I have a class Activity that can have several activities associated with it (List). How can I configure my class with Fluent API to load all other child activities if one parent activity is selected?
Here is my Domain Class for Activity:
public class Activity : ProjectBase
{
private string activityType;
public string ActivityType
{
get { return activityType; }
set { activityType = value; }
}
private string catagory;
public string Catagory
{
get { return catagory; }
set { catagory = value; }
}
private string priority;
public string Priority
{
get { return priority; }
set { priority = value; }
}
public Activity()
:base()
{
}
}
ProjectBase has the List property declared. My database is generated following Table Per Hierarchy and the table for Activity seems generated fine for recursion.
Any suggestion is highly appreciated.
All I had to do was put virtual on the list and it brought all related records:
private List<Activity> activities = new List<Activity>();
public virtual List<Activity> Activities
{
get { return activities; }
set { activities = value; }
}
Thanks for the help people!
Related
I ran into a problem while creating a project. If I use properties (get;set;), the android application crashes at the point of assigning a value to the property.
For example: I created a clean xamarin project to remove the influence of my code.
Property in my class:
public class Item
{
public string Id
{
get { return Id; }
set { Id = value; }
}
}
Property use:
public AboutPage()
{
Item gg = new Item();
gg.Id = "test";
InitializeComponent();
}
App crashes at line:
set { Id = value; }
Error not show.
Error
Help. This is the first time I've seen this. I have downgraded the platform. Used clean projects. What am I doing wrong?
UPD: link to my solution
You could try to change the property like below:
public class Item
{
public string Id { get; set; }
}
or
public class Item
{
private string id;
public string Id
{
get { return id; }
set { id = value; }
}
}
when you impement the INotifyPropertyChanged interface:
public class Item : INotifyPropertyChanged
{
private string id;
public string Id
{
get { return id; }
set { id = value; OnPropertyChanged("Id"); }
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
When you do this:
public string Id
{
get { return Id; }
set { Id = value; }
}
You are essentially creating an infinite loop. This is why your App crashes. You are infinitely calling the setter.
Instead you would either make it an auto property:
public string Id { get; set; }
or add a backing field for the property:
private string _id;
public string Id
{
get => _id;
set => _id = value;
}
My android app is using contacts providers to display all the contacts to the user. I'm using Loaders to load the contacts by following the tutorial/documentation at https://developer.android.com/training/contacts-provider/retrieve-names
But from the link https://developer.android.com/guide/components/loaders, it is mentioned that loaders are deprecated as of Android P.
Loaders have been deprecated as of Android P (API 28). The recommended
option for dealing with loading data while handling the Activity and
Fragment lifecycles is to use a combination of ViewModels and
LiveData. ViewModels survive configuration changes like Loaders but
with less boilerplate. LiveData provides a lifecycle-aware way of
loading data that you can reuse in multiple ViewModels. You can also
combine LiveData using MediatorLiveData, and any observable queries,
such as those from a Room database, can be used to observe changes to
the data. ViewModels and LiveData are also available in situations
where you do not have access to the LoaderManager, such as in a
Service. Using the two in tandem provides an easy way to access the
data your app needs without having to deal with the UI lifecycle. To
learn more about LiveData see the LiveData guide and to learn more
about ViewModels see the ViewModel guide.
So my question is:
1. How can we fetch the contacts using android view Model and live data from contact providers?
2. Can we use Room database for contact providers?
Below you can find the link to the source code where I tried to use the Android View Model and Live data to fetch the contacts from ContactProviders.
https://github.com/deepak786/phonebook-contacts
3. What can be improved in the above source code so that fetching will be faster?
Thanks & Regards
Deepak
Below you can find a very simple solution for loading contacts using MVVM:
https://github.com/NaarGes/Android-Contact-List
Here comes a bit of code in case the link is no longer working.
First, let's create a simple POJO for contacts UserObject.java
public class UserObject {
private String email, name, phone;
public UserObject() {
// EMPTY CONSTRUCTOR FOR FIREBASE REALTIME DATABASE
}
public UserObject(String email, String name, String phone) {
this.email = email;
this.name = name;
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
Now, let's create our repository ContactRepository.java
public class ContactRepository {
private Context context;
private static final String TAG = "debinf ContRepo";
public ContactRepository(Context context) {
this.context = context;
}
public List<UserObject> fetchContacts() {
List<UserObject> contacts = new ArrayList<>();
Cursor cursor = context.getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null);
Log.i(TAG, "fetchContacts: cursor.getCount() is "+cursor.getCount());
if ((cursor != null ? cursor.getCount() : 0) > 0) {
while (cursor.moveToNext()) {
String name = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
String phone = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
UserObject contact = new UserObject("",name, phone);
Log.i(TAG, "fetchContacts: phone is "+phone);
contacts.add(contact);
}
}
if (cursor != null) {
cursor.close();
}
return contacts;
}
}
Next, we create our ContactViewModel.java
public class ContactViewModel extends ViewModel {
private ContactRepository repository;
private MutableLiveData<List<UserObject>> contacts;
public ContactViewModel(Context context) {
repository = new ContactRepository(context);
contacts = new MutableLiveData<>();
}
public MutableLiveData<List<UserObject>> getContacts() {
contacts.setValue(repository.fetchContacts());
return contacts;
}
}
Next, we create a factory for our ViewModel ContactViewModelFactory.java
public class ContactViewModelFactory implements ViewModelProvider.Factory {
private Context context;
public ContactViewModelFactory(Context context) {
this.context = context;
}
#NonNull
#Override
public <T extends ViewModel> T create(#NonNull Class<T> modelClass) {
if (modelClass.isAssignableFrom(ContactViewModel.class)) {
return (T) new ContactViewModel(context);
}
throw new IllegalArgumentException("Unknown ViewModel class");
}
}
Let's not forget to add permission in our AndroidManifest
<uses-permission android:name="android.permission.READ_CONTACTS" />
And finally, we ask for permission in our MainActivity.java
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{Manifest.permission.WRITE_CONTACTS,Manifest.permission.READ_CONTACTS,
Manifest.permission.WRITE_EXTERNAL_STORAGE,Manifest.permission.READ_EXTERNAL_STORAGE}, PERMISSION_REQUEST);
}
and bring our contacts to surface
ContactViewModelFactory factory = new ContactViewModelFactory(this);
viewModel = ViewModelProviders.of(this, factory).get(ContactViewModel.class);
viewModel.getContacts().observe(this, new Observer<List<UserObject>>() {
#Override
public void onChanged(#Nullable List<UserObject> userObjects) {
Log.i(TAG, "ViewModel: userObjects size is "+userObjects.size());
Log.i(TAG, "ViewModel: userObjects size is "+userObjects.get(1).getPhone());
}
});
class ContactsViewModel(private val contentResolver: ContentResolver) : ViewModel()
{
lateinit var contactsList: LiveData<PagedList<Contact>>
fun loadContacts() {
val config = PagedList.Config.Builder()
.setPageSize(20)
.setEnablePlaceholders(false)
.build()
contactsList = LivePagedListBuilder<Int, Contact>(
ContactsDataSourceFactory(contentResolver), config).build()
}
}
class ContactsDataSourceFactory(private val contentResolver: ContentResolver) :
DataSource.Factory<Int, Contact>() {
override fun create(): DataSource<Int, Contact> {
return ContactsDataSource(contentResolver)
}
}
class ContactsDataSource(private val contentResolver: ContentResolver) :
PositionalDataSource<Contact>() {
companion object {
private val PROJECTION = arrayOf(
ContactsContract.Contacts._ID,
ContactsContract.Contacts.LOOKUP_KEY,
ContactsContract.Contacts.DISPLAY_NAME_PRIMARY
)
}
override fun loadInitial(params: LoadInitialParams, callback: LoadInitialCallback<Contact>) {
callback.onResult(getContacts(params.requestedLoadSize, params.requestedStartPosition), 0)
}
override fun loadRange(params: LoadRangeParams, callback: LoadRangeCallback<Contact>) {
callback.onResult(getContacts(params.loadSize, params.startPosition))
}
private fun getContacts(limit: Int, offset: Int): MutableList<Contact> {
val cursor = contentResolver.query(ContactsContract.Contacts.CONTENT_URI,
PROJECTION,
null,
null,
ContactsContract.Contacts.DISPLAY_NAME_PRIMARY +
" ASC LIMIT " + limit + " OFFSET " + offset)
cursor.moveToFirst()
val contacts: MutableList<Contact> = mutableListOf()
while (!cursor.isAfterLast) {
val id = cursor.getLong(cursor.getColumnIndex(PROJECTION[0]))
val lookupKey = cursor.getString(cursor.getColumnIndex(PROJECTION[0]))
val name = cursor.getString(cursor.getColumnIndex(PROJECTION[2]))
contacts.add(Contact(id, lookupKey, name))
cursor.moveToNext()
}
cursor.close()
return contacts
}
}
Please find the full source code here.
I have a Web API where one of the methods in a controller return true or false when validating user id which is a string of numbers. I do no have an actual database yet, so I sort of mocked up the set of values in the repository.
Below is my code:
My repository class:
public class myRepository
{
public myClasses.Employee[] GetAllEmployees()
{
return new myClasses.Employee[]
{
new myClasses.Employee
{
empId="111111",
empFName = "Jane",
empLName="Doe"
},
new myClasses.Employee
{
empId="222222",
empFName = "John",
empLName="Doe"
}
};
}
public bool VerifyEmployeeId(string id)
{
myClasses.Employee[] emp = new myClasses.Employee[]
{
new myClasses.Employee
{
empId="111111",
empFName = "Jane",
empLName="Doe"
},
new myClasses.Employee
{
empId="222222",
empFName = "John",
empLName="Doe"
}
};
for (var i = 0; i <= emp.Length - 1; i++)
{
if (emp[i].empId == id)
return true;
}
return false;
}
}
and my model class:
public class myClasses
{
public class Employee
{
public string empId { get; set; }
public string empFName { get; set; }
public string empLName { get; set; }
}
}
and here is my controller:
public class myClassesController : ApiController
{
private myRepository empRepository;
public myClassesController()
{
this.empRepository = new myRepository();
}
public myClasses.Employee[] GetEmployees()
{
return empRepository.GetAllEmployees();
}
public bool VerifyEmployee(string id)
{
return empRepository.VerifyEmployeeId(string id);
}
}
Now when i compile it I get an error:
} expected
Type or namespace definition, or end-of-file expected
; expected
in line
return empRepository.VerifyEmployeeId(string id);
of my controller.
My question is using boolean the best way to return Success or Failure from Web API method or is there a better way? and also why am I getting this error. I am new to Web API
The compile error is caused by this;
return empRepository.VerifyEmployeeId(string id);
You should rewrite to:
return empRepository.VerifyEmployeeId(id);
You don't have you specify the type of the argument when calling a function.
About returning true or false; if you intend to only check whether the employee is valid or not, I should leave it this way. If you plan to use that employee data more you could rewrite that function so it returns the actual employee itself, and return 404: Not Found when the Employee is not found for instance.
While doing the following simple example, I found the following difficulties
As the title says, I am intending to use the Repository pattern while I am storing data in the Azure table storage.now I have couple of classes, Repository.cs, IRepository.cs, DataContext.cs and the Controller.
During my reading I found some info and been doing as follows.
IRepository.cs
public interface IRepository<T> where T: TableServiceEntity
{
T GetById(int Id);
IQueryable<T> GetAll();
}
and the DataContext.cs
public class DataContext<T>:TableServiceContext where T:TableServiceEntity
{
public DataContext(CloudStorageAccount storageaccount, StorageCredentials credentials)
: base(storageaccount.TableEndpoint.AbsoluteUri, credentials)
{
// _storageAccount = storageaccount;
var storageAccount = CloudStorageAccount.Parse(RoleEnvironment.GetConfigurationSettingValue(KEY_STORAGE));
storageAccount.CreateCloudTableClient().CreateTableIfNotExist(tableName);
}
public IQueryable<T> DeviceTable
{
get { return CreateQuery<T>(tableName); }
}
}
plus some part of the controller(I have already data in the table which I created before)
public class DeviceMeController : Controller
{
private IRepository<Entity>_repository;
public Controller() : this(new Repository<Entity>())
{
}
public Controller(IRepository<Entity> repository)
{
_repository = repository;
}
public ActionResult Index()
{
var List = _repository.GetAll();
return View(deviceList);
}
and the the Implementation of the interface Reposistory.cs, here is where I have an error and got lost somewhere
public class Repository<T>:IRepository<T> where T:TableServiceEntity
{
private DataContext<T> _serviceContext;
// here get tablename as pararameter;
// so the Enities call this function
public Repository()
{
// the same context for multiple tables ?
}
// perhaps it should take the table Name
public void Add(T item)
{
_serviceContext.AddObject(TableName,item);
_serviceContext.SaveChangesWithRetries();
}
public IQueryable<T> GetAll()
{
var results = from c in _serviceContext.Table
select c;
return results;
Error is about the null reference, the debugger shows the variable results is null?
In the end I need to know few things.
what should I do in the Repository.cs constructor? I believe the Datacontext.cs class has to be in a separate class ...
any Hint here
Hy,
first of all I presume you left out some code, because I don't see how you get your context in your repository. But supposing you do set it correctly, (injection?) taking into account the way you desinged your datacontext the repository doesn't need to know the table name because it is set in the following lines of code:
public IQueryable<T> DeviceTable
{
get { return CreateQuery<T>(Constants.DeviceTableName); }
}
So when you create a query based on the IQueryable DeviceTable, the table name is already set.
The thing is I don't see the need for your context class, especially as it can only bring over a single entity type (it is generic and based on an entity).
A basic layout of my Repository for Azure Table Storage is:
public abstract class CloudRepository<TEntity> : ICloudRepository<TEntity>
{
private TableServiceContext _tableServiceContext;
private string _tableName;
public string TableName
{
get { return _tableName ?? ( _tableName = typeof(TEntity).Name.Replace("Entity", string.Empty).ToLower()); }
}
public CloudStorageAccount StorageAccount
{
get
{
return CloudStorageAccount.Parse(RoleEnvironment.GetConfigurationSettingValue("StorageConnectionString"));
}
}
public CloudTableClient TableClient
{
get
{
CloudTableClient cloudTableClient = StorageAccount.CreateCloudTableClient();
cloudTableClient.CreateTableIfNotExist(TableName);
return cloudTableClient;
}
}
public TableServiceContext ServiceContext
{
get
{
return _tableServiceContext ?? (_tableServiceContext = TableClient.GetDataServiceContext());
}
}
public IEnumerable<TEntity> FindAll()
{
return ServiceContext.CreateQuery<TEntity>(TableName).ToList();
}
}
Hope this helps you.
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