When I want to call a method from within a upperclass it doesn't seem to recognize the method even though my program does seem to recognize my classes.
For instance
private decimal Fee { get; set; } = 1.5m;
public new void MethodCredit(decimal amount)
{
if (Fee < amount)
{
Account.**MethodCredit**(amount - Fee);
}
else
{
Console.WriteLine("Fee is greater than the amount you want to transfer");
}
}
The method doesn't seem to exist anyone who knows what the problem is.
Here's the code inside the main Account class
public void MethodCredit(decimal amount)
{
balance += amount;
}
Related
In my REST applications (under GlassFish 4.1.2) I want to convert POJOs to JSON and back again. The examples all make it look easy but I am missing something.
Here is my application:
#ApplicationPath("/")
public class RootApp extends Application {
#Override
public Set<Class<?>> getClasses() {
HashSet set = new HashSet<Class<?>>();
set.add(HelloWorld.class);
return set;
}
#Override
public Set<Object> getSingletons() {
HashSet set = new HashSet<Object>();
MOXyJsonProvider moxyJsonProvider = new MOXyJsonProvider();
moxyJsonProvider.setFormattedOutput(true);
set.add(moxyJsonProvider);
return set;
}
}
And here is the Resource:
#Path("helloworld")
public class HelloWorld {
private static int counter = 1;
#GET
#Produces(MediaType.APPLICATION_JSON)
public Response getInevitableMessage() {
JsonHello hj = new JsonHello("Hello World", counter++);
return Response.ok(hj).build();
}
}
And last and least is the POJO to convert to and from JSON:
public class JsonHello {
private int count;
private String message;
public JsonHello(String message, int count) {
this.message = message;
this.count = count;
}
public int count() { return count; }
public void count(int value) { count = value; }
public String message() { return message; }
public void message(String value) { message = value; }
}
I am referring to the tagged answer in this thread. When I attempt to access "/helloworld" it pitches the following exception:
org.glassfish.jersey.server.ContainerException: java.lang.NoClassDefFoundError: Could not initialize class org.eclipse.persistence.jaxb.BeanValidationHelper
This application works if the resource just returns a string. There is nothing in the web.xml file since I am letting Glassfish set the application via its decorators.
Any idea what I am missing here?
I ended up solving the problem using the direction that #peeskillet suggested. MOXyJsonProvider is unneeded.
One problem that is hard to address is that almost all the examples on the web assume you are configuring your Servlet with a web.xml file, which I am not. All the configuration I do is from inside the Application object. The Jersey documentation does not make this very clear. What ends up working is this:
#Override
public Set<Class<?>> getClasses() {
HashSet set = new HashSet<Class<?>>();
set.add(JacksonFeature.class);
set.add(MyObjectMapperProvider.class);
set.add(Home.class);
set.add(HelloWorld.class);
return set;
}
At this point the REST resources can produce and consume various POJOs which are transcoded into JSON perfectly and without any effort.
Instead of just deleting this question I will put this answer here in hopes of saving someone the amount of time I spent finding this out.
I've got a many-to-many relationship set up via AutoMapping. Now, the save and updates work fine as expected, however the DiscountGroups are not being loaded in DiscountDay when I get the entities afterwards. I cannot for the life of me work out why the _discountGroups list is always empty, even though it's all correct in the database.
I've seen suggestions about using ISet rather than IList however it doesn't seem to make any difference in my case, neiter does using
.Not.LazyLoad()
in the mapping. Removing AsBag() and AsSet() also makes no difference.
The Entities
public class DiscountDay
{
public virtual DayOfWeek DayOfWeek { get; set; }
public virtual Discount Discount { get; set; }
private readonly IList<DiscountGroup> _discountGroups = new List<DiscountGroup>();
public virtual IEnumerable<DiscountGroup> DiscountGroups
{
get { return _discountGroups; }
set { }
}
}
public class DiscountGroup
{
public virtual string Name { get; set; }
private readonly IList<DiscountDay> _discountDay = new List<DiscountDay>();
public virtual IEnumerable<DiscountDay> DiscountDay
{
get { return _discountDay; }
}
}
The Mappings
public class DiscountDayOverride : IAutoMappingOverride<DiscountDay>
{
public void Override(AutoMapping<DiscountDay> mapping)
{
mapping.HasManyToMany( x => x.DiscountGroups )
.AsSet()
.Cascade
.SaveUpdate();
mapping.Cache.ReadWrite();
}
}
public class DiscountGroupOverride : IAutoMappingOverride<DiscountGroup>
{
public void Override(AutoMapping<DiscountGroup> mapping)
{
mapping.HasManyToMany( x => x.DiscountDay )
.AsBag()
.Inverse();
mapping.Cache.ReadWrite();
}
}
Well, I'm a complete and utter numpty. The empty set on DiscountGroups on the DiscountDay entity was causing the issue. For some reason I'd glossed over it and just didn't think that an empty set would do anything.
Updated code:
public virtual IEnumerable<DiscountGroup> DiscountGroups
{
get { return _discountGroups; }
}
I am a newbie to with unity and unit of work pattern and I am trying to write a code, which connects to my webservice and does all the work.
Everything goes well until I use the Database but I get lost when I try to use the webservice.
I have wasted my 2 precious days, searching every single possible article related to it and applying it to my code, but no luck till date.
I know, by writing connection string to web.config and calling it in dbcontext class controller will connect to the required database, but I am not connecting to any database, so what changes I need to do in web/app.config. Also, even if I write my connection logic in dbcontext constructor, it still searches and fills the dbcontext with sql server details. I presume thats happening because I am using DBSet.
Guys, you are requested to have a look at my code, I have done and show me some hope that I can do it. Let me know, if you want any other info related to the code that you want to see.
thanks
DBCONTEXT
public class CVSContext : DbContext
{
public DbSet<CVSViewModel> CVS { get; set; }
public DbSet<Contact> Contacts { get; set; }
public DbSet<Account> Accounts { get; set; }
public CVSContext()
{
//CRM Start
var clientCredentials = new System.ServiceModel.Description.ClientCredentials();
clientCredentials.UserName.UserName = "";
clientCredentials.UserName.Password = "";
var serviceProxy = new Microsoft.Xrm.Sdk.Client.OrganizationServiceProxy(new Uri("http://Organization.svc"), null, clientCredentials, null);
serviceProxy.ServiceConfiguration.CurrentServiceEndpoint.Behaviors.Add(new ProxyTypesBehavior());
HttpContext.Current.Session.Add("ServiceProxy", serviceProxy);
//CRM End
}
}
GENERIC REPOSITORY
public class GenericRepository<TEntity> where TEntity : class
{
internal CVSContext context;
internal DbSet<TEntity> dbSet;
public GenericRepository(CVSContext context)
{
this.context = context;
this.dbSet = context.Set<TEntity>();
}
}
UNIT OF WORK
public interface IUnitOfWork : IDisposable
{
int SaveChanges();
}
public interface IDALContext : IUnitOfWork
{
ICVSRepository CVS { get; set; }
IContactRepository Contacts { get; set; }
//IAccountRepository Accounts { get; set; }
}
public class DALContext : IDALContext
{
private CVSContext dbContext;
private ICVSRepository cvs;
private IContactRepository contacts;
// private IAccountRepository accounts;
public DALContext()
{
dbContext = new CVSContext();
}
public ICVSRepository CVS
{
get
{
if (cvs == null)
cvs = new CVSRepository(dbContext);
return cvs;
}
set
{
if (cvs == value)
cvs = value;
}
}
public IContactRepository Contacts
{
get
{
if (contacts == null)
contacts = new ContactRepository(dbContext);
return contacts;
}
set
{
if (contacts == value)
contacts = value;
}
}
public int SaveChanges()
{
return this.SaveChanges();
}
public void Dispose()
{
if(contacts != null)
contacts.Dispose();
//if(accounts != null)
// accounts.Dispose();
if(dbContext != null)
dbContext.Dispose();
GC.SuppressFinalize(this);
}
}
SERVICE
public interface ICVSService
{
Contact CreateContact(Guid contactName, string productName, int price);
List<CVSViewModel> GetCVS();
List<Contact> GetContacts();
List<Account> GetAccounts();
}
public class CVSService : ICVSService, IDisposable
{
private IDALContext context;
public CVSService(IDALContext dal)
{
context = dal;
}
public List<CVSViewModel> GetCVS()
{
return context.CVS.All().ToList();
}
public List<Contact> GetContacts()
{
return context.Contacts.All().ToList();
}
public List<Account> GetAccounts()
{
return context.Accounts.All().ToList();
}
public Contact CreateContact(Guid contactName, string accountName, int price)
{
var contact = new Contact() { ContactId = contactName };
var account = new Account() { ContactName = accountName, Rent = price, Contact = contact };
//context.Contacts.Create(contact);
context.SaveChanges();
return contact;
}
public void Dispose()
{
if (context != null)
context.Dispose();
}
}
CONTROLLER
public ActionResult Index()
{
ViewData.Model = service.GetContacts();
return View();
}
It's all about proper abstractions. The common abstraction that is used between some data source (could be a db or ws) is the Repository pattern, or at a higher level the Unit of Work pattern. In fact Entity Framework DbContext is an implementation of the Unit of Work pattern, but it is tailored for databases. You can't use to communicate with a web service.
In that case you will have to write your own IRepository<T> abstraction and have a database specific implementation that uses a DbContext under the covers and a web service specific implementation that wraps a web service client proxy under the covers.
However, when your application gets more complex, you often find yourself wanting to have some sort of transaction like behavior. This is what the Unit of Work pattern if for: it presents a business transaction. Using the unit of work pattern to wrap multiple WS calls however, will get painful very soon. It's a lot of work to get right and in that case you will be much better of using a message based architecture.
With a message based architecture you define a single atomic operation (a business transaction or use case) as a specific message, for instance:
public class MoveCustomerCommand
{
public int CustomerId { get; set; }
public Address NewAddress { get; set; }
}
This is just an object (DTO) with a set of properties, but without behavior. Nice about this is that you can pass these kinds of objects over the wire using WCF or any other technology or process them locally without the need for the consumer to know.
Take a look at this article that describes it in detail. This article builds on top of that model and describes how you can write highly maintainable WCF services using this model.
I want to model an 'Expense' object that has a 'Sum' (decimal) field.
In the view, I want to validate that the user enters a positive value.
OTOH I want to make sure I save the object with a negative value in the DB.
Right now, the model looks like this:
//------The model-------
public class Operation {
[Range(typeof(decimal), "0.0001", "79228162514264337593543950335")]
public virtual decimal Sum { get; set; }
[...]
}
public class Expense : Operation
{
public override decimal Sum
{
get
{
return base.Sum;
}
set
{
base.Sum = - Math.Abs(value);
}
}
}
//------In the controller-------
[HttpPost]
public ActionResult CreateExpense(Expense operation, int[] SelectedTags)
{
return CreatePost(operation, SelectedTags);
}
private ActionResult CreatePost(Operation operation, int[] SelectedTags)
{
if (ModelState.IsValid) // <-- this fails
[...]
}
The problem is, the MVC validation works with the object's properties (not the POST'ed form values), sees the negative value and fails to validate.
What should I do to fix this?
It looks to me like I'm not separating concerns (validate user input vs maintain database integrity).
Should I use a view model to hold the user input and then populate the actual model from the view model? Doesn't sound like KISS...
I found out that specifying a separate validation attribute on the property of the inherited class works a treat.
Can't think of something more straight-forward.
Here's how the model looks like now:
public class Operation {
public virtual decimal Sum { get; set; }
}
public class Income : Operation
{
[Range(typeof(decimal), "0.0001", "79228162514264337593543950335")]
public override decimal Sum
{
get { return base.Sum; }
set { base.Sum = Math.Abs(value); }
}
}
public class Expense : Operation
{
[Range(typeof(decimal), "-79228162514264337593543950335", "-0.0001")]
public override decimal Sum
{
get { return base.Sum; }
set { base.Sum = - Math.Abs(value); }
}
}
A validation attribute to check if the value is less than zero is another simple solution.
public class PositiveNumberAttribute : ValidationAttribute
{
protected override ValidationResult IsValid(object number, ValidationContext validationContext)
{
return int.Parse(number.ToString()) >= 0
? ValidationResult.Success : new ValidationResult("Positive value required.");
}
}
Then apply to property
[PositiveNumber]
public virtual decimal Sum { get; set; }
I am fairly new to MVC, but after playing with it (MVC 3/Razor), I am hooked.
I have a few questions:
1) What is the best, or most widely used pattern to develop MVC apps in? Repository, DDD, UOW?
2) I am using the Entity Framework 4, so could some please explain to me or point me to a good source that will explain the Repository Pattern w/EF4? Doesn't EF4 take place as the business layer and the data access layer? Does the Repository Pattern even provide a benefit?
3) Also, one last question, could someone explain the whole relationship between the Controller, the Model and the View? I get the basics, but maybe a little more in depth of the correct way to use it. View Models - Say I have a view that displays customer info, and one that edits it, should I have a view model and an edit model, or can the be passed around?
4) Examples??
Thanks for the help up front,
$("Sam")
** EDIT **
Am I on the right track here:
Public Class HomeController
Inherits System.Web.Mvc.Controller
Function Index(ByVal id As Integer) As ActionResult
Return View(New HomeModel)
End Function
<HttpPost()> _
Function Index(ByVal Model As HomeModel) As ActionResult
Return View(Model)
End Function
End Class
Public Class HomeModel
Private _Repository As IRepository(Of Customer)
Public Property Customer As Customer
Public Sub New()
End Sub
Public Sub New(ByVal ID As Integer)
_Repository = New CustomerRepository
Customer = _Repository.GetByID(ID)
End Sub
End Class
Public Interface IRepository(Of T)
Function GetByID(ByVal ID As Integer) As T
Sub Add(ByVal Entity As T)
Sub Delete(ByVal Entity As T)
End Interface
Public Class CustomerRepository
Implements IRepository(Of Customer)
Public Sub Add(ByVal Entity As Customer) Implements IRepository(Of Customer).Add
End Sub
Public Sub Delete(ByVal Entity As Customer) Implements IRepository(Of Customer).Delete
End Sub
Public Function GetByID(ByVal ID As Integer) As Customer Implements IRepository(Of Customer).GetByID
Return New Customer With {.ID = ID, .FirstName = "Sam", .LastName = "Striano"}
End Function
End Class
Public Class Customer
Public Property ID As Integer
Public Property FirstName As String
Public Property LastName As String
End Class
I use generic repositories that get instantiated in a service class (using Dependency Injection with Ninject).
The service class essentially performs two functions:
It provides all the methods that the controller will consume.
It has a property called ViewModel, that essentially maps the data that the views need into a MyViewModel class.
The Controller consumes the service class. With this "pattern", your controllers look like:
namespace ES.eLearningFE.Areas.Courses.Controllers
{
public partial class CourseController : Controller
{
ICourseDisplayService service;
public CourseController(ICourseDisplayService service)
{
this.service = service;
}
public virtual ActionResult Display(int CourseId, int StepOrder, string PupilName, string TutorName)
{
service.CourseId = CourseId;
service.StepOrder = StepOrder;
service.PupilName = PupilName;
service.TutorName = TutorName;
if (Request.IsAjaxRequest())
{
return PartialView(service.ViewModel);
}
else
{
return View(service.ViewModel);
}
}
}
}
The ViewModel class only hold display data and no methods (except the odd really simple method to retrieve data from another property that is, for example a List<> object).
Works really well. An example of a service class:
namespace ES.eLearning.Domain.Services.Courses
{
public class SqlCourseDisplayService : ICourseDisplayService
{
DataContext db;
public SqlCourseDisplayService(DbDataContextFactory contextFactory)
{
db = contextFactory.Make();
CoursesRepository = new SqlRepository<Course>(db);
StepsRepository = new SqlRepository<CourseStep>(db);
StepLinksRepository = new SqlRepository<StepLink>(db);
UserCoursesRepository = new SqlRepository<UserCourse>(db);
CourseTutorsRepository = new SqlRepository<CourseTutor>(db);
UsersRepository = new SqlRepository<User>(db);
}
#region ICourseDisplayService Members
public ViewModels.CourseDisplayVM ViewModel
{
get
{
return new ViewModels.CourseDisplayVM
{
CourseId = this.CourseId,
CourseName = this.Course.Name,
Steps = this.Steps,
ActiveStepIndex = this.ActiveStepIndex,
CurrentStepIndex = this.CurrentStepIndex,
Pupil = new UserDto { UserId = this.PupilId, UserName = this.PupilName },
Tutors = this.GetTutors(this.CourseId),
Tutor = tutorName == null ? null : new UserDto { UserName = this.TutorName, UserId = this.TutorId}
};
}
}
#region Entities
int courseId;
public int CourseId
{
get
{
if (courseId == 0) throw new ApplicationException("Invalid Course Id!");
return courseId;
}
set
{
if (value == 0) throw new ApplicationException("Invalid Course Id!");
try
{
Course = (from c in CoursesRepository.Query where c.CourseId == value select c).First();
Steps = Course.CourseSteps.ToList();
courseId = value;
}
catch {throw new ApplicationException("No Course found for Course Id: " + value);}
}
}
public Data.Course Course { get; private set; }
public int StepOrder { get; set; }
public List<Data.CourseStep> Steps { get; private set; }
public int ActiveStepIndex
{
get
{
if (PupilName == null)
{
throw new ApplicationException("Pupil not set!");
}
if (CourseId == 0)
{
throw new ApplicationException("Course not set!");
}
try
{
var x = (from uc in UserCoursesRepository.Query where (uc.IdCourse == CourseId) && (uc.UserName == PupilName) select uc).First();
return x.ActiveStepIndex;
}
catch { throw new ApplicationException("Could not get Active Step!"); }
}
}
#endregion
#region Users
string tutorName;
public string TutorName
{
get
{
if (tutorName == null) throw new ApplicationException("Invalid call to get Tutor Name [Null Tutor Name]!");
return tutorName;
}
set
{
tutorName = value;
TutorId = (Guid)Membership.GetUser(tutorName).ProviderUserKey;
}
}
public Guid TutorId { get; set; }
string pupilName;
public string PupilName
{
get { return pupilName; }
set
{
pupilName = value;
PupilId = (Guid)Membership.GetUser(pupilName).ProviderUserKey;
}
}
public Guid PupilId { get; set; }
#endregion
#region Utility Properties
public int CurrentStepIndex { get; set; }
public int StepCount
{
get
{
return Steps == null ? 0 : Steps.Count();
}
}
#endregion
#region Private Utilities
private List<UserDto> GetTutors(int CourseId)
{
return (from ct in CourseTutorsRepository.Query join u in UsersRepository.Query
on ct.TutorName equals u.UserName
where (ct.CourseId == courseId)
select new UserDto { UserName = ct.TutorName, UserId = u.UserId }).ToList();
}
#endregion
#region Repositories
private IRepository<Course> CoursesRepository
{
get;
set;
}
private IRepository<CourseStep> StepsRepository
{
get;
set;
}
private IRepository<StepLink> StepLinksRepository
{
get;
set;
}
private IRepository<UserCourse> UserCoursesRepository
{
get;
set;
}
private IRepository<CourseTutor> CourseTutorsRepository
{
get;
set;
}
private IRepository<User> UsersRepository
{
get;
set;
}
#endregion
#endregion
}
}
May not be everyone's choice, but hey, it works for me... AND (more importantly) my clients and their users.
Edit
As requested in the comment below, the Repository that I use:
namespace ES.eLearning.Domain
{
public class SqlRepository<T> : IRepository<T> where T : class
{
DataContext db;
public SqlRepository(DataContext db)
{
this.db = db;
}
#region IRepository<T> Members
public IQueryable<T> Query
{
get { return db.GetTable<T>(); }
}
public List<T> FetchAll()
{
return Query.ToList();
}
public void Add(T entity)
{
db.GetTable<T>().InsertOnSubmit(entity);
}
public void Delete(T entity)
{
db.GetTable<T>().DeleteOnSubmit(entity);
}
public void Attach(T entity)
{
db.GetTable<T>().Attach(entity);
}
public void Save()
{
db.SubmitChanges();
}
#endregion
}
}
And the IRepository Interface:
namespace Wingspan.Web.Mvc
{
public interface IRepository<TEntity> where TEntity : class
{
List<TEntity> FetchAll();
IQueryable<TEntity> Query {get;}
void Add(TEntity entity);
void Delete(TEntity entity);
void Attach(TEntity entity);
void Save();
}
}
This should help you getting started. There are a lot of tutorials and videos available; for example:
Understanding Models, Views and Controllers
The ASP.NET MVC 2.0 basics and excellent introduction by Scott Hanselman. Personally one of my favorite speakers.
And also at www.asp.net; there are a few tutorials/examples to help you getting started. For example the Music Store sample
Unfortunately, I'm not so familiar with EF4/Repository pattern. But here's a blogpost about this pattern.
1) I would say that the repository pattern is the most widely used, then there is inversion of controll too.
2) I can't really point out the benefits with using a repository for entity framework other than that the controller should not know about how to acces data other then asking a repository. This makes it easy to switch it out sometime.
You can also eager load the data to make sure that the view don't call the database in every iteration of a foreach, for example a collection of users to display data from a child entity. You can probly do this anyway, but I feel that the repository is the right place to do it.
3) I can't tell you about the concept in a more in depth way, but I can tell some about viewmodels. In my opinion you should only use viewmodels if there is anything more then one entity you want to send to the view, for example a list of countries. You can alo use a viewmodel to "flatten" out very complex objects.
I would defiantly say the repository pattern is used a lot. This pattern can be used with Dependency Injection. Using Dependency Injection makes Unit Testing a breeze because you can snap different repositories to an abstract repoistory. Check out http://ninject.org/ for a simple to use Dependecy injector for .NET.
View Models should hold display data and transfer that data from the controller to the view. If you want to edit and display customer info, take a look at this