime, float minDistance, LocationListener listener), with minTime and minDistance set to zero, I'm not seeing the coords coming up on the screen. With that, I'm not recording any locations on the server. When I seed the textviews with sample coords, they are being recorded fine on the server. I am not at a computer that can run the IDE, so don't currently have the code, but am desperate for some help on this. One other thing is that the main activity screen calls a photography app before the user manually clicks "send data". I'm suspicious that I may need to override the main activity's onResume() method to do this location acquisition. Please help, thanks. Mark.

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  • When to drop an IT job

    - by Nippysaurus
    In my career I have had two programming jobs. Both these jobs were in a field that I am most familiar with (C# / MSSQL) but I have quit both jobs for the same reason: unmanageable code and bad (loose) company structure. There was something in common with both these jobs: small companies (in one I was the only developer). Currently I am in the following position: being given written instructions which are almost impossible to follow (somewhat of a fools errand). we are given short time constraints, but seldom asked how long work will take, and when we do it is always too long and needs to be shorter (and when it ends up taking longer than they need it to take, it's always our fault). there is no time for proper documenting, but we get blamed for not documenting (see previous point). Management is constantly screwing me around, saying I'm underperforming on a given task (which is not true, and switching me to a task which is much more confusing). So I must ask my fellow developers: how bad does a job need to be before you would consider jumping ship? And what to look out for when considering taking a job. In future I will be asking about documented procedures, release control, bug management and adoption of new technologies. EDIT: Let me add some more fuel to the fire ... I have been in my current job for just over a year, and the work I am doing almost never uses any of the knowledge I have gained from the other work I have been doing here. Everything is a giant learning curve. Because of this about 30% of my time is learning what is going on with this new product (who's owner / original developer has left the company), 30% trying to find the relevant documentation that helps the whole thing make sense, 30% actually finding where to make the change, 10% actually making the change.

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  • C++ Declarative Parsing Serialization

    - by Martin York
    Looking at Java and C# they manage to do some wicked processing based on special languaged based anotation (forgive me if that is the incorrect name). In C++ we have two problems with this: 1) There is no way to annotate a class with type information that is accessable at runtime. 2) Parsing the source to generate stuff is way to complex. But I was thinking that this could be done with some template meta-programming to achieve the same basic affect as anotations (still just thinking about it). Like char_traits that are specialised for the different types an xml_traits template could be used in a declaritive way. This traits class could be used to define how a class is serialised/deserialized by specializing the traits for the class you are trying to serialize. Example Thoughs: template<typename T> struct XML_traits { typedef XML_Empty Children; }; template<> struct XML_traits<Car> { typedef boost::mpl::vector<Body,Wheels,Engine> Children; }; template<typename T> std::ostream& Serialize(T const&) { // my template foo is not that strong. // but somthing like this. boost::mpl::for_each<typename XML_Traits<T>::Children,Serialize>(data); } template<> std::ostream& Serialize<XML_Empty>(T const&) { /* Do Nothing */ } My question is: Has anybody seen any projects/decumentation (not just XML) out there that uses techniques like this (template meta-programming) to emulate the concept of annotation used in languges like Java and C# that can then be used in code generation (to effectively automate the task by using a declaritive style). At this point in my research I am looking for more reading material and examples.

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  • How to change the link color of the current page with CSS

    - by Josh Curren
    How do I display the link for the current page different from the others? I would like to swap the colors of the text and background. This is what I currently have: The HTML: <div id="header"> <ul id="navigation"> <li class="bio"><a href="http://www.jacurren.com/">Home</a></li> <li class="theatre"><a href="http://www.jacurren.com/theatre.php">Theatre</a></li> <li class="prog"><a href="http://www.jacurren.com/programming.php">Programming</a></li> <li class="resume"><a href="http://www.jacurren.com/resume.php">R&eacute;sum&eacute;</a></li> <li class="portf"><a href="http://www.jacurren.com/portfolio.php">Portfolio</a></li> <li class="contact"><a href="http://www.jacurren.com/contact.php">Contact</a></li> </ul> </div> The CSS: #navigation{ margin:0; padding:0; background:#000000; height:34px; list-style:none; position: relative; top: 80px; } #navigation li{ float:left; clear:none; list-style:none; } #navigation li a{ color:#A60500; display:block; font-size:12px; text-decoration:none; font-weight:bold; padding:10px 18px; } #navigation li a:hover{ color:#640200; background-color:#000000; }

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  • Orbited exception Data must not be unicode.

    - by Sid
    I am working with orbited and once I switch on orbited in production mode it throws the following error on my screen -- <exception caught here> --- File "/usr/lib/python2.6/dist-packages/twisted/web/server.py", line 150, in process self.render(resrc) File "/usr/lib/python2.6/dist-packages/twisted/web/server.py", line 157, in render body = resrc.render(self) File "/usr/local/lib/python2.6/dist-packages/orbited-0.7.10-py2.6.egg/orbited/transports/base.py", line 21, in render self.conn.transportOpened(self) File "/usr/local/lib/python2.6/dist-packages/orbited-0.7.10-py2.6.egg/orbited/cometsession.py", line 322, in transportOpened self.cometTransport.flush() File "/usr/local/lib/python2.6/dist-packages/orbited-0.7.10-py2.6.egg/orbited/transports/base.py", line 45, in flush self.write(self.packets) File "/usr/local/lib/python2.6/dist-packages/orbited-0.7.10-py2.6.egg/orbited/transports/htmlfile.py", line 42, in write self.request.write(payload); File "/usr/lib/python2.6/dist-packages/twisted/web/http.py", line 862, in write self.transport.write(data) File "/usr/lib/python2.6/dist-packages/twisted/internet/tcp.py", line 420, in write abstract.FileDescriptor.write(self, bytes) File "/usr/lib/python2.6/dist-packages/twisted/internet/abstract.py", line 170, in write raise TypeError("Data must not be unicode") exceptions.TypeError: Data must not be unicode I have absolutely no clue as to what could be the problem. Could anyone point me in the right direction.

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  • CanCan polymorphic resource access problem

    - by Call 'naive' True
    Hi everybody, i don't quite understand how to restrict access to links in this particular case with CanCan. I always get "Edit" link displayed. So i believe the problem is in my incorrect definition of cancan methods(load_ and authorize_). I have CommentsController like that: class CommentsController < ApplicationController before_filter :authenticate_user! load_resource :instance_name => :commentable authorize_resource :article def index @commentable = find_commentable #loading our generic object end ...... private def find_commentable params.each { |name, value| if name =~ /(.+)_id$/ return $1.classify.constantize.includes(:comments => :karma).find(value) end } end end and i have in comments/index.html.erb following code that render file from other controller: <%= render :file => "#{get_commentable_partial_name(@commentable)}/show.html.erb", :collection => @commentable %> you can think about "#{get_commentable_partial_name(@commentable)}" like just "articles" in this case. Content of "articles/show.html.erb": <% if can? :update, @commentable %> <%= link_to 'Edit', edit_article_path(@commentable) %> | <% end %> my ability.rb: class Ability include CanCan::Ability def initialize(user) user ||= User.new # guest user if user.role? :admin can :manage, :all elsif user.role? :author can :read, [Article, Comment, Profile] can :update, Article, :user_id => user.id end end end relations with models is: class Comment < ActiveRecord::Base belongs_to :commentable, :polymorphic => true, :dependent => :destroy ... end class Article < ActiveRecord::Base has_many :comments, :as => :commentable, :dependent => :destroy ... end i have tried debug this issue like that user = User.first article = Article.first ability = Ability.new(user) ability.can?(:update, article) and i always get "= true" in ability check Note: user.role == author and article.user_id != user.id if you need more information please write thank's for your time && sorry for my english

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  • How to create a platform ontop of CSLA? <-- if in case it make sense

    - by Peejay
    Hi all! here is the senario, i'm developing an application using csla 3.8 / c#.net, the application will have different modules. its like an ERP, it will have accounting, daily time record, recruitment etc as modules. Now the requirement is to check for common entities per module and build a "platform" (<- the boss calls it that way) from it. for example, DTR will have an entity "employee", Recruitment will have "Applicant" so one common entity that you can derive from both that can be put in the platform is "Person". "Person" will contain typical info like name, address, contact info etc. I know it sounds like OOP 101. the thing is, i dont know how i am to go about it. how i wish it was just a simple inheritance but the requirement is like to create an API of some sort to be used by the modules using CSLA. in csla you create smart objects right, inheriting from the base classes of csla like businessListbase, readonlylistbase etc. right? what if for example i created a businessbase Applicant class, it will have properties like salary demand, availability date etc. now for the personal info i will need the "Person" from the "platform" and implement it to the applicant class. so in summary i have several questions: how to create such platform? if such platform is possible, how will it be implemented on each module's entities? (im already inheriting from base clases of csla) if incase 1 and 2 are possible, does it have advantages on development and maintenace of the app? the reason why i'm asking #3 is because the way i see it, even if i am able to create a platform for that, i will be needing to define properties of the platform entity on my module entities so to have validation and all. im sorry if i'm typing nonesense i'm really confused. hope someone could enlighten me. thank you all!

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  • What's the next steps for moving from appengine to full django?

    - by tomcritchlow
    Hey guys, I'm super new to programming and I've been using appengine to help me learn python and general coding. I'm getting better quickly and I'm loving it all the way :) Appengine was awesome for allowing me to just dive into writing my app and getting something live that works (see http://www.7bks.com/). But I'm realising that the longer I continue to learn on appengine the more I'm constraining myself and locking myself into a single system. I'd like to move to developing on full django (since django looks super cool!). What are my next steps? To give you a feel for my level of knowledge: I'm not a unix user I'm not familiar with command line controls (I still use appengine/python completely via the appengine SDK) I've never programmed in anything other than python, anywhere other than appengine I know the word SQL, but don't know what MySQL is really or how to use it. So, specifically: What are the skills I need to learn to get up and running with full django/python? If I'm going to host somewhere else I suppose I'll need to learn some sysadmin type skills (maybe even unix?). Is there anywhere that offers easy hosting (like appengine) but that supports django? I hear such great things about heroku I'm considering switching to RoR and going there I appreciate that I'm likely not quite ready to move away from appengine just yet but I'm a fiercely passionate learner (http://www.7bks.com/blog/179001) and would love it if I knew all the steps I needed to learn so I could set about learning them. At the moment, I don't even know what the steps are I need to learn! Thank you very much. Sorry this isn't a specific programming question but I've looked around and haven't found a good how-to for someone of my level of experience and I think others would appreciate a good roadmap for the things we need to learn to get up and running. Thanks, Tom PS - if anyone is in London and fancies showing me the ropes in person that would be super awesome :)

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  • Schema for element with Attributes and Child nodes

    - by Matthew
    I am trying to write xsd type schema for an element that has a custom type to include addition attributes to extend a base type. I am running into trouble getting the syntax right. <xs:element name="graphs"> <xs:complexType> <xs:sequence> <xs:element name="graph" minOccurs="1" maxOccurs="unbounded" type="graphType"> <!-- child elements --> </xs:element> </xs:sequence> </xs:complexType> </xs:element> <xs:complexType name="graphType"> <xs:simpleContent> <xs:extension base="xs:string"> <xs:attribute name="title" type="xs:string"/> <xs:attribute name="type" type="xs:string"/> </xs:extension> </xs:simpleContent> </xs:complexType> I thought this would be something very common, but having read many tuts and forums, I cant seem to find an answer that works for me.

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  • How to write a flexible modular program with good interaction possibilities between modules?

    - by PeterK
    I went through answers on similar topics here on SO but could't find a satisfying answer. Since i know this is a rather large topic, i will try to be more specific. I want to write a program which processes files. The processing is nontrivial, so the best way is to split different phases into standalone modules which then would be used as necessary (since sometimes i will be only interested in the output of module A, sometimes i would need output of five other modules, etc). The thing is, that i need the modules to cooperate, because the output of one might be the input of another. And i need it to be FAST. Moreover i want to avoid doing certain processing more than once (if module A creates some data which then need to be processed by module B and C, i don't want to run module A twice to create the input for modules B,C ). The information the modules need to share would mostly be blocks of binary data and/or offsets into the processed files. The task of the main program would be quite simple - just parse arguments, run required modules (and perhaps give some output, or should this be the task of the modules?). I don't need the modules to be loaded at runtime. It's perfectly fine to have libs with a .h file and recompile the program every time there is a new module or some module is updated. The idea of modules is here mainly because of code readability, maintaining and to be able to have more people working on different modules without the need to have some predefined interface or whatever (on the other hand, some "guidelines" on how to write the modules would be probably required, i know that). We can assume that the file processing is a read-only operation, the original file is not changed. Could someone point me in a good direction on how to do this in C++ ? Any advice is wellcome (links, tutorials, pdf books...).

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  • c++ Design pattern for CoW, inherited classes, and variable shared data?

    - by krunk
    I've designed a copy-on-write base class. The class holds the default set of data needed by all children in a shared data model/CoW model. The derived classes also have data that only pertains to them, but should be CoW between other instances of that derived class. I'm looking for a clean way to implement this. If I had a base class FooInterface with shared data FooDataPrivate and a derived object FooDerived. I could create a FooDerivedDataPrivate. The underlying data structure would not effect the exposed getters/setters API, so it's not about how a user interfaces with the objects. I'm just wondering if this is a typical MO for such cases or if there's a better/cleaner way? What peeks my interest, is I see the potential of inheritance between the the private data classes. E.g. FooDerivedDataPrivate : public FooDataPrivate, but I'm not seeing a way to take advantage of that polymorphism in my derived classes. class FooDataPrivate { public: Ref ref; // atomic reference counting object int a; int b; int c; }; class FooInterface { public: // constructors and such // .... // methods are implemented to be copy on write. void setA(int val); void setB(int val); void setC(int val); // copy constructors, destructors, etc. all CoW friendly private: FooDataPrivate *data; }; class FooDerived : public FooInterface { public: FooDerived() : FooInterface() {} private: // need more shared data for FooDerived // this is the ???, how is this best done cleanly? };

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  • Problem creating a custom input element using FluentHtml (MVCContrib)

    - by seth
    Hi there, I just recently started dabbling in ASP.NET MVC 1.0 and came across the wonderful MVCContrib. I had originally gone down the path of creating some extended html helpers, but after finding FluentHTML decided to try my hand at creating a custom input element. Basically I am wanting to ultimately create several custom input elements to make it easier for some other devs on the project I'm working on to add their input fields to the page and have all of my preferred markup to render for them. So, in short, I'd like to wrap certain input elements with additional markup.. A TextBox would be wrapped in an <li /> for example. I've created my custom input elements following Tim Scott's answer in another question on here: DRY in the MVC View. So, to further elaborate, I've created my class, "TextBoxListItem": public class TextBoxListItem : TextInput<TextBox> { public TextBoxListItem (string name) : base(HtmlInputType.Text, name) { } public TextBoxListItem (string name, MemberExpression forMember, IEnumerable<IBehaviorMarker> behaviors) : base(HtmlInputType.Text, name, forMember, behaviors) { } public override string ToString() { var liBuilder = new TagBuilder(HtmlTag.ListItem); liBuilder.InnerHtml = ToString(); return liBuilder.ToString(TagRenderMode.SelfClosing); } } I've also added it to my ViewModelContainerExtensions class: public static TextBox TextBoxListItem<T>(this IViewModelContainer<T> view, Expression<Func<T, object>> expression) where T : class { return new TextBoxListItem(expression.GetNameFor(view), expression.GetMemberExpression(), view.Behaviors) .Value(expression.GetValueFrom(view.ViewModel)); } And lastly, I've added it to ViewDataContainerExtensions as well: public static TextBox TextBoxListItem(this IViewDataContainer view, string name) { return new TextBox(name).Value(view.ViewData.Eval(name)); } I'm calling it in my view like so: <%= this.TextBoxListItem("username").Label("Username:") %> Anyway, I'm not getting anything other than the standard FluentHTML TextBox, not wrapped in <li></li> elements. What am I missing here? Thanks very much for any assistance.

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  • Retrieving models from form with ModelMultipleChoiceField

    - by colinjameswebb
    I am having difficulties with forms, specifically ModelMultipleChoiceField. I've pieced together this code from various examples, but it sadly doesn't work. I would like to be able to: Search for some Works on work_search.html Display the results of the search, with checkboxes next to each result Select the Works I want, via the checkboxes After pressing Add, display which works were selected. I believe everything is okay except the last part. The page simply displays "works" :( Here is the code - sorry about the length. Models.py class Work(models.Model): title = models.CharField(max_length=200) artist = models.CharField(max_length=200) writers = models.CharField(max_length=200) def __unicode__(self): return self.title + ' - ' + self.artist forms.py class WorkSelectForm(forms.Form): def __init__(self, queryset, *args, **kwargs): super(WorkSelectForm, self).__init__(*args, **kwargs) self.fields['works'] = forms.ModelMultipleChoiceField(queryset=queryset, widget=forms.CheckboxSelectMultiple()) views.py def work_search(request): query = request.GET.get('q', '') if query: qset = ( Q(title__icontains=query) | Q(artist__icontains=query) | Q(writers__icontains=query) ) results = Work.objects.filter(qset).distinct() form = WorkSelectForm(results) return render_to_response("work_search.html", {"form": form, "query": query }) else: results = [] return render_to_response("work_search.html", {"query": query }) def add_works(request): #if request.method == POST: form = WorkSelectForm(request.POST) #if form.isvalid(): items = form.fields['works'].queryset return render_to_response("add_works.html", {"items":items}) work_search.html {% extends "base.html" %} {% block content %} <h1>Search</h1> <form action="." method="GET"> <label for="q">Search: </label> <input type="text" name="q" value="{{ query|escape }}"> <input type="submit" value="Search"> </form> {% if query %} <h2>Results for "{{ query|escape }}":</h2> <form action="add_works" method="post"> <ul> {% if form %} {{ form.as_ul }} {% endif %} </ul> <input type="submit" value="Add"> </form> {% endif %} {% endblock %} add_works.html {% extends "base.html" %} {% block content %} {% if items %} {% for item in items %} {{ item }} {% endfor %} {% else %} <p>Nothing selected</p> {% endif %} {% endblock %}

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  • Creating PowerShell Automatic Variables from C#

    - by Uros Calakovic
    I trying to make automatic variables available to Excel VBA (like ActiveSheet or ActiveCell) also available to PowerShell as 'automatic variables'. PowerShell engine is hosted in an Excel VSTO add-in and Excel.Application is available to it as Globals.ThisAddin.Application. I found this thread here on StackOverflow and started created PSVariable derived classes like: public class ActiveCell : PSVariable { public ActiveCell(string name) : base(name) { } public override object Value { get { return Globals.ThisAddIn.Application.ActiveCell; } } } public class ActiveSheet : PSVariable { public ActiveSheet(string name) : base(name) { } public override object Value { get { return Globals.ThisAddIn.Application.ActiveSheet; } } } and adding their instances to the current POwerShell session: runspace.SessionStateProxy.PSVariable.Set(new ActiveCell("ActiveCell")); runspace.SessionStateProxy.PSVariable.Set(new ActiveSheet("ActiveSheet")); This works and I am able to use those variables from PowerShell as $ActiveCell and $ActiveSheet (their value change as Excel active sheet or cell change). Then I read PSVariable documentation here and saw this: "There is no established scenario for deriving from this class. To programmatically create a shell variable, create an instance of this class and set it by using the PSVariableIntrinsics class." As I was deriving from PSVariable, I tried to use what was suggested: PSVariable activeCell = new PSVariable("ActiveCell"); activeCell.Value = Globals.ThisAddIn.Application.ActiveCell; runspace.SessionStateProxy.PSVariable.Set(activeCell); Using this, $ActiveCell appears in my PowerShell session, but its value doesn't change as I change the active cell in Excel. Is the above comment from PSVariable documentation something I should worry about, or I can continue creating PSVariable derived classes? Is there another way of making Excel globals available to PowerShell?

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  • Alternative to using c:out to prevent XSS

    - by lynxforest
    I'm working on preventing cross site scripting (XSS) in a Java, Spring based, Web application. I have already implemented a servlet filter similar to this example http://greatwebguy.com/programming/java/simple-cross-site-scripting-xss-servlet-filter/ which sanitizes all the input into the application. As an extra security measure I would like to also sanitize all output of the application in all JSPs. I have done some research to see how this could be done and found two complementary options. One of them is the use of Spring's defaultHtmlEscape attribute. This was very easy to implement (a few lines in web.xml), and it works great when your output is going through one of spring's tags (ie: message, or form tags). The other option I have found is to not directly use EL expressions such as ${...} and instead use <c:out value="${...}" /> That second approach works perfectly, however due to the size of the application I am working on (200+ JSP files). It is a very cumbersome task to have to replace all inappropriate uses of EL expressions with the c:out tag. Also it would become a cumbersome task in the future to make sure all developers stick to this convention of using the c:out tag (not to mention, how much more unreadable the code would be). Is there alternative way to escape the output of EL expressions that would require fewer code modifications? Thank you in advance.

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  • one two-directed tcp socket of two one-directed? (linux, high volume, low latency)

    - by osgx
    Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE network benchmark - measure latency and bandwidth for sizes from 2^1 up to 2^13 bytes, each size sent and received 3 times at least (in teal task the number of sends is greater. both processes will be sending and receiving, like ping-pong maybe). The benefit of 2 uni-directed connections come from linux: http://lxr.linux.no/linux+v2.6.18/net/ipv4/tcp_input.c#L3847 3847/* 3848 * TCP receive function for the ESTABLISHED state. 3849 * 3850 * It is split into a fast path and a slow path. The fast path is 3851 * disabled when: ... 3859 * - Data is sent in both directions. Fast path only supports pure senders 3860 * or pure receivers (this means either the sequence number or the ack 3861 * value must stay constant) ... 3863 * 3864 * When these conditions are not satisfied it drops into a standard 3865 * receive procedure patterned after RFC793 to handle all cases. 3866 * The first three cases are guaranteed by proper pred_flags setting, 3867 * the rest is checked inline. Fast processing is turned on in 3868 * tcp_data_queue when everything is OK. All other conditions for disabling fast path is false. And only not-unidirected socket stops kernel from fastpath in receive

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  • one two-directed tcp socket OR two one-directed? (linux, high volume, low latency)

    - by osgx
    Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE network benchmark - measure latency and bandwidth for sizes from 2^1 up to 2^13 bytes, each size sent and received 3 times at least (in teal task the number of sends is greater. both processes will be sending and receiving, like ping-pong maybe). The benefit of 2 uni-directed connections come from linux: http://lxr.linux.no/linux+v2.6.18/net/ipv4/tcp_input.c#L3847 3847/* 3848 * TCP receive function for the ESTABLISHED state. 3849 * 3850 * It is split into a fast path and a slow path. The fast path is 3851 * disabled when: ... 3859 * - Data is sent in both directions. Fast path only supports pure senders 3860 * or pure receivers (this means either the sequence number or the ack 3861 * value must stay constant) ... 3863 * 3864 * When these conditions are not satisfied it drops into a standard 3865 * receive procedure patterned after RFC793 to handle all cases. 3866 * The first three cases are guaranteed by proper pred_flags setting, 3867 * the rest is checked inline. Fast processing is turned on in 3868 * tcp_data_queue when everything is OK. All other conditions for disabling fast path is false. And only not-unidirected socket stops kernel from fastpath in receive

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  • C# class can not disguise to be another class because GetType method cannot be override

    - by zinking
    there is a statement in the CLR via C# saying in C#, one class cannot disguise to be another, because GetType is virutal and thus it cannot be override but I think in C# we can still hide the parent implementation of GetType. I must missed something if I hide the base GetType implementation then I can disguise my class to be another class, is that correct? The key here is not whether GetType is virutal or not, the question is can we disguise one class to be another in C# Following is the NO.4 answer from the possible duplicate, so My question is more on this. is this kind of disguise possible, if so, how can we say that we can prevent class type disguise in C# ? regardless of the GetType is virtual or not While its true that you cannot override the object.GetType() method, you can use "new" to overload it completely, thereby spoofing another known type. This is interesting, however, I haven't figured out how to create an instance of the "Type" object from scratch, so the example below pretends to be another type. public class NotAString { private string m_RealString = string.Empty; public new Type GetType() { return m_RealString.GetType(); } } After creating an instance of this, (new NotAString()).GetType(), will indeed return the type for a string. share|edit|flag answered Mar 15 at 18:39 Dr Snooze 213 By almost anything that looks at GetType has an instance of object, or at the very least some base type that they control or can reason about. If you already have an instance of the most derived type then there is no need to call GetType on it. The point is as long as someone uses GetType on an object they can be sure it's the system's implementation, not any other custom definition. – Servy Mar 15 at 18:54 add comment

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  • Blocking error in celery

    - by dmitry
    I have no idea what's this. Python 2.7 + django-1.5.1 + httpd + rabbitmq + django-celery==3.0.17 Tasks are not executed because of some error. Below is celery's log. Maybe someone has faced it before. [2013-06-24 17:10:03,792: CRITICAL/MainProcess] Can't decode message body: AttributeError("'JoinInfo' object has no attribute '__dict__'",) (type:u'application/x-python-serialize' encoding:u'binary' raw:'\'\\x80\\x02}q\\x01(U\\x07expiresq\\x02NU\\x03utcq\\x03\\x88U\\x04argsq\\x04cdjango.contrib.auth.models\\nUser\\nq\\x05)\\x81q\\x06}q\\x07(U\\x08usernameq\\x08X\\x19\\x00\\x00\\[email protected]\\nfirst_nameq\\tX\\x05\\x00\\x00\\x00BibbyU\\tlast_nameq\\nX\\x08\\x00\\x00\\x00OffshoreU\\r_client_cacheq\\x0bccopy_reg\\n_reconstructor\\nq\\x0ccbongoregistration.models\\nClient\\nq\\rc__builtin__\\nobject\\nq\\x0eN\\x87Rq\\x0f}q\\x10(h\\nX\\x08\\x00\\x00\\x00OffshoreU\\x1bpurchase_confirmation_emailq\\x11X\\x1f\\x00\\x00\\[email protected]\\x1dpurchase_confirmation_email_1q\\x12X!\\x00\\x00\\[email protected]\\x06_stateq\\x13cdjango.db.models.base\\nModelState\\nq\\x14)\\x81q\\x15}q\\x16(U\\x06addingq\\x17\\x89U\\x02dbq\\x18U\\x07defaultq\\x19ubU\\x0buser_ptr_idq\\x1aJ\\xb4\\xa2\\x03\\x00U\\x08is_staffq\\x1b\\x89U\\x08postcodeq\\x1cX\\x08\\x00\\x00\\x00AB11 5BSU\\x0cdegree_limitq\\x1dK\\x06U\\x07messageq\\x1eX\\xd1E\\x00\\x00<table id="container" style="margin: 0px; padding: 0px; width: 100%; background-color: #ffffff;" cellspacing="0" cellpadding="0"... (22911b)'') Traceback (most recent call last): File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/messaging.py", line 556, in _receive_callback decoded = None if on_m else message.decode() File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/transport/base.py", line 147, in decode self.content_encoding, accept=self.accept) File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/serialization.py", line 187, in decode return decode(data) File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/serialization.py", line 74, in pickle_loads return load(BytesIO(s)) AttributeError: 'JoinInfo' object has no attribute '__dict__'

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  • Spring Security ACL: NotFoundException from JDBCMutableAclService.createAcl

    - by user340202
    Hello, I've been working on this task for too long to abandon the idea of using Spring Security to achieve it, but I wish that the community will provide with some support that will help reduce the regret that I have for choosing Spring Security. Enough ranting and now let's get to the point. I'm trying to create an ACL by using JDBCMutableAclService.createAcl as follows: [code] public void addPermission(IWFArtifact securedObject, Sid recipient, Permission permission, Class clazz) { ObjectIdentity oid = new ObjectIdentityImpl(clazz.getCanonicalName(), securedObject.getId()); this.addPermission(oid, recipient, permission); } @Override @Transactional(propagation = Propagation.REQUIRED, isolation = Isolation.READ_UNCOMMITTED, readOnly = false) public void addPermission(ObjectIdentity oid, Sid recipient, Permission permission) { SpringSecurityUtils.assureThreadLocalAuthSet(); MutableAcl acl; try { acl = this.mutableAclService.createAcl(oid); } catch (AlreadyExistsException e) { acl = (MutableAcl) this.mutableAclService.readAclById(oid); } // try { // acl = (MutableAcl) this.mutableAclService.readAclById(oid); // } catch (NotFoundException nfe) { // acl = this.mutableAclService.createAcl(oid); // } acl.insertAce(acl.getEntries().length, permission, recipient, true); this.mutableAclService.updateAcl(acl); } [/code] The call throws a NotFoundException from the line: [code] // Retrieve the ACL via superclass (ensures cache registration, proper retrieval etc) Acl acl = readAclById(objectIdentity); [/code] I believe this is caused by something related to Transactional, and that's why I have tested with many TransactionDefinition attributes. I have also doubted the annotation and tried with declarative transaction definition, but still with no luck. One important point is that I have used the statement used to insert the oid in the database earlier in the method directly on the database and it worked, and also threw a unique constraint exception at me when it tried to insert it in the method. I'm using Spring Security 2.0.8 and IceFaces 1.8 (which doesn't support spring 3.0 but definetely supprorts 2.0.x, specially when I keep caling SpringSecurityUtils.assureThreadLocalAuthSet()). My AppServer is Tomcat 6.0, and my DB Server is MySQL 6.0 I wish to get back a reply soon because I need to get this task off my way

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  • SQL n:m Inheritance join

    - by Nightmares
    I want to join a table which contains n:m relationship between groups. (Groups are defined in a separate table). This table only has entries listing a member_group_id and a parent_group_id. Given this structure: id(int) | member_group_id(int) | parent_group_id(int) The "base" query looks like this: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.member_group_id = p1.member_group_id The "base" query correctly shows all relationships (I checked by doing it manually.) The problem is when I try to apply a where clause to this query to filter for a specific group as "point of origin" (the first group for which I want all parent groups) it returns only the closest parents. For example like this: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.member_group_id = p1.member_group_id where p1.group_id = 1 Can anyone give a clue how I can fix this? Or a different approach to realize this. (I suppose I could always do this in my C++ source code on the server side but I would have to transfer a entire table which has a high growth potential to the application server.) UPDATE: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.group_id = p1.member_group_id Typing mistake confirmed. Now I don't get past first level of inheritance period. Thanks at denied for pointing that out.

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  • Can't get KnownType to work with WCF

    - by Kelly Cline
    I have an interface and a class defined in separate assemblies, like this: namespace DataInterfaces { public interface IPerson { string Name { get; set; } } } namespace DataObjects { [DataContract] [KnownType( typeof( IPerson ) ) ] public class Person : IPerson { [DataMember] public string Name { get; set; } } } This is my Service Interface: public interface ICalculator { [OperationContract] IPerson GetPerson ( ); } When I update my Service Reference for my Client, I get this in the Reference.cs: public object GetPerson() { return base.Channel.GetPerson(); I was hoping that KnownType would give me IPerson instead of "object" here. I have also tried [KnownType( typeof( Person ) ) ] with the same result. I have control of both client and server, so I have my DataObjects (where Person is defined) and DataInterfaces (where IPerson is defined) assemblies in both places. Is there something obvious I am missing? I thought KnownType was the answer to being able to use interfaces with WCF. ----- FURTHER INFORMATION ----- I removed the KnownType from the Person class and added [ServiceKnownType( typeof( Person ) ) ] to my service interface, as suggested by Richard. The client-side proxy still looks the same, public object GetPerson() { return base.Channel.GetPerson(); , but now it doesn't blow up. The client just has an "object", though, so it has to cast it to IPerson before it is useful. var person = client.GetPerson ( ); Console.WriteLine ( ( ( IPerson ) person ).Name );

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  • How can I send rich emails using the user's mail client ?

    - by Brann
    I need my .net program to send rich emails (usually containing table data, around 20 columns x 10 rows) using the user's mail infrastructure, allowing him to review/edit the mail before sending it, and storing the mail in his 'sent items' folder. mailto: seems the obvious choice, but unfortunately, it doesn't support neither attachments nor html bodies. It seems some clients support some extra features (e.g. Outlook 97 used to support a &Attach tag, but this is not the case for more recent versions). I could use mailto and try to format the text body to look nice (using tabs, etc), but this isn't really elegant and wouldn't support huge data. using automation seems a very huge task, as I would need to automate dozens of clients (4 or 5 versions of outlook, lotusnotes, thunderbid, etc.) ... This would be a huge task and it's not really my core business ... I could send emails through code and write my own mail form to let the user edit the mail, but this would have a lot of drawbacks : the user would need to manually configure the mail server settings he wouldn't have access to his contact directory the mail wouldn't be sent in his sent items folder This seems a quite common issue, but I haven't found any satisfying solution yet ; does someone knows of a library supporting this (ie containing automation logic for most mainstream email clients?). Or an alternative to mailto ?

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