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  • Bad practice to have models made up of other models?

    - by mattruma
    I have a situation where I have Model A that has a variety of properties. I have discovered that some of the properties are similar across other models. My thought was I could create Model B and Model C and have Model A be a composite with a Model B property and a Model C property. Just trying to determine if this is the best way to handle this situation.

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  • How can I create a small relational database in MySQL?

    - by Sergio Tapia
    I need to make a small database in MySQL that has two tables. Clothes and ClotheType Clothes has: ID, Name, Color, Brand, Price, ClotheTypeID ClotheType has: ID, Description In Microsoft SQL it would be: create table Clothes( id int, primary key(id), name varchar(200), color varchar(200), brand varchar(200), price varchar(200), clothetypeid int, foreign key clothetypeid references ClotheType(id) ) I need this in MySQL.

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  • What resources will help me understand the fundamentals of Relational Database Design.

    - by Rachel
    This are few of the fundamental database questions which has always given me trouble. I have tried using google and wiki but I somehow I miss out on understanding the functionality rather than terminology. If possible would really appreciate if someone can share more insights on this questions using some visual representative examples. What is a key? A candidate key? A primary key? An alternate key? A foreign key? What is an index and how does it help your database? What are the data types available and when to use which ones?

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  • Is it better to use a relational database or document-based database for an app like Wufoo?

    - by mboyle
    I'm working on an application that's similar to Wufoo in that it allows our users to create their own databases and collect/present records with auto generated forms and views. Since every user is creating a different schema (one user might have a database of their baseball card collection, another might have a database of their recipes) our current approach is using MySQL to create separate databases for every user with its own tables. So in other words, the databases our MySQL server contains look like: main-web-app-db (our web app containing tables for users account info, billing, etc) user_1_db (baseball_cards_table) user_2_db (recipes_table) .... And so on. If a user wants to set up a new database to keep track of their DVD collection, we'd do a "create database ..." with "create table ...". If they enter some data in and then decide they want to change a column we'd do an "alter table ....". Now, the further along I get with building this out the more it seems like MySQL is poorly suited to handling this. 1) My first concern is that switching databases every request, first to our main app's database for authentication etc, and then to the user's personal database, is going to be inefficient. 2) The second concern I have is that there's going to be a limit to the number of databases a single MySQL server can host. Pretending for a moment this application had 500,000 user databases, is MySQL designed to operate this way? What if it were a million, or more? 3) Lastly, is this method going to be a nightmare to support and scale? I've never heard of MySQL being used in this way so I do worry about how this affects things like replication and other methods of scaling. To me, it seems like MySQL wasn't built to be used in this way but what do I know. I've been looking at document-based databases like MongoDB, CouchDB, and Redis as alternatives because it seems like a schema-less approach to this particular problem makes a lot of sense. Can anyone offer some advice on this?

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  • Spring 3 MVC - Form Failure Causes Exception When Reloading JSP

    - by jboyd
    Using Spring 3 MVC, please bear with the long code example, it's quite simple, but I want to make sure all relevant information is posted. Basically here is the use case: There is a registration page, a user can login, OR fill out a registration form. The login form is a simple HTML form, the registration form is a more complicated, Spring bound form that uses a RegistrationFormData bean. Here is the relevant code: UserController.java ... @RequestMapping(value = "/login", method = RequestMethod.GET) public String login(Model model) { model.addAttribute("registrationInfo", new ProfileAdminFormData()); return "login"; } ... @RequestMapping(value = "/login.do", method = RequestMethod.POST) public String doLogin( @RequestParam(value = "userName") String userName, @RequestParam(value = "password") String password, Model model) { logger.info("login.do : userName=" + userName + ", password=" + password); try { getUser().login(userName, password); } catch (UserNotFoundException ex) { logger.error(ex); model.addAttribute("loginError", ex.getWebViewableErrorMessage()); return "login"; } return "redirect:/"; } ... @RequestMapping(value = "/register.do") public String register( @ModelAttribute(value = "registrationInfo") ProfileAdminFormData profileAdminFormData, BindingResult result, Model model) { //todo: redirect if (new RegistrationValidator(profileAdminFormData, result).validate()) { try { User().register(profileAdminFormData); return "index"; } catch (UserException ex) { logger.error(ex); model.addAttribute("registrationErrorMessage", ex.getWebViewableErrorMessage()); return "login"; } } return "login"; } and the JSP: ... <form:form commandName="registrationInfo" action="register.do"> ... So the problem here is that when login fails I get an exception because there is no bean "registrationInfo" in the model attributes. What I need is that regardless of the path through this controller that the "registrationInfo" bean is not null, that way if login fails, as opposed to registration, that bean is still in the model. As you can see I create the registrationInfo object explicitly in my controller in the method bound to "/login", which is what I thought was going to be kind of a setup method" Something doesn't feel right about the "/login" method which sets up the page, but I needed to that in order to get the page to render at all without throwing an exception because there is no "registrationInfo" model attribute, as needed by the form in the JSP

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  • If I create a transient property in the model, isn't this managed by core data then?

    - by mystify
    Just to grok this: If I had a transient property, lets say averagePrice, and I mark that as "transient" in the data modeler: This will not be persistet, and no column will be created in SQLite for that? And: If I make my own NSManagedObject subclass with an averagePrice property, does it make any sense to model that property in the xcdatamodel file? Would it make a difference if I would simply create a property in my subclass and not model that in the entity? (I think: yes, it doesn't matter at all ... but not sure)

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  • JPA: what is the proper pattern for iterating over large result sets?

    - by Caffeine Coma
    Let's say I have a table with millions of rows. Using JPA, what's the proper way to iterate over a query against that table, such that I don't have all an in-memory List with millions of objects? I suspect that the following will blow up if the table is large: List<Model> models = entityManager().createQuery("from Model m", Model.class).getResultList(); for (Model model : models) { // do something with model } Is pagination (looping and manually updating setFirstResult()/setMaxResult()) really the best solution?

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  • ASP.NET MVC Unit Testing Controllers - Repositories

    - by Brian McCord
    This is more of an opinion seeking question, so there may not be a "right" answer, but I would welcome arguments as to why your answer is the "right" one. Given an MVC application that is using Entity Framework for the persistence engine, a repository layer, a service layer that basically defers to the repository, and a delete method on a controller that looks like this: public ActionResult Delete(State model) { try { if( model == null ) { return View( model ); } _stateService.Delete( model ); return RedirectToAction("Index"); } catch { return View( model ); } } I am looking for the proper way to Unit Test this. Currently, I have a fake repository that gets used in the service, and my unit test looks like this: [TestMethod] public void Delete_Post_Passes_With_State_4() { //Arrange var stateService = GetService(); var stateController = new StateController( stateService ); ViewResult result = stateController.Delete( 4 ) as ViewResult; var model = (State)result.ViewData.Model; //Act RedirectToRouteResult redirectResult = stateController.Delete( model ) as RedirectToRouteResult; stateController = new StateController( stateService ); var newresult = stateController.Delete( 4 ) as ViewResult; var newmodel = (State)newresult.ViewData.Model; //Assert Assert.AreEqual( redirectResult.RouteValues["action"], "Index" ); Assert.IsNull( newmodel ); } Is this overkill? Do I need to check to see if the record actually got deleted (as I already have Service and Repository tests that verify this)? Should I even use a fake repository here or would it make more sense just to mock the whole thing? The examples I'm looking at used this model of doing things, and I just copied it, but I'm really open to doing things in a "best practices" way. Thanks.

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  • What's The Best Object-Relational Mapping Tool For .NET?

    - by Icono123
    I've worked on a few Java web projects and we've always used Hibernate for our data object layer. I haven't worked on a large scale ASP.NET site and I'm unsure which solution to choose. I'm tempted to try NHibernate, but I don't like the fact that they use so many third party libraries. I found this list on Wikipedia of available ORM software: http://en.wikipedia.org/wiki/List_of_object-relational_mapping_software#.NET What ORM have you used? Was it easy to use? Would you recommend using it again? Was it used on a small, medium, or large project? Would you write your own? Thanks.

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  • How to map combinations of things to a relational database?

    - by Space_C0wb0y
    I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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  • Passing ViewModel for backbone.js from MVC3 Server-Side

    - by Roman
    In ASP.NET MVC there is Model, View and Controller. MODEL represents entities which are stored in database and essentially is all the data used in a application (for example, generated by EntityFramework, "DB First" approach). Not all data from model you want to show in the view (for example, hashs of passwords). So you create VIEW MODEL, each for every strongly-typed-razor-view you have in application. Like this: using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace MyProject.ViewModels.SomeController.SomeAction { public class ViewModel { public ViewModel() { Entities1 = new List<ViewEntity1>(); Entities2 = new List<ViewEntity2>(); } public List<ViewEntity1> Entities1 { get; set; } public List<ViewEntity2> Entities2 { get; set; } } public class ViewEntity1 { //some properties from original DB-entity you want to show } public class ViewEntity2 { } } When you create complex client-side interfaces (I do), you use some pattern for javascript on client, MVC or MVVM (I know only these). So, with MVC on client you have another model (Backbone.Model for example), which is third model in application. It is a bit much. Why don`t we use the same ViewModel model on a client (in backbone.js or another framework)? Is there a way to transfer CS-coded model to JS-coded? Like in MVVM pattern, with knockout.js, when you can do like this: in SomeAction.cshtml: <div style="display: none;" id="view_model">@Json.Encode(Model)</div> after that in Javascript-code var ViewModel = ko.mapping.fromJSON($("#view_model").get(0).innerHTML); now you can extend your ViewModel with some actions, event handlers, etc: ko.utils.extend(ViewModel, { some_function: function () { //some code } }); So, we are not building the same view model on the client again, we are transferring existing view model from server. At least, data. But knockout.js is not suitable for me, you can`t build complex UI with it, it is just data-binding. I need something more structural, like backbone.js. The only way to build ViewModel for backbone.js I can see now is re-writing same ViewModel in JS from server with hands. Is there any ways to transfer it from server? To reuse the same viewmodel on server view and client view?

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  • Asp.NET MVC View with different objects

    - by user195910
    If i have a controller action "Create" that returns a view with the following as the Model type: public class PaymentModel { public Model.SummaryInformation SummaryInformation; public Model.CardDetail CardDetail; } If there is a button on this view that POST's to an action "New" and I want that action to recieve a different object e.g. public class PaymentNewModel { public Model.CardDetail CardDetail; } Is this possible? I do not want to use the same Model when the view is rendered to the Model that is POSTed

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  • html code in anchor tag text in c# razor

    - by Tripping
    I am trying to show the rupee sign: ₹ code: &#8377 ; in my anchor tag. I have tried a few things but nothing works ... please help @{ string _text = String.Format("{0} {1} {2} {3} {4}", @Html.DisplayFor(model => model.NoOfBedrooms), "bedroom flat", @Html.DisplayFor(model => model.TransactionTypeDescription), @Html.Raw(&#8377;), @Html.DisplayFor(model => model.Price)); string _rental = ""; if (Model.TransactionType == 2) { _rental = " per month"; } else { _rental = ""; }; string _linkText = _text + _rental; } @Html.ActionLink(_linkText, "Details", "Property", new { id = Model.PropertyId }, null)

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  • Visual-C++ Linker Error

    - by LordByron
    I have a class called MODEL in which public static int theMaxFrames resides. The class is defined in its own header file. theMaxFrames is accessed by a class within the MODEL class and by one function, void set_up(), which is also in the MODEL class. The Render.cpp source file contains a function which calls a function in the Direct3D.cpp source file which in turn calls the set_up() function through a MODEL object. This is the only connection between these two source files and theMaxFrames. When I try to compile my code I get the following error messages: 1Direct3D.obj : error LNK2001: unresolved external symbol "public: static int MODEL::theMaxFrames" (?theMaxFrames@MODEL@@2HA) 1Render.obj : error LNK2001: unresolved external symbol "public: static int MODEL::theMaxFrames" (?theMaxFrames@MODEL@@2HA) 1C:\Users\Byron\Documents\Visual Studio 2008\Projects\xFileViewer\Debug\xFileViewer.exe : fatal error LNK1120: 1 unresolved externals

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  • Type casting Collections using Conversion Operators

    - by Vyas Bharghava
    The below code gives me User-defined conversion must convert to or from enclosing type, while snippet #2 doesn't... It seems that a user-defined conversion routine must convert to or from the class that contains the routine. What are my alternatives? Explicit operator as extension method? Anything else? public static explicit operator ObservableCollection<ViewModel>(ObservableCollection<Model> modelCollection) { var viewModelCollection = new ObservableCollection<ViewModel>(); foreach (var model in modelCollection) { viewModelCollection.Add(new ViewModel() { Model = model }); } return viewModelCollection; } Snippet #2 public static explicit operator ViewModel(Model model) { return new ViewModel() {Model = model}; } Thanks in advance!

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  • Which relational databases exist with a public API for a high level language?

    - by Jens Schauder
    We typically interface with a RDBMS through SQL. I.e. we create a sql string and send it to the server through JDBC or ODBC or something similar. Are there any RDBMS that allow direct interfacing with the database engine through some API in Java, C#, C or similar? I would expect an API that allows constructs like this (in some arbitrary pseudo code): Iterator iter = engine.getIndex("myIndex").getReferencesForValue("23"); for (Reference ref: iter){ Row row = engine.getTable("mytable").getRow(ref); } I guess something like this is hidden somewhere in (and available from) open source databases, but I am looking for something that is officially supported as a public API, so one finds at least a note in the release notes, when it changes. In order to make this a question that actually has a 'best' answer: I prefer languages in the order given above and I will prefer mature APIs over prototypes and research work, although these are welcome as well.

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  • Asp.net mvc 3: Strange Validation

    - by coure06
    I have applied DataAnnotation based validations to two of my properties like this [Required(ErrorMessage = "Title is required")] public string Title { get; set; } [Required(ErrorMessage = "Description is required")] public string Description { get; set; } Here is the view page's code @Html.LabelFor(model => model.Obj.Title) @Html.EditorFor(model => model.Obj.Title) @Html.LabelFor(model => model.Obj.Description) @Html.TextAreaFor(model => model.Obj.Description) The Problem is that on click of submit button, on client side (js) its only giving me error for for Title and not for the Description. But Its giving me validation error for the Description after the postback. What possible causes?

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