I have 4 classes namely ClassA, ClassADto, ClassAA(inner class to ClassA) and the final Result class.
ClassAA
{
public int HouseNumber{get;set;}
public string StreetName{get;set;}
public string State{get;set;}
}
ClassA
{
public int Age{get;set;}
public string Name{get;set;}
public ClassAA AObj[get;set;}
}
ClassADto
{
public int Age{get;set;}
public string Name{get;set;}
}
class Result
{
public string StreetName{get;set;}
public int TotalCount{get;set;}
public int TodaysDate{get;set;}
public List<ClassADto> AObjectsList{get;set;}
}
Now my aim is map the 'Result' class with the List of ClassA object to fill it the property 'AObjectsList' as below:
Result data= map mapper.map>(obj);
Also at the same time in automapper i want to use custom function either using 'Resolve' or 'AfterMap' to set properties like 'TodaysDate' to current datetime of system and property 'TotalCount' by counting the number of data.
I tried in many ways using 'CreateMap' and also used 'ForMembers' as from 'classAA' we only need the 'StreetName' but it didn't work. Need some help please.
One time typing approach ;)
public static Result ToResult(this List<ClassA> users)
{
return new Result
{
TotalCount = users.Count,
TodaysDate = DateTime.Today,
AObjectsList = users
.Select(user => new ClassADto
{
Name = user.Name,
Age = user.Age
})
.ToList()
};
}
// Usage
var users = new List<ClassA> { new ClassA(), new ClassA() };
var result = users.ToResult();
I often want to refine posted data before use it, for example
public class Song() {
public String[] tags;
public String csvTags;
public void setTagsWithCsv() {
// this one should be more complicated for handling real data
this.tags = csvTags.split(",");
}
}
In this case, I have to call setTagsWithCsv method inside the method of the controller class.
#RequestMapping(value = "/song/create", method = POST)
public String createSong(Song song) {
song.setTagsWithCsv();
songService.create(song); // some code like this will come here
...
}
Is there any way to call the method with an annotation like '#PostConstruct'? The method should be called after a post request.
Maybe you just provided a bad example, but If your Song is in a form of POJO, you do it on a call to setCsvTags
public class Song {
private String[] tags;
private String csvTags;
public void setCsvTags(String csvTags) {
this.csvTags = csvTags;
this.tags = csvTags.split(",");
}
public void setTags(String[] tags) {
this.tags == tags;
String newCsvTags = Arrays.toString(tags);
this.csvTags = newCsvTags.substring(1, newCsvTags.length() - 1); // get rid of []
}
}
or make a method, without keeping explicit tags array
public class Song {
private String csvTags;
public void getTags() {
return csvTags.split(",");
}
}
Otherwise, there is no standard way of doing this, you can play with request interception before reaching your Controller, but I think it would be just a waste of time.
I have a project where Entity Classes and Business classes are mixed up. The entity beans are part of the business and all is used through the whole project.
How can I best refactor those classes to separate those layers. I also want to keep the changes to the implementers as minimal as possible. Preferable no changes, otherwise hundreds of references need to be updated.
How should I rename the classes and work through this?
Example of mixed code:
// Mixed business-entity class
public final class Language {
private final Long id;
private final String code;
private final String description;
//Constructor
public Language() {
}
//getters and setters
public String getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
...
//Business is a part of this class
public static Language findByUser(User user) {
Language language;
...implementation to find user language...
return language;
}
....
}
// Implementing class
public class Messenger {
public Messenger() {
}
public static void sendEmail() {
...
Language emailLanguage = Language.findByUser(user):
...
}
}
I want to separte those layers in:
// Entity Class
public final class Language {
private final Long id;
private final String code;
private final String description;
//Constructor
public Language() {
}
//getters and setters
public String getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
...
}
// Business Class
public final class LanguageImpl {
public LanguageImpl() {
}
public static Language findByUser(User user) {
Language language;
...implementation to find user language...
return language;
}
....
}
Provide minimal changes to implementation classes, preferable no changes. Otherwise a lot of work will come because of the references all over the code-base.
// Implementing class
public class Messenger {
public Messenger() {
}
public static void sendEmail() {
...
Language emailLanguage = Language.findByUser(user);
...
}
}
How do I work through this refactoring?
How should I rename my classes?
Any thoughts would be very helpful! Thanks!
This is my solution. Please review and accept this if it looks good. Thanks!
The mixed business-entity class is re-used as a wrapper class. This makes it possible to re-use this in all implementing classes where no changes are needed.
public final class Language Extends LanguageImpl{
private final LanguageEntity languageEntity;
//Constructor
public Language(LanguageEntity le) {
languageEntity = le;
}
//Wrapper method
public static Language findByUser(User user) {
LanguageEntity le = findEntityByUser(user);
Language language = new Language(le);
return language;
}
....
}
A new Entity class is created (LanguageEntity) in a new package. This avoids package and naming conflicts with the original mixed class (Language). All entity fields and methods from the mixed class are moved here.
package com.test.entity;
public final class LanguageEntity {
private final Long id;
private final String code;
private final String description;
//Constructor
public LanguageEntity() { }
//getters and setters
public String getId() { return this.id; }
public void setId(Long id) { this.id = id; }
...
}
A new business class is created (LanguageImpl) in a new package. All business methods are moved here. The original mixed class will extend this new business class.
package com.test.impl
public final class LanguageImpl {
//Constructor
public LanguageImpl() { }
//Business is a part of this class
public static LanguageEntity findEntityByUser(User user) {
LanguageEntity language;
...implementation to find user language...
return language;
}
....
}
This is an implementing class that does not need changes. Hundreds of implementation locations remain unchanged, which saves a lot of work. Hurray!
public class Messenger {
public Messenger() { }
public static void sendEmail() {
...
Language emailLanguage = Language.findByUser(user):
...
}
}
And for future development, the new combination LanguageEntity and LanguageImpl will be used. The original Language will be deprecated.
Please leave comments on this solution. Other solutions are more than welcome!
I'm investigating Neo4j and have a question with regards to object eager/lazy loading. Lets say I have class Trolley with has Set<Item> (with getters/setters). If I do the following:
Trolley t = new Trolley(...); // create empty trolley
t.addItem(f); // add one item to the trolley
t.persist(); // persist the object
I then later find the trolley based on the nodeId:
repo.findOne(xxx); // returns the trolley successfully
When I do something like:
trolley.getItems().size()
this is empty. I guess this is the intended behaviour. Is there any mechanism similar to JPA where is the session/tx is open to load the collection dynamically.
Code:
#NodeEntity
public class Trolley
{
#Indexed
private String name;
#RelatedTo
private Set<Item> items;
public Trolley(){}
public Trolley(String name)
{
this.name = name;
}
public void addItem(Item item)
{
this.items.add(item);
}
public Set<Item> getItems()
{
return items;
}
}
#NodeEntity
public class Item
{
private String name;
public Item(){}
public Item(String name)
{
this.name = name;
}
public String getName()
{
return name;
}
}
#Test
public void trolleyWithItemPersist()
{
Trolley trolley = new Trolley("trolley1").persist();
// Persisting - however I would've expected a cascade to
// occur when adding to the collection.
Item item = new Item("item1").persist();
// now add to the trolley
trolley.addItem(item);
// persist
trolley.persist();
// Now use repo to get trolley
Trolley loadedTrolley = trolleyRepository.findOne(trolley.getNodeId());
// should have one item
assertEquals(1, loadedTrolley.getItems().size());
}
Afaik, in Spring Data Jpa, to populate an lazy loaded field you need to annotate the method which call the findOne(xxx) with
#Transactional
from (org.springframework.transaction.annotation.Transactional)
Maybe it works also with neo4j...
I'm not really an skilled developper on Spring Data but this is the only way I know to retrieve lazy loaded fields. If someone has a better solution, feel free to write it!
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