Complex rule for XPO class

Question

I want to accomplish a simple rule for an XPO class.

The situation is as : - I have a Vehicle class :

public class Vehicle : BaseObject
{
    public Vehicle(Session session)
        : base(session)
    {
    }
    public override void AfterConstruction()
    {
        base.AfterConstruction();
    }

    //...properties

    [Association, DevExpress.Xpo.Aggregated]
    public XPCollection<MeterEntry> MeterEntries
    {
        get { return GetCollection<MeterEntry>("MeterEntries"); }
    }

}

• And a MeterEntry class :

  public class MeterEntry : BaseObject { public MeterEntry(Session session) : base(session) { } public override void AfterConstruction() { base.AfterConstruction(); }

  private int _MeterValue;
  private DateTime _Date;
  
  public int MeterValue
  {
      get
      {
          return _MeterValue;
      }
  
      set
      {
          SetPropertyValue("MeterValue", ref _MeterValue, value);
      }
  }
  
  public DateTime Date
  {
      get
      {
          return _Date;
      }
  
      set
      {
          SetPropertyValue("Date", ref _Date, value);
      }
  }
  
  [Association]
  public Vehicle Vehicle { get; set; }
  

  }

I tried this Rule:

RuleCriteria("MeterValue >= Vehicle.MeterEntries[Date <=  xxx ].Max(MeterValue)")]

In the xxx I want the value of the current object's Date smtng like : TargetObject.Date but it doesn't work, any ideas ?

Answer 1

You need to use the ^ character.

RuleCriteria("MeterValue >= Vehicle.MeterEntries[Date <= ^.^.Date].Max(MeterValue)")]

See more about Parent Relationship Traversal Operator at: https://documentation.devexpress.com/#CoreLibraries/CustomDocument4928