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  • Newbie question: undefined local variable or method , why??

    - by Mellon
    I am new in Rails (I am using Rails 3.0.3), currently I am following the book "Agile Web Development with Rails" to develop a simple rails application. I followed the book to: --create a model 'Cart' class; --implement 'add_to_cart' method in my 'store_controller', I have a line of code <%=button_to "Add to Cart", :action => add_to_cart, :id => product %> in my /store/index.html.erb As you see, there is :action => add_to_cart in my index.html.erb, which will invoke the add_to_cart method in my *Controllers/store_controller.rb* But after I refresh the browser, I got the error "undefined local variable or method 'add_to_cart'", apparently I do have the method add_to_cart in my 'store_controller.rb', why I got this error??? What is the possible cause??? Here are my codes: store_controller.rb class StoreController < ApplicationController def index @products = Product.find_products_for_sale end def add_to_cart product = Product.find(params[:id]) @cart = find_cart @cart.add_product(product) end private def find_cart session[:cart] ||= Cart.new end end /store/index.html.erb <h1>Your Pragmatic Catalog</h1> <% @products.each do |product| -%> <div class="entry"> <%= image_tag(product.image_url) %> <h3><%=h product.title %></h3> <%= product.description %> <div class="price-line"> <span class="price"><%= number_to_currency(product.price) %></span> <!-- START_HIGHLIGHT --> <!-- START:add_to_cart --> **<%= button_to 'Add to Cart', :action => 'add_to_cart', :id => product %>** <!-- END:add_to_cart --> <!-- END_HIGHLIGHT --> </div> </div> <% end %> Model/cart.rb class Cart attr_reader :items def initialize @items = [] end def add_product(product) @items << product end end

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  • I have a question about URI templates in WCF Services

    - by Debby
    I have a web service with following operation contract and my service is hosted at http://localhost:9002/Service.svc/ [OperationContract] [WebGet(UriTemplate = "/Files/{Filepath}")] Stream DownloadFile(string Filepath); This web service would let users download file, if the proper filepath is provided (assuming, I somehow find out that proper filepath). Now, I can access this service from a browser by typing, http://localhost:9002/Service.svc/Files/(Filepath} If {filepath} is some simple string, its not a problem, but I want to send the location of the file. Lets us say users want to download file C:\Test.mp3 on the server. But how can I pass C:\Test.mp3 as {Filepath}? I get an error when I type http://localhost:9002/Service.svc/Files/C:\Test.mp3 in the browser. I am new to web services and find that this community is the quickest way to get answers to my questions.

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  • Jquery selector question

    - by fizzer
    Hi, I have a working selector but I just wondered whether there was another way I could write it. Here's the html structure: THIS IS TEXT I WANT TO SELECT item 1 item 2 item 3 I have a click event attached to the nested listitems. In the click event I am trying to select the anchor tag. I have used the follwing selector: $(this).parents('li').children('a') Is this the most efficient way of selecting the anchor tag?

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  • PHP question on XSS

    - by user318466
    I need help in solving the following MCQ: Which of the following filtering techniques prevents cross-site scripting (XSS) vulnerabilities? A. Strip all occurrences of the string script. B. Strip all occurrences of the string javascript. C. Enable magic_quotes_gpc. D. None of the above. I think once the word java script is deleted there is no more threat. Am I correct ?

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  • Unix Interview Question [closed]

    - by Rachel
    I am giving some interviews right now and recently I was asked this questions in Interview and I was not sure of the answer, in your opinion are this kind of questions worthwhile for Interview process and if yes than how would you go about approaching this kind of questions. How to get number of files in directory without using wc ? How to get all files in descending order on size ? What is the significance of ? in file searching ? Would appreciate if you can provide answers for this questions so that I could learn something about them as I am not sure for this questions.

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  • Android Layout question

    - by Nils
    Hello, I need to create a map with items on it (the map consists of a drawable object, which represents a room) and I thought about using buttons with background images for the items so that they are clickable. I guess the AbsoluteLayout fits here the best, but unfortunately it's deprecated. What layout would you recommend me for this kind of application ? Is there another layout which supports X/Y coordinates ?

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  • Best practise question

    - by sid_com
    Hello! With version would you prefer? #!/usr/bin/env perl use warnings; use strict; use 5.010; my $p = 7; # 33 my $prompt = ' : '; my $key = 'very important text'; my $value = 'Hello, World!'; my $length = length $key . $prompt; $p -= $length; Option 1: $key = $key . ' ' x $p . $prompt; Option 2: if ( $p > 0 ) { $key = $key . ' ' x $p . $prompt; } else { $key = $key . $prompt; } say "$key$value"

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  • Question about WeakHashMap

    - by michael
    Hi, In the Javadoc of "http://java.sun.com/j2se/1.4.2/docs/api/java/util/WeakHashMap.html", it said "Each key object in a WeakHashMap is stored indirectly as the referent of a weak reference. Therefore a key will automatically be removed only after the weak references to it, both inside and outside of the map, have been cleared by the garbage collector." And then Note that a value object may refer indirectly to its key via the WeakHashMap itself; that is, a value object may strongly refer to some other key object whose associated value object, in turn, strongly refers to the key of the first value object. But should not both Key and Value should be used weak reference in WeakHashMap? i.e. if there is low on memory, GC will free the memory held by the value object (since the value object most likely take up more memory than key object in most cases)? And if GC free the Value object, the Key Object can be free as well? Basically, I am looking for a HashMap which will reduce memory usage when there is low memory (GC collects the value and key objects if necessary). Is it possible in Java? Thank you.

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  • JQuery UI question, how do you add variables into the dialog box

    $('.openDialog').click(function(event){ var width=$(this).attr('width'); var height=$(this).attr('height'); alert(width + ' ' + height); event.preventDefault(); $("#dialog").dialog({autoOpen: false, modal: true}); $('#dialog').dialog('option', 'width', width); $('#dialog').dialog('open'); $('#dialog p').load('http://pagetoload.com/page.html .content'); }); As you can see above i'm trying to open a dialog box with a passed in parameter of width and height, however when I try and pass in the value of width on this line: $('#dialog').dialog('option', 'width', width); it doesn't work, any ideas why or how to get around that? Thanks

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  • Question about [Pure] methods

    - by devoured elysium
    Is the following method Pure? I'd say so, as it doesn't change in anyway the current class, thus, everything we can now currenly "see" in the class, before running this method will still be exactly the same after. Am I correct? class Set { ... public ISet<T> UnionWith(ISet<T> set) { ISet<T> unionSet = ... foreach (Element element in this) { unionSet.Add(element); } foreach (Element element in set) { unionSet.Add(element); } return unionSet; } }

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  • Small Python optional arguments question

    - by ooboo
    I have two functions: def f(a,b,c=g(b)): blabla def g(n): blabla c is an optional argument in function f. If the user does not specify its value, the program should compute g(b) and that would be the value of c. But the code does not compile - it says name 'b' is not defined. How to fix that? Someone suggested: def g(b): blabla def f(a,b,c=None): if c is None: c = g(b) blabla But this doesn't work, because maybe the user intended c to be None and then c will have another value.

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  • A question about friend functions

    - by Als
    I faced a problem recently with a 3rd party library which generates classes from a xml. Here is a gist of it: class B; class A { void doSomething(); friend class B; }; class B { void doSomething(); void doSomethingMore() { doSomething(); } }; The compiler flags call to the function doSomething() as ambiguous and flags it as an compiler error. It is easy to understand why it gives the error.Class B being friend of class A, every member of class B has access to all the members of class A. Renaming of the either of functions resolved my problem but it got me thinking that shouldn't in this case the compiler should give a priority to the class's own member function over the function in another class of which it is a friend?

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  • Constructor and Destructors in C++ [Not a question] [closed]

    - by Jack
    I am using gcc. Please tell me if I am wrong - Lets say I have two classes A & B class A { public: A(){cout<<"A constructor"<<endl;} ~A(){cout<<"A destructor"<<endl;} }; class B:public A { public: B(){cout<<"B constructor"<<endl;} ~B(){cout<<"B destructor"<<endl;} }; 1) The first line in B's constructor should be a call to A's constructor ( I assume compiler automatically inserts it). Also the last line in B's destructor will be a call to A's destructor (compiler does it again). Why was it built this way? 2) When I say A * a = new B(); compiler creates a new B object and checks to see if A is a base class of B and if it is it allows 'a' to point to the newly created object. I guess that is why we don't need any virtual constructors. ( with help from @Tyler McHenry , @Konrad Rudolph) 3) When I write delete a compiler sees that a is an object of type A so it calls A's destructor leading to a problem which is solved by making A's destructor virtual. As user - Little Bobby Tables pointed out to me all destructors have the same name destroy() in memory so we can implement virtual destructors and now the call is made to B's destructor and all is well in C++ land. Please comment.

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  • Simple java synchronization question

    - by Misha Koshelev
    I was wondering, which is correct: Option One class A { public void methodOne() { synchronized(this) { modifyvalue notifyAll() } } public void methodTwo() { while (valuenotmodified) { synchronized(this) { wait() } } } Option Two class A { public void methodOne() { modifyvalue synchronized(this) { notifyAll() } } public void methodTwo() { while (valuenotmodified) { synchronized(this) { wait() } } } and why?

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  • authentication question (security code generation logic)

    - by Stick it to THE MAN
    I have a security number generator device, small enough to go on a key-ring, which has a six digit LCD display and a button. After I have entered my account name and password on an online form, I press the button on the security device and enter the security code number which is displayed. I get a different number every time I press the button and the number generator has a serial number on the back which I had to input during the account set-up procedure. I would like to incorporate similar functionality in my website. As far as I understand, these are the main components: Generate a unique N digit aplha-numeric sequence during registration and assign to user (permanently) Allow user to generate an N (or M?) digit aplha-numeric sequence remotely For now, I dont care about the hardware side, I am only interested in knowing how I may choose a suitable algorithm that will allow the user to generate an N (or M?) long aplha-numeric sequence - presumably, using his unique ID as a seed Identify the user from the number generated in step 2 (which decryption method is the most robust to do this?) I have the following questions: Have I identified all the steps required in such an authentication system?, if not please point out what I have missed and why it is important What are the most robust encryption/decryption algorithms I can use for steps 1 through 3 (preferably using 64bits)?

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  • Beginner PHP Question

    - by user317128
    I am working on an example from a php book and am getting an error on line 8 with this code <?php $agent = getenv("HTTP_USER_AGENT"); if (preg_match("/MSIE/i", "$agent")); { $result = "You are using Microsoft Internet Explorer"; } else if (preg_match("/Mozilla/i", "$agent")); { $result = "You are using Mozilla firefox"; } else {$result = "you are using $agent"; } echo $result; ?>

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  • Question about Architecture for Viewing Images in ASP.NET MVC App

    - by Charlie Flowers
    I have an approach in mind for an image viewer in a web app, and want to get a sanity check and any thoughts you stackoverflowers might have. Here's the whirlwind nutshell summary: I'm working on an ASP.NET MVC application that will run in my company's retail stores. Even though it is a web application, we own the store machines and have control over them. We have a "windows agent" running on the store machine which we can talk to from the browser via javascript (it is a WCF service, and our web app has permission to talk to it from the browser). One of the web pages needs to be an "image viewer" page with some common things like Rotate & Zoom. Now, there are some WebForms controls that offer Rotate and Zoom. However, they take up server resources and generate a good bit of traffic between the server and the browser. For example, the Rotate function would cause an ajax call to the server, which would then generate a new image written to a .NET Canvas object, which would then be written to a file on the server, which would then be returned from the ajax call and refreshed inside the browser. Normally, that's a pretty good way of doing things. But in our case, we have code running on the store machine that we can communicate with. This leads me to consider the following approach: When the user asks to view an image, we tell our "windows agent" to download it from our image server to the store machine. We then redirect our browser to our image viewer page, which will pull the image from the local file we just wrote to the store machine. When the user clicks "Rotate", we cause JavaScript code in the browser to call our "windows agent" software, asking it to perform the "Rotate" function. The "windows agent" does the rotation using the same kind of imaging control that would formerly have been used on the server, but it does so now on the store machine. Javascript in the browser then refreshes the image on the page to show the newly rotated image. Zoom and similar features would be implemented the same way. This seems to be much more efficient, scalable, and responsive for the end-users. However, I've never heard of anything like it being done, mostly because it's rare to have this combination of a web app plus a "windows agent" on the client machine. What do you think? Feasible? Reasonable? Any pitfalls I overlooked or improvements / suggestions you can see? Has anyone done anything like this who would like to offer the wisdom of experience? Thanks!

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  • Spring URL mapping question

    - by es11
    I am using Java with Spring framework. Given the following url: www.mydomain.com/contentitem/234 I need to map all requests that come to /contentitem/{numeric value} mapped to a given controller with the "numeric value" passed as a parameter to the controller. Right now in my servlet container xml I have simple mappings similar to the following: ... <entry key="/index.html"> <ref bean="homeController" /> </entry> ... I am just wondering what I need to add to the mapping in order to achieve what I described? Edit: I unaccepted the answer temporarily because I can't seem to figure out how to do the mapping in my web.xml (I am using annotations as described in axtavt's answer below). How do I add a proper <url-pattern>..</url-pattern> in my <servlet-mapping> so that the request for "/contentitem/{numeric_value}" gets properly picked up? Thanks!

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  • jQuery plugin question - populate select options with JSON data

    - by user331884
    I'm trying to fill selects with json data from a web service. I'm getting error 'Object doesn't support this property or method.' when I do this $(this).html(options.join'')); Any ideas what I'm doing wrong? ;(function($) { $.fillSelect = {}; $.fn.fillSelect = function(url, map) { var jsonpUrl = url + "?callback=?"; $.getJSON(jsonpUrl, function(d) { var options = []; var txt = map[0]; var val = map[1]; options.push('<option>--Select--</option>'); $.each(d, function(index, item) { options.push('<option value="' + item[val] + '">' + item[txt] + '</option>'); }); $(this).html(options.join('')); //getting error Object doesn't support this property or method } }; })(jQuery);

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  • php website url matching question

    - by jj
    hi, i am new to a php site, only familiar with .net web forms sites. i can't figure out how routing is working on this php site. www.oursite.com/suggestions.php is to suggestions.php www.oursite.com/suggestions also loads the php fine www.oursite.com/suggestions/ loads the php, but no css is applied www.oursite.com/suggestions/anything - anything that comes after the '/' is ignored and suggestions is loaded without css. so oursite.com/suggestions////// works, as does oursite.com/suggestions/2/2/2/2/whatever i have searched but not found any good explanation on how this is working. can someone explain or provide a good resource? thank you.

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  • Fundamental question about boxing / c#

    - by maxp
    Is it possible to change the value stored inside bar after it has been added? I have tried 'boxing' the string foo but it doesnt work. string foo = "aaaaaaa"; var bar = new System.Web.UI.HtmlControls.HtmlGenericControl("div") { InnerHtml =foo }; foo = "zzzzzz"; plcBody.Controls.Add(bar);//want this to contain 'zzzzzz'

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  • summer experiment: GWT & python for a trading game- arch question

    - by sadhu_
    Hi, As a summer learning experiment, I'm thinking of coding up a web front end for a trading game i wrote in python, that generates share prices and random snippets of text. I am sort of struggling with how this should work on the back-end though. I'd rather have my GWT client page interact with the python share price generator, than to try and re-code it in java. I suppose i could use an sqlite db, and then use jdbc to pick up the prices, but i was wondering if there is a better way, for me to be able to poll some python script either from my client page, or from the serverside java code ? I found this python wrapper, but i'm not sure how i could use it though: http://code.google.com/apis/visualization/documentation/dev/gviz_api_lib.html Thanks.

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