Relations Recompute

• Let's add a relation to our demo

public class DemoColumnsCollection : UIControllerBase
{
    public readonly Models.Orders Orders = new Models.Orders();
    public readonly Models.Customers Customers = new Models.Customers();
    public DemoColumnsCollection()
    {
        From = Orders;
        Relations.Add(Customers, Customers.CustomerID.IsEqualTo(Orders.CustomerID));

        Columns.Add(Orders.OrderID);
        Columns.Add(Orders.CustomerID);
        Columns.Add(Orders.OrderDate);
    }
    public void Run()
    {
        Execute();
    }
    protected override void OnLoad()
    {
        View = () => new Views.DemoColumnsCollectionView(this);
    }
} 

Relations will only recompute based on columns that were added before the relation’s first column in the column collection

public class DemoColumnsCollection : UIControllerBase
{
    public readonly Models.Orders Orders = new Models.Orders();
    public readonly Models.Customers Customers = new Models.Customers();
    public DemoColumnsCollection()
    {
        From = Orders;
        Relations.Add(Customers, Customers.CustomerID.IsEqualTo(Orders.CustomerID));

        Columns.Add(Orders.OrderID);
        Columns.Add(Orders.CustomerID);
        Columns.Add(Customers.CustomerID);
        Columns.Add(Orders.OrderDate);
    }
    public void Run()
    {
        Execute();
    }
    protected override void OnLoad()
    {
        View = () => new Views.DemoColumnsCollectionView(this);
    }
} 

• Note that if the Columns.Add of the Customers.CustomerID column is after the call to Columns.Add of the Orders.CustomerID column, the relation to Customers will automatically recompute (refresh) whenever the value of Orders.CustomerID changes
• Note that if the Columns.Add of the Customers.CustomerID column is Before the call to Columns.Add of the Orders.CustomerID column, the relation to Customers will NOT automatically recompute (refresh) whenever the value of Orders.CustomerID changes, it'll only evaluate once when you enter the row.
• Note that you can also use the __RecomputePath property to explore the recompute of a relation. For more information see Columns Recompute

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