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  • Using views as a data interface between modules in a database

    - by Stefan
    Hello, I am working on the database layout of a straighforward small database in Mysql. We want to modularize this system in order to have more flexiblity for different implementations we are going to make. Now, the idea was to have one module in the database (simple a group of tables with constraints between them) pass its data to the next module via views. In this way, changes in one module would not affect the other ones, as we can make sure in the view that the right data is present there at any time, although the underlying structure of tables might be different. The structure of the App handling the database would likewise be modularized. Is this something that is sometimes done? On a technical side, as I understand views can't have primary keys - how would I then adress such a view? What other issues should be considered?

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  • In C#, can I hide/modify accessors in subclasses?

    - by Diego
    I'm not even sure what this principle is called or how to search for it, so I sincerely apologize if it has been brought up before, but the best way to do it is with an example. class Properties { public string Name { get; set; } } class MyClass { class SubProperties: Properties { public override Name { get { return GetActualName(); } set { _value = SetActualName(value); } } } public SubProperties ClassProperties; private GetActualName() { ClassProperties.Name = "name"; } private SetActualName(string s) { ClassProperties.Name = SomeOtherFunction(s); } } The idea is to have any object that instantiates MyClass have a fully accessible property ClassProperties. To that object, it would look exactly like a Properties object, but behind the scenes, MyClass is actually computing and modifying the results of the fields. This method of declaration is obviously wrong since I can't access GetActualName() and SetActualName() from within the SubProperties definition. How would I achieve something like this?

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  • How do I prevent JAXB from binding superclass methods of the @XmlRootElement when marshalling?

    - by Matt Fisher
    I have a class that is annotated as the @XmlRootElement with @XmlAccessorType(XmlAccessType.NONE). The problem that I am having is that the superclass's methods are being bound, when I do not want them to be bound, and cannot update the class. I am hoping there is an annotation that I can put on the root element class to prevent this from happening. Example: @XmlRootElement @XmlAccessorType(XmlAccessType.NONE) public class Person extends NamedObject { @XmlElement public String getId() { ... } } I would expect that only the methods annotated @XmlElement on Person would be bound and marshalled, but the superclass's methods are all being bound, as well. The resulting XML then has too much information. How do I prevent the superclass's methods from being bound without having to annotate the superclass, itself?

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  • django class with an array of "parent" foreignkeys issue

    - by user298032
    Let's say I have a class called Fruit with child classes of the different kinds of Fruit with their own specific attributes, and I want to collect them in a FruitBasket: class Fruit(models.Model):     type = models.CharField(max_length=120,default='banana',choices=FRUIT_TYPES)     ... class Banana(Fruit):     """banana (fruit type)"""     length = models.IntegerField(blank=True, null=True)     ... class Orange(Fruit):     """orange (fruit type)"""     diameter = models.IntegerField(blank=True, null=True)     ... class FruitBasket(models.Model):     fruits = models.ManyToManyField(Fruit)     ... The problem I seem to be having is when I retrieve and inspect the Fruits in a FruitBasket, I only retrieve the Fruit base class and can't get at the Fruit child class attributes. I think I understand what is happening--when the array is retrieved from the database, the only fields that are retrieved are the Fruit base class fields. But is there some way to get the child class attributes as well without multiple expensive database transactions? (For example, I could get the array, then retrieve the child Fruit classes by the id of each array element). thanks in advance, Chuck

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  • Two models, one STI and a Validation

    - by keruilin
    Let's say I have two tables -- Products and Orders. For the sake of simplicity assume that only one product can be purchased at a time so there is no join table like order_items. So the relationship is that Product has many orders, and Order belongs to product. Therefore, product_id is a fk in the Order table. The product table is STI -- with the subclasses being A, B, C. When the user orders subclass Product C, two special validations must be checked on the Order model fields order_details and order_status. These two fields can be nil for all other Product subclasses (ie A and B). In other words, no validation needs to run for these two fields when a user purchases A and B. My question is: How do I write validations (perhaps custom?) in the Order model so that the Order model knows to only run the validations for the two fields -- order_details and order_status -- when Product subclass C is being saved to the orders table?

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  • Can can I reference extended methods/params without having to cast from the base class object return

    - by Greg
    Hi, Is there away to not have a "cast" the top.First().Value() return to "Node", but rather have it automatically assume this (as opposed to NodeBase), so I then see extended attributes for the class I define in Node? That is is there a way to say: top.Nodes.First().Value.Path; as opposed to now having to go: ((Node)top.Nodes.First().Value).Path) thanks [TestMethod()] public void CreateNoteTest() { var top = new Topology(); Node node = top.CreateNode("a"); node.Path = "testpath"; Assert.AreEqual("testpath", ((Node)top.Nodes.First().Value).Path); // *** HERE *** } class Topology : TopologyBase<string, Node, Relationship> { } class Node : NodeBase<string> { public string Path { get; set; } } public class NodeBase<T> { public T Key { get; set; } public NodeBase() { } public NodeBase(T key) { Key = key; } } public class TopologyBase<TKey, TNode, TRelationship> where TNode : NodeBase<TKey>, new() where TRelationship : RelationshipBase<TKey>, new() { // Properties public Dictionary<TKey, NodeBase<TKey>> Nodes { get; private set; } public List<RelationshipBase<TKey>> Relationships { get; private set; } }

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  • Virgin STI Help

    - by Mutuelinvestor
    I am working on a horse racing application and I'm trying to utilize STI to model a horse's connections. A horse's connections is comprised of his owner, trainer and jockey. Over time, connections can change for a variety of reasons: The horse is sold to another owner The owner switches trainers or jockey The horse is claimed by a new owner As it stands now, I have model this with the following tables: horses connections (join table) stakeholders (stakeholder has three sub classes: jockey, trainer & owner) Here are my clases and associations: class Horse < ActiveRecord::Base has_one :connection has_one :owner_stakeholder, :through => :connection has_one :jockey_stakeholder, :through => :connection has_one :trainer_stakeholder, :through => :connection end class Connection < ActiveRecord::Base belongs_to :horse belongs_to :owner_stakeholder belongs_to :jockey_stakeholder belongs_to :trainer_stakeholder end class Stakeholder < ActiveRecord::Base has_many :connections has_many :horses, :through => :connections end class Owner < Stakeholder # Owner specific code goes here. end class Jockey < Stakeholder # Jockey specific code goes here. end class Trainer < Stakeholder # Trainer specific code goes here. end One the database end, I have inserted a Type column in the connections table. Have I modeled this correctly. Is there a better/more elegant approach. Thanks in advance for you feedback. Jim

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  • Presenting an image cropping interface

    - by wkw
    I'm trying to engineer a UI for cropping images in iphone OS and suspect I'm going about things the hard way. My goal is pretty much what the Tapbots duo have done with Pastebot. In that app, they dim the source image but provide a movable and resizable cropping view and the image you're cropping is in a zoomable scrollview; when you resize or move the underlying image, the cropping view adjusts appropriately. I mocked up a composite image which will give a sense of the design I'm after, along with how I presently have my view hierarchy setup, viewable here The approach I've started with is the following: UIImageView with the image to crop is in a scrollview, a plain UIView with black fill and suitable transparency/alpha setting is added in front of the imageview. I then use a custom UIView which is a sibling to the scrollview at a higher level, which implements the drawRect: method and for the most part calls CGImageCreateWithImageInRect to get the portion of the image's bitmap that matches the position of the cropping view and draws that to the CGContext. in the viewcontroller I'm using the UIScrollViewDelegate methods to track scrolling and passing those changes to the custom cropping UIView so it stays in sync with the scroll contentOffset. That much is finally working. But trying to keep in sync as the scrollview zoomScale changes is when I figured I should ask for help. Looking for suggestions or guidance. My initial approach just seems like more work than is required. Could this be done with a masking layer in the ImageView? And if so, how would I setup the tracking for moving and resizing the cropping rect? My experience working with layers is non-nil, but very limited thus far.

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  • Javascript static method intheritance

    - by Matteo Pagliazzi
    I want to create a javascript class/object that allow me to have various method: Model class Model.all() » static method Model.find() » static method Model delete() » instance method Model save() » instance method Model.create() » static that returns a new Model instance For static method I can define them using: Model.staticMethod(){ method } while for instance method is better to use: function Model(){ this.instanceMethod = function(){} } and then create a new instance or using prototype? var m = function Model(){ } m.prototype.method() = function(){ } Now let's say that I want to create a new class based on Model, how to inherit not only its prototypes but also its static methods?

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  • How to inherit constructors with arguments in .NET?

    - by Soumya92
    I have a "MustInherit" .NET class which declares a constructor with an integer parameter. However, Visual Studio gives me an error when I create any derived class stating that there is no constructor that can be called without any arguments. Is it possible to inherit the constructor with arguments? Right now, I have to use Public Sub New(ByVal A As Integer) MyBase.New(A) End Sub in the derived classes. Is there any way to avoid this?

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  • UIVIewController wrong position before rotate

    - by zegnus
    I have the starter point of my application this window (white background): - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { mainScreen = [[MainScreenController alloc] initWithNibName:@"MainScreenController" bundle:[NSBundle mainBundle]]; // add it to the main window [window addSubview:[mainScreen view]]; // show view [window makeKeyAndVisible]; NSLog(@"started"); return YES; } And MainScreenController is an UIViewController with (blackBackground) created by the Interface Builder. The application executes perfectly but the first time, the black view is moved up like the height of the status iphone pannel (leaving white rectangle at the bottom). If I rotate the iPhone twice, the view is perfectly positioned in the right place, filling all the screen with the black background. Any idea? Thanks!

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  • spring - constructor injection and overriding parent definition of nested bean

    - by mdma
    I've read the Spring 3 reference on inheriting bean definitions, but I'm confused about what is possible and not possible. For example, a bean that takes a collaborator bean, configured with the value 12 <bean name="beanService12" class="SomeSevice"> <constructor-arg index="0"> <bean name="beanBaseNested" class="SomeCollaborator"> <constructor-arg index="0" value="12"/> </bean> </constructor-arg> </bean> I'd then like to be able to create similar beans, with slightly different configured collaborators. Can I do something like <bean name="beanService13" parent="beanService12"> <constructor-arg index="0"> <bean> <constructor-arg index="0" value="13"/> </bean> </constructor> </bean> I'm not sure this is possible and, if it were, it feels a bit clunky. Is there a nicer way to override small parts of a large nested bean definition? It seems the child bean has to know quite a lot about the parent, e.g. constructor index. I'd prefer not to change the structure - the parent beans use collaborators to perform their function, but I can add properties and use property injection if that helps. This is a repeated pattern, would creating a custom schema help? Thanks for any advice!

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  • Programming interface

    - by user309010
    Hi All, I currently building a data collection system [mainly "EFM" - enterprise feed back management] using .NET. I was wondering if there is a possibility to provide the user to script and manipulate the objects - like a programming language but with minor functionalities Thanks

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  • Is it possible to add JPA annotation to superclass instance variables?

    - by Kristofer Borgstrom
    Hi, I am creating entities that are the same for two different tables. In order do table mappings etc. different for the two entities but only have the rest of the code in one place - an abstract superclass. The best thing would be to be able to annotate generic stuff such as column names (since the will be identical) in the super class but that does not work because JPA annotations are not inherited by child classes. Here is an example: public abstract class MyAbstractEntity { @Column(name="PROPERTY") //This will not be inherited and is therefore useless here protected String property; public String getProperty() { return this.property; } //setters, hashCode, equals etc. methods } Which I would like to inherit and only specify the child-specific stuff, like annotations: @Entity @Table(name="MY_ENTITY_TABLE") public class MyEntity extends MyAbstractEntity { //This will not work since this field does not override the super class field, thus the setters and getters break. @Column(name="PROPERTY") protected String property; } Any ideas or will I have to create fields, getters and setters in the child classes? Thanks, Kris

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  • Is there any way to manipulate variables passed in to a child class constructor before passing it of

    - by Matt
    Hi, Is there any way to delay calling a superclass constructor so you can manipulate the variables first? Eg. public class ParentClass { private int someVar; public ParentClass(int someVar) { this.someVar = someVar; } } public class ChildClass : ParentClass { public ChildClass(int someVar) : base(someVar) { someVar = someVar + 1 } } I want to be able to send the new value for someVar (someVar + 1) to the base class constructor rather than the one passed in to the ChildClass constructor. Is there any way to do this? Thanks, Matt

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  • C# BinarySearch breaks when inheriting from something that implements IComparable<T>?

    - by Ender
    In .NET the BinarySearch algorithm (in Lists, Arrays, etc.) appears to fail if the items you are trying to search inherit from an IComparable instead of implementing it directly: List<B> foo = new List<B>(); // B inherits from A, which implements IComparable<A> foo.Add(new B()); foo.BinarySearch(new B()); // InvalidOperationException, "Failed to compare two elements in the array." Where: public abstract class A : IComparable<A> { public int x; public int CompareTo(A other) { return x.CompareTo(other.x); } } public class B : A {} Is there a way around this? Implementing CompareTo(B other) in class B doesn't seem to work.

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  • UI Components for Windows Mobile Applications (.NET Compact Framework)

    - by splattne
    Applications which run on mobile devices have special user interface requirements. I think Apple did a great job introducing innovative controls on the iPhone/iPod touch platform. Now, I have to design an application for the Windows Mobile platform using the .NET Compact Framework (Visual Studio 2008). I wonder if there are some commercial or open source UI control sets available which are similar to the iPhone / iPod touch UI elements: Scrolling panels based on gestures Instead of a dropdownlist: a new panel with a large list of items Sliding panels etc. I couldn't find any useful products/code. Maybe there is somebody out there with more experience who could help.

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  • How can I bind events to strongly typed datasets of different types?

    My application contains several forms which consist of a strongly typed datagridview, a strongly typed bindingsource, and a strongly typed table adapter. I am using some code in each form to update the database whenever the user leaves the current row, shifts focus away from the datagrid or the form, or closes the form. This code is the same in each case, so I want to make a subclass of form, from which all of these forms can inherit. But the strongly typed data objects all inherit from component, which doesn't expose the events I want to bind to or the methods I want to invoke. The only way I can see of gaining access to the events is to use: Type(string Name).GetEvent(string EventName).AddEventHandler(object Target,Delegate Handler) Similarly, I want to call the Update method of the strongly typed table adapter, and am using Type(string Name).GetMethod(String name, Type[] params).Invoke(object target, object[] params). It works ok, but it seems very heavy handed. Is there a better way? Here is my code for the main class: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data; using System.Data.SqlClient; using System.ComponentModel; namespace MyApplication { public class AutoSaveDataGridForm: Form { private DataRow PreviousRow; public Component Adapter { private get; set; } private Component dataGridView; public Component DataGridView { private get { return dataGridView; } set { dataGridView = value; Type t = dataGridView.GetType(); t.GetEvent("Leave").AddEventHandler(dataGridView, new EventHandler(DataGridView_Leave)); } } private Component bindingSource; public Component BindingSource { private get { return bindingSource; } set { bindingSource = value; Type t = bindingSource.GetType(); t.GetEvent("PositionChanged").AddEventHandler(bindingSource, new EventHandler(BindingSource_PositionChanged)); } } protected void Save() { if (PreviousRow != null && PreviousRow.RowState != DataRowState.Unchanged) { Type t = Adapter.GetType(); t.GetMethod("Update", new Type[] { typeof(DataRow[]) }).Invoke(Adapter, new object[] { new DataRow[] { PreviousRow } }); } } private void BindingSource_PositionChanged(object sender, EventArgs e) { BindingSource bindingSource = sender as BindingSource; DataRowView CurrentRowView = bindingSource.Current as DataRowView; DataRow CurrentRow = CurrentRowView.Row; if (PreviousRow != null && PreviousRow != CurrentRow) { Save(); } PreviousRow = CurrentRow; } private void InitializeComponent() { this.SuspendLayout(); // // AutoSaveDataGridForm // this.FormClosed += new System.Windows.Forms.FormClosedEventHandler(this.AutoSaveDataGridForm_FormClosed); this.Leave += new System.EventHandler(this.AutoSaveDataGridForm_Leave); this.ResumeLayout(false); } private void DataGridView_Leave(object sender, EventArgs e) { Save(); } private void AutoSaveDataGridForm_FormClosed(object sender, FormClosedEventArgs e) { Save(); } private void AutoSaveDataGridForm_Leave(object sender, EventArgs e) { Save(); } } } And here is a (partial) form which implements it: public partial class FileTypesInherited :AutoSaveDataGridForm { public FileTypesInherited() { InitializeComponent(); } private void FileTypesInherited_Load(object sender, EventArgs e) { // TODO: This line of code loads data into the 'sharedFoldersInformationV2DataSet.tblFileTypes' table. You can move, or remove it, as needed. this.tblFileTypesTableAdapter.Fill(this.sharedFoldersInformationV2DataSet.tblFileTypes); this.BindingSource = tblFileTypesBindingSource; this.Adapter = tblFileTypesTableAdapter; this.DataGridView = tblFileTypesDataGridView; } }

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  • Super class variables not printing through sub class

    - by Abhishek Singh
    Can u tell me why this code is not displaying any result on the console. class employee { protected String name; protected double salary; protected String dob; public employee(String name, double salary, String dob) { this.name = name; this.salary = salary; this.dob = dob; } public employee(String name, double salary) { this.name = name; this.salary = salary; } } public class Manage extends employee { String dept1; public Manage(String name, double salary, String dob, String dept1) { super(name, salary, dob); this.dept1 = dept1; } public Manage(String name, double salary, String dept1) { super(name, salary); this.dept1 = dept1; } public static void main(String args[]) { employee e = new employee("Vikas", 122345); employee e2 = new employee("Vikas", 122345, "12-2-1991"); Manage m = (Manage) new Manage("Vikas", 122345, "Sales"); Manage m2 = new Manage("Vikas", 122345, "12-2-1991", "sales"); m.display(); m2.display(); } public void display() { System.out.println("Name " + name); System.out.println("Salary " + salary); System.out.println("Birth " + dob); System.out.println("Department " + dept1); } }

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  • How to prevent Visual Studio setting my default font sizes in an inherited control

    - by Colin
    I have a base class for all my textboxes and I want to set the default font in that class. So I started with this: public partial class MyTextBox : TextBox { public WmlTextBox() { InitializeComponent(); //Font for the whole application can be altered in the Appearance class Font = new Appearance().TextBoxFont; } } I then stripped out all the code in the form that was setting the font of the textboxes. Of course this worked fine until I altered an item on the page. Visual Studio picked up the default font for the application (set in the Appearance class), and generated code in the designer for all TextBoxes to set it to that specific font. How can I stop visual studio from generating code from my default font? I want to allow the developers to change the property, but I want to set the default font centrally.

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  • How to upload file via the JSON interface in Rails

    - by akafazov
    Hi, I have a web service in Rails which among all else should provide file upload functionality to the clients. The clients all use JSON to talk to the webservice. I use the Paperclip plugin for upload management. The problem is I do not know how to upload a file via JSON. All works in the web formular, but I cannot find information on how to consctruct my JSON Request to send files to the server. Can somebody help out? Regards, Angel Kafazov

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  • Forward declaration of derived inner class

    - by Loom
    I ran into problem implementing some variations of factory method. // from IFoo.h struct IFoo { struct IBar { virtual ~IBar() = 0; virtual void someMethod() = 0; }; virtual IBar *createBar() = 0; }; // from Foo.h struct Foo : IFoo { // implementation of Foo, Bar in Foo.cpp struct Bar : IBar { virtual ~Bar(); virtual void someMethod(); }; virtual Bar *createBar(); // implemented in Foo.cpp }; I'd like to place declaration of Foo::Bar in Foo.cpp. For now I cannot succeed: struct Foo : IFoo { //struct Bar; //1. error: invalid covariant return type // for ‘virtual Foo::Bar* //struct Bar : IBar; //2. error: expected ‘{’ before ‘;’ token virtual Bar *createBar(); // virtual IBar *createBar(); // Is not acceptable by-design }; Is there a trick to have just forward declaration of Boo in Foo.hpp and to have full declaration in Foo.cpp?

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  • Base class pointer vs inherited class pointer?

    - by Goose Bumper
    Suppose I have a class Dog that inherits from a class Animal. What is the difference between these two lines of code? Animal *a = new Dog(); Dog *d = new Dog(); In one, the pointer is for the base class, and in the other, the pointer is for the derived class. But when would this distinction become important? For polymorphism, either one would work exactly the same, right?

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