I want to create a report with two business objects. Does XAF allow this?

Description:
I have two business objects to show in one report:

C#
[DefaultClassOptions]  
public class DomainObject1 : BaseObject {  
    public DomainObject1(Session session) : base(session) { }  

    private string domainObject1Name;  
    public string DomainObject1Name {  
        get { return domainObject1Name;}  
        set { SetPropertyValue("DomainObject1Name", ref domainObject1Name, value); }  
    }  
}  

[DefaultClassOptions]  
public class DomainObject2 : BaseObject {  
    public DomainObject2(Session session) : base(session) { }  

    private string domainObject2Name;  
    public string DomainObject2Name {  
        get { return domainObject2Name; }  
        set { SetPropertyValue("DomainObject2Name", ref domainObject2Name, value); }  
    }  
 }  

Answer:
Currently, XAF allows this only by adding an additional persistent class that will have associations with the necessary persistent classes.
However, we have a suggestion to implement a more advanced way to show a report for several business objects Reports, XAFCore - Temporary classes for hybrid views and reports.
First of all, you need to create a singleton class that will include associations with two necessary persistent classes, and obtain their XPCollection that you wish to show in your report. The second step is to create an object of the Singleton class. To do this, use the UpdateDatabaseAfterUpdateSchema() method of the Updater unit. Now, you will be able to create a report of the Singleton type and show two business objects in one report.
Modified BOs:

C#
[DefaultClassOptions]  
public class DomainObject1 : BaseObject {  
    public DomainObject1(Session session) : base(session) { }  

    private string domainObject1Name;  
    public string DomainObject1Name {  
        get { return domainObject1Name;}  
        set { SetPropertyValue("DomainObject1Name", ref domainObject1Name, value); }  
    }  

    private Singleton singleObject;  
    [Association("Singleton-DomainObjects1", typeof(DomainObject1))]  
    private Singleton SingleObject {  
        get { return singleObject; }  
        set { SetPropertyValue("SingleObject", ref singleObject, value); }  
    }  
}  

[DefaultClassOptions]  
public class DomainObject2 : BaseObject {  
    public DomainObject2(Session session) : base(session) { }  

    private string domainObject2Name;  
    public string DomainObject2Name {  
        get { return domainObject2Name; }  
        set { SetPropertyValue("DomainObject2Name", ref domainObject2Name, value); }  
    }  

    private Singleton singleObject;  
    [Association("Singleton-DomainObjects2", typeof(DomainObject2))]  
    private Singleton SingleObject {  
        get { return singleObject; }  
        set { SetPropertyValue("SingleObject", ref singleObject, value); }  
    }  
}  

Visual Basic
<DefaultClassOptions()> _  
 Public Class DomainObject1  
    Inherits BaseObject  
    Public Sub New(ByVal session As Session)  
        MyBase.New(session)  
    End Sub  

    Private domainObject1Name_Renamed As String  
    Public Property DomainObject1Name() As String  
        Get  
            Return domainObject1Name_Renamed  
        End Get  
        Set(ByVal value As String)  
            SetPropertyValue("DomainObject1Name", domainObject1Name_Renamed, value)  
        End Set  
    End Property  

    Private singleObject_Renamed As Singleton  
    <Association("Singleton-DomainObjects1", GetType(DomainObject1))> _  
    Private Property SingleObject() As Singleton  
        Get  
            Return singleObject_Renamed  
        End Get  
        Set(ByVal value As Singleton)  
            SetPropertyValue("SingleObject", singleObject_Renamed, value)  
        End Set  
    End Property  
End Class  
<DefaultClassOptions()> _  
Public Class DomainObject2  
    Inherits BaseObject  
    Public Sub New(ByVal session As Session)  
        MyBase.New(session)  
    End Sub  

    Private domainObject2Name_Renamed As String  
    Public Property DomainObject2Name() As String  
        Get  
            Return domainObject2Name_Renamed  
        End Get  
        Set(ByVal value As String)  
            SetPropertyValue("DomainObject2Name", domainObject2Name_Renamed, value)  
        End Set  
    End Property  

    Private singleObject_Renamed As Singleton  
    <Association("Singleton-DomainObjects2", GetType(DomainObject2))> _  
    Private Property SingleObject() As Singleton  
        Get  
            Return singleObject_Renamed  
        End Get  
        Set(ByVal value As Singleton)  
            SetPropertyValue("SingleObject", singleObject_Renamed, value)  
        End Set  
    End Property  
End Class  

The Singleton class must be written in the following manner:

C#
[VisibleInReports(true)]  
public class Singleton : BaseObject {  
    public Singleton(Session session) : base(session) { }  

    public static Singleton GetInstance(Session session) {  
        Singleton result = session.FindObject<Singleton>(null);  
        if ((object.ReferenceEquals(result, null))) {  
            result = new Singleton(session);  
            result.Save();  
        }  
        return result;  
    }  

    [Association("Singleton-DomainObjects1",typeof(DomainObject1))]  
    public XPCollection<DomainObject1> DomainObjects1 {  
        get {  
            XPCollection<DomainObject1> coll = new XPCollection<DomainObject1>(Session);  
            return coll;  
        }  
    }  

    [Association("Singleton-DomainObjects2", typeof(DomainObject2))]  
    public XPCollection<DomainObject2> DomainObjects2 {  
        get {  
            XPCollection<DomainObject2> coll = new XPCollection<DomainObject2>(Session);  
            return coll;  
        }  
    }  
}  

Visual Basic
<VisibleInReports(True)> _  
Public Class Singleton  
    Inherits BaseObject  
    Public Sub New(ByVal session As Session)  
        MyBase.New(session)  
    End Sub  

    Public Shared Function GetInstance(ByVal session As Session) As Singleton  
        Dim result As Singleton = session.FindObject(Of Singleton)(Nothing)  
        If (Object.ReferenceEquals(result, Nothing)) Then  
            result = New Singleton(session)  
            result.Save()  
        End If  
        Return result  
    End Function  

    <Association("Singleton-DomainObjects1", GetType(DomainObject1))> _  
    Public ReadOnly Property DomainObjects1() As XPCollection(Of DomainObject1)  
        Get  
            Dim coll As XPCollection(Of DomainObject1) = New XPCollection(Of DomainObject1)(Session)  
            Return coll  
        End Get  
    End Property  

    <Association("Singleton-DomainObjects2", GetType(DomainObject2))> _  
    Public ReadOnly Property DomainObjects2() As XPCollection(Of DomainObject2)  
        Get  
            Dim coll As XPCollection(Of DomainObject2) = New XPCollection(Of DomainObject2)(Session)  
            Return coll  
        End Get  
    End Property  
End Class  

You need to create an instance of the singleton class in the UpdateDatabaseAfterUpdateSchema method:

C#
public class Updater : ModuleUpdater {  
    public Updater(Session session, Version currentDBVersion) : base(session, currentDBVersion) { }  
    public override void UpdateDatabaseAfterUpdateSchema() {  
        base.UpdateDatabaseAfterUpdateSchema();  
        Singleton.GetInstance(Session);  
    }  
}  

Visual Basic
Public Class Updater  
    Inherits ModuleUpdater  
    Public Sub New(ByVal session As Session, ByVal currentDBVersion As Version)  
        MyBase.New(session, currentDBVersion)  
    End Sub  
    Public Overrides Sub UpdateDatabaseAfterUpdateSchema()  
        MyBase.UpdateDatabaseAfterUpdateSchema()  
        Singleton.GetInstance(Session)  
    End Sub  
End Class