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  • Sort a data grid based on a specified column.

    - by o vamsi krishna
    Developed a winform project using VB 2008. I'm using a .xls sheet as source. My appln has 7 columns and unspecified rows. I want to sort all the columns based on a specified column and allot a serial number as per the sorted order. If two items in the specified column are same we should consider another column for the equal items and sort them in that order. plz help me in this issue.

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  • Restricting access to records. Is claim-based permissions a good idea.

    - by Vitalik
    in .net Claim-based identity framework If i wanted to restrict users to do an operation (view or edit) on let's say an account, a particular account #123456.(i am talking about business entity, like a bank account.) Is it a good idea to create a claim for each account they can view or edit? Any disadvantages of having a lot of claims in a set? a system admin might have access to all accounts in the system thus creating hundreds of claims (maybe more than one for each account)

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  • Examples of temporal database designs? [closed]

    - by miku
    I'm researching various database design for historical record keeping - because I would like to implement a prototypical web application that (excessively) tracks changes made by users and let them undo things, see revisions, etc. I'd love use mercurial or git as backend (with files as records) - since they already implement the kind of append-only changes I imagine. I tried git and dulwich (python git API) - and it went ok - but I was concerned about performance; Bi-temporal database design lets you store a row along with time periods, when this record was valid. This sure sound more performant than to operate on files on disk (as in 1.) - but I had little luck finding real-world examples (e.g. from open source projects), that use this kind of design and are approachable enough to learn from them. Revisions à la MediaWiki revisions or an extra table for versions, as in Redmine. The problem here is, that DELETE would take the whole history with it. I looked at NoSQL solutions, too. With a document oriented approach, it would be simple to just store the whole history of an entity within the document itself - which would reduce design plus implementation time in contrast to a RDBMS approach. However, in this case I'm a bit concerned about ACID-properties, which would be important in the application. I'd like ask about experiences about real-world and pragmatic designs for temporal data.

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  • How to improve designer and developer work flow?

    - by mbdev
    I work in a small startup with two front end developers and one designer. Currently the process starts with the designer sending a png file with the whole page design and assets if needed. My task as front end developer is to convert it to a HTML/CSS page. My work flow currently looks like this: Lay out the distinct parts using html elements. Style each element very roughly (floats, minimal fonts and padding) so I can modify it using inspection. Using Chrome Developer Tools (inspect) add/change css attributes while updating the css file. Refresh the page after X amount of changes Use Pixel Perfect to refine the design more. Sit with the designer to make last adjustments. Inferring the paddings, margins, font sizes using trial and error takes a lot of time and I feel the process could become more efficient but not sure how to improve it. Using PSD files is not an option since buying Photoshop for each developer is currently not considered. Design guide is also not available since design is still evolving and new features are introduced. Ideas for improving the process above and sharing how the process looks like in your company will be great.

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  • MVC + 3 tier; where ViewModels come into play?

    - by mikhairu
    I'm designing a 3-tiered application using ASP.NET MVC 4. I used the following resources as a reference. CodeProject: MVC + N-tier + Entity Framework Separating data access in ASP.NET MVC I have the following desingn so far. Presentation Layer (PL) (main MVC project, where M of MVC was moved to Data Access Layer): MyProjectName.Main Views/ Controllers/ ... Business Logic Layer (BLL): MyProjectName.BLL ViewModels/ ProjectServices/ ... Data Access Layer (DAL): MyProjectName.DAL Models/ Repositories.EF/ Repositories.Dapper/ ... Now, PL references BLL and BLL references DAL. This way lower layer does not depend on the one above it. In this design PL invokes a service of the BLL. PL can pass a View Model to BLL and BLL can pass a View Model back to PL. Also, BLL invokes DAL layer and DAL layer can return a Model back to BLL. BLL can in turn build a View Model and return it to PL. Up to now this pattern was working for me. However, I've ran into a problem where some of my ViewModels require joins on several entities. In the plain MVC approach, in the controller I used a LINQ query to do joins and then select new MyViewModel(){ ... }. But now, in the DAL I do not have access to where ViewModels are defined (in the BLL). This means I cannot do joins in DAL and return it to BLL. It seems I have to do separate queries in DAL (instead of joins in one query) and BLL would then use the result of these to build a ViewModel. This is very inconvenient, but I don't think I should be exposing DAL to ViewModels. Any ideas how I can solve this dilemma? Thanks.

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  • Name for Osherove's modified singleton pattern?

    - by Kazark
    I'm pretty well sold on the "singletons are evil" line of thought. Nevertheless, there are limited occurrences when you want to limit the creation of an object. Roy Osherove advises, If you're planning to use a singleton in your design, separate the logic of the singleton class and the logic that makes it a singleton (the part that initializes a static variables, for example) into two separate classes. That way, you can keep the single responsibility principle (SRP) and also have a way to override singleton logic. (The Art of Unit Testing 261-262) This pattern still perpetuates the global state. However, it does result in a testable design, so it seems to me to be a good pattern for mitigating the damage of a singleton. However, Osherove does not give a name to this pattern; but naming a pattern, according to the Gang of Four, is important: Naming a pattern immediately increases our design vocabulary. It lets us design at a higher level of abstraction. (3) Is there a standard name for this pattern? It seems different enough from a standard singleton to deserve a separate name. Decoupled Singleton, perhaps?

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  • Advice on choosing a book to read

    - by Kioshiki
    I would like to ask for some recommendations on useful books to read. Initially I had intended on posting quite a long description of my current issue and asking for advice. But I realised that I didn’t have a clear idea of what I wanted to ask. One thing that is clear to me is that my knowledge in various areas needs improving and reading is one method of doing that. Though choosing the right book to read seems like a task in itself when there are so many books out there. I am a programmer but I also deal with analysis, design & testing. So I am not sure what type of book to read. One option might be to work through two books at the same time. I had thought maybe one about design or practices and another of a more technical focus. Recently I came across one book that I thought might be useful to read: http://xunitpatterns.com/index.html It seems like an interesting book, but the comments I read on amazon.co.uk show that the book is probably longer than it needs to be. Has anyone read it and can comment on this? Another book that I already own and would probably be a good one to finish reading is this: http://www.amazon.co.uk/Code-Complete-Practical-Handbook-Construction/dp/0735619670/ref=sr_1_1?ie=UTF8&qid=1309438553&sr=8-1 Has anyone else read this who can comment on its usefulness? Beyond these two I currently have no clear idea of what to read. I have thought about reading a book related to OO design or the GOF design patterns. But I wonder if I am worrying too much about the process and practices and not focusing on the actual work. I would be very grateful for any suggestions or comments. Many Thanks, Kioshiki

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  • Relationship between SOA and OOA

    - by TheSilverBullet
    Thomas Erl defines SOA as follows in his site: Service-oriented computing represents a new generation distributed computing platform. As such, it encompasses many things, including its own design paradigm and design principles, design pattern catalogs, pattern languages, a distinct architectural model, and related concepts, technologies, and frameworks. This definitely sounds like a whole new category which is parallel to object orientation. Almost one in which you would expect an entirely new language to exist for. Like procedural C and object oriented C#. Here is my understanding: In real life, we don't have entirely new language for SOA. And most application which have SOA architecture have an object oriented design underneath it. SOA is a "strategy" to make the entire application/service distributed and reliable. SOA needs OOPS working underneath it. Is this correct? Where does SOA (if at all it does) fit in with object oriented programming practices? Edit: I have learnt through answers that OOA and SOA work with each other and cannot be compared (in a "which is better" way). I have changed the title to "Relationship between SOA and OOA" rather than "comparison".

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  • Must all AI states be able to react to any event?

    - by Prog
    FSMs implemented with the State design pattern are a common way to design AI agents. I am familiar with the State design pattern and know how to implement it. How is this used in games to design AI agents? Consider a simplified class Monster, representing an AI agent: class Monster { State state; // other fields omitted public void update(){ // called every game-loop cycle state.execute(this); } public void setState(State state){ this.state = state; } // irrelevant stuff omitted } There are several State subclasses implementing execute() differently. So far, classic State pattern. AI agents are subject to environmental effects and other objects communicating with them. For example, an AI agent might tell another AI agent to attack (i.e. agent.attack()). Or a fireball might tell an AI agent to fall down. This means that the agent must have methods such as attack() and fallDown(), or commonly some message receiving mechanism to understand such messages. With an FSM, the current State of the agent should be the one taking care of such method calls - i.e. the agent delegates to the current state upon every event. Is this correct? If correct, how is this done? Are all states obligated by their superclass to implement methods such as attack(), fallDown() etc., so the agent can always delegate to them on almost every event? Or is it done in some other way?

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  • Did I Inadvertently Create a Mediator in my MVC?

    - by SoulBeaver
    I'm currently working on my first biggish project. It's a frontend facebook application that has, since last Tuesday, spanned some 6000-8000 LOC. I say this because I'm using the MVC, an architecture I have never rigidly enforced in any of my hobby projects. I read part of the PureMVC book, but I didn't quite grasp the concept of the Mediator. Since I didn't understand and didn't see the need for it, my project has yet to use a single mediator. Yesterday I went back to the design board because of some requirement changes and noticed that I could move all UI elements out of the View and into its own class. The View essentially only managed the lifetime of the UI and all events from the UI or Model. Technically, the View has now become a 'Mediator' between the Model and UI. Therefore, I realized today, I could just move all my UI stuff back into the View and create a mediator class that handles all events from the view and model. Is my understanding correct in thinking that I have devolved my View as it currently is (handling events from the Model and UI) into a Mediator and that the UI class is what should be the View?

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  • How to learn to deliver quality software designs when working on a tight deadline?

    - by chester89
    I read many books about how to design great software, but I kind of struggle to come up with a good design decisions when it comes to business apps, especially when the timeframe is tough. In the company I currently work for, the following situation happen all the time: my teamlead tells me that there's a task to do, I call some guy or a girl from business who tells me exactly what is it they want, and then I start coding. The task always fits in some existing application (we do only web apps or web services), usually it's purpose is to pull data from one datasource and put into the other one, with some business logic attached in the process. I start coding and then, after spending some time on a problem, my code didn't work as expected - either because of technical mistake or my lack of knowledge of the domain. The business is ringing me 2-3 times a day to hurry me up. I ask my team lead to help, he comes up, sees my code and goes like 'What's this?'. Then he throws away about half of my code, including all the design decisions I made, writes 2-3 methods that does the job (each of them usually 200-300 lines long or more, by the way), and task is complete, code works as it should have. The guy is smarter than me, obviously, and I'm aware of that. My goal is to be better software developer, that means write better code, not finish the job quicker with some crappy code. And the thing is, when I have enough time to tackle a problem, I can come up with a design that is good (in my opinion, of course), but I fall short to do so when I'm on a tight deadline. What should I do? I am fully aware that it's rather vague explanation, but please bear with me

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  • can we have one attribute with multiple values in an eav design?

    - by Shekhar
    i am doing a database design using EAV. I am facing an issue when i try to model an entity with attribute having multiple values? For example Entity id | name | description 1 | configuration1 | configuration1 Attribute id | entityId | name | type 1 | 1 |att1 | string 2 | 1 |att2 | int 3 |1 | att3 | List (How will i model this?) Value id | attributeId | value 1 | 1 | a 2 | 2 | 1 3 | 3 | b 4 | 3 | c 5 | 3 |d Is this the correct way to handle list of values? Please provide any helpful link to model this? Thanks Shekhar

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  • MVC model flow?

    - by fuzzygoat
    I am setting up an application using the MVC model and I have a query regrading the flow of information from the UI to the data model. What I need to do is place data from the UI in the model, what I have done is write a method in the view which collects the required data in an object and then passes it to the model. The model then takes ownership of the data so that the view can release its ownership. Does this sound sensible?

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  • Table Disobeys W3C Box Model, Ie8 Ignores Fixed Table Width !

    - by Axel Myers
    Hi, I'm having hard time with tables and column widths. Update: I'm using XHTML Strict 1.0. The page is: http://www.pro-turk.net/try The first problem I have is, I have a column with a fixed width of 100px and 4px padding, but it disobeys my padding depending on the value. The column width (as the distance between two borders according to W3C Box Model) is 156 px even if padding is 0 or 4. Only the position of the text changes. According to W3C Box Model ( available at www.pro-turk.net/box_model.png ), borders and paddings aren't included in WIDTH attribute, so why does it render wrongly ? The second problem is, when you look the page I gave with IE8, the first cell in the second row has 150px fixed width, but ie shows it about 50% of the total table width regardless of what i say.

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  • Storing GenericForeignKey content_type in another model?

    - by slypete
    I have a typical definition/instance situation in my data modeling. I'm trying to store the content_type of a GenericForeignKey in another model (the definition model) like so: class IndicatorFieldInstance(models.Model): definition = models.ForeignKey(IndicatorField) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey(definition.content_type, 'object_id') indicator_instance = models.ForeignKey(IndicatorInstance) I've also tried it like this: content_object = generic.GenericForeignKey('definition__content_type', 'object_id') Neither of these methods seem to work. Is it possible to achieve this? For reference, here's the definition model: class IndicatorField(models.Model): name = models.CharField(max_length='255') content_type = models.ForeignKey(ContentType) indicator = models.ForeignKey(Indicator) Thanks, Pete

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  • How useful are design patterns when it comes to web programming?

    - by Raja
    Background: My organization uses Microsoft .Net (3.5) with SQL Server 2005 as back end. With RAD being the norm and Agile being the widely used process. I have always found using design patterns difficult since it involves a bit more understanding and bit more training. Can you give me some examples where design patterns have solved real time problems in Web programming? What is the criteria for using any design pattern? What is the benefit reaped from it. I know it is a general question but this would help me a bunch.

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  • Django display manytomany field in form when definition is on other model

    - by John
    Hi I have the definition for my manytomany relationship on one model but want to display the field on the form of my other model. How do I do this? for example: # classes class modelA(models.Model): name = models.CharField(max_length=300) manytomany = models.ManyToManyField(modelA) class modelB(models.Model): name = models.CharField(max_length=300) # forms class modelBForm(forms.ModelForm): class Meta: model = modelB If I then used modelBForm it would show a select box with the models from modelA rather than just name. Thanks

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  • Can I create a transaction using ADO NET Entity Data Model?

    - by Junior Mayhé
    Hi is it possible on the following try-catch to execute a set of statements as a transaction using ADO NET Entity Data Model? [ValidateInput(false)] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Customer c) { try { c.Created = DateTime.Now; c.Active = true; c.FullName = Request.Form["FirstName"]; db.AddToCustomer(c); db.SaveChanges(); Log log = new Log();//another entity model object log.Created = DateTime.Now; log.Message = string.Format(@"A new customer was created with customerID {0}", c.CustomerID); db.AddToLog(log); db.SaveChanges(); return RedirectToAction("CreateSuccess", "Customer"); } catch { return View(); } } Any thoughts would be very appreciated.

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  • How to map a Entity Data Model conceptual model property to a storage model column using the "Serial

    - by codekaizen
    I have a conceptual model in EDM where one of the entities has a property which is essentially a big value object whose properties aren't really useful as columns in the datamodel. I'd like to apply the Serialized LOB pattern to it so that I can fit it into a 192 byte binary column. How do I map this in the EDM v4? Is it even possible at this time? Actually, is it possible in any ORM?

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  • how to save a fitted R model for later use

    - by ahala
    Sorry for this novice question: if I fit a lm() model or loess() model, and save the model somewhere in a file or in database, for later using by third party with predict() method, do I have to save the entire model object? Since returned model object contains orginal raw data, this returned object can be huge.

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  • Which type of Rails model association should I use in this situation?

    - by jstayton
    I have two models/tables in my Rails application: discussions and comments. Each discussion has_many comments, and each comment belongs_to a discussion. My discussions table also includes a first_comment_id column and last_comment_id column for convenience and speed. I want to be able to call discussion.last_comment for the last comment model, but the following (in my discussion model) isn't working to make this happen: has_one :first_comment, :class_name => "Comment" has_one :last_comment, :class_name => "Comment" When I call discussion.last_comment, the following SQL is run: SELECT * FROM `comments` WHERE (`comments`.discussion_id = 1) LIMIT 1 It's using the discussions.id column to join against comments.discussion_id, when I want it to join discussions.last_comment_id against comments.id. Am I using the wrong type of association here? Thanks for your help!

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  • WPF List of ViewModels bound to list of Model objects.

    - by Eric
    In the model, I have: public ObservableCollection<Item> Items { get; private set; } In the ViewModel, I have a corresponding list of ItemViewModels: public ObservableCollection<ItemViewModel> ItemViewModels ... In the XAML, I will bind (in this case a TreeView) to the ItemViewModels property. My question is, what goes in the "..." in the ViewModel shown above? I am hoping for a line or two of code to binds these two ObservableCollections (providing the type of the ViewModel to construct for each model object). However, what I'm fearing is necessary is a bunch of code to handle the Items.CollectionChanged event and manually updates the ItemViewModels list by constructing ViewModels as necessary. Thanks! Eric

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  • Rails multi level model security

    - by rballz
    I have the need to do the following in Rails to mirror a desktop application: a User and an Office 'owns' a record, if you don't own the record on a user or office level you're kicked into the public realm. user gets read,write,delete to the model record office gets read/write/delete to the model record other or public gets read/write/delete to the model record e.g. UserA owns a model record with read/write/delete OfficeA owns a model with read/write other/public gets read I was wondering if a plugin/gem existed to grant this functionality?

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  • Why can't I register a custom model binder for a List<int>?

    - by quarksoup
    I have an action that looks like public ActionResult GetUsers(List<int> userIds) {//do stuff} The list of userIds can become quite long, so I want to use Json.Net to deserialize it. To do so I created an IModelBinder implementation, which works fine for other objects, but never gets called for a List. The IModelBind looks like this public class JsonBinder : System.Web.Mvc.IModelBinder { public object BindModel(System.Web.Mvc.ControllerContext controllerContext, System.Web.Mvc.ModelBindingContext bindingContext) { //Do model binding stuff using Json.Net } } And I register this model binder with this line ModelBinders.Binders.Add(typeof(List<int>), new JsonBinder()); However the JsonBinder is never called. Why is this? Should I be using a ValueProvider?

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