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  • Email Collector / Implementation

    - by Tian
    I am implementing a simple RoR webpage that collect emails from visitors and store them as objects. I'm using it as a mini-project to try RoR and BDD. I can think of 3 features for Cucumber: 1. User submits a valid email address 2. User submits an existing email address 3. User submits an invalid email My question is, for scenarios 2 and 3, is it better to handle this via the controller? or as methods in a class? Perhaps something that throws errors if an instance is instantiated in sceanrio 2 or 3? Implementation is below, love to hear some code reviews in addition to answers to questions above. Thanks! MODEL: class Contact < ActiveRecord::Base attr_accessor :email end VIEW: <h1>Welcome To My Experiment</h1> <p>Find me in app/views/welcome/index.html.erb</p> <%= flash[:notice] %> <% form_for @contact, :url => {:action => "index"} do |f| %> <%= f.label :email %><br /> <%= f.text_field :email %> <%= submit_tag 'Submit' %> <% end %> CONTROLLER: class WelcomeController < ApplicationController def index @contact = Contact.new unless params[:contact].nil? @contact = Contact.create!(params[:contact]) flash[:notice] = "Thank you for your interest, please check your mailbox for confirmation" end end end

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  • what libraries or platforms should I use to build web apps that provide real-time, asynchronous data

    - by Daniel Sterling
    This is a less a question with a simple, practical answer and more a question to foster discussion on the real-time data exchange topic. I'll begin with an example: Google Wave is, at its core, a real-time asynchronous data synchronization engine. Wave supports (or plans to support) concurrent (real-time) document collaboration, disconnected (offline) document editing, conflict resolution, document history and playback with attribution, and server federation. A core part of Wave is the Operational Transformation engine: http://www.waveprotocol.org/whitepapers/operational-transform The OT engine manages document state. Changes between clients are merged and each client has a sane and consistent view of the document at all times; the final document is eventually consistent between all connected clients. My question is: is this system abstract or general enough to be used as a library or generic framework upon which to build web apps that synchronize real-time, asynchronous state in each client? Is the Wave protocol directly used by any current web applications (besides Google's client)? Would it make sense to directly use it for generic state synchronization in a web app? What other existing libraries or frameworks would you consider using when building such a web app? How much code in such an app might be domain-specific logic vs generic state synchronization logic? Or, put another way, how leaky might the state synchronization abstractions be? Comments and discussion welcomed!

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  • EAGLContext, EAGLSharegroups, RenderBuffers, FrameBuffers, oh my!

    - by quixoto
    Hi all, I'm trying to wrap my head around the OpenGL object model on iPhone OS. I'm currently rendering into a few different UIViews (build on CAEAGLayers) on the screen. I currently have each of these as using separate EAGLContext, each of which has a color renderbuffer and a framebuffer. I'm rendering similar things in them, and I'd like to share textures between these instances to save memory overhead. My current understanding is that I could use the same setup (some number of contexts, each with a FBO/RBO) but if I spawn the later ones using the EAGLShareGroup of the first one, then I can simply use the texture names (GLuints) from the first one in the later ones. Is this accurate? If this is the case, I guess the followup question is: what's the benefit to having it be a "sharegroup"? Could I just reuse the same context, and attach multiple FBOs/RBOs to that context? I think I'm struggling with the abstraction layer of a sharegroup, which seems to share "objects" (textures and other named things) but not "state" (matrices, enabled/disabled states) which are owned by the context. What's the best way to think of this? Thanks for any enlightenment!

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  • is mysql index useful on column 'state' when only doing bit-operations on the column?

    - by Geert-Jan
    I have a lot of domain entities (stored in mysql) which undergo lots of different operations. Each operation is executed from a different program. I need to keep (flow)-state for these entities which I implemented in as a long field 'flowstate' used as a bitset. to query mysql for entities which have undergone a certain operation I do something like: select * from entities where state >> 7 & 1 = 1 Indicating bit 7 (cooresponding to operation 7) has run. (<-- simplified) Anyway, I really didn't pay attention to the performance implications of this setup in the beginning, and I think I'm in a bit of trouble since queries as the above run pretty slow. What I'd like to know: Does an mysql index on 'flowstate' help at all? After all it's not a single value Mysql can quickly find using a binary sort or whatever. If it doesn't, are there any other things I could do to speed things up? . Are there special 'mask-indices' for fields with use-cases as the above? TIA, Geert-jan

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  • Flex HttpService POST limited to 543 Byte per Form field?

    - by motto
    Hi, I am getting a FaultEvent when trying to send form fields through HTTPService that contain more than 542 chars. Initializing the HttpService: httpServ = new HTTPService(); httpServ.method = 'POST'; httpServ.url = ENDPOINT_URL; //http://localhost:3001/ReportError.aspx httpServ.resultFormat = HTTPService.RESULT_FORMAT_TEXT; httpServ.contentType = HTTPService.CONTENT_TYPE_FORM; httpServ.addEventListener(ResultEvent.RESULT, OnErrorSent); httpServ.addEventListener(FaultEvent.FAULT, OnFault); Sending the request: var params:Object = {}; //params["stack"] = e.stackTrace.slice(0, 542); //length 542 = works //params["stack2"] = e.stackTrace.slice(1, 543); //length 542 = works (just to show that it's not about the content itself) params["stack3"] = e.stackTrace.slice(0, 543); //length 543 = fails I also seem to be able to create many form fields (with 542 length) so that it's not a limit of the request itself but of the form field: var params:Object = {}; params["stack"] = e.stackTrace.slice(0, 542); //length 542 params["stack2"] = e.stackTrace.slice(1, 543); //length 542 params["stack3"] = e.stackTrace.slice(2, 544); //length 542 // Length > 1600 chars The receiving party is an ASP.NET 4 site on the same domain and port. I hope someone already came across a similar restrictions or has some general advice on how to trace this problem down further. Thanks in advance.

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  • Examples of monoids/semigroups in programming

    - by jkff
    It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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  • BlackBerry Library problems. (jre6 + NET_RIM_BLACKBERRY)

    - by kimera84
    Hi Everyone, I'm new in blackberry environement programming, I'm developing an application for this device and there are some probs about libraries that I don't understand. I have the main project called: npoBBerry - his library is NET_RIM_BLACKBERRY (from 4.6.1 version...) it includes other two projects: Npo - his library is standard jre6 (Npo inlcudes NpoCore) NpoCore - his library is standard jre6 Compliance was set... In Java Compiler level is set to 1.4 for all. Now the problem is that I'm not able to build my project. 4 errors: Error preverifying class ch.yek.npo.model.Advertising Error preverifying class ch.yek.npo.repository.Repository$1 Error!: Error: preverifier failed: C:\Program Files\eclipse\plugins\net.rim.eide.componentpack4.6.1_4.6.1.27\components\bin\preverify.ex ... Error!: Error: preverifier failed: C:\Program Files\eclipse\plugins\net.rim.eide.componentpack4.6.1_4.6.1.27\components\bin\preverify.ex ... I know that libraries are differents but maybe I'm missing something. NpoCore represents models, interfaces Npo just take data from a repository NpoBBeryy just use this data from Services... Please help and thanks in advance... :)

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  • Routing is using ID has action and action has ID after submitting a form

    - by Victor Martins
    I have a model User that has_one user_profile and a User_Profile belongs_to user in the User controller I have: def personal @user = User.find_by_id(params[:id]) @user_profile = @user.user_profile @user_profile ||= @user.build_user_profile end def update_personal @user = User.find_by_id(params[:id]) if @user.user_profile.update_attributes(params[:user_profile]) flash[:notice] = "OK" redirect_to @user else flash[:notice] = "Fail" render :action => 'update_personal' end end In my personal.html.erb view I have: <% semantic_form_for @user_profile, :url => { :action => "update_personal"} do |form| %> <%= form.inputs %> <%= form.buttons %> <%end%> And on the rountes I have: map.resources :users, :member => { :personal => :get, :update_personal => :put } Now the strange thing is that I can do: users/1/personal to see the form but when I submit I get this error: Unknown action No action responded to 1. It's trying to find an action with the name 1. Can anyone point me out on the right direction?

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  • Codeplex/Sourceforge for internal use

    - by Josh
    I'm looking for a free/open source collaborative project manager that can be deployed internally in my workplace that would act similar to Codeplex or Sourceforge. Does anyone know of something like this, and if so do you have experience with it. Requirements: Open Source or Free Locally Deployable Has the same types of features found in Sourceforge / Codeplex Issue/Feature Tracking Community Interaction (ie. Voting, Roles, etc.) SCM Integration (Optional) .NET/Windows Friendly (Optional) Every business ends up having internal utilities, and domain specific apps that developers create to make life easier. Given the input of the internal developer community they have the potential to become much better (can you say GMail...), and I would simply like to foster such an environment internally by providing an easy place for that interaction to take place. UPDATE: So I like what I am seeing in both Trac and GForge, but both are heavily geared towards UNIX/Subversion environments. I should have specified this, but we are a MS shop from top to bottom. How practical do you think it is going to be to try and use these in a MS .NET environment? Would that be like trying to shove a square peg through a round hole?

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  • Rails 1.0 - Using composed_of gives me a wrong number of arguments (1 for 5) error

    - by Tristan Havelick
    I am developing a Rails 1.0 application (I can't upgrade, it's a strange situation) for which I am trying to use the :composed_of functionality. I have a class called StreetAddress: class StreetAddress attr_reader :address, :address2, :city, :state_id, :zip_code def initialize(address, address2, city, state_id, zip_code) @address = address @address2 = address2 @city = city @state_id = state_id @zip_code = zip_code end end and a model class called Hotel class Hotel < ActiveRecord::Base composed_of :street_address # ... end which has columns: "id", "brand_id", "code", "location_name", "address", "address2", "city", "state_id", "zip_code", "phone_number", "phone_ext", "fax_number", "time_zone", "url", "room_service_email", "manager_name", "manager_email" However when I try to access the aggregation I get an error: >> h = Hotel.find(1) => #<Hotel:0x38ad718 @attributes={"fax_number"=>"1-623-420-0124", "city"=>"Twin Falls", "address2"=>"285", "brand_id"=>"1", "code"=>"XZWUXUSZ", "manager_email"= >"[email protected]", "url"=>"http://www.xycdkzolukfvu.hom", "ph one_number"=>"1-805-706-9995", "zip_code"=>"72436", "phone_ext"=>"48060", "id"=> "1", "manager_name"=>"Igor Mcdowell", "room_service_email"=>"Duis.risus@Donecvit ae.ca", "time_zone"=>"America/Boise", "state_id"=>"15", "address"=>"P.O. Box 457 , 7405 Dignissim Avenue", "location_name"=>"penatibus et magnis"}> >> h.street_address ArgumentError: wrong number of arguments (1 for 5) from (eval):3:in `initialize' from (eval):3:in `new' from (eval):3:in `street_address' from (irb):6 Why?

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  • Help, my CentOS servers keep going down , No route to host after a random uptime [closed]

    - by user249071
    Hello , I have a couple of Centos linux servers, that have a very simple task, they run nginx + fastcgi for php , and some NFS mounts between them, readonly They have some RPC commands to start some downloading processes with wget, nothing fancy , from a main server, but their behavior is very unstable, they simply go down, we tried to monitor ram , processor usage, even network connections, they don't load up so much, max network connections up to... 250 max, 15% processor usage and memory , well, doesn't even fill up, 2.5GB from 8GB max , I have no ideea why can a linux server go down like that, they aren't even public servers, no domain names installed no public serving, for sites. The only thing that I've discovered was that if i didn't restart the network service every couple of hours or so... the servers were becoming very slow, starting apps very slow, but not repoting a high usage of resources...Maybe Centos doesn't free the timeout connections, or something like that...It's based on Red Hat right? I'm not a linux expert , but I'm sure that there are a few guys out there that can easily have an answer to this , or even have some leads to what i can do ... I haven't installed snort, or other things to view if we have some DOS attacks, still the scheduled script that restarts the network each hour should put the system back online, and it doesn't.... Thank you in advance

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  • How can I merge multiple Compass Resources into one, with one score?

    - by Brent Fisher
    I am trying to integrate compass into my platform using the JDBC ResultSetToResourceMapping. What I want to do is set it up so that I could have multiple result set mappings, tied to one Resource, that produces one result, with one score, and a merged score. I have tried to trick Compass into doing this by mapping the same id across them, even though the property fields are different, but it just ends up giving me separate hits for each. E.g. I have the following Data Model, Cases and Comments. One case might have several comments. Say I search for a term that appears in multiple comments. Right now, I a hit for each one, each with a different score. Is there a way that I could merge or aggregate those hits into one hit? Say, instead of Score Entity ID Snippets 100.0% Case 3558 ... The fox jumped over the lazy dog ... 60.0% Case 3558 ... In Alabama today, three jumping turtles were ... 25.0% Case 3558 ... Three jumpers fled the scene... I get Score Entity ID Snippets 100.0% Case 3558 The fox jumped over the lazy dog ...In Alabama today, three jumping turtles were ... Three jumpers fled the scene... Where the latter score is an aggregated score.

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  • Session expiry times?

    - by user246114
    Hi, I've enabled sessions on my app: // appengine-web.xml <sessions-enabled>true</sessions-enabled> they seem to work when I load different pages under my domain. If I close the browser however, looks like the session is terminated. Restarting the browser shows the last session is no longer available. That could be fine, just wondering if this is documented anywhere, so I can rely on this fact? I tried the following just to test if we can tweak it: // in web.xml <session-config> <session-timeout>10</session-timeout> </session-config> also // in my servlet getThreadLocalRequest().getSession().setMaxInactiveInterval(60 * 5); but same behavior, session data is no longer available after browser restart. I looked at the stats for my project and I see data being used for something like "_ah_SESSION" objects. Are those the sessions from above? If so, shouldn't they be cleaned since they're no longer valid? (Hopefully gae takes care of that automatically?) Thanks

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  • is there an equivalent of a trigger for general stored procedure execution on sql server

    - by Arj
    Hi All, Hope you can help. Is there a way to detect when a stored proc is being run on SQL Server without altering the SP itself? Here's the requirement. We need to track users running reports from our enterprise data warehouse as the core product we use doesn't allow for this. Both core product reports and a slew of in-house ones we've added all return their data from individual stored procs. We don't have a practical way of altering the parts of the product webpages where reports are called from. We also can't change the stored procs for the core product reports. (It would be trivial to add a logging line to the start/end of each of our inhouse ones). What I'm trying to find therefore, is whether there's a way in SQL Server (2005 / 2008) to execute a logging stored proc whenever any other stored procedure runs, without altering those stored procedures themselves. We have general control over the SQL Server instance itself as it's local, we just don't want to change the product stored procs themselves. Any one have any ideas? Is there a kind of "stored proc executing trigger"? Is there an event model for SQL Server that we can hook custom .Net code into? (Just to discount it from the start, we want to try and make a change to SQL Server rather than get into capturing the report being run from the products webpages etc) Thoughts appreciated Thanks

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  • How do I exclude data from local table schema_migrations from being pushed to Heroku DB?

    - by Thierry Lam
    I was able to push my Ruby on Rails app with MySQL(local dev) to the Heroku server along with migrating my model with the command heroku rake db:migrate. I have also read the documentation on Database Import/Export. Is that doc referring to pushing actual data from my local dev DB to whichever Heroku's DB? Do I need to modify anything in the file database.yml to make it happen? I ran the following command: heroku db:push and I am getting the error: Sending data 2 tables, 3 records !!! Caught Server Exception | ETA: --:--:-- Taps Server Error: PGError ERROR: duplicate key value violates unique constraint "unique_schema_migrations" I have 2 tables, one I create for my app and the other schema_migrations. The total number of entries among the 2 tables is 3. I'm also printing the number of entries I have in the table I have created and it's showing 0. Any ideas what I might be missing or what I am doing wrong? EDIT: I figured out the above, Heroku's DB already have schema_migrations the moment I ran migrate. New question: Does anyone know how I can exclude data from a specific table from being pushed to Heroku DB. The table to exclude in this case will be schema_migrations. Not so good solution: I googled around and someone else was having the same issue. He suggested naming the schema_migrations table to zschema_migrations. In this way data from the other tables will be pushed properly until it fails on the last table. It's a pretty bad solution but will do for the time being. A better solution will be to use an existing Rails command which can reset a specific table from a database. I don't think Rake can do that.

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  • Export database data to csv from view by date range asp.net mvc3

    - by Benjamin Randal
    I am trying to find a way to export data from my database and save it as a .csv file. Ideally the user will be able to select a date range on a view, which will display the data to be exported, then the user can click an "export to CSV" link. I've done quite a bit of searching and but have not found much specific enough to help me step through the process. Any help would be great. I would like to export data from this database model... { public class InspectionInfo { [Key] public int InspectionId { get; set; } [DisplayName("Date Submitted")] [DataType(DataType.Date)] // [Required] public DateTime Submitted { get; set; } [DataType(DataType.MultilineText)] [MaxLength(1000)] // [Required] public string Comments { get; set; } // [Required] public Contact Contact { get; set; } [ForeignKey("Contact")] public Int32 ContactId { get; set; } [MaxLength(100)] public String OtherContact { get; set; } I have a service for search also, just having difficulty implementing public SearchResults SearchInspections(SearchRequest request) { using (var db = new InspectionEntities()) { var results = db.InspectionInfos .Where( i=> ( (null == request.StartDate || i.Submitted >= request.StartDate.Value) && (null == request.EndDate || i.Submitted <= request.EndDate.Value) ) ) .OrderBy(i=>i.Submitted) .Skip(request.PageSize*request.PageIndex).Take(request.PageSize); return new SearchResults{ TotalResults=results.Count(), PageIndex=request.PageIndex, Inspections=results.ToList(), SearchRequest=request }; } }

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  • Compile Assembly Output generated by VC++?

    - by SDD
    I have a simple hello world C program and compile it with /FA. As a consequence, the compiler also generates the corresponding assembly listing. Now I want to use masm/link to assemble an executable from the generated .asm listing. The following command line yields 3 linker errors: \masm32\bin\ml /I"C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include" /c /coff asm_test.asm \masm32\bin\link /SUBSYSTEM:CONSOLE /LIBPATH:"C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\lib" asm_test.obj indicating that the C-runtime functions were not linked to the object files produced earlier: asm_test.obj : error LNK2001: unresolved external symbol @__security_check_cookie@4 asm_test.obj : error LNK2001: unresolved external symbol _printf LINK : error LNK2001: unresolved external symbol _wmainCRTStartup asm_test.exe : fatal error LNK1120: 3 unresolved externals Here is the generated assembly listing ; Listing generated by Microsoft (R) Optimizing Compiler Version 15.00.30729.01 TITLE c:\asm_test\asm_test\asm_test.cpp .686P .XMM include listing.inc .model flat INCLUDELIB OLDNAMES PUBLIC ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ ; `string' EXTRN @__security_check_cookie@4:PROC EXTRN _printf:PROC ; COMDAT ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ CONST SEGMENT ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ DB 'hello world!', 0aH, 00H ; `string' CONST ENDS PUBLIC _wmain ; Function compile flags: /Ogtpy ; COMDAT _wmain _TEXT SEGMENT _argc$ = 8 ; size = 4 _argv$ = 12 ; size = 4 _wmain PROC ; COMDAT ; File c:\users\octon\desktop\asm_test\asm_test\asm_test.cpp ; Line 21 push OFFSET ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ call _printf add esp, 4 ; Line 22 xor eax, eax ; Line 23 ret 0 _wmain ENDP _TEXT ENDS END I am using the latest masm32 version (6.14.8444).

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  • compile Boost as static Universal binary lib

    - by Albert
    I want to have a static Universal binary lib of Boost. (Preferable the latest stable version, that is 1.43.0, or newer.) I found many Google hits with similar problems and possible solutions. However, most of them seems outdated. Also none of them really worked. Right now, I am trying sudo ./bjam --toolset=darwin --link=static --threading=multi \ --architecture=combined --address-model=32_64 \ --macosx-version=10.4 --macosx-version-min=10.4 \ install That compiles and install fine. However, the produced binaries seems broken. az@ip245 47 (openlierox) %file /usr/local/lib/libboost_signals.a /usr/local/lib/libboost_signals.a: current ar archive random library az@ip245 49 (openlierox) %lipo -info /usr/local/lib/libboost_signals.a input file /usr/local/lib/libboost_signals.a is not a fat file Non-fat file: /usr/local/lib/libboost_signals.a is architecture: x86_64 az@ip245 48 (openlierox) %otool -hv /usr/local/lib/libboost_signals.a Archive : /usr/local/lib/libboost_signals.a /usr/local/lib/libboost_signals.a(trackable.o): Mach header magic cputype cpusubtype caps filetype ncmds sizeofcmds flags MH_MAGIC_64 X86_64 ALL 0x00 OBJECT 3 1536 SUBSECTIONS_VIA_SYMBOLS /usr/local/lib/libboost_signals.a(connection.o): Mach header magic cputype cpusubtype caps filetype ncmds sizeofcmds flags MH_MAGIC_64 X86_64 ALL 0x00 OBJECT 3 1776 SUBSECTIONS_VIA_SYMBOLS /usr/local/lib/libboost_signals.a(named_slot_map.o): Mach header magic cputype cpusubtype caps filetype ncmds sizeofcmds flags MH_MAGIC_64 X86_64 ALL 0x00 OBJECT 3 1856 SUBSECTIONS_VIA_SYMBOLS /usr/local/lib/libboost_signals.a(signal_base.o): Mach header magic cputype cpusubtype caps filetype ncmds sizeofcmds flags MH_MAGIC_64 X86_64 ALL 0x00 OBJECT 3 1776 SUBSECTIONS_VIA_SYMBOLS /usr/local/lib/libboost_signals.a(slot.o): Mach header magic cputype cpusubtype caps filetype ncmds sizeofcmds flags MH_MAGIC_64 X86_64 ALL 0x00 OBJECT 3 1616 SUBSECTIONS_VIA_SYMBOLS Any suggestion how to get that correct?

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  • How to validate presence of an uploaded file in rails?

    - by brad
    I'm playing around creating a rails file uploader and have struck a problem that should have an obvious solution. How do I check that a file has been selected in my form and uploaded? Here is my new.html.erb view <h2>Upload File</h2> <% form_for(@upload_file, :url => {:action => 'save'}, :html => {:multipart => true}) do |f| %> <%= f.error_messages %> <p> <%= f.label :file -%> <%= f.file_field :upload -%> </p> <p> <%= f.label :description %> <%= f.text_field :description %> </p> <p> <%= f.label :file_type %> <%= f.select :file_type, ["XML Data"] %> </p> <p><%= f.submit 'Upload File' %></p> <% end %> and here is my upload_file.rb model class UploadFile < ActiveRecord::Base validates_presence_of :description validates_presence_of :file_type validates_presence_of :upload def upload=(upload_file_field) self.name = "#{Time.now.strftime("%Y%m%d%H%M%S")}_#{upload_file_field.original_filename}" File.open("#{RAILS_ROOT}/public/upload/#{self.name}", "wb") { |f| f.write(upload_file_field.read) } end end If I use this as shown here, the validation validates_presence_of :upload always fails and I am returned to my form with an error message. I'd be very grateful if someone could explain how to do this validation correctly, and I'd be even more grateful if they could explain why it works. Thanks.

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  • How to distinguish between two different UDP clients on the same IP address?

    - by Ricket
    I'm writing a UDP server, which is a first for me; I've only done a bit of TCP communications. And I'm having trouble figuring out exactly how to distinguish which user is which, since UDP deals only with packets rather than connections and I therefore cannot tell exactly who I'm communicating with. Here is pseudocode of my current server loop: DatagramPacket p; socket.receive(p); // now p contains the user's IP and port, and the data int key = getKey(p); if(key == 0) { // connection request key = makeKey(p); clients.add(key, p.ip); send(p.ip, p.port, key); // give the user his key } else { // user has a key // verify key belongs to that IP address // lookup the user's session data based on the key // react to the packet in the context of the session } When designing this, I kept in mind these points: Multiple users may exist on the same IP address, due to the presence of routers, therefore users must have a separate identification key. Packets can be spoofed, so the key should be checked against its original IP address and ignored if a different IP tries to use the key. The outbound port on the client side might change among packets. Is that third assumption correct, or can I simply assume that one user = one IP+port combination? Is this commonly done, or should I continue to create a special key like I am currently doing? I'm not completely clear on how TCP negotiates a connection so if you think I should model it off of TCP then please link me to a good tutorial or something on TCP's SYN/SYNACK/ACK mess. Also note, I do have a provision to resend a key, if an IP sends a 0 and that IP already has a pending key; I omitted it to keep the snippet simple. I understand that UDP is not guaranteed to arrive, and I plan to add reliability to the main packet handling code later as well.

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  • Computing complex math equations in python

    - by dassouki
    Are there any libraries or techniques that simplify computing equations ? Take the following two examples: F = B * { [ a * b * sumOf (A / B ''' for all i ''' ) ] / [ sumOf(c * d * j) ] } where: F = cost from i to j B, a, b, c, d, j are all vectors in the format [ [zone_i, zone_j, cost_of_i_to_j], [..]] This should produce a vector F [ [1,2, F_1_2], ..., [i,j, F_i_j] ] T_ij = [ P_i * A_i * F_i_j] / [ SumOf [ Aj * F_i_j ] // j = 1 to j = n ] where: n is the number of zones T = vector [ [1, 2, A_1_2, P_1_2], ..., [i, j, A_i_j, P_i_j] ] F = vector [1, 2, F_1_2], ..., [i, j, F_i_j] so P_i would be the sum of all P_i_j for all j and Aj would be sum of all P_j for all i I'm not sure what I'm looking for, but perhaps a parser for these equations or methods to deal with multiple multiplications and products between vectors? To calculate some of the factors, for example A_j, this is what i use from collections import defaultdict A_j_dict = defaultdict(float) for A_item in TG: A_j_dict[A_item[1]] += A_item[3] Although this works fine, I really feel that it is a brute force / hacking method and unmaintainable in the case we want to add more variables or parameters. Are there any math equation parsers you'd recommend? Side Note: These equations are used to model travel. Currently I use excel to solve a lot of these equations; and I find that process to be daunting. I'd rather move to python where it pulls the data directly from our database (postgres) and outputs the results into the database. All that is figured out. I'm just struggling with evaluating the equations themselves. Thanks :)

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  • C++ error: expected initializer before ‘&’ token

    - by Werner
    Hi, the following piece of C++ code compiled two years ago in a suse 10.1 Linux machine. #ifndef DATA_H #define DATA_H #include <iostream> #include <iomanip> inline double sqr(double x) { return x*x; } enum Direction { X,Y,Z }; inline Direction next(const Direction d) { switch(d) { case X: return Y; case Y: return Z; case Z: return X; } } inline ostream& operator<<(ostream& os,const Direction d) { switch(d) { case X: return os << "X"; case Y: return os << "Y"; case Z: return os << "Z"; } } ... ... Now, I am trying to compile it on Ubuntu 9.10 and I get the error: data.h:20: error: expected initializer before ‘&’ token which is referred to the line of: inline ostream& operator<<(ostream& os,const Direction d) the g++ used on this machine is: Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.1-4ubuntu9' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu9) Could you give me some hint about this error? Thanks

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  • GPIB connection to external device using MATLAB

    - by hkf
    Is there a way to establish a GPIB connection using MATLAB without the instrument control Tool box? (I don't have it). Also is there a way for MATLAB to know what the external device's RS232 parameter values are ( Baud rate, stop bit etc..). For the RS232 connection I have the following code: % This function is meant to send commands to Potentiostat Model 263A. % A run includes turning the cell on, reading current for time t1, turning % the cell off, waiting for time t2. % t1 is the duration [secs] for which the Potentiostat must run (cell is on) % t2 is the duration [secs] to on after off % n is the number of runs % port is the serial port name such as COM1 function [s] = Potentiostat_control(t1,t2,n) port = input('type port name such as COM1', 's') s = serial(port); set(s,'BaudRate', 9600, 'DataBits', 8, 'Parity', 'even', 'StopBits', 2 ,'Terminator', 'CR/LF'); fopen(s) %fprintf(s,'RS232?') disp(['Total runs requested = ' num2str(n)]) disp('i denotes number of runs executed so far..'); for i=1:n i %data1 = query(s, '*IDN?') fprintf(s,'%s','CELL 1'); % sends the command 'CELL 1' %fprintf(s,'%s','READI'); pause(t1); fprintf(s,'%s','CELL 0'); %fprintf(s,'%s','CLEAR'); pause(t2); end fclose(s)

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  • Business entity: private instance VS single instance

    - by taoufik
    Suppose my WinForms application has a business entity Order, the entity is used in multiple views, each view handles a different domain or use-case in the application. As an example, one managing orders, the other one digging into one order and displaying additional data. If I'd use nHibernate (or any other ORM) and use one session/dataContext per view (or per db action), I'd end up getting two different instances for the same Order (let's say orderId = 1). Although functionally the same entity, they are technically two different instances. Yes, I could implement Equals/GetHashcode to make them "seem" the same. Why would you go for a single instance per entity vs private instances per view or per use-case? Having single instances has the advantage of sharing INotifyPropertyChanged events, and sharing additional (non-persistent) data. Having a private instance in each view would give you the flexibility of the undo functionality on a view level. In the example above, I'd allow the user to change order details, and give them the flexibility to not save the change. Here, synchronisation between the view/use-case happens on a data persistence level. What would your argument be?

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  • How do I specify Open ID Realm in spring security ?

    - by Salvin Francis
    We are using Spring security in our application with support for username / password based authentication as well as Open id based authentication. The issue is that google gives a different open id for the return url specified and we have at least 2 different entry points in our application from where open id is configured into our system. Hence we decided to use open id realm. http://blog.stackoverflow.com/2009/0...ue-per-domain/ http://groups.google.com/group/googl...unts-api?pli=1 how is it possible to integrate realm into our spring configuration/code ? This is how we are doing it in traditional openid library code: AuthRequest authReq = consumerManager.authenticate(discovered, someReturnToUrl,"http://www.example.com"); This works and gives same open id for different urls from our site. our configuration: Code: ... <http auto-config="false"> <!-- <intercept-url> tags are here --> <remember-me user-service-ref="someRememberedService" key="some key" /> <form-login login-page="/Login.html" authentication-failure-url="/Login.html?error=true" always-use-default-target="false" default-target-url="/MainPage.html"/> <openid-login authentication-failure-url="/Login.html?error=true" always-use-default-target="true" default-target-url="/MainPage.html" user-service-ref="someOpenIdUserService"/> </http> ... <beans:bean id="someOpenIdUserService" class="com.something.MyOpenIDUserDetailsService"> </beans:bean> <beans:bean id="openIdAuthenticationProvider" class="com.something.MyOpenIDAuthenticationProvider"> <custom-authentication-provider /> <beans:property name="userDetailsService" ref="someOpenIdUserService"/> </beans:bean> ...

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