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• Can we create a class from a xml file ?

  - by panzerschreck

  Hello, Is it possible to create a class dynamically by reading an xml file ( in java preferably) ? if yes, please provide pointers on how to do it. In the process of development, we have come up with a class that has 5 attributes, all these attributes correspond to an entry in the xml file, now if the user adds/modifies the xml entry the object corresponding to it must change automatically, one approach would be generate the source code, before compile time.Is there any other way ? Is there any common pattern to model such changes in the system ? Thanks,

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• Why getting active record error when trying to work on arrays?

  - by keruilin

  I have the following association in my User model: has_and_belongs_to_many :friends, :class_name => 'User', :foreign_key => 'friend_id' I have the following uniqueness constraint in my user_users table: UNIQUE KEY `no_duplicate_friends` (`user_id`,`friend_id`) In my code, I am retrieving a user's friends -- friends = user.friends. friends is an array. I have a scenario where I want add the user with all those friends to the friends array. Ex: friends << user_with_all_those_homies However, I get the following error: ActiveRecord::StatementInvalid: Mysql::Error: Duplicate entry '18-18' for key 'no_duplicate_friends': INSERT INTO `users_users` (`friend_id`, `user_id`) VALUES (18, 18) What gives?

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• How to extend a website?

  - by eltados

  This is quite a concept idea. I would like to create a website that can be extend by different programmer a bit "a la facebook" Let's me explain i want to develop a very simple core application that for example would store images and i want to develop or allow external developer to develop web app that would be able to act on the image i can take this example of an OS that would store files and you can "install" different program for example to view the files or edit. How can i reproduce the model in the Web / cloud plateform using API ? I hope this question make sense to any body. Thank you by advance

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• Django User "per project" group assignation

  - by Ben G

  Hi, Here's my problem : my site has users, which can create projects, and access other user's projects. Each project can assign different rights to users. So, i could have Project A : user "John" is in group "manager" , and Project "B" user "John" is in group "worker". How could I use the Django User authentication model to do that ? From a SQL point a view, what i would like is to be able to add "project_id" in the primary key for the "auth_user_groups" table. I don't think profile is of any help here. Any advice ? UPDATE : "worker" and "manager" are just two examples of the permission group (or "roles") that my application defines. There will be more in the future. Eg : i will probably also have "admin", "reporting", etc...

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• Multiple children in single form in rails

  - by CaptnCraig

  I have a model that has an arbitrary number of children entities. For simplicity lets call the entities Orders and Items. I would like to have a create Orders form where I input the order information, as well as add as many items as I want. If I click the "Add another item" button, a new set of form elements will be added to input the new data, amounts, etc.. I could hack this out in pure javascript, but I'm pretty sure there has to be a more magical, railsish way to do it, maybe with a partial view or something. I'm just a little too new to rails to know what it is. What is the best way to dynamically add the new form elements, and then to access them in the create controller?

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• Resetting Objects vs. Constructing New Objects

  - by byronh

  Is it considered better practice and/or more efficient to create a 'reset' function for a particular object that clears/defaults all the necessary member variables to allow for further operations, or to simply construct a new object from outside? I've seen both methods employed a lot, but I can't decide which one is better. Of course, for classes that represent database connections, you'd have to use a reset method rather than constructing a new one resulting in needless connecting/disconnecting, but I'm talking more in terms of abstraction classes. Can anyone give me some real-world examples of when to use each method? In my particular case I'm thinking mostly in terms of ORM or the Model in MVC. For example, if I would want to retrieve a bunch of database objects for display and modify them in one operation.

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• OOP App Architecture: Which layer does a lazy loader sit in?

  - by JW

  I am planning the implemention an Inheritance Mapper pattern for an application component http://martinfowler.com/eaaCatalog/inheritanceMappers.html One feature it needs to have is for a domain object to reference a large list of aggreageted items (10,000 other domain objects) So I need some kind of lazy loading collection to be passed out of the aggregate root domain object to other domain objects. To keep my (php) model scripts organised i am storing them in two folders: MyComponent\ controllers\ models\ domain\ <- domain objects, DDD repository, DDD factory daccess\ <- PoEAA data mappers, SQL queries etc views\ But now I am racking my brains wondering where my lazy loading collection sits. Any suggestions / justifications for putting it in one place over another another? DDD = Domain Driven Design Patterns, Eric Evans - book PoEAA = Patterns of Application Architecture Patterns, Martin Fowler - book

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• What is the fastest way to validate that a field has no more than n words?

  - by James A. Rosen

  I have a Ruby-on-Rails model: class Candidate < ActiveRecord::Base validates_presence_of :application_essay validate :validate_length_of_application_essay protected def validate_length_of_application_essay return if application_essay.blank? # don't add a second error message if they didn't fill it out errors.add(:application_essay, :too_long), unless ... end end Without dropping into C, what is the fastest way to check that the application_essay contains no more than 500 words? You can assume that most essays will be at least 200 words, are unlikely to be more than 5000 words, and are in English (or the pseudo-English sometimes called "business-ese"). You can also classify anything you want as a "word" as long as your classification would be immediately obvious to a typical user. (NB: this is not the place to debate what a "typical user" is :) )

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• Sharepoint 2010, get the Distinct Values of a User Profile Property?

  - by Michael Stum

  Is there any way in SharePoint 2010 to get the Distinct values of a property accross all users? For example, I want a list of all Departments in the Profile Store. In SQL I can do SELECT DISTINCT(PropertyVal) FROM [ProfileDB].[dbo].[UserProfileValue] WHERE PropertyID = 14 but accessing the SQL Database is a big no-no of course, so I wonder if there is something in the object model? Note that accessing the User Information List on an SPSite is not good enough, as only a fraction of all users is in that list. I want to get it directly from the Profile Store.

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• Handling Dialogs in WPF with MVVM

  - by Ray Booysen

  In the MVVM pattern for WPF, handling dialogs is one of the more complex operations. As your view model does not know anything about the view, dialog communication can be interesting. I can expose an ICommand that when the view invokes it, a dialog can appear. Does anyone know of a good way to handle results from dialogs? I am speaking about windows dialogs such as MessageBox. One of the ways we did this was have an event on the viewmodel that the view would subscribe to when a dialog was required. public event EventHandler<MyDeleteArgs> RequiresDeleteDialog; This is OK, but it means that the view requires code which is something I would like to stay away from.

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• Is there an API for listing queues and exchanges on RabbitMQ?

  - by parsenome

  I've looked quite a bit, but I haven't been able to find a good programmatic way to list the queues on a RabbitMQ server. This is important because I need to clean up my queues and exchanges when I'm done with them. I don't always have a good "done" event that can be used to trigger a cleanup, so I'd like to do it with more of a garbage collection model. If I can list the queues, I can verify that the objects that they're related to shouldn't be producing more entries and clean them up. I know I can use rabbitmqctl to do it, but that needs elevated privileges. Since I haven't been able to find a way to list the queues programmatically, I've been keeping a list of names in the database. That works, but it's ugly.

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• ASP.net MVC: Getting a Partial View's HTML from inside of the controller

  - by Harry

  I have developed a simple mechanism for my mvc website to pull in html via jquery which then populates a specified div. All is well and it looks cool. My problem is that i'm now creating html markup inside of my controller (Which is very easy to do in VB.net btw) I'd rather not mix up the sepparation of concerns. Is it possible to use a custom 'MVC View User Control' to suit this need? Can I create an instance of a control, pass in the model data and render to html? It would then be a simple matter of rendering and passing back to the calling browser.

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• Suggestions on how to track tag count for a particular object

  - by Robin Fisher

  Hi, I'm looking for suggestions on how to track the number of tags associated with a particular object in Rails. I'm using acts_as_taggable_on and it's working fine. What I would like to be able to do is search for all objects that have no tags, preferably through a scope i.e. Object.untagged.all My first thought was to use an after_save callback to update an attribute called "taggings_count" in my model: def update_taggings_count self.taggings_count = self.tag_list.size self.save end Unfortunately, this does the obvious thing of putting me in an infinite loop. I need to use an after_save callback because the tag_list is not updated until the main object is saved. Would appreciate any suggestions as I'm on the verge of rolling my own tagging system. Regards Robin

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• Rails - Trying to query from a date range...everything from today

  - by ChrisWesAllen

  I'm trying to figure the best way to query a date range from rails...I looked around on Google but am unsure about how to use this syntax. I have a Model that has various events and I like to add to my find condition a caveat that should only show events where the field :st_date is today or later, in effect only show me data that is current, nothing that happened before today. I ran into a problem because I have no end date to stop the query, I want to query everything from today to next month. I was thinking something like @events = Event.find(:all, :conditions => ["start_date between ? and ?", date.Today, date.next_month.beginning_of_month]) but I get the error undefined local variable or method `date'...... Do I need do anything particular to use the Date class? Or is there something wrong with my query syntax? I would really appreciate any help.

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• Timespan not accepting day in MVC3

  - by middelpat

  I have a MVC3 application in which i want to set a timespan to for example 2 days and 5 hours. when i enter 02:05:00:00 it gives me the following exception: System.OverflowException: SqlDbType.Time overflow. Value '2.05:00:00' is out of range. Must be between 00:00:00.0000000 and 23:59:59.9999999. When i enter 05:00:00 it correctly saves 5 hours into the database. according to MSDN timespan has a property for days. How do i correctly set the days? Model: public class ProductionTimeVM { [Required] public TimeSpan DefaultTime { get; set; } } In my view i just use: @Html.TextBoxFor(x => x.DefaultTime) For my controller: public ActionResult SaveProductionTime(ProductionTimeVM vm) { ProductionTime productionTime = new ProductionTime(); productionTime.Default = vm.DefaultTime; //some more code } Any idea's?

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• Concise description of the lua vm?

  - by anon

  I've skimmed Programing in Lua, I've looked at the Lua Reference. However, they both tells me this function does this, but not how. When reading SICP, I got this feeling of: "ah, here's the computational model underlying scheme"; I'm trying to get the same sense concerning lua -- i.e. a concise description of it's vm, a "how" rather than a "what". Does anyone know of a good document (besides the C source) describing this? Thanks!

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• How do you use printf from Assembly?

  - by bobobobo

  I have an MSVC++ project set up to compile and run assembly code. In main.c: #include <stdio.h> void go() ; int main() { go() ; // call the asm routine } In go.asm: .586 .model flat, c .code go PROC invoke puts,"hi" RET go ENDP end But when I compile and run, I get an error in go.asm: error A2006: undefined symbol : puts How do I define the symbols in <stdio.h> for the .asm files in the project?

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• ASP.Net Roles: Page-Level Security Question

  - by jlrolin

  We're currently in the process of re-creating a brand new security model that dwarfs our existing process. Right now, we plan on grabbing a user's roles during the login process and then using a Base Page class to check if the user has the role of the corresponding page the user is navigating to. We can limit the menu's options by the user's roles as well, but we have had problems with users navigating to pages in our system by typing them in or having old bookmarks. Obviously, we need some sort of page level access. A simple function in our Base Page class that checks the role in the Arraylist against the page's assigned role would work, but I was wondering if there was any built-in functionality to support this or a cleaner solution possibly.

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• Using indexes on/through a MySQL view

  - by Peeja

  We've got a MySQL table in which rows are never updated, but instead new rows are added and the old ones marked obsolete. Think Rails' acts_as_paranoid, but for every update. To make working with Rails sane, we've got a view which selects only the rows which are "current". That makes a much better "table" for our ActiveRecord model. The snag: our indexes aren't being used anymore. Queries on the view don't use the underlying tables' indexes. You can't add an index to a view. Without indexes, the app is unbearably slow. The only solution we've come up with is to build a materialized view, but that's a pain in MySQL because they're not natively supported. Is there a better way to do this?

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• How to define supported BlackBerry OS versions and models for application?

  - by Lyubomyr Dutko

  After company wins a project it is usual to mention in contract what devices are supported and what OS versions are supported. But taking into account BlackBerry it appears sometimes to be tricky, as you can have the same device model, but two and(or) more different OS versions (or within same OS different package versions). And in this situation application may need to be updated. So the main question here is what is expected to be mentioned in contract? Could you please share some your experience of resolving such problems? So as a good example can be case of video playback issue on Storm: some issue exists on 5.0.0.XXX (network provider A) and doesn't exist on 5.0.0.YYY (network provider B), or could be following: 5.0.0.XXX1 (network provider A) - issue exist 5.0.0.XXX2 (network provider A) - issue doesn't exist The point here is to define some boundaries of development company responsibility

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• How to set default values to all wrong or null parameters of method?

  - by Roman

  At the moment I have this code (and I don't like it): private RenderedImage private RenderedImage getChartImage (GanttChartModel model, String title, Integer width, Integer height, String xAxisLabel, String yAxisLabel, Boolean showLegend) { if (title == null) { title = ""; } if (xAxisLabel == null) { xAxisLabel = ""; } if (yAxisLabel == null) { yAxisLabel = ""; } if (showLegend == null) { showLegend = true; } if (width == null) { width = DEFAULT_WIDTH; } if (height == null) { height = DEFAULT_HEIGHT; } ... } How can I improve it? I have some thoughts about introducing an object which will contain all these parameters as fields and then, maybe, it'll be possible to apply builder pattern. But still don't have clear vision how to implement that and I'm not sure that it's worth to be done. Any other ideas?

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• How to use a 3rd party control inside the viewmodel?

  - by Sander

  I have a 3rd party control which among other things performs loading of some data. I want my viewmodel to keep track of this load operation and adjust its own state accordingly. If it were up to me, I'd do the data loading far away from the view, but it is not. So, I seem to be in the situation where my viewmodel depends on my view. How do I best handle this? I feel rather dirty making the view publish events to the viewmodel but I don't see any other reasonable way to get this info into the viewmodel. A similar situation might crop up with standard controls, too - imagine if your viewmodel depends on the events coming from a MediaElement - how do you properly model this? Do you put the MediaElement into the viewmodel? That doesn't sound right. If publishing the events to the viewmodel is indeed the most reasonable way, is there some common pattern used for this? How do you do it?

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• Best evidence to offer a sandboxed appdomain for a C# evaluator.

  - by scope-creep

  I have a c# evaluator which uses the (I think) the .Net 4 new simplified sandboxed appdomain model to host the c# assembly, with remoting doing the rest. The call to create the appdomain is Evidence ev = new Evidence(); ev.AddHostEvidence(new Zone(SecurityZone.Trusted)); PermissionSet pset = SecurityManager.GetStandardSandbox(ev); AppDomainSetup ads = new AppDomainSetup(); ads.ApplicationBase = "C:\\Sandbox"; // Create the sandboxed domain. AppDomain sandbox = AppDomain.CreateDomain( "Sandboxed Domain", ev, ads, pset, null); The c# eval is embedded in a server app, but I don't want give the sandbox to much control unless it bo bo's the caller. What i'm looking for is regarding some clarification as to what to provide as Evidence from the caller. I'm looking for advice and guidance. Any help would be appreciated.

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• How do i style a JSON feed in my view?

  - by stephenmurdoch

  My rails app gets the following JSON feed from mixcloud and sticks the results into my index page At the moment when I do this, the entire contents of my feed are displayed unformatted in one big blob of scary looking text (without the curly JSON brackets) I only want to display specific values from the feed in the view. From the feed in question lets say for simplicity that I just wanted to display all values with a key of "url" In case I'm doing something wrong here's my code: # podcast controller def index # I'm using a class method to get the feed @feed = Podcast.feed end # podcast model def self.feed feed = JSON.parse(open("http://api.mixcloud.com/alivefrommaryhill/feed").read) end # index.html.haml .feed = @feed I can't figure out how to style the results and display only certain items from the feed. Is my approach wrong?

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• MongoDB: embedding performance question

  - by Alex

  I just started learning MongoDB, and I really like the idea of embedding collections instead of referencing them. MongoDB's documentation recommends to use embedding if performance is needed. I just thought about a simple forum model. Let's say, every board category has several boards, every board has several topics, and every topic has several messages. All of these collections are embedded. After some time the size of the board category will be huge. Way more than the 2MB limit. Does this mean that there's a flaw in this design?

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