Search Results

Search found 9718 results on 389 pages for 'classes'.

Page 275/389 | < Previous Page | 271 272 273 274 275 276 277 278 279 280 281 282  | Next Page >

• does class/object models have a out-of-the-box equivalent to a database foreign key constraint

  - by Greg

  Hi, Does does class/object models have a out-of-the-box equivalent to a database foreign key constraint? Assume the language is C# please. That is say Class A has a field that references Class B and vica-versa. If I have Object A & B (instantiated from these classes) what happens if I delete Object B? Does it auto-delete or throw a constraint issue if it still exists in Object A as a reference? That is, for this scenario is there a way to ensure when a Object A is delete that either (a) object B is delete like a cascade delete, or (b) a constraint exception is thrown as the expectation is that the reference in Class B should be non-null?

  Read the article

• Create an Action<T> to "set" a property, when I am provided with the LINQ Expression for the "get"

  - by Alex

  I'd like to be able to generate a compiled expression to set a property, given the lambda expression that provides the "get" method for a property. Here's what I'm looking for: public Action<int> CreateSetter<T>(Expression<Func<T, int>> getter) { // returns a compiled action using the details of the getter expression tree, or null // if the write property is not defined. } I'm still trying to understand the various types of Expression classes, so if you can point me in the right direction that would be great.

  Read the article

• Hibernate - Persisting polymorphic joins

  - by Marty Pitt

  Hi I'm trying to understand how to best implement a polymorphic one-to-many in hibernate. Eg: @MappedSuperclass public class BaseEntity { Integer id; // etc... } @Entity public class Author extends BaseEntity {} @Entity public class Post extends BaseEntity {} @Entity public class Comment extends BaseEntity {} And now, I'd like to also persist audit information, with the following class: @Entity public class AuditEvent { @ManyToOne // ? BaseEntity entity; } What is the appropriate mapping for auditEvent.entity? Also, how will Hibernate actually persist this? Would a series of join tables be generated (AuditEvent_Author , AuditEvent_Post, AuditEvent_Comment), or is there a better way? Note, I'd rather not have my other entity classes expose the other side of the join (eg., List<AuditEvent> events on BaseEntity) - but if that's the cleanest way to implement, then it will suffice.

  Read the article

• Loop through collections

  - by ScG

  I have two classes class A { public string something { get; set; } public IList<B> b= new List<B>(); } class B { public string else { get; set; } public string elseelse { get; set; } } I have populated an object of class A called obj. How can I loop through this object and print values. Do I have to use two foreach's like the one show here or is there a better way? foreach (var z in obj) { // print z.something; foreach (var x in z.b) { // print x.elseelse; } }

  Read the article

• Global Import/using Aliasing in .NET

  - by Josh Stodola

  Using import aliasing in a single class, we can reference class library namespaces by assigning our own custom alias like this: ' VB Imports Db = Company.Lib.Data.Objects // C# using Db = Company.Lib.Data.Objects; And then we are able to reference the classes inside of Company.Lib.Data.Objects by using the Db alias that we assigned. Is it possible to do this at the global level so that the alias is applied to the entire solution instead of the given file? Currently, we are working with web applications, so I was hoping we could add something to web.config, but I am also interested in whether or not this is possible with windows forms, console apps, and/or class libraries.

  Read the article

• Updating a database periodically with Java

  - by MSR

  I would like to perform updates to a MySQL database using two separate classes (that do different things) -- one doing so every 10 seconds, and the second every minute. I have a few gaps in my Java knowledge and I'm wondering what the best way to achieve it is. Importantly, if connectivity to the database is lost, I need reconnection attempts to occur indefinitely, and I'm guessing the use of Prepared Statements will make queries more efficient. Should the connection to the database be left open all the time or closed between the updates being run? Maybe I also need to think about clearing objects/resources out of memory if the class instances are going to be run indefinitely.

  Read the article

• Basic View Switch Code Crashes iPhone simulator

  - by Ouija

  I've been trying to switch two views from two separate view controllers for a while and it never works, the simulator always crashes to the home screen. I'm using Xcode 3.2.5 and this is my code - SwitchViewsViewController.h #import <UIKit/UIKit.h> #import "SecondViewController.h" @interface SwitchViewsViewController : UIViewController { } -(IBAction)pushButton; @end SwitchViewsViewController.m #import "SwitchViewsViewController.h" #import "SecondViewController.h" @implementation SwitchViewsViewController -(IBAction)pushButton { SecondViewController *screen = [[SecondViewController alloc] initWithNibName:nil bundle:nil screen.modalTransitionStyle = UIModalTransitionStyleCoverVertical; [self presentModalViewController:screen animated:YES] [screen release]; } SecondViewController.h #import <UIKit/UIKit.h> @interface SecondViewController : UIViewController { } -(IBAction)pushBack; @end SecondViewController.m #import "SecondViewController.h" @implementation SecondViewController -(IBAction)pushBack{ [self dismissModalViewControllerAnimated:YES]; } In interface builder, all i've done is linked the file's owner classes and the buttons. Also made the SwitchViewsViewController load first, and not MainWindow. Everything builds but when I try to run the app it crashes and sends it to the home screen. Can anyone help me with this?

  Read the article

• Class Members Over Exports

  - by VirusEcks

  When Using DLLs or Code-injecting to be Specific this is an example class only intended for explaining class test { int newint1; char newchararray[512]; void (*newfunction1)( int newarg1 ); int newfunction2( bool newarg1, char newarg2 ) { return newint1; } } mynewclass1; that covers most common elements that's included in classes now when exporting this function to another DLL or application and missed an element of those, either data member or function member, private or public what happens or changed their order ? and if each function is assigned it's value when Code-Injecting like mynewclass1.newfunction1 = (void *)(newexportedfunction); what's the happens in this case, if members of the class are pointers that are assigned after class construction and then missed one member or changed their order ?

  Read the article

• Real-world examples of populating a GWT CellTable using a clean MVP pattern?

  - by piehole

  We are using the GWT-Presenter framework and attempting to use CellTable to put together an updateable grid. It seems as though several of the GWT constructs for CellTable don't lend themselves to easily breaking up the logic into clean view and presenter code. Examples: 1) Within the View's constructor, the CellTable is defined and each column is created by anonymous inner classes that extend the Column class to provide the onValue() method. 2) The FieldUpdater interface must be implemented to provide logic to execute when a user alters data in a cell. This seems like it would best fit in the Presenter's onBind() method, but FieldUpdaters often need access to the Cell or Column which belong in the view. CellTable does not have accessor methods to get hold of the Columns or Cells, so it seems the only way for the Presenter to get them is for me to create a multitude of member variables on the View and accessors on my Display interface. Can anyone provide good examples for dealing with CellTable in GWT-Presenter or a comparable MVP

  Read the article

• Is there an equivalent to C++'s "friend class" in Java?

  - by Ricket

  In C++ there is a concept of a "friend", which has access to a class's private variables and functions. So if you have: class Foo { friend class Bar; private: int x; } then any instance of the class Bar can modify any Foo instance's x member, despite it being private, because Bar is a friend of Foo. Now I have a situation in Java where this functionality would come in handy. There are three classes: Database, Modifier, Viewer. The Database is just a collection of variables (like a struct). Modifier should be "friends" with Database; that is, it should be able to read and write its variables directly. But Viewer should only be able to read Database's variables. How is this best implemented? Is there a good way to enforce Viewer's read-only access of Database?

  Read the article

• Many-to-many relationship in oop

  - by Manu

  what is best way to model many-to-many relationship? lets say we have a two classes , Team and Player any given Player can be in multiple Team s any Team can have as many Player s as they like I like to call methods like playerX.getTeamList() to get the list of all the Team s he/she is in teamY.getPlayerList() to get the list of all the Player s in the team (or have some other way to do this effectively) I can think of two ways of doing this , but they just don't feels like good oop pattens. can you think of any good ways , perhaps a design patten ?

  Read the article

• Understanding reflection

  - by sdmiller

  I recently started work at a new company and a .net web application we have is built using reflection. I have only been out of school for a year and haven't worked with this concept. After studying the code... it looks like there is a single backend interface of type object that has about 20 classes that inherit from it. lots of generic gets and sets On the surface it looks like standard inheritance to me. I guess my question is, what makes this reflection? Is it because the interface is not strongly typed? Thanks

  Read the article

• Localizing formatting functions instead of properties in VS.NET resources

  - by LexL

  I noticed that .NET framework uses formatting functions, generated the same way localizable string are. There is a resource file Resources.resx with resource string TestString. So you may use it in code like this: string localizableValue = Resources.TestString; Now, imagine you need a formattable localizable string, to use it in string.Format function. So everytime you use it, you have to write something like this: string localizableFormattedValue = string.Format(Resources.TestFormatString, someParam1, someParam2); The observation says that in .NET framework generated resource classes already include the above construction. So instead of string property, a string function is generated. The resulting code looks like this: string localizableFormattedValue = Resources.TestFormatString(someParam1, someParam2); The question is - how do they do this? Is it some custom Microsoft feature (resx generator) or I'm missing something obvious?

  Read the article

• IPhone: Controllers, Delagates, DataSources, etc all in one class?

  - by MLS

  Hi All, I am learning iPhone programming. I am starting with a simple example of displaying recently used documents in a UITableView. What I am confused about is why do I need to have several classes and why cant I just use one? Example, My class is called RecentFileList. I need to implement controller, delegate and datasource as well as the actual table view. Can't I just do this all in my RecentFileList Class versus having to create a RecentFileListDelegate RecentFileListController, RecentFileListDataSource class, etc, etc. Related to this can one define a class like: @interface FileListView : NSObject <UITableViewDelegate> <UITableViewController> <UITableViewDataSource { // code } @end or would I just do the work to make my class a delegate and controller in init()?

  Read the article

• Is there anything wrong with taking immediate actions in constructors?

  - by pestaa

  I have classes like this one: class SomeObject { public function __construct($param1, $param2) { $this->process($param1, $param2); } ... } So I can instantly "call" it as some sort of global function just like new SomeObject($arg1, $arg2); which has the benefits of staying concise, being easy to understand, but might break unwritten rules of semantics by not waiting till a method is called. Should I continue to feel bad because of a bad practice, or there's really nothing to worry about? Clarification: I do want an instance of the class. I do use internal methods of the class only. I initialize the object in the constructor, but call the "important" action-taker methods too. I am selfish in the light of these sentences.

  Read the article

• Is there a server side API for Team Foundaion Server

  - by Ralph Shillington

  It would seem there is precious little documentation on programming against a TFS 2010 instance. What bits I have found, have next to nothing in the case of documentation beyond barebones listing of client access classes and their members, most likely autogenerated from the code comments. As I'm interested in building a silverlight client against TFS, I will need access to server side API (ideally the silverlight app will talk to my server (mainly for work items) and my server will in turn talk to the TFS server for the goods. Where is the doumentation (if any) for this kind of TFS integration?

  Read the article

• Formal name of Magento’s Class Override Design Pattern?

  - by Alan Storm

  Magento is a newish (past 5 years) PHP based Ecommerce system with an architecture that's similar to the Java Spring framework (or so I've been told) One of the features of the Framework is certain classes are not directly instantiated. Rather than do something like $model = new Mage_Foo_Model_Name(); you pass an identifier into a static method on a global application object $model = Mage::getModel('foo/name'); and this instantiates the class for you. One of the wins with this approach is getModel checks a global configuration system for the foo/name identifier, and instantiates the class name it finds in the configuration system. This allows you to change the behavior of a Model system wide with a single configuration change. Is there a formal, Gang of Four or otherwise, name that describes this system/design pattern? The instantiation itself looks like a classic Factory pattern, but I'm specifically interested in the whole "override a class in the system via configuration" aspect. Is there a name/concept that covers this, or is it contained within the worldview of a Factory?

  Read the article

• Unit Testing Example, on a class with required fields?

  - by Mastro

  I'm new to developing Unit test and I can't find an example of how to test an existing class I have. The class has a save method which does an insert or update in the database when the user clicks Save in the UI. But the save method has required fields that need to be populated. And has other fields that do not. So how can I run this test properly? Was trying to write it out.. Give a user When user saves object Then Field1 is required then Field2 is required Then Field3 is required WhenUserSavesObject() object = new object object.field1 IsNot Nothing something like that right? And what about the other fields that are optional? How would I test the save method to make sure it takes all those values properly? Was trying to use BDD but not sure if I should try it or not. Can't find any example of classes with many properties that are needed when calling a test method.

  Read the article

• How can I fix Grails error: "No domain class found for name PrivacyOptions. Please try again and e

  - by ?????

  I'm just getting started with Groovy/Grails. I added a new domain controller to my project, and generate-controller doesn't like it. There are other indications something's wrong: If I run the app no table is actually created in the database for this. I've reduced the DomainController to one String field and no constraints, just to make sure there wasn't something wrong with my specification. I also tried renaming it, just in case there was something about the original name (Privacy) that conflicted with something. I'm sure I have the correct name, and that the file is called PrivacyOptions.groovy and inside the class is also called PrivacyOptions. Here's the error: Running script /opt/local/grails/scripts/GenerateController.groovy Environment set to development Domain class not found in grails-app/domain, trying hibernate mapped classes... No domain class found for name PrivacyOptions. Please try again and enter a valid domain class name

  Read the article

• Doubt about a particular pattern of Javascript class definition

  - by fenderplayer

  Recently i saw the following code that creates a class in javascript: var Model.Foo = function(){ // private stuff var a, b; // public properties this.attr1 = ''; this.attr2 = ''; if(Model.Foo._init === 'undefined'){ Model.Foo.prototype = { func1 : function(){ //...}, func2 : function(){ //... }, //other prototype functions } } Model.Foo._init = true; } // Instantiate and use the class as follows: var foo = new Model.Foo(); foo.func1(); I guess the _init variable is used to make sure we don't define the prototypes again. Also, i feel the code is more readable since i am placing everything in a function block (so in oop-speak, all attributes and methods are in one place). Do you see any issues with the code above? Any pitfalls of using this pattern if i need to create lots of classes in a big project?

  Read the article

• What is a good solution to link different tables in Hibernate based on some field value?

  - by serg555

  I have article table and several user tables a_user, b_user, ... with exactly the same structure (but different data). I can't change anything in *_user tables except their table name prefix but can change everything else (user tables contain only user information, there is nothing about article or user_type in them). I need to link article to a user (many-to-one), but user table name is defined by user_type field. For example Article table record: ... user_id="5" user_type="a" means that it is linked to a user with id=5 from a_user table (id 5 is not unique in users scope, each user table can have its id 5). Any suggestions how to handle this situation? How can I map this relation in Hibernate (xml mapping, no annotations) so it will automatically pick up correct user for an article during select/update? How should I map user tables (one or multiple classes?)? I would need to run some queries like this: from Article a where a.userType=:type and a.user.name=:name Thanks.

  Read the article

• How to build custom sqlite with provider under Android?

  - by dr4cul4

  Hi, I have a really strange problem. I need to build custom sqlite3 database engine under Android OS, but I also want to use database provider implementation. Unfortunately when examining sources of Android 1.6 I noticed that it's not so easy. Many classes including android.database.; packages use original provider, also many other parts of framework use android.database.sqlite.; packages directly, wich ofcourse make this abstraction a bit confusing and unnesesary. But going to my question. If there is any way that I could extend database interfaces to use custom implmentation of sqlite (or any other database)?

  Read the article

• More swing design & actions

  - by takoi

  Im pretty new to gui programming so i've been reading through every post on this site about swing and design. Whats been answered over and over again is that one should have a class which handles all the action. Like this: (GUI being some JFrame) Now, this works great for one-way actions, like OpenDialog. But the actions for buttons in DialogA and B will have to have access to all the components (there will be many) in its dialog, and the controller. This is where im stuck. The only sane way i can see is to put it in DialogA/B but i would then need to pass the controller all the way down, through classes that dont even need it, and it'll get all spaghetti. Really dont want that. Someone must have encountered this problem before. So where should i put this Action? Or should i just drop the whole design?

  Read the article

• Tallying records using annotate() not working as should.

  - by 47

  I have two classes: Vehicle and Issues....a Vehicle object can have several issues recorded in the Issues class. What I want to do is to have a list of all issues, with each vehicle appearing only once and the total number of issues shown, plus other details....clicking on the record will then take the user to another page with all those issues for a selected vehicle shown in detail now. I tried this out using annotate, but I could only access the count and vehicle foreign key, but none of the other fields in the Vehicle class. class Issues(models.Model): vehicle = models.ForeignKey(Vehicle) description = models.CharField('Issue Description', max_length=30,) type = models.CharField(max_length=10, default='Other') status = models.CharField(max_length=12, default='Pending') priority = models.IntegerField(default='8', editable=False) date_time_added = models.DateTimeField(default=datetime.today, editable=False) last_updated = models.DateTimeField(default=datetime.today, editable=False) def __unicode__(self): return self.description The code I was using to annotate is: issues = Issues.objects.all().values('vehicle').annotate(count=Count('id')) What could be the problem?

  Read the article

• What's the best way to store custom objects in relational database?

  - by user342610

  I have my objects with their properties. Objects could change their structure: properties may be added/removed/changed. Objects could be absolutely dropped. So object's metadata (description, classes, call them like you want :) )could be changed. The database should store objects schemas and instances of these objects. What's the best way to organise a relational database structure to store data mentioned above? Currently I see only two ways: 1) Store objects schemas in a few tables: schema general data,schema properties, possible properties types. Store instances in their tables: instance general data, a few tables - per each type from possible properties types table to store instance properties data. And so on. 2) store objects schemas like in p1 but store instances like XML files in one table: one table for general instance info and one table with instance XML. please, don't ask why/for what I need this. Just need to store custom objects and DB should work fast :)

  Read the article

< Previous Page | 271 272 273 274 275 276 277 278 279 280 281 282  | Next Page >