在ASP.NET MVC中创建包含父类属性的ViewModel

Question

I am trying to understand how to create a ViewModel that contains properties from a class in my domain model as well as properties from a parent class.

I want to have a ViewModel that contains all of the LoadSession properties and the TradingPartner Description , but I'm not sure how to map this all up in the ViewModel. Any help or advice would be greatly appreciated.

This is my main class I'm accessing named LoadSession :

public partial class LoadSession
{
    public LoadSession()
    {
        this.AcceptedTransactions = new HashSet<AcceptedTransaction>();
        this.RejectedTransactions = new HashSet<RejectedTransaction>();
    }

    public int LoadSessionId { get; set; }
    public int Import { get; set; }
    public string FilePath { get; set; }
    public string TradingPartnerBatchId { get; set; }
    public System.DateTime Started { get; set; }
    public int RecordsOnFile { get; set; }
    public int RecordsAfterGroupFilter { get; set; }
    public int RecordsAccepted { get; set; }
    public int RecordsRejected { get; set; }
    public System.DateTime Completed { get; set; }
    public bool Success { get; set; }
    public Nullable<int> Extract { get; set; }

    public virtual ICollection<AcceptedTransaction> AcceptedTransactions { get; set; }
    public virtual Extract Extract1 { get; set; }
    public virtual Import Import1 { get; set; }
    public virtual ICollection<RejectedTransaction> RejectedTransactions { get; set; }
}

The Import property is a foreign key for this Import class (Import = ImportId):

public partial class Import
{
    public Import()
    {
        this.GroupPlans = new HashSet<GroupPlan>();
        this.ImportGroups = new HashSet<ImportGroup>();
        this.MatchingGroups = new HashSet<MatchingGroup>();
        this.LoadSessions = new HashSet<LoadSession>();
    }

    public int ImportId { get; set; }
    public string Description { get; set; }
    public int Format { get; set; }
    public int Interface { get; set; }

    public virtual Interface Interface1 { get; set; }
    public virtual Format Format1 { get; set; }
    public virtual ICollection<GroupPlan> GroupPlans { get; set; }
    public virtual ICollection<ImportGroup> ImportGroups { get; set; }
    public virtual ICollection<MatchingGroup> MatchingGroups { get; set; }
    public virtual ICollection<LoadSession> LoadSessions { get; set; }
}

The Interface property is a foreign key for this Interface class (Interface = InterfaceId):

public partial class Interface
{
    public Interface()
    {
        this.Extracts1 = new HashSet<Extracts1>();
        this.Imports = new HashSet<Import>();
    }

    public int InterfaceId { get; set; }
    public string Description { get; set; }
    public int TradingPartner { get; set; }

    public virtual ICollection<Extracts1> Extracts1 { get; set; }
    public virtual ICollection<Import> Imports { get; set; }
    public virtual TradingPartner TradingPartner1 { get; set; }
}

And the TradingPartner property is a foreign key for this TradingPartner class (TradingPartner = TradingPartnerId):

public partial class TradingPartner
{
    public TradingPartner()
    {
        this.Interfaces = new HashSet<Interface>();
    }

    public int TradingPartnerId { get; set; }
    public string Description { get; set; }

    public virtual ICollection<Interface> Interfaces { get; set; }
}

Answer 1

Well, those are all your domain objects right...

Create a repository that takes your Domain object and transforms then to into a view model with the properties you need...

I am not sure what it is your view needs, but from your statements you state that you want properties of Load session + TradingPartner.Description So create something like this...

public class LoadSessionTradingPrtNrVM
{
    public LoadSession()
    {
        this.AcceptedTransactions = new HashSet<AcceptedTransaction>();
        this.RejectedTransactions = new HashSet<RejectedTransaction>();
    }

    public int LoadSessionId { get; set; }
    public int Import { get; set; }
    public string FilePath { get; set; }
    public string TradingPartnerBatchId { get; set; }
    public System.DateTime Started { get; set; }
    public int RecordsOnFile { get; set; }
    public int RecordsAfterGroupFilter { get; set; }
    public int RecordsAccepted { get; set; }
    public int RecordsRejected { get; set; }
    public System.DateTime Completed { get; set; }
    public bool Success { get; set; }
    public Nullable<int> Extract { get; set; }
    public string Description { get; set; }

    public virtual ICollection<AcceptedTransaction> AcceptedTransactions { get; set; }
    public virtual Extract Extract1 { get; set; }
    public virtual Import Import1 { get; set; }
    public virtual ICollection<RejectedTransaction> RejectedTransactions { get; set; }
}

To get from Domain models to ViewModels you would use a repository, or some other pattern that takes what you get from your database and transforms it into what you need for your views.

This is kind of raw, but the theory should hold...

public class DataRepository {

      LoadSessionTradingPrtNrVM TransformToVM(LoadSession inputA, TradingPartner inputB){
            LoadSessionTradingPrtNrVM newOBJ = new LoadSessioNTradingPrtNrVM();
            newOBJ.LoadSessionId = ipnutA.LoadSessionID;
            newOBJ.Import = inputA.Import
            //Here is the property from your Transform object
            newOBJ.Description = inputB.Description
            //...  Continue to transform one object into the other... 
            //You could add as many members from as many different objects as you want into 
            //Your view model following that pattern. 
      }
}

I didn't have a chance to run this through a C# compiler, but you should get the general idea. I am sure there is a more elegant pattern that can accomplish the same thing. But this is a decent solution off the top of my head.

Answer 2

Another option is to include the domain model objects as properties in the view model. For example:

// View model.
public class UserViewModel
{
    public AddressModel Address;  // Assuming "AddressModel" is a doman model.
    public string FirstName;
    public string LastName;
}

And in the view you can access the properties as:

@Model.Address.AddressLine1
@Model.Address.City
// etc...

The Html helpers handle this just fine, but if you are manually naming inputs in your view don't forget to adjust those names to match.