Using Information from the parent class in the Inner class

• Let's use the Order_Details table in our inner controller

public class ShowOrdersToDemoInnerClasses : UIControllerBase
{
    public readonly Models.Orders Orders = new Models.Orders();
    public readonly NumberColumn Items = new NumberColumn("Items", "2");
    public readonly NumberColumn TotalQuantity = new NumberColumn("Total Quantity", "4");
    public readonly NumberColumn TotalAmount = new NumberColumn("Total Amount", "5C");
    public ShowOrdersToDemoInnerClasses()
    {
        From = Orders;
    }
    public void Run()
    {
        Execute();
    }
    protected override void OnLoad()
    {
        View = () => new Views.ShowOrdersToDemoInnerClassesView(this);
    }
    protected override void OnEnterRow()
    {
        new GetTotals(this).Run();
    }
    class GetTotals : BusinessProcessBase
    {
        readonly Models.Order_Details Order_Details = new Models.Order_Details();
        ShowOrdersToDemoInnerClasses _parent;
        public GetTotals(ShowOrdersToDemoInnerClasses parent)
        {
            _parent = parent;
            From = Order_Details;
        }
        public void Run()
        {
            Execute();
        }
    }
} 

• To Filter the GetTotals inner controller based on the current order in the parent controller we'll add the following line:

public class ShowOrdersToDemoInnerClasses : UIControllerBase
{
    public readonly Models.Orders Orders = new Models.Orders();
    public readonly NumberColumn Items = new NumberColumn("Items", "2");
    public readonly NumberColumn TotalQuantity = new NumberColumn("Total Quantity", "4");
    public readonly NumberColumn TotalAmount = new NumberColumn("Total Amount", "5C");
    public ShowOrdersToDemoInnerClasses()
    {
        From = Orders;
    }
    public void Run()
    {
        Execute();
    }
    protected override void OnLoad()
    {
        View = () => new Views.ShowOrdersToDemoInnerClassesView(this);
    }
    protected override void OnEnterRow()
    {
        new GetTotals(this).Run();
    }
    class GetTotals : BusinessProcessBase
    {
        readonly Models.Order_Details Order_Details = new Models.Order_Details();
        ShowOrdersToDemoInnerClasses _parent;
        public GetTotals(ShowOrdersToDemoInnerClasses parent)
        {
            _parent = parent;
            From = Order_Details;
            Where.Add(Order_Details.OrderID.IsEqualTo(_parent.Orders.OrderID));
        }
        public void Run()
        {
            Execute();
        }
    }
} 

• We use the _parent field, to access the parent controller, and get the current value of the OrderID column in the Orders Entity.
• An inner class can access any of it's parent class fields, including private members - that is what makes it the perfect match for a migrated inner task.
• Now let's update the parent's local columns with the information we gather for each row.

public class ShowOrdersToDemoInnerClasses : UIControllerBase
{
    public readonly Models.Orders Orders = new Models.Orders();
    public readonly NumberColumn Items = new NumberColumn("Items", "2");
    public readonly NumberColumn TotalQuantity = new NumberColumn("Total Quantity", "4");
    public readonly NumberColumn TotalAmount = new NumberColumn("Total Amount", "5C");
    public ShowOrdersToDemoInnerClasses()
    {
        From = Orders;
    }
    public void Run()
    {
        Execute();
    }
    protected override void OnLoad()
    {
        View = () => new Views.ShowOrdersToDemoInnerClassesView(this);
    }
    protected override void OnEnterRow()
    {
        new GetTotals(this).Run();
    }
    class GetTotals : BusinessProcessBase
    {
        readonly Models.Order_Details Order_Details = new Models.Order_Details();
        ShowOrdersToDemoInnerClasses _parent;
        public GetTotals(ShowOrdersToDemoInnerClasses parent)
        {
            _parent = parent;
            From = Order_Details;
            Where.Add(Order_Details.OrderID.IsEqualTo(_parent.Orders.OrderID));
        }
        public void Run()
        {
            _parent.Items.Value = 0;
            _parent.TotalQuantity.Value = 0;
            _parent.TotalAmount.Value = 0;
            Execute();
        }
        protected override void OnLeaveRow()
        {
            _parent.Items.Value++;
            _parent.TotalQuantity.Value += Order_Details.Quantity;
            _parent.TotalAmount.Value += Order_Details.Quantity * Order_Details.UnitPrice;
        }
    }
} 

• Note that inner classes are great and easy to use, but they are used a lot less in .NET than they were used in Magic.
• Many of the subtasks you've written in magic, will be simple methods in .NET
• And in other cases, I would prefer to have a clear and separate controller, that will be easier to reuse than an inner class.

• Exercise Inner Classes

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