Change in property values of children and grandchildren objects (related to 3182)

[Chicagoan2016]

This is related to #3182

We have a hierarchy of objects as follows
Order - Parent
LineItem - Child
LineItemDetail - Grand child.

In Order and LineItem objects, we have business rules that calculate the 'GrandCost' and TotalCost' respectively.

In LineItemDetail we have a property 'Cost' which is calculated by a business rule (inside LineItemDetail). In LineItem (Which is parent of LineItemDetail) 'TotalCost' is calculated from 'Cost' properties of LineItemDetails (it's children).

Since the Cost property is calculated inside business rule. It's not triggering the Rules Engine and the business rule for TotalCost in LineItem is not getting called.
Should we override the 'Save' methods in Order and LineItem objects and explicitly call the business rules for 'GrandTotal' and 'TotalCost'?

Kind Regards

[Chicagoan2016]

Well, overriding the Save didn't work : ).
Since 'Save' in top most object (Oder) is called first and at the time, the LineItem's TotalCost is not calculated yet : )

[kcabral817]

What I did was:

 protected override void PropertyHasChanged(IPropertyInfo property)
        {
            base.PropertyHasChanged(property);
            BusinessRules.CheckRules();
            BusinessRules.CheckObjectRules();
        }

        protected override void OnChildChanged(ChildChangedEventArgs e)
        {
            base.OnChildChanged(e);
            BusinessRules.CheckRules();
        }

I put this in the business class and do my magic there. When the child or a property changes, it invokes the business rules to do the calculations. I do this in my purchase order classes when calculating the total line items. I think Rocky answered a similar question last week and has a method called something like "OnChildChange" but I can't remember.

[Chicagoan2016]

@kcabral817 Finally got a chance to work on this. I put in both methods as you recommended but still no luck. My understanding is, since 'Cost' is set by a business rule, it's not triggering business rule engine.

[rockfordlhotka]

This should work:

// .NET 6 console app
// NuGet reference to Csla v6

using Csla;
using Csla.Configuration;
using Csla.Core;
using Csla.Rules;
using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddCsla();
var provider = services.BuildServiceProvider();
var ApplicationContext = provider.GetRequiredService<ApplicationContext>();

var portal = ApplicationContext.GetRequiredService<IDataPortal<Order>>();
var order = portal.Create();
var details = order.LineItems[0].LineItemDetails[0];
details.Quantity = 10;
details.Price = 4.2;
Console.WriteLine($"Detail: {details.Cost}");
Console.WriteLine($"Total:  {order.LineItems[0].TotalCost}");
Console.WriteLine($"Grand:  {order.TotalCost}");


// ==============================================================================

[Serializable]
public class Order : BusinessBase<Order>
{
  public static readonly PropertyInfo<int> IdProperty = RegisterProperty<int>(nameof(Id));
  public int Id
  {
    get => GetProperty(IdProperty);
    set => SetProperty(IdProperty, value);
  }

  public static readonly PropertyInfo<LineItemList> LineItemsProperty = RegisterProperty<LineItemList>(nameof(LineItems));
  public LineItemList LineItems
  {
    get => GetProperty(LineItemsProperty);
    private set => LoadProperty(LineItemsProperty, value);
  }

  public static readonly PropertyInfo<double> TotalCostProperty = RegisterProperty<double>(nameof(TotalCost));
  public double TotalCost
  {
    get => GetProperty(TotalCostProperty);
    private set => LoadProperty(TotalCostProperty, value);
  }
  protected override void OnChildChanged(ChildChangedEventArgs e)
  {
    base.OnChildChanged(e);
    if (e.PropertyChangedArgs?.PropertyName == "TotalCost")
    {
      BusinessRules.CheckRules(TotalCostProperty);
    }
  }

  protected override void AddBusinessRules()
  {
    base.AddBusinessRules();
    BusinessRules.AddRule(new CalcTotalCost() { PrimaryProperty = TotalCostProperty });
  }

  [Create]
  private void Create()
  {
    LineItems = ApplicationContext.GetRequiredService<IChildDataPortal<LineItemList>>().CreateChild();
  }

  public class CalcTotalCost : BusinessRule
  {
    protected override void Execute(IRuleContext context)
    {
      var target = (Order)context.Target;
      double total = 0;
      foreach (var detail in target.LineItems)
      {
        total += detail.TotalCost;
      }
      context.AddOutValue(total);
    }
  }
}

[Serializable]
public class LineItem : BusinessBase<LineItem>
{
  public static readonly PropertyInfo<int> IdProperty = RegisterProperty<int>(nameof(Id));
  public int Id
  {
    get => GetProperty(IdProperty);
    set => SetProperty(IdProperty, value);
  }

  public static readonly PropertyInfo<LineItemDetailList> LineItemDetailsProperty = RegisterProperty<LineItemDetailList>(nameof(LineItemDetails));
  public LineItemDetailList LineItemDetails
  {
    get => GetProperty(LineItemDetailsProperty);
    private set => LoadProperty(LineItemDetailsProperty, value);
  }

  public static readonly PropertyInfo<double> TotalCostProperty = RegisterProperty<double>(nameof(TotalCost));
  public double TotalCost
  {
    get => GetProperty(TotalCostProperty);
    private set => LoadProperty(TotalCostProperty, value);
  }
  protected override void OnChildChanged(ChildChangedEventArgs e)
  {
    base.OnChildChanged(e);
    if (e.PropertyChangedArgs?.PropertyName == "Quantity" || e.PropertyChangedArgs?.PropertyName == "Price")
    {
      BusinessRules.CheckRules(TotalCostProperty);
      OnPropertyChanged(TotalCostProperty);
    }
  }

  protected override void AddBusinessRules()
  {
    base.AddBusinessRules();
    BusinessRules.AddRule(new CalcTotalCost() { PrimaryProperty = TotalCostProperty });
  }

  [CreateChild]
  private void Create()
  {
    LineItemDetails = ApplicationContext.GetRequiredService<IChildDataPortal<LineItemDetailList>>().CreateChild();
  }

  public class CalcTotalCost : BusinessRule
  {
    protected override void Execute(IRuleContext context)
    {
      var target = (LineItem)context.Target;
      double total = 0;
      foreach (var detail in target.LineItemDetails)
      {
        total += detail.Cost;
      }
      context.AddOutValue(total);
    }
  }
}

[Serializable]
public class LineItemDetail : BusinessBase<LineItemDetail>
{
  public static readonly PropertyInfo<int> IdProperty = RegisterProperty<int>(nameof(Id));
  public int Id
  {
    get => GetProperty(IdProperty);
    set => SetProperty(IdProperty, value);
  }

  public static readonly PropertyInfo<int> QuantityProperty = RegisterProperty<int>(nameof(Quantity));
  public int Quantity
  {
    get => GetProperty(QuantityProperty);
    set => SetProperty(QuantityProperty, value);
  }

  public static readonly PropertyInfo<double> PriceProperty = RegisterProperty<double>(nameof(Price));
  public double Price
  {
    get => GetProperty(PriceProperty);
    set => SetProperty(PriceProperty, value);
  }

  public static readonly PropertyInfo<double> CostProperty = RegisterProperty<double>(nameof(Cost));
  public double Cost
  {
    get => GetProperty(CostProperty);
    private set => LoadProperty(CostProperty, value);
  }

  protected override void AddBusinessRules()
  {
    base.AddBusinessRules();
    BusinessRules.AddRule(new CostRule(QuantityProperty, PriceProperty, CostProperty));
    BusinessRules.AddRule(new Csla.Rules.CommonRules.Dependency(PriceProperty, QuantityProperty));
  }

  [CreateChild]
  private void Create()
  { }
}

public class CostRule : BusinessRule
{
  public CostRule(IPropertyInfo quantityProperty, IPropertyInfo priceProperty, IPropertyInfo costProperty)
  {
    PrimaryProperty = quantityProperty;
    InputProperties.Add(quantityProperty);
    InputProperties.Add(priceProperty);
    AffectedProperties.Add(costProperty);
  }

  protected override void Execute(IRuleContext context)
  {
    var quantity = (int)context.InputPropertyValues[InputProperties[0]];
    var price = (double)context.InputPropertyValues[InputProperties[1]];
    var cost = quantity * price;
    context.AddOutValue(AffectedProperties[1], cost);
  }
}

[Serializable]
public class LineItemList : BusinessListBase<LineItemList, LineItem>
{
  [CreateChild]
  private void Create()
  {
    Add(ApplicationContext.GetRequiredService<IChildDataPortal<LineItem>>().CreateChild());
  }
}

[Serializable]
public class LineItemDetailList : BusinessListBase<LineItemDetailList, LineItemDetail>
{
  [CreateChild]
  private void Create()
  {
    Add(ApplicationContext.GetRequiredService<IChildDataPortal<LineItemDetail>>().CreateChild());
  }
}

[Chicagoan2016]

Something interesting is going on here, Let me recap the object graph
Order - parent
LineItems -- child collection
LineItem - Individual child object
LineItemDetails - grand child collections
LineItemDetail - individual grand child object

LineItemDetail has cost property which is calculated by a business rule. LineItem has TotalCost which is sum of cost(s) of LineItemDetails while Order
has GrandCost which is sum of TotalCost(s) of LineItems.

I added the following code to Order class

   protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e)
        {
            if (e.ChildObject is LineItems)
            {
                BusinessRules.CheckRules(LineItemsProperty);
                OnPropertyChanged(LineItemsProperty);
            }
            base.OnChildChanged(e);
        }

and  the following to LineItem

	    protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e)
        {
            if (e.ChildObject is LineItemDetails)
            {
                BusinessRules.CheckRules(LineItemDetailsProperty);
                OnPropertyChanged(LineItemDetailsProperty);
            }
            base.OnChildChanged(e);
        }

This didn't work 

But when I added the following line after base.OnChildChanged
    BusinessRules.CheckRules();
it's working :)

[Chicagoan2016]

@rockfordlhotka Thank you Sir, I am going to try your solution.

[Chicagoan2016]

@rockfordlhotka I guess I found the culprit code. In our case we have implemented the AddItem method on LineItemDetails collection and we pass both quantity and price as arguments to AddItem.
The thing I don't understand is, after AddItem we do set other properties on LineItemDetail and that's not detected by the code (below) in LineItem.

    protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e)
        {
            if (e.ChildObject is LineItemDetails)
            {
                BusinessRules.CheckRules(LineItemDetailsProperty);
                OnPropertyChanged(LineItemDetailsProperty);
            }
            base.OnChildChanged(e);
        }

[Chicagoan2016]

@rockfordlhotka putting a breakpoint showed that e.ChildObject is LineItemDetail (the individual object and not the collection) in the code below

        protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e)
        {
            if (e.ChildObject is LineItemDetails)
            {
                BusinessRules.CheckRules(TotalCostProperty);
                OnPropertyChanged(TotalCostProperty);
            }
            base.OnChildChanged(e);
        }

If I understand correctly, since I wasn't adding or removing items (individual objects) from LineItemDetails the code wasn't working, instead, I was changing the state of individual object(s) so when I changed

if (e.ChildObject is LineItemDetail) //To individual child object

the code started working.

[Chicagoan2016]

@rockfordlhotka
To be on the safe side I don't miss adding or removing items to the collection, I included an additional check, so it's like this now

   protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e)
        {
            if (e.ChildObject is LineItemDetail || e.ChildObject is LineItemDetails)
            {
                BusinessRules.CheckRules(TotalCostProperty);
                OnPropertyChanged(TotalCostProperty);
            }
            base.OnChildChanged(e);
        }