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ASP.NET MVC 2: Linq to SQL entity w/ ForeignKey relationship and Default ModelBinder strangeness

- by Simon

Once again I'm having trouble with Linq to Sql and the MVC Model Binder. I have Linq to Sql generated classes, to illustrate them they look similar to this: public class Client { public int ClientID { get; set; } public string Name { get; set; } } public class Site { public int SiteID { get; set; } public string Name { get; set; } } public class User { public int UserID { get; set; } public string Name { get; set; } public int? ClientID { get; set; } public EntityRef<Client> Client { get; set; } public int? SiteID { get; set; } public EntityRef<Site> Site { get; set; } } The 'User' has a relationship with the 'Client' and 'Site . The User class has nullable ClientIDs and SiteIDs because the admin users are not bound to a Client or Site. Now I have a view where a user can edit a 'User' object, the view has fields for all the 'User' properties. When the form is submitted, the appropiate 'Save' action is called in my UserController: public ActionResult Save(User user, FormCollection form) { //form['SiteID'] == 1 //user.SiteID == 1 //form['ClientID'] == 1 //user.ClientID == null } The problem here is that the ClientID is never set, it is always null, even though the value is in the FormCollection. To figure out whats going wrong I set breakpoints for the ClientID and SiteID getters and setters in the Linq to Sql designer generated classes. I noticed the following: SiteID is being set, then ClientID is being set, but then the Client EntityRef property is being set with a null value which in turn is setting the ClientID to null too! I don't know why and what is trying to set the Client property, because the Site property setter is never beeing called, only the Client setter is being called. Manually setting the ClientID from the FormCollection like this: user.ClientID = int.Parse(form["ClientID"].ToString()); throws a 'ForeignKeyReferenceAlreadyHasValueException', because it was already set to null before. The only workaround I have found is to extend the generated partial User class with a custom method: Client = default(EntityRef<Client>) but this is not a satisfying solution. I don't think it should work like this? Please enlighten me someone. So far Linq to Sql is driving me crazy! Best regards

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Mocking methods that call other methods Still hit database.Can I avoid it?

- by devnet247

Hi, It has been decided to write some unit tests using moq etc..It's lots of legacy code c# (this is beyond my control so cannot answer the whys of this) Now how do you cope with a scenario when you dont want to hit the database but you indirectly still hit the database? This is something I put together it's not the real code but gives you an idea. How would you deal with this sort of scenario? Basically calling a method on a mocked interface still makes a dal call as inside that method there are other methods not part of that interface?Hope it's clear [TestFixture] public class Can_Test_this_legacy_code { [Test] public void Should_be_able_to_mock_login() { var mock = new Mock<ILoginDal>(); User user; var userName = "Jo"; var password = "password"; mock.Setup(x => x.login(It.IsAny<string>(), It.IsAny<string>(),out user)); var bizLogin = new BizLogin(mock.Object); bizLogin.Login(userName, password, out user); } } public class BizLogin { private readonly ILoginDal _login; public BizLogin(ILoginDal login) { _login = login; } public void Login(string userName, string password, out User user) { //Even if I dont want to this will call the DAL!!!!! var bizPermission = new BizPermission(); var permissionList = bizPermission.GetPermissions(userName); //Method I am actually testing _login.login(userName,password,out user); } } public class BizPermission { public List<Permission>GetPermissions(string userName) { var dal=new PermissionDal(); var permissionlist= dal.GetPermissions(userName); return permissionlist; } } public class PermissionDal { public List<Permission> GetPermissions(string userName) { //I SHOULD NOT BE GETTING HERE!!!!!! return new List<Permission>(); } } public interface ILoginDal { void login(string userName, string password,out User user); } public interface IOtherStuffDal { List<Permission> GetPermissions(); } public class Permission { public int Id { get; set; } public string Name { get; set; } } Any suggestions? Am I missing the obvious? Is this Untestable code? Very very grateful for any suggestions.

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Help with method logic in Java, hw

- by Crystal

I have a Loan class that in its printPayment method, it prints the amortization table of a loan for a hw assignment. We are also to implement a print first payment method, and a print last payment method. Since my calculation is done in the printPayment method, I didn't know how I could get the value in the first or last iteration of the loop and print that amount out. One way I can think of is to write a new method that might return that value, but I wasn't sure if there was a better way. Here is my code: public abstract class Loan { public void setClient(Person client) { this.client = client; } public Person getClient() { return client; } public void setLoanId() { loanId = nextId; nextId++; } public int getLoanId() { return loanId; } public void setInterestRate(double interestRate) { this.interestRate = interestRate; } public double getInterestRate() { return interestRate; } public void setLoanLength(int loanLength) { this.loanLength = loanLength; } public int getLoanLength() { return loanLength; } public void setLoanAmount(double loanAmount) { this.loanAmount = loanAmount; } public double getLoanAmount() { return loanAmount; } public void printPayments() { double monthlyInterest; double monthlyPrincipalPaid; double newPrincipal; int paymentNumber = 1; double monthlyInterestRate = interestRate / 1200; double monthlyPayment = loanAmount * (monthlyInterestRate) / (1 - Math.pow((1 + monthlyInterestRate),( -1 * loanLength))); System.out.println("Payment Number | Interest | Principal | Loan Balance"); // amortization table while (loanAmount >= 0) { monthlyInterest = loanAmount * monthlyInterestRate; monthlyPrincipalPaid = monthlyPayment - monthlyInterest; newPrincipal = loanAmount - monthlyPrincipalPaid; loanAmount = newPrincipal; System.out.printf("%d, %.2f, %.2f, %.2f", paymentNumber++, monthlyInterest, monthlyPrincipalPaid, loanAmount); } } /* //method to print first payment public double getFirstPayment() { } method to print last payment public double getLastPayment() { }*/ private Person client; private int loanId; private double interestRate; private int loanLength; private double loanAmount; private static int nextId = 1; } Thanks!

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Ladder word-like game GUI problems

- by sasquatch90

Ok so I've written my own version of game which should look like this : http://img199.imageshack.us/img199/6859/lab9a.jpg but mine looks like that : http://img444.imageshack.us/img444/7671/98921674.jpg How can I fix this ? Is there a way to do the layout completely differently ? Here's the code : Main.java : import java.util.Scanner; import javax.swing.*; import java.awt.*; public class Main { public static void main(String[] args){ final JFrame f = new JFrame("Ladder Game"); Scanner sc = new Scanner(System.in); System.out.println("Creating game data..."); System.out.println("Height: "); while (!sc.hasNextInt()) { System.out.println("int, please!"); sc.next(); } final int height = sc.nextInt(); Grid[]game = new Grid[height]; for(int L = 0; L < height; L++){ Grid row = null; int i = L+1; String s; do { System.out.println("Length "+i+", please!"); s = sc.next(); } while (s.length() != i); Element[] line = new Element[s.length()]; Element single = null; String[] temp = null; String[] temp2 = new String[s.length()]; temp = s.split(""); for( int j = temp2.length; j>0; j--){ temp2[j-1] = temp[j]; } for (int k = 0 ; k < temp2.length ; k++) { if( k == 0 ){ single = new Element(temp2[k], 2); } else{ single = new Element(temp2[k], 1); } line[k] = single; } row = new Grid(line); game[L] = row; } //############################################ //THE GAME STARTS HERE //############################################ JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS)); panel.setBackground(Color.ORANGE); panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); for(int i = 0; i < game.length; i++){ panel.add(game[i].create()); } f.setContentPane(panel); f.pack(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); boolean end = false; boolean word = false; String tekst; while( !end ){ while( !word ){ tekst = JOptionPane.showInputDialog("Input word: "); for(int i = 0; i< game.length; i++){ if(game[i].equalLength(tekst)){ if(game[i].equalValue(tekst)){ word = true; for(int j = 0; j< game.length; j++){ game[i].repaint(); } } } } } word = false; for(int i = 0; i < game.length; i++){ if(game[i].solved()){ end = true; } else { end = false; } } } } } Grid.java import javax.swing.*; import java.awt.*; public class Grid extends JPanel{ private Element[]e; private Grid[]g; public Grid(){} public Grid( Element[]elements ){ e = new Element[elements.length]; for(int i=0; i< e.length; i++){ e[i] = elements[i]; } } public Grid(Grid[]grid){ g = new Grid[grid.length]; for(int i=0; i<g.length; i++){ g[i] = grid[i]; } Dimension d = new Dimension(600, 600); setMinimumSize(d); setPreferredSize(new Dimension(d)); setMaximumSize(d); } public JPanel create(){ JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS)); panel.setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2)); for(int j = 0; j < e.length; j++){ panel.add(e[j].paint()); } return panel; } @Override public void repaint(){ } public boolean equalLength(String s){ int len = s.length(); boolean equal = false; for(int j = 0; j < e.length; j++){ if(e.length == len){ equal = true; } } return equal; } public boolean equalValue(String s){ int len = s.length(); boolean equal = false; String[] temp = null; String[] temp2 = new String[len]; temp = s.split(""); for( int j = len; j>0; j--){ temp2[j-1] = temp[j]; } for(int j = 0; j < e.length; j++){ if( e[j].letter().equals(temp2[j]) ){ equal = true; } else { equal = false; } } if(equal){ for(int i = 0; i < e.length; i++){ e[i].changeState(3); } } return equal; } public boolean solved(){ boolean solved = false; for(int j = 0; j < e.length; j++){ if(e[j].getState() == 3){ solved = true; } else { solved = false; } } return solved; } @Override public String toString(){ return ""; } } Element.java import javax.swing.*; import java.awt.*; public class Element { final int INVISIBLE = 0; final int EMPTY = 1; final int FIRST_LETTER = 2; final int OTHER_LETTER = 3; private int state; private String letter; public Element(){ } //empty block public Element(int state){ this("", 0); } //filled block public Element(String s, int state){ this.state = state; this.letter = s; } public JButton paint(){ JButton button = null; if( state == EMPTY ){ button = new JButton(""); button.setBackground(Color.WHITE); } else if ( state == FIRST_LETTER ){ button = new JButton(letter); button.setBackground(Color.red); } else { button = new JButton(letter); button.setBackground(Color.yellow); } button.setSize(20,20); return button; } public void changeState(int s){ state = s; } public String letter(){ return letter; } public int getState(){ return state; } @Override public String toString(){ return "["+letter+"]"; } }

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Generics List Interface...newb question

- by newToProgramming

The List interface is the following: public interface List<E>{ public boolean add(Object e); public boolean remove(Object e); public boolean contains(Object e); ...etc Why aren't the add, remove and contains methods written like the following? public boolean add(E e) public boolean remove(E e) public boolean contains(E e)

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ADO Exception in HQL query

- by Yoav

I have 2 classes: Project and DataStructure. Class Project contains member List<DataStructure. My goal is to load a Project and all its DataStructures in one call. public class Project { public virtual string Id { get { } set { } } public virtual string Name { get { } set { } } public virtual ISet<DataStructure> DataStructures { get { } set { } } } public class DataStructure { public virtual string Id { get { } set { } } public virtual string Name { get { } set { } } public virtual string Description { get { } set { } } public virtual Project Project { get { } set { } } public virtual IList<DataField> Fields { get { } set { } } } Note that DataStructure also contains a list of class DataField but I don’t want to load these right now. Mapping in Fluent NHibernate: public class ProjectMap : ClassMap<Project> { public ProjectMap() { Table("PROJECTS"); Id(x => x.Pk, "PK"); Map(x => x.Id, "ID"); Map(x => x.Name, "NAME"); HasMany<DataStructure>(x => x.DataStructures).KeyColumn("FK_PROJECT"); } } public class DataStructureMap : ClassMap<DataStructure> { public DataStructureMap() { Table("DATA_STRUCTURES"); Map(x => x.Id, "ID"); Map(x => x.Name, "NAME"); Map(x => x.Description, "DESCRIPTION"); References<Project>(x => x.Project, "FK_PROJECT"); HasMany<DataField>(x => x.Fields).KeyColumn("FK_DATA_STRUCTURE"); } } This is my query: using (ISession session = SessionFactory.OpenSession()) { IQuery query = session.CreateQuery("from Project pr left join pr.DataStructure"); project = query.List<Project>(); } query.List() returns this exception: NHibernate.Exceptions.GenericADOException: Could not execute query[SQL: SQL not available] ---> System.ArgumentException: The value "System.Object[]" is not of type "Project" and cannot be used in this generic collection.

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PHP Copy-Paste Detector

- by user1615069

My problem is that when I run phpcpd command I always get 0% doubled code result, no matter if it's my project, if it's any php module's files, or if it's a file I created to check if phpcpd works...For example when I check the file below it also displays 0%: phpcpd folder/file.php: <?php class Class_Two { public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; echo 'ok'; } } } class Class_Two { public function aaa() { if(2 == 2) { echo 'ok'; } } public function aaa() { if(2 == 2) { echo 'ok'; } } } Any suggestions on why isn't it working properly? Or maybe it is supposed to do some other tasks?

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JComobox is not showing in the JDialog

- by Pujan Srivastava

I have 2 classes. when I put bold 3 lines in the method addCourses() the dialog does not show combobox in the Panel but when I remove from addCourses and put those bold lines in the constructor, JComboBox are shown in the Panel. But data will not show because data items updates to ComboBox will happen after Constructor is created. How can I solve this problem. this.mainPanel.add(courseCombo, BorderLayout.NORTH); this.mainPanel.add(sessionCombo, BorderLayout.CENTER); this.mainPanel.add(courseButton, BorderLayout.SOUTH); public class Updator { CourseListFrame clf = new CourseListFrame(); for(...){ clf.addContentsToBox(displayName, className); } clf.addCourses(); } and second class is public class CourseListFrame extends JDialog implements ActionListener { public JPanel mainPanel = new JPanel(new BorderLayout(2, 2)); public JButton courseButton = new JButton(("Submit")); public JComboBox courseCombo; public JComboBox sessionCombo; public Multimap<String, String> map; // = HashMultimap.create(); public static CourseListFrame courseListDialog; public CourseListFrame() { super(this.getMainFrame()); this.getContentPane().add(mainPanel); map = HashMultimap.create(); courseCombo = new JComboBox(); courseCombo.addItem("Select Courses"); courseCombo.addActionListener(this); sessionCombo = new JComboBox(); } public void addContentsToBox(String course, String session) { map.put(course, session); courseCombo.addItem(course); } public void actionPerformed(ActionEvent e) { JComboBox cb = (JComboBox) e.getSource(); String str = (String) cb.getSelectedItem(); setSessionCombo(str); } public void setSessionCombo(String course) { if (map.containsKey(course)) { sessionCombo.removeAllItems(); Iterator it = map.get(course).iterator(); while (it.hasNext()) { sessionCombo.addItem(it.next()); } } } public void addCourses() { this.mainPanel.add(courseCombo, BorderLayout.NORTH); this.mainPanel.add(sessionCombo, BorderLayout.CENTER); this.mainPanel.add(courseButton, BorderLayout.SOUTH); } public static void showCourseListDialog() { if (courseListDialog == null) { courseListDialog = new CourseListFrame(); } courseListDialog.pack(); courseListDialog.setVisible(true); courseListDialog.setSize(260, 180); } }

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Using nested classes for constants?

- by antirysm

What's wrong with using nested classes to group constants? Like so: public static class Constants { public static class CategoryA { public const string ValueX = "CatA_X"; public const string ValueY = "CatA_Y"; } public static class CategoryB { public const string ValueX = "CatB_X"; public const string ValueY = "CatB_Y"; } } Used like so: Console.WriteLine(Constants.CategoryA.ValueY); Console.WriteLine(Constants.CategoryB.ValueX); You could also make the "Constants"-class partial...

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How come Java doesn't accept my LinkedList in a Generic, but accepts its own?

- by master chief

For a class assignment, we can't use any of the languages bultin types, so I'm stuck with my own list. Anyway, here's the situation: public class CrazyStructure <T extends Comparable<? super T>> { MyLinkedList<MyTree<T>> trees; //error: type parameter MyTree is not within its bound } However: public class CrazyStructure <T extends Comparable<? super T>> { LinkedList<MyTree<T>> trees; } Works. MyTree impleements the Comparable interface, but MyLinkedList doesn't. However, Java's LinkedList doesn't implement it either, according to this. So what's the problem and how do I fix it? MyLinkedList: public class MyLinkedList<T extends Comparable<? super T>> { private class Node<T> { private Node<T> next; private T data; protected Node(); protected Node(final T value); } Node<T> firstNode; public MyLinkedList(); public MyLinkedList(T value); //calls node1.value.compareTo(node2.value) private int compareElements(final Node<T> node1, final Node<T> node2); public void insert(T value); public void remove(T value); } MyTree: public class LeftistTree<T extends Comparable<? super T>> implements Comparable { private class Node<T> { private Node<T> left, right; private T data; private int dist; protected Node(); protected Node(final T value); } private Node<T> root; public LeftistTree(); public LeftistTree(final T value); public Node getRoot(); //calls node1.value.compareTo(node2.value) private int compareElements(final Node node1, final Node node2); private Node<T> merge(Node node1, Node node2); public void insert(final T value); public T extractMin(); public int compareTo(final Object param); }

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Crystal Reports : How to add an external assembly class?

- by Sunil

I am using VS2010, CrystalReport13 & MVC3. My problem is unable to add an external assembly in Crystal Report using "Database Expert" Option. I have a class named WeeklyReportModel in an external assembly. In my web project, data retrieving from DB as IEnumerable collection of WeeklyReportModel. I tried ProjectData - .NetObjects in Crystal Report for adding the WeeklyReportModel. But this external assembly is not showing under ".NetObjects". Then I tried other option as Create New Connection - ADO.Net – Make New Connection and pointed this External Assembly. It has been added under Ado.Net node, but while expanding displays as "...no items found..." Totally frustrated. Please help. External Assembly Class: namespace SMS.Domain { public class WeeklyReportModel { public int StoreId { get; set; } public string StoreName{ get; set; } public decimal Saturday { get; set; } public decimal Sunday { get; set; } public decimal Monday { get; set; } public decimal Tuesday { get; set; } public decimal Wednesday { get; set; } public decimal Thurday { get; set; } public decimal Friday { get; set; } public decimal Average { get; set; } public string DateRange { get; set; } } } In Controller-action[Data retrieving as Collection Of WeeklyReportModel] namespace SMS.UI.Controllers { public class ReportController : Controller { public ActionResult StoreWeeklyReport(string id) { DateTime weekStart, weekClose; string[] dateArray = id.Split('_'); weekStart = Convert.ToDateTime(dateArray[0].ToString()); weekClose = Convert.ToDateTime(dateArray[1].ToString()); SMS.Infrastructure.Report.AuditReport weeklyReport = new SMS.Infrastructure.Report.AuditReport(); IEnumerable<SMS.Domain.WeeklyReportModel> weeklyRpt = weeklyReport.ReportByStore().WeeklyReport(weekStart, weekClose); Session["WeeklyData"] = weeklyRpt; Response.Redirect("~/Reports/Weekly/StoreWeekly.aspx"); return View(); } } } Thanks in advance.

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Advanced Model Binding vs 2010

- by user281180

Can I have an example of advanced model binding using ajaxpost? I have two classes Person and Test as follows: public class person{ public ArrayList Name = new ArrayList(); public Test []test {get;set;} } public class Test { public int ID{get;set;} public int mark{get;set;} } My Controller could be [HttpPost] public EmptyResult CaseTest(Person person) { return new EmptyResult(); } How do I post the values from the view?

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Command Not working in separate thread in J2me.

- by RishiPatel

I am creating a bluetooth application. I created a simple midlet with a exit command and i create a thread for finding the service and discovering the device. While doing so it displays a animated screen on which i added the parent commandListener for exit command. After successful connection both user is represented with greetings(Current screen calls the parent Display method setCurrent for displaying itself). This screen also have CommandListener set to the parent. Now i want to add few more commands. I Implemented the CommandLIstener Interface in this class, added few commands but the commands are not working. I dont whats wen wrong. I am giving u Code snippets to fully describle my issue : - package name Imports here public class MyMidlet extends MIDlet implements CommandListener { public CommandListener theListener; public Display theDisplay; public Command exitCommand; public MyMidlet() { // Retrieve the display for this MIDlet //Create the initial screen } public void startApp() throws MIDletStateChangeException { } public void pauseApp() { } public void destroyApp(boolean unconditional) { } public void commandAction(Command c, Displayable d) { // Determine if the exit command was selected if (c == exitCommand) { //End application here notifyDestroyed(); } else { //Start the new thread here } } } Now here is the code for the class which is invoked by the above midlet in a separate thread; package here; imports here public class MyService implements Runnable, CommandListener { private MyMidlet parent; private StreamConnection conn; private OutputStream output; private InputStream input; public Command sendCommand; private TextField messageToSend Form form; public BChatService(boolean isServer, BChatMidlet parent) { //some stuff here this.parent = parent; } public void run() { //functino for showing animation here try { input = conn.openInputStream(); output = conn.openOutputStream(); } catch (IOException e) { displayError("IO Error", "An error occurred while opening " + "the input and output streams" + "(IOException: " + e.getMessage() + ")"); try { conn.close(); } catch (Exception ex) { } return; } // Create the Form here when service is discoverd and greets the users Command sendCommand = new Command("Send", Command.ITEM, 2); exitCommand = new Command("Exit", Command.EXIT, 1); form.addCommand(exitCommand); form.addCommand(sendCommand); parent.theDisplay.setCurrent(form); form.setCommandListener(this); public void commandAction(Command c, Displayable d) { if (c == exitCommand) { // End the game parent.destroyApp(true); parent.notifyDestroyed(); } if(c == sendCommand) { form.append("SOme text here"); } } } When i select the Send command, the string doesnt append in form neither exit command works. What can be the possible cause for it?? I need to implement this functionality...Is there any other way to achieve this??

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Handling Model Inheritance in ASP.NET MVC2

- by enth

I've gotten myself stuck on how to handle inheritance in my model when it comes to my controllers/views. Basic Model: public class Procedure : Entity { public Procedure() { } public int Id { get; set; } public DateTime ProcedureDate { get; set; } public ProcedureType Type { get; set; } } public ProcedureA : Procedure { public double VariableA { get; set; } public int VariableB { get; set; } public int Total { get; set; } } public ProcedureB : Procedure { public int Score { get; set; } } etc... many of different procedures eventually. So, I do things like list all the procedures: public class ProcedureController : Controller { public virtual ActionResult List() { IEnumerable<Procedure> procedures = _repository.GetAll(); return View(procedures); } } but now I'm kinda stuck. Basically, from the list page, I need to link to pages where the specific subclass details can be viewed/edited and I'm not sure what the best strategy is. I thought I could add an action on the ProcedureController that would conjure up the right subclass by dynamically figuring out what repository to use and loading the subclass to pass to the view. I had to store the class in the ProcedureType object. I had to create/implement a non-generic IRepository since I can't dynamically cast to a generic one. public virtual ActionResult Details(int procedureID) { Procedure procedure = _repository.GetById(procedureID, false); string className = procedure.Type.Class; Type type = Type.GetType(className, true); Type repositoryType = typeof (IRepository<>).MakeGenericType(type); var repository = (IRepository)DependencyRegistrar.Resolve(repositoryType); Entity procedure = repository.GetById(procedureID, false); return View(procedure); } I haven't even started sorting out how the view is going to determine which partial to load to display the subclass details. I'm wondering if this is a good approach? This makes determining the URL easy. It makes reusing the Procedure display code easy. Another approach is specific controllers for each subclass. It simplifies the controller code, but also means many simple controllers for the many procedure subclasses. Can work out the shared Procedure details with a partial view. How to get to construct the URL to get to the controller/action in the first place? Time to not think about it. Hopefully someone can show me the light. Thanks in advance.

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How can data not stored in a DB be accessed from any activity in Android?

- by jul

hi, I'm passing data to a ListView to display some restaurant names. Now when clicking on an item I'd like to start another activity to display more restaurant data. I'm not sure about how to do it. Shall I pass all the restaurant data in a bundle through the intent object? Or shall I just pass the restaurant id and get the data in the other activity? In that case, how can I access my restaurantList from the other activity? In any case, how can I get data from the restaurant I clicked on (the view only contains the name)? Any help, pointers welcome! Thanks Jul ListView lv= (ListView)findViewById(R.id.listview); lv.setAdapter( new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,restaurantList.getRestaurantNames())); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Intent i = new Intent(Atable.this, RestaurantEdit.class); Bundle b = new Bundle(); //b.putInt("id", ? ); startActivityForResult(i, ACTIVITY_EDIT); } }); RestaurantList.java package org.digitalfarm.atable; import java.util.ArrayList; import java.util.List; public class RestaurantList { private List<Restaurant> restaurants = new ArrayList<Restaurant>(); public List<Restaurant> getRestaurants() { return this.restaurants; } public void setRestaurants(List<Restaurant> restaurants) { this.restaurants = restaurants; } public List<String> getRestaurantNames() { List<String> restaurantNames = new ArrayList<String>(); for (int i=0; i<this.restaurants.size(); i++) { restaurantNames.add(this.restaurants.get(i).getName()); } return restaurantNames; } } Restaurant.java package org.digitalfarm.atable; public class Restaurant { private int id; private String name; private float latitude; private float longitude; public int getId() { return this.id; } public void setId(int id) { this.id = id; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } public float getLatitude() { return this.latitude; } public void setLatitude(float latitude) { this.latitude = latitude; } public float getLongitude() { return this.longitude; } public void setLongitude(float longitude) { this.longitude = longitude; } }

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Single entity with single view or two views in mvc3 vs2010?

- by user2905798

I have the following entity model public class Employee { public int Employee ID{get;set;} public string employeename{get;set;} public datetime employeeDOb{get;set;} public datetime? employeeDateOfJoin{get;set;} public string empFamilyname{get;set;} public datetime empFamilyDob{get;set;} } here I have to design a view for collecting employee information and employee family information. Since I am working on already available data, where in empFamilyDob was not mandatory. But now it is being made mandatory, the previous data doesn't contain EmpFamilyDob. So naturally I have added this new property EmpFamilyDob to the Model and made it required through DataAnnotations. Now there are two set of views to be developed. 1. A view which simply allows to collect the employee information without employee family information. i.e, empFamilyName and EmpFamilyDob.--This view is used by the Hr section to insert empplyee details Since the empFamilyname and EmpFamilyDob being now made mandatory, some other section will edit the data and update the EmpFamilyName and EmpFamilyDob as and when the information about employee family details are received. I have action controller for CreateNew and Edit Which is being generated by using the default model. There are two user actions being performed. 1.When the user clicks the Create new -- he will be able to update only the Employee information 2.As and when the other section receives the employee family details they update the familyname and family date of birth. i.e, EmployeeFamilyname and EmployeFamilyDob. While creating new record the uses should be able to update employee information only and while editing the information he should be able to update the employeefamily information. Since I have a single view with most of these fields as required and not allowing null , How can I achieve this in a sincle view? I have recorrected the model like this public class Employee { public int Employee ID{get;set;} public string employeename{get;set;} public datetime employeeDOb{get;set;} public datetime? employeeDateOfJoin{get;set;} public string empFamilyname{get;set;} public datetime? empFamilyDob{get;set;} } Now by default I hope the createnew action would insert null value for empFamilyname(string datatype) and empFamilyDob . In the Edit action the user should be made to enter empFamilyname and empFamilyDob(mandatory). As there is every chance that the user might edit other information about the employee(like employeeDob) I don't want to go for partial views. Can you help me out with some illustration. Thanks in advance

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C# do nested classes need to be instantiated?

- by JL

In the following scenario: public class outerclass { public innerClass Ic {get;set} public class innerClass { } } Do you need to instantiate the inner class property before assigning values to it, like this? public class outerclass { public outerclass() { this.Ic = new innerClass(); } public innerClass Ic {get;set} public class innerClass { } }

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How to iterate a list inside a list in java?

- by user2142786

Hi i have two value object classes . package org.array; import java.util.List; public class Father { private String name; private int age ; private List<Children> Childrens; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public List<Children> getChildrens() { return Childrens; } public void setChildrens(List<Children> childrens) { Childrens = childrens; } } second is for children package org.array; public class Children { private String name; private int age ; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } } and i want to print there value i nested a list inside a list here i am putting only a single value inside the objects while in real i have many values . so i am nesting list of children inside father list. how can i print or get the value of child and father both. here is my logic. package org.array; import java.util.ArrayList; import java.util.Iterator; import java.util.List; public class ArrayDemo { public static void main(String[] args) { List <Father> fatherList = new ArrayList<Father>(); Father father = new Father(); father.setName("john"); father.setAge(25); fatherList.add(father); List <Children> childrens = new ArrayList<Children>(); Children children = new Children(); children.setName("david"); children.setAge(2); childrens.add(children); father.setChildrens(childrens); fatherList.add(father); Iterator<Father> iterator = fatherList.iterator(); while (iterator.hasNext()) { System.out.println(iterator.toString()); } } }

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What’s New in ASP.NET 4.0 Part Two: WebForms and Visual Studio Enhancements

- by Rick Strahl

In the last installment I talked about the core changes in the ASP.NET runtime that I’ve been taking advantage of. In this column, I’ll cover the changes to the Web Forms engine and some of the cool improvements in Visual Studio that make Web and general development easier. WebForms The WebForms engine is the area that has received most significant changes in ASP.NET 4.0. Probably the most widely anticipated features are related to managing page client ids and of ViewState on WebForm pages. Take Control of Your ClientIDs Unique ClientID generation in ASP.NET has been one of the most complained about “features” in ASP.NET. Although there’s a very good technical reason for these unique generated ids - they guarantee unique ids for each and every server control on a page - these unique and generated ids often get in the way of client-side JavaScript development and CSS styling as it’s often inconvenient and fragile to work with the long, generated ClientIDs. In ASP.NET 4.0 you can now specify an explicit client id mode on each control or each naming container parent control to control how client ids are generated. By default, ASP.NET generates mangled client ids for any control contained in a naming container (like a Master Page, or a User Control for example). The key to ClientID management in ASP.NET 4.0 are the new ClientIDMode and ClientIDRowSuffix properties. ClientIDMode supports four different ClientID generation settings shown below. For the following examples, imagine that you have a Textbox control named txtName inside of a master page control container on a WebForms page. <%@Page Language="C#" MasterPageFile="~/Site.Master" CodeBehind="WebForm2.aspx.cs" Inherits="WebApplication1.WebForm2" %> <asp:Content ID="content" ContentPlaceHolderID="content" runat="server" ClientIDMode="Static" > <asp:TextBox runat="server" ID="txtName" /> </asp:Content> The four available ClientIDMode values are: AutoID This is the existing behavior in ASP.NET 1.x-3.x where full naming container munging takes place. <input name="ctl00$content$txtName" type="text" id="ctl00_content_txtName" /> This should be familiar to any ASP.NET developer and results in fairly unpredictable client ids that can easily change if the containership hierarchy changes. For example, removing the master page changes the name in this case, so if you were to move a block of script code that works against the control to a non-Master page, the script code immediately breaks. Static This option is the most deterministic setting that forces the control’s ClientID to use its ID value directly. No naming container naming at all is applied and you end up with clean client ids: <input name="ctl00$content$txtName" type="text" id="txtName" /> Note that the name property which is used for postback variables to the server still is munged, but the ClientID property is displayed simply as the ID value that you have assigned to the control. This option is what most of us want to use, but you have to be clear on that because it can potentially cause conflicts with other controls on the page. If there are several instances of the same naming container (several instances of the same user control for example) there can easily be a client id naming conflict. Note that if you assign Static to a data-bound control, like a list child control in templates, you do not get unique ids either, so for list controls where you rely on unique id for child controls, you’ll probably want to use Predictable rather than Static. I’ll write more on this a little later when I discuss ClientIDRowSuffix. Predictable The previous two values are pretty self-explanatory. Predictable however, requires some explanation. To me at least it’s not in the least bit predictable. MSDN defines this value as follows: This algorithm is used for controls that are in data-bound controls. The ClientID value is generated by concatenating the ClientID value of the parent naming container with the ID value of the control. If the control is a data-bound control that generates multiple rows, the value of the data field specified in the ClientIDRowSuffix property is added at the end. For the GridView control, multiple data fields can be specified. If the ClientIDRowSuffix property is blank, a sequential number is added at the end instead of a data-field value. Each segment is separated by an underscore character (_). The key that makes this value a bit confusing is that it relies on the parent NamingContainer’s ClientID to build its own ClientID value. This effectively means that the value is not predictable at all but rather very tightly coupled to the parent naming container’s ClientIDMode setting. For my simple textbox example, if the ClientIDMode property of the parent naming container (Page in this case) is set to “Predictable” you’ll get this: <input name="ctl00$content$txtName" type="text" id="content_txtName" /> which gives an id that based on walking up to the currently active naming container (the MasterPage content container) and starting the id formatting from there downward. Think of this as a semi unique name that’s guaranteed unique only for the naming container. If, on the other hand, the Page is set to “AutoID” you get the following with Predictable on txtName: <input name="ctl00$content$txtName" type="text" id="ctl00_content_txtName" /> The latter is effectively the same as if you specified AutoID because it inherits the AutoID naming from the Page and Content Master Page control of the page. But again - predictable behavior always depends on the parent naming container and how it generates its id, so the id may not always be exactly the same as the AutoID generated value because somewhere in the NamingContainer chain the ClientIDMode setting may be set to a different value. For example, if you had another naming container in the middle that was set to Static you’d end up effectively with an id that starts with the NamingContainers id rather than the whole ctl000_content munging. The most common use for Predictable is likely to be for data-bound controls, which results in each data bound item getting a unique ClientID. Unfortunately, even here the behavior can be very unpredictable depending on which data-bound control you use - I found significant differences in how template controls in a GridView behave from those that are used in a ListView control. For example, GridView creates clean child ClientIDs, while ListView still has a naming container in the ClientID, presumably because of the template container on which you can’t set ClientIDMode. Predictable is useful, but only if all naming containers down the chain use this setting. Otherwise you’re right back to the munged ids that are pretty unpredictable. Another property, ClientIDRowSuffix, can be used in combination with ClientIDMode of Predictable to force a suffix onto list client controls. For example: <asp:GridView runat="server" ID="gvItems" AutoGenerateColumns="false" ClientIDMode="Static" ClientIDRowSuffix="Id"> <Columns> <asp:TemplateField> <ItemTemplate> <asp:Label runat="server" id="txtName" Text='<%# Eval("Name") %>' ClientIDMode="Predictable"/> </ItemTemplate> </asp:TemplateField> <asp:TemplateField> <ItemTemplate> <asp:Label runat="server" id="txtId" Text='<%# Eval("Id") %>' ClientIDMode="Predictable" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> generates client Ids inside of a column in the master page described earlier: <td> <span id="txtName_0">Rick</span> </td> where the value after the underscore is the ClientIDRowSuffix field - in this case “Id” of the item data bound to the control. Note that all of the child controls require ClientIDMode=”Predictable” in order for the ClientIDRowSuffix to be applied, and the parent GridView controls need to be set to Static either explicitly or via Naming Container inheritance to give these simple names. It’s a bummer that ClientIDRowSuffix doesn’t work with Static to produce this automatically. Another real problem is that other controls process the ClientIDMode differently. For example, a ListView control processes the Predictable ClientIDMode differently and produces the following with the Static ListView and Predictable child controls: <span id="ctrl0_txtName_0">Rick</span> I couldn’t even figure out a way using ClientIDMode to get a simple ID that also uses a suffix short of falling back to manually generated ids using <%= %> expressions instead. Given the inconsistencies inside of list controls using <%= %>, ids for the ListView might not be a bad idea anyway. Inherit The final setting is Inherit, which is the default for all controls except Page. This means that controls by default inherit the parent naming container’s ClientIDMode setting. For more detailed information on ClientID behavior and different scenarios you can check out a blog post of mine on this subject: http://www.west-wind.com/weblog/posts/54760.aspx. ClientID Enhancements Summary The ClientIDMode property is a welcome addition to ASP.NET 4.0. To me this is probably the most useful WebForms feature as it allows me to generate clean IDs simply by setting ClientIDMode="Static" on either the page or inside of Web.config (in the Pages section) which applies the setting down to the entire page which is my 95% scenario. For the few cases when it matters - for list controls and inside of multi-use user controls or custom server controls) - I can use Predictable or even AutoID to force controls to unique names. For application-level page development, this is easy to accomplish and provides maximum usability for working with client script code against page controls. ViewStateMode Another area of large criticism for WebForms is ViewState. ViewState is used internally by ASP.NET to persist page-level changes to non-postback properties on controls as pages post back to the server. It’s a useful mechanism that works great for the overall mechanics of WebForms, but it can also cause all sorts of overhead for page operation as ViewState can very quickly get out of control and consume huge amounts of bandwidth in your page content. ViewState can also wreak havoc with client-side scripting applications that modify control properties that are tracked by ViewState, which can produce very unpredictable results on a Postback after client-side updates. Over the years in my own development, I’ve often turned off ViewState on pages to reduce overhead. Yes, you lose some functionality, but you can easily implement most of the common functionality in non-ViewState workarounds. Relying less on heavy ViewState controls and sticking with simpler controls or raw HTML constructs avoids getting around ViewState problems. In ASP.NET 3.x and prior, it wasn’t easy to control ViewState - you could turn it on or off and if you turned it off at the page or web.config level, you couldn’t turn it back on for specific controls. In short, it was an all or nothing approach. With ASP.NET 4.0, the new ViewStateMode property gives you more control. It allows you to disable ViewState globally either on the page or web.config level and then turn it back on for specific controls that might need it. ViewStateMode only works when EnableViewState="true" on the page or web.config level (which is the default). You can then use ViewStateMode of Disabled, Enabled or Inherit to control the ViewState settings on the page. If you’re shooting for minimal ViewState usage, the ideal situation is to set ViewStateMode to disabled on the Page or web.config level and only turn it back on particular controls: <%@Page Language="C#" CodeBehind="WebForm2.aspx.cs" Inherits="Westwind.WebStore.WebForm2" ClientIDMode="Static" ViewStateMode="Disabled" EnableViewState="true" %>  <asp:TextBox runat="server" ID="txtName" ViewStateMode="Enabled" />  <asp:TextBox runat="server" ID="txtAddress" /> Note that the EnableViewState="true" at the Page level isn’t required since it’s the default, but it’s important that the value is true. ViewStateMode has no effect if EnableViewState="false" at the page level. The main benefit of ViewStateMode is that it allows you to more easily turn off ViewState for most of the page and enable only a few key controls that might need it. For me personally, this is a perfect combination as most of my WebForm apps can get away without any ViewState at all. But some controls - especially third party controls - often don’t work well without ViewState enabled, and now it’s much easier to selectively enable controls rather than the old way, which required you to pretty much turn off ViewState for all controls that you didn’t want ViewState on. Inline HTML Encoding HTML encoding is an important feature to prevent cross-site scripting attacks in data entered by users on your site. In order to make it easier to create HTML encoded content, ASP.NET 4.0 introduces a new Expression syntax using <%: %> to encode string values. The encoding expression syntax looks like this: <%: "<script type='text/javascript'>" + "alert('Really?');</script>" %> which produces properly encoded HTML: <script type='text/javascript' >alert('Really?');</script> Effectively this is a shortcut to: <%= HttpUtility.HtmlEncode( "<script type='text/javascript'>" + "alert('Really?');</script>") %> Of course the <%: %> syntax can also evaluate expressions just like <%= %> so the more common scenario applies this expression syntax against data your application is displaying. Here’s an example displaying some data model values: <%: Model.Address.Street %> This snippet shows displaying data from your application’s data store or more importantly, from data entered by users. Anything that makes it easier and less verbose to HtmlEncode text is a welcome addition to avoid potential cross-site scripting attacks. Although I listed Inline HTML Encoding here under WebForms, anything that uses the WebForms rendering engine including ASP.NET MVC, benefits from this feature. ScriptManager Enhancements The ASP.NET ScriptManager control in the past has introduced some nice ways to take programmatic and markup control over script loading, but there were a number of shortcomings in this control. The ASP.NET 4.0 ScriptManager has a number of improvements that make it easier to control script loading and addresses a few of the shortcomings that have often kept me from using the control in favor of manual script loading. The first is the AjaxFrameworkMode property which finally lets you suppress loading the ASP.NET AJAX runtime. Disabled doesn’t load any ASP.NET AJAX libraries, but there’s also an Explicit mode that lets you pick and choose the library pieces individually and reduce the footprint of ASP.NET AJAX script included if you are using the library. There’s also a new EnableCdn property that forces any script that has a new WebResource attribute CdnPath property set to a CDN supplied URL. If the script has this Attribute property set to a non-null/empty value and EnableCdn is enabled on the ScriptManager, that script will be served from the specified CdnPath. [assembly: WebResource( "Westwind.Web.Resources.ww.jquery.js", "application/x-javascript", CdnPath = "http://mysite.com/scripts/ww.jquery.min.js")] Cool, but a little too static for my taste since this value can’t be changed at runtime to point at a debug script as needed, for example. Assembly names for loading scripts from resources can now be simple names rather than fully qualified assembly names, which make it less verbose to reference scripts from assemblies loaded from your bin folder or the assembly reference area in web.config: <asp:ScriptManager runat="server" id="Id" EnableCdn="true" AjaxFrameworkMode="disabled"> <Scripts> <asp:ScriptReference Name="Westwind.Web.Resources.ww.jquery.js" Assembly="Westwind.Web" /> </Scripts> </asp:ScriptManager> The ScriptManager in 4.0 also supports script combining via the CompositeScript tag, which allows you to very easily combine scripts into a single script resource served via ASP.NET. Even nicer: You can specify the URL that the combined script is served with. Check out the following script manager markup that combines several static file scripts and a script resource into a single ASP.NET served resource from a static URL (allscripts.js): <asp:ScriptManager runat="server" id="Id" EnableCdn="true" AjaxFrameworkMode="disabled"> <CompositeScript Path="~/scripts/allscripts.js"> <Scripts> <asp:ScriptReference Path="~/scripts/jquery.js" /> <asp:ScriptReference Path="~/scripts/ww.jquery.js" /> <asp:ScriptReference Name="Westwind.Web.Resources.editors.js" Assembly="Westwind.Web" /> </Scripts> </CompositeScript> </asp:ScriptManager> When you render this into HTML, you’ll see a single script reference in the page: <script src="scripts/allscripts.debug.js" type="text/javascript"></script> All you need to do to make this work is ensure that allscripts.js and allscripts.debug.js exist in the scripts folder of your application - they can be empty but the file has to be there. This is pretty cool, but you want to be real careful that you use unique URLs for each combination of scripts you combine or else browser and server caching will easily screw you up royally. The script manager also allows you to override native ASP.NET AJAX scripts now as any script references defined in the Scripts section of the ScriptManager trump internal references. So if you want custom behavior or you want to fix a possible bug in the core libraries that normally are loaded from resources, you can now do this simply by referencing the script resource name in the Name property and pointing at System.Web for the assembly. Not a common scenario, but when you need it, it can come in real handy. Still, there are a number of shortcomings in this control. For one, the ScriptManager and ClientScript APIs still have no common entry point so control developers are still faced with having to check and support both APIs to load scripts so that controls can work on pages that do or don’t have a ScriptManager on the page. The CdnUrl is static and compiled in, which is very restrictive. And finally, there’s still no control over where scripts get loaded on the page - ScriptManager still injects scripts into the middle of the HTML markup rather than in the header or optionally the footer. This, in turn, means there is little control over script loading order, which can be problematic for control developers. MetaDescription, MetaKeywords Page Properties There are also a number of additional Page properties that correspond to some of the other features discussed in this column: ClientIDMode, ClientTarget and ViewStateMode. Another minor but useful feature is that you can now directly access the MetaDescription and MetaKeywords properties on the Page object to set the corresponding meta tags programmatically. Updating these values programmatically previously required either <%= %> expressions in the page markup or dynamic insertion of literal controls into the page. You can now just set these properties programmatically on the Page object in any Control derived class on the page or the Page itself: Page.MetaKeywords = "ASP.NET,4.0,New Features"; Page.MetaDescription = "This article discusses the new features in ASP.NET 4.0"; Note, that there’s no corresponding ASP.NET tag for the HTML Meta element, so the only way to specify these values in markup and access them is via the @Page tag: <%@Page Language="C#" CodeBehind="WebForm2.aspx.cs" Inherits="Westwind.WebStore.WebForm2" ClientIDMode="Static" MetaDescription="Article that discusses what's new in ASP.NET 4.0" MetaKeywords="ASP.NET,4.0,New Features" %> Nothing earth shattering but quite convenient. Visual Studio 2010 Enhancements for Web Development For Web development there are also a host of editor enhancements in Visual Studio 2010. Some of these are not Web specific but they are useful for Web developers in general. Text Editors Throughout Visual Studio 2010, the text editors have all been updated to a new core engine based on WPF which provides some interesting new features for various code editors including the nice ability to zoom in and out with Ctrl-MouseWheel to quickly change the size of text. There are many more API options to control the editor and although Visual Studio 2010 doesn’t yet use many of these features, we can look forward to enhancements in add-ins and future editor updates from the various language teams that take advantage of the visual richness that WPF provides to editing. On the negative side, I’ve noticed that occasionally the code editor and especially the HTML and JavaScript editors will lose the ability to use various navigation keys like arrows, back and delete keys, which requires closing and reopening the documents at times. This issue seems to be well documented so I suspect this will be addressed soon with a hotfix or within the first service pack. Overall though, the code editors work very well, especially given that they were re-written completely using WPF, which was one of my big worries when I first heard about the complete redesign of the editors. Multi-Targeting Visual Studio now targets all versions of the .NET framework from 2.0 forward. You can use Visual Studio 2010 to work on your ASP.NET 2, 3.0 and 3.5 applications which is a nice way to get your feet wet with the new development environment without having to make changes to existing applications. It’s nice to have one tool to work in for all the different versions. Multi-Monitor Support One cool feature of Visual Studio 2010 is the ability to drag windows out of the Visual Studio environment and out onto the desktop including onto another monitor easily. Since Web development often involves working with a host of designers at the same time - visual designer, HTML markup window, code behind and JavaScript editor - it’s really nice to be able to have a little more screen real estate to work on each of these editors. Microsoft made a welcome change in the environment. IntelliSense Snippets for HTML and JavaScript Editors The HTML and JavaScript editors now finally support IntelliSense scripts to create macro-based template expansions that have been in the core C# and Visual Basic code editors since Visual Studio 2005. Snippets allow you to create short XML-based template definitions that can act as static macros or real templates that can have replaceable values that can be embedded into the expanded text. The XML syntax for these snippets is straight forward and it’s pretty easy to create custom snippets manually. You can easily create snippets using XML and store them in your custom snippets folder (C:\Users\rstrahl\Documents\Visual Studio 2010\Code Snippets\Visual Web Developer\My HTML Snippets and My JScript Snippets), but it helps to use one of the third-party tools that exist to simplify the process for you. I use SnippetEditor, by Bill McCarthy, which makes short work of creating snippets interactively (http://snippeteditor.codeplex.com/). Note: You may have to manually add the Visual Studio 2010 User specific Snippet folders to this tool to see existing ones you’ve created. Code snippets are some of the biggest time savers and HTML editing more than anything deals with lots of repetitive tasks that lend themselves to text expansion. Visual Studio 2010 includes a slew of built-in snippets (that you can also customize!) and you can create your own very easily. If you haven’t done so already, I encourage you to spend a little time examining your coding patterns and find the repetitive code that you write and convert it into snippets. I’ve been using CodeRush for this for years, but now you can do much of the basic expansion natively for HTML and JavaScript snippets. jQuery Integration Is Now Native jQuery is a popular JavaScript library and recently Microsoft has recently stated that it will become the primary client-side scripting technology to drive higher level script functionality in various ASP.NET Web projects that Microsoft provides. In Visual Studio 2010, the default full project template includes jQuery as part of a new project including the support files that provide IntelliSense (-vsdoc files). IntelliSense support for jQuery is now also baked into Visual Studio 2010, so unlike Visual Studio 2008 which required a separate download, no further installs are required for a rich IntelliSense experience with jQuery. Summary ASP.NET 4.0 brings many useful improvements to the platform, but thankfully most of the changes are incremental changes that don’t compromise backwards compatibility and they allow developers to ease into the new features one feature at a time. None of the changes in ASP.NET 4.0 or Visual Studio 2010 are monumental or game changers. The bigger features are language and .NET Framework changes that are also optional. This ASP.NET and tools release feels more like fine tuning and getting some long-standing kinks worked out of the platform. It shows that the ASP.NET team is dedicated to paying attention to community feedback and responding with changes to the platform and development environment based on this feedback. If you haven’t gotten your feet wet with ASP.NET 4.0 and Visual Studio 2010, there’s no reason not to give it a shot now - the ASP.NET 4.0 platform is solid and Visual Studio 2010 works very well for a brand new release. Check it out. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET

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Code Contracts: Unit testing contracted code

- by DigiMortal

Code contracts and unit tests are not replacements for each other. They both have different purpose and different nature. It does not matter if you are using code contracts or not – you still have to write tests for your code. In this posting I will show you how to unit test code with contracts. In my previous posting about code contracts I showed how to avoid ContractExceptions that are defined in code contracts runtime and that are not accessible for us in design time. This was one step further to make my randomizer testable. In this posting I will complete the mission. Problems with current code This is my current code. public class Randomizer { public static int GetRandomFromRangeContracted(int min, int max) { Contract.Requires<ArgumentOutOfRangeException>( min < max, "Min must be less than max" ); Contract.Ensures( Contract.Result<int>() >= min && Contract.Result<int>() <= max, "Return value is out of range" ); var rnd = new Random(); return rnd.Next(min, max); } } As you can see this code has some problems: randomizer class is static and cannot be instantiated. We cannot move this class between components if we need to, GetRandomFromRangeContracted() is not fully testable because we cannot currently affect random number generator output and therefore we cannot test post-contract. Now let’s solve these problems. Making randomizer testable As a first thing I made Randomizer to be class that must be instantiated. This is simple thing to do. Now let’s solve the problem with Random class. To make Randomizer testable I define IRandomGenerator interface and RandomGenerator class. The public constructor of Randomizer accepts IRandomGenerator as argument. public interface IRandomGenerator { int Next(int min, int max); } public class RandomGenerator : IRandomGenerator { private Random _random = new Random(); public int Next(int min, int max) { return _random.Next(min, max); } } And here is our Randomizer after total make-over. public class Randomizer { private IRandomGenerator _generator; private Randomizer() { _generator = new RandomGenerator(); } public Randomizer(IRandomGenerator generator) { _generator = generator; } public int GetRandomFromRangeContracted(int min, int max) { Contract.Requires<ArgumentOutOfRangeException>( min < max, "Min must be less than max" ); Contract.Ensures( Contract.Result<int>() >= min && Contract.Result<int>() <= max, "Return value is out of range" ); return _generator.Next(min, max); } } It seems to be inconvenient to instantiate Randomizer now but you can always use DI/IoC containers and break compiled dependencies between the components of your system. Writing tests for randomizer IRandomGenerator solved problem with testing post-condition. Now it is time to write tests for Randomizer class. Writing tests for contracted code is not easy. The main problem is still ContractException that we are not able to access. Still it is the main exception we get as soon as contracts fail. Although pre-conditions are able to throw exceptions with type we want we cannot do much when post-conditions will fail. We have to use Contract.ContractFailed event and this event is called for every contract failure. This way we find ourselves in situation where supporting well input interface makes it impossible to support output interface well and vice versa. ContractFailed is nasty hack and it works pretty weird way. Although documentation sais that ContractFailed is good choice for testing contracts it is still pretty painful. As a last chance I got tests working almost normally when I wrapped them up. Can you remember similar solution from the times of Visual Studio 2008 unit tests? Cannot understand how Microsoft was able to mess up testing again. [TestClass] public class RandomizerTest { private Mock<IRandomGenerator> _randomMock; private Randomizer _randomizer; private string _lastContractError; public TestContext TestContext { get; set; } public RandomizerTest() { Contract.ContractFailed += (sender, e) => { e.SetHandled(); e.SetUnwind(); throw new Exception(e.FailureKind + ": " + e.Message); }; } [TestInitialize()] public void RandomizerTestInitialize() { _randomMock = new Mock<IRandomGenerator>(); _randomizer = new Randomizer(_randomMock.Object); _lastContractError = string.Empty; } #region InputInterfaceTests [TestMethod] [ExpectedException(typeof(Exception))] public void GetRandomFromRangeContracted_should_throw_exception_when_min_is_not_less_than_max() { try { _randomizer.GetRandomFromRangeContracted(100, 10); } catch (Exception ex) { throw new Exception(string.Empty, ex); } } [TestMethod] [ExpectedException(typeof(Exception))] public void GetRandomFromRangeContracted_should_throw_exception_when_min_is_equal_to_max() { try { _randomizer.GetRandomFromRangeContracted(10, 10); } catch (Exception ex) { throw new Exception(string.Empty, ex); } } [TestMethod] public void GetRandomFromRangeContracted_should_work_when_min_is_less_than_max() { int minValue = 10; int maxValue = 100; int returnValue = 50; _randomMock.Setup(r => r.Next(minValue, maxValue)) .Returns(returnValue) .Verifiable(); var result = _randomizer.GetRandomFromRangeContracted(minValue, maxValue); _randomMock.Verify(); Assert.AreEqual<int>(returnValue, result); } #endregion #region OutputInterfaceTests [TestMethod] [ExpectedException(typeof(Exception))] public void GetRandomFromRangeContracted_should_throw_exception_when_return_value_is_less_than_min() { int minValue = 10; int maxValue = 100; int returnValue = 7; _randomMock.Setup(r => r.Next(10, 100)) .Returns(returnValue) .Verifiable(); try { _randomizer.GetRandomFromRangeContracted(minValue, maxValue); } catch (Exception ex) { throw new Exception(string.Empty, ex); } _randomMock.Verify(); } [TestMethod] [ExpectedException(typeof(Exception))] public void GetRandomFromRangeContracted_should_throw_exception_when_return_value_is_more_than_max() { int minValue = 10; int maxValue = 100; int returnValue = 102; _randomMock.Setup(r => r.Next(10, 100)) .Returns(returnValue) .Verifiable(); try { _randomizer.GetRandomFromRangeContracted(minValue, maxValue); } catch (Exception ex) { throw new Exception(string.Empty, ex); } _randomMock.Verify(); } #endregion } Although these tests are pretty awful and contain hacks we are at least able now to make sure that our code works as expected. Here is the test list after running these tests. Conclusion Code contracts are very new stuff in Visual Studio world and as young technology it has some problems – like all other new bits and bytes in the world. As you saw then making our contracted code testable is easy only to the point when pre-conditions are considered. When we start dealing with post-conditions we will end up with hacked tests. I hope that future versions of code contracts will solve error handling issues the way that testing of contracted code will be easier than it is right now.

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TDD and WCF behavior

- by Frederic Hautecoeur

Some weeks ago I wanted to develop a WCF behavior using TDD. I have lost some time trying to use mocks. After a while i decided to just use a host and a client. I don’t like this approach but so far I haven’t found a good and fast solution to use Unit Test for testing a WCF behavior. To Implement my solution I had to : Create a Dummy Service Definition; Create the Dummy Service Implementation; Create a host; Create a client in my test; Create and Add the behavior; Dummy Service Definition This is just a simple service, composed of an Interface and a simple implementation. The structure is aimed to be easily customizable for my future needs. Using Clauses : 1: using System.Runtime.Serialization; 2: using System.ServiceModel; 3: using System.ServiceModel.Channels; The DataContract: 1: [DataContract()] 2: public class MyMessage 3: { 4: [DataMember()] 5: public string MessageString; 6: } The request MessageContract: 1: [MessageContract()] 2: public class RequestMessage 3: { 4: [MessageHeader(Name = "MyHeader", Namespace = "http://dummyservice/header", Relay = true)] 5: public string myHeader; 6: 7: [MessageBodyMember()] 8: public MyMessage myRequest; 9: } The response MessageContract: 1: [MessageContract()] 2: public class ResponseMessage 3: { 4: [MessageHeader(Name = "MyHeader", Namespace = "http://dummyservice/header", Relay = true)] 5: public string myHeader; 6: 7: [MessageBodyMember()] 8: public MyMessage myResponse; 9: } The ServiceContract: 1: [ServiceContract(Name="DummyService", Namespace="http://dummyservice",SessionMode=SessionMode.Allowed )] 2: interface IDummyService 3: { 4: [OperationContract(Action="Perform", IsOneWay=false, ProtectionLevel=System.Net.Security.ProtectionLevel.None )] 5: ResponseMessage DoThis(RequestMessage request); 6: } Dummy Service Implementation 1: public class DummyService:IDummyService 2: { 3: #region IDummyService Members 4: public ResponseMessage DoThis(RequestMessage request) 5: { 6: ResponseMessage response = new ResponseMessage(); 7: response.myHeader = "Response"; 8: response.myResponse = new MyMessage(); 9: response.myResponse.MessageString = 10: string.Format("Header:<{0}> and Request was <{1}>", 11: request.myHeader, request.myRequest.MessageString); 12: return response; 13: } 14: #endregion 15: } Host Creation The most simple host implementation using a Named Pipe binding. The GetBinding method will create a binding for the host and can be used to create the same binding for the client. 1: public static class TestHost 2: { 3: 4: internal static string hostUri = "net.pipe://localhost/dummy"; 5: 6: // Create Host method. 7: internal static ServiceHost CreateHost() 8: { 9: ServiceHost host = new ServiceHost(typeof(DummyService)); 10: 11: // Creating Endpoint 12: Uri namedPipeAddress = new Uri(hostUri); 13: host.AddServiceEndpoint(typeof(IDummyService), GetBinding(), namedPipeAddress); 14: 15: return host; 16: } 17: 18: // Binding Creation method. 19: internal static Binding GetBinding() 20: { 21: NamedPipeTransportBindingElement namedPipeTransport = new NamedPipeTransportBindingElement(); 22: TextMessageEncodingBindingElement textEncoding = new TextMessageEncodingBindingElement(); 23: 24: return new CustomBinding(textEncoding, namedPipeTransport); 25: } 26: 27: // Close Method. 28: internal static void Close(ServiceHost host) 29: { 30: if (null != host) 31: { 32: host.Close(); 33: host = null; 34: } 35: } 36: } Checking the service A simple test tool check the plumbing. 1: [TestMethod] 2: public void TestService() 3: { 4: using (ServiceHost host = TestHost.CreateHost()) 5: { 6: host.Open(); 7: 8: using (ChannelFactory<IDummyService> channel = 9: new ChannelFactory<IDummyService>(TestHost.GetBinding() 10: , new EndpointAddress(TestHost.hostUri))) 11: { 12: IDummyService svc = channel.CreateChannel(); 13: try 14: { 15: RequestMessage request = new RequestMessage(); 16: request.myHeader = Guid.NewGuid().ToString(); 17: request.myRequest = new MyMessage(); 18: request.myRequest.MessageString = "I want some beer."; 19: 20: ResponseMessage response = svc.DoThis(request); 21: } 22: catch (Exception ex) 23: { 24: Assert.Fail(ex.Message); 25: } 26: } 27: host.Close(); 28: } 29: } Running the service should show that the client and the host are running fine. So far so good. Adding the Behavior Add a reference to the Behavior project and add the using entry in the test class. We just need to add the behavior to the service host : 1: [TestMethod] 2: public void TestService() 3: { 4: using (ServiceHost host = TestHost.CreateHost()) 5: { 6: host.Description.Behaviors.Add(new MyBehavior()); 7: host.Open();¨ 8: … If you set a breakpoint in your behavior and run the test in debug mode, you will hit the breakpoint. In this case I used a ServiceBehavior. To add an Endpoint behavior you have to add it to the endpoints. 1: host.Description.Endpoints[0].Behaviors.Add(new MyEndpointBehavior()) To add a contract or an operation behavior a custom attribute should work on the service contract definition. I haven’t tried that yet. All the code provided in this blog and in the following files are for sample use. Improvements I don’t like to instantiate a client and a service to test my behaviors. But so far I have' not found an easy way to do it. Today I am passing a type of endpoint to the host creator and it creates the right binding type. This allows me to easily switch between bindings at will. I have used the same approach to test Mex Endpoints, another post should come later for this. Enjoy !

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ASP.NET Web Forms Extensibility: Handler Factories

- by Ricardo Peres

An handler factory is the class that implements IHttpHandlerFactory and is responsible for instantiating an handler (IHttpHandler) that will process the current request. This is true for all kinds of web requests, whether they are for ASPX pages, ASMX/SVC web services, ASHX/AXD handlers, or any other kind of file. Also used for restricting access for certain file types, such as Config, Csproj, etc. Handler factories are registered on the global Web.config file, normally located at %WINDIR%\Microsoft.NET\Framework<x64>\vXXXX\Config for a given path and request type (GET, POST, HEAD, etc). This goes on section <httpHandlers>. You would create a custom handler factory for a number of reasons, let me list just two: A centralized place for using dependency injection; Also a centralized place for invoking custom methods or performing some kind of validation on all pages. Let’s see an example using Unity for injecting dependencies into a page, suppose we have this on Global.asax.cs: 1: public class Global : HttpApplication 2: { 3: internal static readonly IUnityContainer Unity = new UnityContainer(); 4: 5: void Application_Start(Object sender, EventArgs e) 6: { 7: Unity.RegisterType<IFunctionality, ConcreteFunctionality>(); 8: } 9: } We instantiate Unity and register a concrete implementation for an interface, this could/should probably go in the Web.config file. Forget about its actual definition, it’s not important. Then, we create a custom handler factory: 1: public class UnityPageHandlerFactory : PageHandlerFactory 2: { 3: public override IHttpHandler GetHandler(HttpContext context, String requestType, String virtualPath, String path) 4: { 5: IHttpHandler handler = base.GetHandler(context, requestType, virtualPath, path); 6: 7: //one scenario: inject dependencies 8: Global.Unity.BuildUp(handler.GetType(), handler, String.Empty); 9: 10: return (handler); 11: } 12: } It inherits from PageHandlerFactory, which is .NET’s included factory for building regular ASPX pages. We override the GetHandler method and issue a call to the BuildUp method, which will inject required dependencies, if any exist. An example page with dependencies might be: 1: public class SomePage : Page 2: { 3: [Dependency] 4: public IFunctionality Functionality 5: { 6: get; 7: set; 8: } 9: } Notice the DependencyAttribute, it is used by Unity to identify properties that require dependency injection. When BuildUp is called, the Functionality property (or any other properties with the DependencyAttribute attribute) will receive the concrete implementation associated with it’s type, as registered on Unity. Another example, checking a page for authorization. Let’s define an interface first: 1: public interface IRestricted 2: { 3: Boolean Check(HttpContext ctx); 4: } An a page implementing that interface: 1: public class RestrictedPage : Page, IRestricted 2: { 3: public Boolean Check(HttpContext ctx) 4: { 5: //check the context and return a value 6: return ...; 7: } 8: } For this, we would use an handler factory such as this: 1: public class RestrictedPageHandlerFactory : PageHandlerFactory 2: { 3: private static readonly IHttpHandler forbidden = new UnauthorizedHandler(); 4: 5: public override IHttpHandler GetHandler(HttpContext context, String requestType, String virtualPath, String path) 6: { 7: IHttpHandler handler = base.GetHandler(context, requestType, virtualPath, path); 8: 9: if (handler is IRestricted) 10: { 11: if ((handler as IRestricted).Check(context) == false) 12: { 13: return (forbidden); 14: } 15: } 16: 17: return (handler); 18: } 19: } 20: 21: public class UnauthorizedHandler : IHttpHandler 22: { 23: #region IHttpHandler Members 24: 25: public Boolean IsReusable 26: { 27: get { return (true); } 28: } 29: 30: public void ProcessRequest(HttpContext context) 31: { 32: context.Response.StatusCode = (Int32) HttpStatusCode.Unauthorized; 33: context.Response.ContentType = "text/plain"; 34: context.Response.Write(context.Response.Status); 35: context.Response.Flush(); 36: context.Response.Close(); 37: context.ApplicationInstance.CompleteRequest(); 38: } 39: 40: #endregion 41: } The UnauthorizedHandler is an example of an IHttpHandler that merely returns an error code to the client, but does not cause redirection to the login page, it is included merely as an example. One thing we must keep in mind is, there can be only one handler factory registered for a given path/request type (verb) tuple. A typical registration would be: 1: <httpHandlers> 2: <remove path="*.aspx" verb="*"/> 3: <add path="*.aspx" verb="*" type="MyNamespace.MyHandlerFactory, MyAssembly"/> 4: </httpHandlers> First we remove the previous registration for ASPX files, and then we register our own. And that’s it. A very useful mechanism which I use lots of times.

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Entity Framework 4.3.1 Code based Migrations and Connector/Net 6.6

- by GABMARTINEZ

Code-based migrations is a new feature as part of the Connector/Net support for Entity Framework 4.3.1. In this tutorial we'll see how we can use it so we can keep track of the changes done to our database creating a new application using the code first approach. If you don't have a clear idea about how code first works we highly recommend you to check this subject before going further with this tutorial. Creating our Model and Database with Code First From VS 2010 1. Create a new console application 2. Add the latest Entity Framework official package using Package Manager Console (Tools Menu, then Library Package Manager -> Package Manager Console). In the Package Manager Console we have to type Install-Package EntityFramework This will add the latest version of this library. We will also need to make some changes to your config file. A <configSections> was added which contains the version you have from EntityFramework. An <entityFramework> section was also added where you can set up some initialization. This section is optional and by default is generated to use SQL Express. Since we don't need it for now (we'll see more about it below) let's leave this section empty as shown below. 3. Create a new Model with a simple entity. 4. Enable Migrations to generate the our Configuration class. In the Package Manager Console we have to type Enable-Migrations; This will make some changes in our application. It will create a new folder called Migrations where all the migrations representing the changes we do to our model. It will also create a Configuration class that we'll be using to initialize our SQL Generator and some other values like if we want to enable Automatic Migrations. You can see that it already has the name of our DbContext. You can also create you Configuration class manually. 5. Specify our Model Provider. We need to specify in our Class Configuration that we'll be using MySQLClient since this is not part of the generated code. Also please make sure you have added the MySql.Data and the MySql.Data.Entity references to your project. using MySql.Data.Entity; // Add the MySQL.Data.Entity namespace public Configuration() { this.AutomaticMigrationsEnabled = false; SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator()); // This will add our MySQLClient as SQL Generator } 6. Add our Data Provider and set up our connection string <connectionStrings> <add name="PersonalContext" connectionString="server=localhost;User Id=root;database=Personal;" providerName="MySql.Data.MySqlClient" /> </connectionStrings> <system.data> <DbProviderFactories> <remove invariant="MySql.Data.MySqlClient" /> <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.6.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" /> </DbProviderFactories> </system.data> * The version recommended to use of Connector/Net is 6.6.2 or earlier. At this point we can create our database and then start working with Migrations. So let's do some data access so our database get's created. You can run your application and you'll get your database Personal as specified in our config file. Add our first migration Migrations are a great resource as we can have a record for all the changes done and will generate the MySQL statements required to apply these changes to the database. Let's add a new property to our Person class public string Email { get; set; } If you try to run your application it will throw an exception saying The model backing the 'PersonelContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269). So as suggested let's add our first migration for this change. In the Package Manager Console let's type Add-Migration AddEmailColumn Now we have the corresponding class which generate the necessary operations to update our database. namespace MigrationsFromScratch.Migrations { using System.Data.Entity.Migrations; public partial class AddEmailColumn : DbMigration { public override void Up(){ AddColumn("People", "Email", c => c.String(unicode: false)); } public override void Down() { DropColumn("People", "Email"); } } } In the Package Manager Console let's type Update-Database Now you can check your database to see all changes were succesfully applied. Now let's add a second change and generate our second migration public class Person { [Key] public int PersonId { get; set;} public string Name { get; set; } public string Address {get; set;} public string Email { get; set; } public List<Skill> Skills { get; set; } } public class Skill { [Key] public int SkillId { get; set; } public string Description { get; set; } } public class PersonelContext : DbContext { public DbSet<Person> Persons { get; set; } public DbSet<Skill> Skills { get; set; } } If you would like to customize any part of this code you can do that at this step. You can see there is the up method which can update your database and the down that can revert the changes done. If you customize any code you should make sure to customize in both methods. Now let's apply this change. Update-database -verbose I added the verbose flag so you can see all the SQL generated statements to be run. Downgrading changes So far we have always upgraded to the latest migration, but there may be times when you want downgrade to a specific migration. Let's say we want to return to the status we have before our last migration. We can use the -TargetMigration option to specify the migration we'd like to return. Also you can use the -verbose flag. If you like to go back to the Initial state you can do: Update-Database -TargetMigration:$InitialDatabase or equivalent: Update-Database -TargetMigration:0 Migrations doesn't allow by default a migration that would ocurr in a data loss. One case when you can got this message is for example in a DropColumn operation. You can override this configuration by setting AutomaticMigrationDataLossAllowed to true in the configuration class. Also you can set your Database Initializer in case you want that these Migrations can be applied automatically and you don't have to go all the way through creating a migration and updating later the changes. Let's see how. Database Initialization by Code We can specify an initialization strategy by using Database.SetInitializer (http://msdn.microsoft.com/en-us/library/gg679461(v=vs.103)). One of the strategies that I found very useful when you are at a development stage (I mean not for production) is the MigrateDatabaseToLatestVersion. This strategy will make all the necessary migrations each time there is a change in our model that needs a database replication, this also implies that we have to enable AutomaticMigrationsEnabled flag in our Configuration class. public Configuration() { AutomaticMigrationsEnabled = true; AutomaticMigrationDataLossAllowed = true; SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator()); // This will add our MySQLClient as SQL Generator } In the new EntityFramework section of your Config file we can set this at a context level basis. The syntax is as follows: <contexts> <context type="Custom DbContext name, Assembly name"> <databaseInitializer type="System.Data.Entity.MigrateDatabaseToLatestVersion`2[[ Custom DbContext name, Assembly name], [Configuration class name, Assembly name]], EntityFramework" /> </context> </contexts> In our example this would be: The syntax is kind of odd but very convenient. This way all changes will always be applied when we do any data access in our application. There are a lot of new things to explore in EF 4.3.1 and Migrations so we'll continue writing some more posts about it. Please let us know if you have any questions or comments, also please check our forums here where we keep answering questions in general for the community. Hope you found this information useful. Happy MySQL/.Net Coding!

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Breaking through the class sealing

- by Jason Crease

Do you understand 'sealing' in C#? Somewhat? Anyway, here's the lowdown. I've done this article from a C# perspective, but I've occasionally referenced .NET when appropriate. What is sealing a class? By sealing a class in C#, you ensure that you ensure that no class can be derived from that class. You do this by simply adding the word 'sealed' to a class definition: public sealed class Dog {} Now writing something like " public sealed class Hamster: Dog {} " you'll get a compile error like this: 'Hamster: cannot derive from sealed type 'Dog' If you look in an IL disassembler, you'll see a definition like this: .class public auto ansi sealed beforefieldinit Dog extends [mscorlib]System.Object Note the addition of the word 'sealed'. What about sealing methods? You can also seal overriding methods. By adding the word 'sealed', you ensure that the method cannot be overridden in a derived class. Consider the following code: public class Dog : Mammal { public sealed override void Go() { } } public class Mammal { public virtual void Go() { } } In this code, the method 'Go' in Dog is sealed. It cannot be overridden in a subclass. Writing this would cause a compile error: public class Dachshund : Dog { public override void Go() { } } However, we can 'new' a method with the same name. This is essentially a new method; distinct from the 'Go' in the subclass: public class Terrier : Dog { public new void Go() { } } Sealing properties? You can also seal seal properties. You add 'sealed' to the property definition, like so: public sealed override string Name { get { return m_Name; } set { m_Name = value; } } In C#, you can only seal a property, not the underlying setters/getters. This is because C# offers no override syntax for setters or getters. However, in underlying IL you seal the setter and getter methods individually - a property is just metadata. Why bother sealing? There are a few traditional reasons to seal: Invariance. Other people may want to derive from your class, even though your implementation may make successful derivation near-impossible. There may be twisted, hacky logic that could never be second-guessed by another developer. By sealing your class, you're protecting them from wasting their time. The CLR team has sealed most of the framework classes, and I assume they did this for this reason. Security. By deriving from your type, an attacker may gain access to functionality that enables him to hack your system. I consider this a very weak security precaution. Speed. If a class is sealed, then .NET doesn't need to consult the virtual-function-call table to find the actual type, since it knows that no derived type can exist. Therefore, it could emit a 'call' instead of 'callvirt' or at least optimise the machine code, thus producing a performance benefit. But I've done trials, and have been unable to demonstrate this If you have an example, please share! All in all, I'm not convinced that sealing is interesting or important. Anyway, moving-on... What is automatically sealed? Value types and structs. If they were not always sealed, all sorts of things would go wrong. For instance, structs are laid-out inline within a class. But what if you assigned a substruct to a struct field of that class? There may be too many fields to fit. Static classes. Static classes exist in C# but not .NET. The C# compiler compiles a static class into an 'abstract sealed' class. So static classes are already sealed in C#. Enumerations. The CLR does not track the types of enumerations - it treats them as simple value types. Hence, polymorphism would not work. What cannot be sealed? Interfaces. Interfaces exist to be implemented, so sealing to prevent implementation is dumb. But what if you could prevent interfaces from being extended (i.e. ban declarations like "public interface IMyInterface : ISealedInterface")? There is no good reason to seal an interface like this. Sealing finalizes behaviour, but interfaces have no intrinsic behaviour to finalize Abstract classes. In IL you can create an abstract sealed class. But C# syntax for this already exists - declaring a class as a 'static', so it forces you to declare it as such. Non-override methods. If a method isn't declared as override it cannot be overridden, so sealing would make no difference. Note this is stated from a C# perspective - the words are opposite in IL. In IL, you have four choices in total: no declaration (which actually seals the method), 'virtual' (called 'override' in C#), 'sealed virtual' ('sealed override' in C#) and 'newslot virtual' ('new virtual' or 'virtual' in C#, depending on whether the method already exists in a base class). Methods that implement interface methods. Methods that implement an interface method must be virtual, so cannot be sealed. Fields. A field cannot be overridden, only hidden (using the 'new' keyword in C#), so sealing would make no sense.

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Opposite Force to Apply to a Collided Rigid Body?

- by Milo

I'm working on the physics for my GTA2-like game so I can learn more about game physics. The collision detection and resolution are working great. I'm now just unsure how to compute the force to apply to a body after it collides with a wall. My rigid body looks like this: /our simulation object class RigidBody extends Entity { //linear private Vector2D velocity = new Vector2D(); private Vector2D forces = new Vector2D(); private float mass; private Vector2D v = new Vector2D(); //angular private float angularVelocity; private float torque; private float inertia; //graphical private Vector2D halfSize = new Vector2D(); private Bitmap image; private Matrix mat = new Matrix(); private float[] Vector2Ds = new float[2]; private Vector2D tangent = new Vector2D(); private static Vector2D worldRelVec = new Vector2D(); private static Vector2D relWorldVec = new Vector2D(); private static Vector2D pointVelVec = new Vector2D(); private static Vector2D acceleration = new Vector2D(); public RigidBody() { //set these defaults so we don't get divide by zeros mass = 1.0f; inertia = 1.0f; setLayer(LAYER_OBJECTS); } protected void rectChanged() { if(getWorld() != null) { getWorld().updateDynamic(this); } } //intialize out parameters public void initialize(Vector2D halfSize, float mass, Bitmap bitmap) { //store physical parameters this.halfSize = halfSize; this.mass = mass; image = bitmap; inertia = (1.0f / 20.0f) * (halfSize.x * halfSize.x) * (halfSize.y * halfSize.y) * mass; RectF rect = new RectF(); float scalar = 10.0f; rect.left = (int)-halfSize.x * scalar; rect.top = (int)-halfSize.y * scalar; rect.right = rect.left + (int)(halfSize.x * 2.0f * scalar); rect.bottom = rect.top + (int)(halfSize.y * 2.0f * scalar); setRect(rect); } public void setLocation(Vector2D position, float angle) { getRect().set(position.x,position.y, getWidth(), getHeight(), angle); rectChanged(); } public Vector2D getPosition() { return getRect().getCenter(); } @Override public void update(float timeStep) { doUpdate(timeStep); } public void doUpdate(float timeStep) { //integrate physics //linear acceleration.x = forces.x / mass; acceleration.y = forces.y / mass; velocity.x += (acceleration.x * timeStep); velocity.y += (acceleration.y * timeStep); //velocity = Vector2D.add(velocity, Vector2D.scalarMultiply(acceleration, timeStep)); Vector2D c = getRect().getCenter(); v.x = getRect().getCenter().getX() + (velocity.x * timeStep); v.y = getRect().getCenter().getY() + (velocity.y * timeStep); setCenter(v.x, v.y); forces.x = 0; //clear forces forces.y = 0; //angular float angAcc = torque / inertia; angularVelocity += angAcc * timeStep; setAngle(getAngle() + angularVelocity * timeStep); torque = 0; //clear torque } //take a relative Vector2D and make it a world Vector2D public Vector2D relativeToWorld(Vector2D relative) { mat.reset(); Vector2Ds[0] = relative.x; Vector2Ds[1] = relative.y; mat.postRotate(JMath.radToDeg(getAngle())); mat.mapVectors(Vector2Ds); relWorldVec.x = Vector2Ds[0]; relWorldVec.y = Vector2Ds[1]; return relWorldVec; } //take a world Vector2D and make it a relative Vector2D public Vector2D worldToRelative(Vector2D world) { mat.reset(); Vector2Ds[0] = world.x; Vector2Ds[1] = world.y; mat.postRotate(JMath.radToDeg(-getAngle())); mat.mapVectors(Vector2Ds); worldRelVec.x = Vector2Ds[0]; worldRelVec.y = Vector2Ds[1]; return worldRelVec; } //velocity of a point on body public Vector2D pointVelocity(Vector2D worldOffset) { tangent.x = -worldOffset.y; tangent.y = worldOffset.x; pointVelVec.x = (tangent.x * angularVelocity) + velocity.x; pointVelVec.y = (tangent.y * angularVelocity) + velocity.y; return pointVelVec; } public void applyForce(Vector2D worldForce, Vector2D worldOffset) { //add linear force forces.x += worldForce.x; forces.y += worldForce.y; //add associated torque torque += Vector2D.cross(worldOffset, worldForce); } @Override public void draw( GraphicsContext c) { c.drawRotatedScaledBitmap(image, getPosition().x, getPosition().y, getWidth(), getHeight(), getAngle()); } public Vector2D getVelocity() { return velocity; } public void setVelocity(Vector2D velocity) { this.velocity = velocity; } } The way it is given force is by the applyForce method, this method considers angular torque. I'm just not sure how to come up with the vectors in the case where: RigidBody hits static entity RigidBody hits other RigidBody that may or may not be in motion. Would anyone know a way (without too complex math) that I could figure out the opposite force I need to apply to the car? I know the normal it is colliding with and how deep it collided. My main goal is so that say I hit a building from the side, well the car should not just stay there, it should slowly rotate out of it if I'm more than 45 degrees. Right now when I hit a wall I only change the velocity directly which does not consider angular force. Thanks!

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