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  • Installing Paperclip - "undefined method `has_attached_file` for" - Ruby on Rails

    - by bgadoci
    I just installed the plugin for Paperclip and I am getting an error message "undefined method has_attached_file for. Not sure why I am getting this. Here is the full error message. NoMethodError (undefined method `has_attached_file' for #<Class:0x10338acd0>): /Users/bgadoci/.gem/ruby/1.8/gems/will_paginate-2.3.12/lib/will_paginate/finder.rb:170:in `method_missing' app/models/post.rb:2 app/controllers/posts_controller.rb:50:in `show' For some reason it is referencing the will_paginate gem. From what I can find, it seems that either there is something wrong w/ my PostsController#index or perhaps a previously attempt at installing the gem instead of the plugin (in which case I have read I should be able to remedy through the /config/environments.rb file somehow). I didn't think that previous gem installation would matter as I did it in an old version of the site that I trashed before installing the plugin. In the current version of the site I show that the Table has been updated with the Paperclip columns after migration. Here is my code: PostsController#index def index @tag_counts = Tag.count(:group => :tag_name, :order => 'count_all DESC', :limit => 20) conditions, joins = {}, :votes @vote_counts = Vote.count(:group => :post_title, :order => 'count_all DESC', :limit => 20) conditions, joins = {}, :votes unless(params[:tag_name] || "").empty? conditions = ["tags.tag_name = ? ", params[:tag_name]] joins = [:tags, :votes] end @posts=Post.paginate( :select => "posts.*, count(*) as vote_total", :joins => joins, :conditions=> conditions, :group => "votes.post_id", :order => "created_at DESC", :page => params[:page], :per_page => 5) @popular_posts=Post.paginate( :select => "posts.*, count(*) as vote_total", :joins => joins, :conditions=> conditions, :group => "votes.post_id", :order => "vote_total DESC", :page => params[:page], :per_page => 3) respond_to do |format| format.html # index.html.erb format.xml { render :xml => @posts } format.json { render :json => @posts } format.atom end end Post Model class Post < ActiveRecord::Base has_attached_file :photo validates_presence_of :body, :title has_many :comments, :dependent => :destroy has_many :tags, :dependent => :destroy has_many :votes, :dependent => :destroy belongs_to :user after_create :self_vote def self_vote # I am assuming you have a user_id field in `posts` and `votes` table. self.votes.create(:user => self.user) end cattr_reader :per_page @@per_page = 10 end /views/posts/new.html.erb <h1>New post</h1> <%= link_to 'Back', posts_path %> <% form_for(@post, :html => { :multipart => true}) do |f| %> <%= f.error_messages %> <p> <%= f.label :title %><br /> <%= f.text_field :title %> </p> <p> <%= f.label :body %><br /> <%= f.text_area :body %> </p> <p> <%= f.file_field :photo %> </p> <p> <%= f.submit 'Create' %> </p> <% end %>

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  • Runge-Kutta (RK4) integration for game physics

    - by Kai
    Gaffer on Games has a great article about using RK4 integration for better game physics. The implementation is straightforward but the math behind it confuses me. I understand derivatives and integrals on a conceptual level but I haven't manipulated equations in a long time. Here's the brunt of Gaffer's implementation: void integrate(State &state, float t, float dt) { Derivative a = evaluate(state, t, 0.0f, Derivative()); Derivative b = evaluate(state, t+dt*0.5f, dt*0.5f, a); Derivative c = evaluate(state, t+dt*0.5f, dt*0.5f, b); Derivative d = evaluate(state, t+dt, dt, c); const float dxdt = 1.0f/6.0f * (a.dx + 2.0f*(b.dx + c.dx) + d.dx); const float dvdt = 1.0f/6.0f * (a.dv + 2.0f*(b.dv + c.dv) + d.dv) state.x = state.x + dxdt * dt; state.v = state.v + dvdt * dt; } Can anybody explain in simple terms how RK4 works? Specifically, why are we averaging the derivatives at 0.0f, 0.5f, 0.5f, and 1.0f? How is averaging derivatives up to the 4th order different from doing a simple euler integration with a smaller timestep? After reading the accepted answer below, and several other articles, I have a grasp on how RK4 works. To answer my own questions: Can anybody explain in simple terms how RK4 works? RK4 takes advantage of the fact that we can get a much better approximation of a function if we use its higher-order derivatives rather than just the first or second derivative. That's why the Taylor series converges much faster than Euler approximations. (take a look at the animation on the right side of that page) Specifically, why are we averaging the derivatives at 0.0f, 0.5f, 0.5f, and 1.0f? The Runge-Kutta method is an approximation of a function that samples derivatives of several points within a timestep, unlike the Taylor series which only samples derivatives of a single point. After sampling these derivatives we need to know how to weigh each sample to get the closest approximation possible. An easy way to do this is to pick constants that coincide with the Taylor series, which is how the constants of a Runge-Kutta equation are determined. This article made it clearer for me: http://web.mit.edu/10.001/Web/Course%5FNotes/Differential%5FEquations%5FNotes/node5.html. Notice how (15) is the Taylor series expansion while (17) is the Runge-Kutta derivation. How is averaging derivatives up to the 4th order different from doing a simple euler integration with a smaller timestep? Mathematically it converges much faster than doing many Euler approximations. Of course, with enough Euler approximations we can gain equal accuracy to RK4, but the computational power needed doesn't justify using Euler.

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  • Xtragrid Devexpress SetRowcellValue

    - by Learner
    const int index = 1; object val = repositoryItemComboBox3.Items[index]; gridView2.SetRowCellValue(gridView2.FocusedRowHandle, object w= gridView2.GetRowCellValue(gridView2.FocusedRowHandle, "gridColumn3",val); but w does not gets updated what do I have to do more?

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  • Raudus vs ExtPascal: Delphi web developement alternatives that use ExtJS

    - by user193655
    Delphi developers has several tools (several alternatives to ASP.NET) for building web applications. While No.1 framework is Intraweb, there is a lot of interest around ExtJS, that has 2 incarnations: 1) the opensource ExtPascal 2) the closedsource Raudus Now the products are different, Raudus never supports the latest ExtJS version (while ExtPascal does because as far as I read it "almost automatically updates itself to the latest ExJS version"), Raudus "seems" much RAD (much similar to Intraweb from the RAD point of view). Anyway why chose one or the other? Why Raudus (since it is free) cannot become Open Source? Or does Raudus use ExtPascal behind the scenes?

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  • ExtJS GridPanel Scrollbar does not appear in IE7 but it does in Firefox, etc

    - by Snowright
    Setup I have an accordion layout containing a "properties" panel that nests two inner panels. The first inner panel holds a Ext.DataView, while the second panel is the Ext.grid.GridPanel in question. In the screenshot below, the white space containing the folder icon is the dataview, and below that is the gridpanel. Problem In Firefox, Chrome, and Opera, there is a scrollbar that appears when my gridpanel has an overflow of properties. It is only in Internet Explorer that it does not appear. I am, however, able to scroll using my mouse scroll button in all browsers, including IE. I've also tried removing our custom css file in case it was affecting it somehow, but there was no change in doing so. I'm not sure exactly what code I should show as I don't know where the exact problem is coming from but here is the code for the mainpanel and gridpanel. var mainPanel = new Ext.Panel({ id : 'main-property-panel', title : 'Properties', height : 350, autoWidth : true, tbar : [comboPropertyActions], items : [panel1] //panel1 holds the DataView }); var propertiesGrid = new Ext.grid.GridPanel({ stripeRows : true, height : mainPanel.getSize().height-iconDataView.getSize().height-mainPanel.getFrameHeight(), autoWidth : true, store : propertiesStore, cm : propertiesColumnModel }) //Add gridpanel to mainPanel mainPanel.add(propertiesGrid); mainPanel.doLayout(); Any help into the right direction would be greatly appreciated. Thank you.

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  • How do you set tab view to scroll?

    - by DrogoNevets
    I have managed to set up a tabbed view for my app (woo!) and have the following xml for the UI <TabHost xmlns:android="http://schemas.android.com/apk/res/android" android:id="@android:id/tabhost" android:layout_width="fill_parent" android:layout_height="wrap_content"> <LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="5dp"> <TabWidget android:id="@android:id/tabs" android:layout_width="fill_parent" android:layout_height="wrap_content" /> <FrameLayout android:id="@android:id/tabcontent" android:layout_width="fill_parent" android:layout_height="fill_parent" /> </LinearLayout> <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <Spinner android:id="@+id/areaSpinner" android:layout_width="fill_parent" android:layout_height="@dimen/one_row" /> <Spinner android:id="@+id/cragSpinner" android:layout_width="fill_parent" android:layout_height="@dimen/one_row" /> <Spinner android:id="@+id/routeSpinner" android:layout_width="fill_parent" android:layout_height="@dimen/one_row" /> <DatePicker android:id="@+id/dateClimbed" android:layout_width="fill_parent" android:layout_height="wrap_content" /> <Spinner android:id="@+id/styleSpinner" android:layout_width="fill_parent" android:layout_height="@dimen/one_row" /> <Spinner android:id="@+id/detailsSpinner" android:layout_width="fill_parent" android:layout_height="@dimen/one_row" /> <TextView android:id="@+id/climbNotes" android:layout_width="fill_parent" android:layout_height="@dimen/three_row" /> </LinearLayout> yet am seemingly unable to scroll down to see the rest of the form (cuts off at one of the spinners, why is this? and how do i fix it?

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  • CSS/HTML: How to simulate IFRAME with CSS?

    - by BBnight
    I want to have a header DIV and a footer DIV always displayed on my web page, regardless of when you scroll down the page. How do I accomplish this using only CSS (without IFRAMES) For example: <div id=header>Always display on top, regardless if you have scrolled down the page</div> <div id=main_content>...</div> <div id=footer>Always display on the bottom</div>

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  • A simple augmented reality application in C#

    - by Ian
    Hi All, I would like to start a personal project that will give me a lot of new concept to learn and understand. After some thought, I figured that an Augmented Reality related project will be the most beneficial for me because of the following reasons: I haven't tried interfacing a program with a live video/camera feed I haven't done any "image processing" project I haven't done any "graphics rendering" ever With that said, you can assume that I will totally suck at AR. So I'm here to ask for some advice regarding the best way to go through this. st milestone project that I am thinking of is to take a cheap webcam and read some Data Matrix using C#. nd milestone project will render some text-overlay on the feed when presented with a certain Data Matrix. rd milestone project will actually render some 3D shapes. I've searched all-around and found some nice yet advanced materials for AR: http://sites.google.com/site/augmentedrealitytestingsite/ http://soldeveloper.com/ http://www.mperfect.net/wpfAugReal/ So I came here to ask the following: Do you think my milestone is reasonable given my "deficiencies"? In order to start Milestone 1, can you give some materials that I can study? I prefer online materials. Thanks!

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  • Component based game engine design

    - by a_m0d
    I have been looking at game engine design (specifically focused on 2d game engines, but also applicable to 3d games), and am interested in some information on how to go about it. I have heard that many engines are moving to a component based design nowadays rather than the traditional deep-object hierarchy. Do you know of any good links with information on how these sorts of designs are often implemented? I have seen evolve your hierarchy, but I can't really find many more with detailed information (most of them just seem to say "use components rather than a hierarchy" but I have found that it takes a bit of effort to switch my thinking between the two models). Any good links or information on this would be appreciated, and even books, although links and detailed answers here would be preferred.

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  • Map external directory to web.xml

    - by prometheus
    Is there an easy way to map a directory in the web.xml or other deployment descriptor (jetty.xml, etc) files? For example, if I have a directory /opt/files/ is there a way that I can access its files and sub-directories by visiting http://localhost/some-mapping/? It strikes me that there should be some simple way of doing this, but I haven't been able to find out how (via google, stackoverflow, etc). All I've found are servlets that mimic fileservers, which is not what I would like. For reference I am using jetty on an AIX box.

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  • QtWebKit problems playing HTML5 video

    - by oskar
    I have a simple Qt application that launches a window with a QWebView. I tried several sites using the video tag with h.264, and it either can't play the video at all (as in youtube or sublime video), or it renders the video poorly, with black lines covering parts of it, like when viewing the video here. Is this a known issue with QtWebKit, or have I neglected to do something that would make it work better? My code is below. #include <QtGui/QApplication> #include <QWebView> int main(int argc, char *argv[]) { QApplication a(argc, argv); QWebView *view = new QWebView(); view->load(QUrl("http://webkit.org/blog/140/html5-media-support/")); view->show(); return a.exec(); }

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  • How do I create Tetris Blocks in XNA with C#?

    - by Slateboard
    I'm making a Tetris Clone in C# with XNA, and I'm unsure of how to actually implement the blocks. I don't think that making the shapes as images will work (because parts are removed when lines are formed), so I Have blocks to make up the pieces like This. Unfortunately, I don't know how to actually define the blocks to make the pieces, nor do I know how to manipulate them to make them rotate, etc. Edit: I would also need assistance in learning how to make the Tetris Grid too.

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  • Developing for Mac, without a Mac.

    - by speeder
    Hello I am a "lone wolf" game developer, and games sell more on Mac (because noone make Mac games... bizarre), so I need to make Mac games. My problem is: I don't own a Mac, and I have no way to get one (unless someone donate one to me...), I don't have money even to upgrade my crappy 3 year old PC, or buy a netbook... So, how I develop for Mac without a Mac? I guess that if I installed Mac OS on my machine, it would do, or can I just use Open Darwin instead? Or Mac OS run on virtual machines?

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  • Using Clojure with Vaadin

    - by Icarus
    Hi, Has anyone tried implementing a web application with Clojure ( using Compojure ) and Vaadin ? I had seen an article on using Clojure with JWT for creating web apps. Vaadin is based on GWT so you get a lot of the advantages of GWT ( though Vaadin is completely Server-centric). And Clojure gives the advantage that you can use any Java Based Framework, so what thoughts on the Clojure + Vaadin based web application ?

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  • C# XNA: AI Engine?

    - by Rosarch
    I'm developing a game with zombie running around in a swamp. I want AIs to have functionality like "chase this target" or "run away". A major stumbling block is pathfinding. Is there a good pathfinding/AI engine in XNA, or should I roll my own? Does anyone have any experience with this: http://www.codeplex.com/simpleAI?

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  • Adding custom options in binded dropdown in asp.net

    - by MarceloRamires
    I have a bound dropdown list populated with a table of names through a select, and databinding. it shoots selectedindexchanged that (through a postback) updates a certain gridview. What happens is, since it runs from changing the index, the one that always comes selected (alexander) can only me chosen if you choose another one, then choose alexander. poor alexander. What I want is to put a blanc option at the beginning (default) and (if possible) a option as second. I can't add this option manually, since the binding wipes whatever was in the dropdown list and puts the content of the datasource.

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  • asp.NET Dynamic Data Site and asp.NET MVC-2 site together

    - by loviji
    Hi, I have created firstly ASP.NET MVC 2. and write more functionality. After I create asp.NET Dynamic Data Site. now, when I click on run button in Visual Studio, mvc app. opened in browser as http://localhost:50062. and asp.NET Dynamic Data Site as http://localhost:58395/cms/. but i want to merge this app. in one. can I use asp.NET Dynamic Data Site and asp.NET MVC-2 at the same time?

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  • java Filter URL pattern specific to request params

    - by Rohit Desai
    Hi All, We have a situation where we want to use filter for URL's containing some specific request parameters. e.g htt://mydomain.com/?id=78&formtype=simple_form&....... htt://mydomain.com/?id=788&formtype=special_form&....... and so on , id are fetched at run time, I want configure filter in web.xml only if formtype=special_form. How should achieve the solution . Can filter be configure with regex patterns? Really appreciate your help on this. Thanks, Rohit

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  • Communicate with the local machine from a web page

    - by Earlz
    Hello. We have a web application. There are physical devices that we need to be able to communicate with, and we have access to all of our clients computers to install whatever software we need. Now, for the question: Is there a way to make this browser-agnostic? As in, not requiring ActiveX controls? One of my ideas was to install a custom made webserver on each client and then have javascript on our webpage that communicates with that webserver. This could be done by the same way that http://earlz.biz.tm javascript can access subdomains assigned to 127.0.0.1 such as http://loopback.earlz.biz.tm The problem with this of course is that the client's custom made webserver would be forced to run on port 80(which will have conflicts at least sometimes), or we would have to use a nonstandard port for our web application, which is quite undesirable. Does anyone else have ideas on how to do this?

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  • How to fix type names conflicts in Dynamic Data

    - by SDReyes
    Hi Guys! We're working in a Dynamic Data project that will handle entities coming from two different namespaces: myModel.Abby and myModel.Ben. whose classes are: Abby myModel.Abby.Car myModel.Abby.Lollipop Ben myModel.Ben.Car myModel.Ben.Apple So myModel.Abby.Car and myModel.Ben.Car are homonym. when I try to register both ObjectContext's, an exception is thrown telling us that there are type name conflicts between the mentioned classes (although the types belong to different namespaces). How can we overcome type-name conflicts, caused by repeated type names among different namespaces?

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  • error C2146: syntax error : missing ';' before identifier 'vertices'

    - by numerical25
    I would usually search for this error. But in VS C++ Express, this error comes up for just about every mistake you do. Any how I recieve this error below error C2146: syntax error : missing ';' before identifier 'vertices' everytime I add the following code at the top of my document // Create vertex buffer SimpleVertex vertices[] = { D3DXVECTOR3( 0.0f, 0.5f, 0.5f ), D3DXVECTOR3( 0.5f, -0.5f, 0.5f ), D3DXVECTOR3( -0.5f, -0.5f, 0.5f ), }; below is the code in it's entirety. Cant figure out whats wrong. thanks // include the basic windows header file #include "D3Dapp.h" class MyGame: public D3Dapp { public: bool Init3d(); }; MyGame game; // Create vertex buffer SimpleVertex vertices[] = { D3DXVECTOR3( 0.0f, 0.5f, 0.5f ), D3DXVECTOR3( 0.5f, -0.5f, 0.5f ), D3DXVECTOR3( -0.5f, -0.5f, 0.5f ), }; // the entry point for any Windows program int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { game.InitWindow(hInstance , nCmdShow); return game.Run(); } bool MyGame::Init3d() { D3Dapp::Init3d(); return true; }

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  • Deploying xbap in a full trust mode

    - by SituStarz
    I have xbap which needs to run on a full trust mode because my application needs to upload a file from the client machine to process. I have to provide a installation steps to install. If i do it as a click one instillation, do i still get a security error? If so what is the best way to resolve it? If i install it in remote server, I saw couple of options in internet like creating certificates and ask user to import this certificate. Other option is to ask the user to allow access to xbap applications which provides access to all xbap applications (not so good). what is best way? It would be really great, if some could provide me the installation steps for both scenarios.

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