Search Results

Search found 40226 results on 1610 pages for 'object relational model'.

Page 276/1610 | < Previous Page | 272 273 274 275 276 277 278 279 280 281 282 283  | Next Page >

  • Is it safe to put reference to current user in User model in Rails?

    - by Art Shayderov
    You know, I think I have to check current user in the model callbacks (like before_update). Rather than rely solely on adding where ('something.user_id = ?', 'current_user.id') in the controllers. I need something like Thread.CurrentPrincipal in .NET Is it safe to put reference to current user in User model? I'm sorry I don't really understand how it works under the hood yet. Or how you do it The Rails way? Sorry if this a silly question.

    Read the article

  • Qt – How to add calculated column in QsqlRelationalTableModel ?

    - by user289175
    I have an table view showed part description, quantity, price And I have a Model/View using this code model = new QSqlRelationalTableModel(this); model->setTable("parts"); model->setRelation(3,QSqlRelation("part_tbl","part_id","part_desc")); model->select(); ui->tableView->setModel(model); I need to add a new column that shows quantity * price in the table view. It's important to know I'm using QsqlRelationalTableModel Help is appreciated, Thanks in advance

    Read the article

  • Can you cast an object to one that implements an interface? (JAVA)

    - by DDP
    Can you cast an object to one that implements an interface? Right now, I'm building a GUI, and I don't want to rewrite the Confirm/Cancel code (A confirmation pop-up) over and over again. So, what I'm trying to do is write a class that gets passed the class it's used in and tells the class whether or not the user pressed Confirm or Cancel. The class always implements a certain interface. Code: class ConfirmFrame extends JFrame implements ActionListener { JButton confirm = new JButton("Confirm"); JButton cancel = new JButton("Cancel"); Object o; public ConfirmFrame(Object o) { // Irrelevant code here add(confirm); add(cancel); this.o = (/*What goes here?*/)o; } public void actionPerformed( ActionEvent evt) { o.actionPerformed(evt); } } I realize that I'm probably over-complicating things, but now that I've run across this, I really want to know if you can cast an object to another object that implements a certain interface.

    Read the article

  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

    Read the article

  • How to load COM object in smart device project?

    - by Daan
    I want to create a .NET CF application for Windows Mobile 5. In this application, I want to load a COM object based on the ProgID (or CLSID). How do I load this COM object in such a way that I can access its methods as if it were just another .NET object? In addition: how can I configure the projects / solutions in Visual Studio in such a way, that when I debug the application, I am sure that the COM object that is loaded is the one that is installed on the device, not one that may be accessible through the debugger? I have tried adding the .ocx file as a Reference, but I get an error, and I am not sure about 'question 2'. I have also tried loading the COM object using Type type = Type.GetTypeFromProgID("my.prog.id") MyObject myObject = (MyObject)Activator.CreateInstance(type) ...but this results in an InvalidCastException on the second line.

    Read the article

  • 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.

    Read the article

  • 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.

    Read the article

  • 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?

    Read the article

  • How to pass associative Array parameter from javascript to ActiveX object?

    - by Rory
    I'd like to pass an associative array (or simply an object with property names & values) to my ActiveXObject. I can't find anyone who has successfully and simply passed complex data from javascript to an ActiveX object. My ActiveX object is being loaded in IE, and it's mine so I can change the method signature & code to whatever will work. I also have control over the structure of the javascript. Without a simple way of doing this I'm thinking of url-encoding the data and sending it as a string. But that does seem a little silly if it's possible just to pass an object. The ActiveX object is coded in C# if that makes any difference...

    Read the article

  • How does Hibernate detect dirty state of an entity object?

    - by ???'Lenik
    Is it using some kind of byte codes modification to the original classes? Or, maybe Hibernate get the dirty state by compare the given object with previously persisted version? I'm having a problem with hashCode() and equals() methods for complicated objects. I feel it would be very slow to compute hash code if the object has collection members, and cyclic references are also a problem. If Hibernate won't use hashCode()/equals() to check the dirty state, I guess I should not use equals()/hashCode() for the entity object (not value object), but I'm also afraid if the same operator (==) is not enough. So, the questions are: How does Hibernate know if a property of an object is changed? Do you suggest to override the hashCode()/equals() methods for complicated objects? What if they contains cyclic references? And, also, Would hashCode()/equals() with only the id field be enough?

    Read the article

  • 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?

    Read the article

  • 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

    Read the article

  • 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)

    Read the article

  • 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.

    Read the article

  • 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?

    Read the article

  • Best practices about creating a generic object dictionary in C#? Is this bad?

    - by JimDaniel
    For clarity I am using C# 3.5/Asp.Net MVC 2 Here is what I have done: I wanted the ability to add/remove functionality to an object at run-time. So I simply added a generic object dictionary to my class like this: public Dictionary<int, object> Components { get; set; } Then I can add/remove any kind of .Net object into this dictionary at run-time. To insert an object I do something like this: var tag = new Tag(); myObject.Components.Add((int)Types.Components.Tag, tag); Then to retrieve I just do this: if(myObject.Components.ContainsKey((int)Types.Components.Tag)) { var tag = myObject.Components[(int)Types.Components.Tag] as Tag; if(tag != null) { //do stuff } } Somehow I feel sneaky doing this. It works okay, but I am wondering what you guys think about it as a best practice. Thanks for your input, Daniel

    Read the article

  • 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?

    Read the article

  • 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?

    Read the article

  • 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

    Read the article

  • 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)

    Read the article

  • 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

    Read the article

< Previous Page | 272 273 274 275 276 277 278 279 280 281 282 283  | Next Page >