Many to many with Aurelius

BIZ TMS Aurelius
1
I have not located at the user manual for Aurelius examples relationship many to many.
Does anyone have this documentation or something?
Preferably it is bidirectional
2

You should create an intermediate class that represents the Many-to-many relationship (since a many-to-many is just two one-to-many relationships anyway), for example:


TStudentRoom = class
  FStudent: TStudent;
  FRoom: TRoom;


3

So that would for example mean:


TStudent=class
    [ManyValuedAssociation([], CascadeTypeAll, 'fStudent')] 
    property StudentRoom: TList<TStudentRoom> read fStudentRoom write fStudentRoom ;
end;

TClass=class
    [ManyValuedAssociation([], CascadeTypeAll, 'fClass')] 
    property StudentRoom: TList<TStudentRoom> read fStudentRoom write fStudentRoom ;
end;

TStudentRoom=class
    [Association([TAssociationProp.Lazy], [])]
    [JoinColumn('ID_STUDENT', [])]
    fStudent: Proxy<TStudent>;

    [Association([TAssociationProp.Lazy], [])]
    [JoinColumn('ID_CLASS', [])]
    fClass: Proxy<TClass>;
end;


One would ideally want some behaviour like:

TStudent=class
    property Rooms: TList<TRoom> read GetRooms write SetRooms;
end;

TClass=class
    property Students: TList<TSTudent> read GetStudents write SetStudents;
end;

The logic of translating an M:N into two 1:N relations would be taken care of behind-the-scenes.

How would you advise to get this desired behaviour?

4

There is no such automatic behaviour in Aurelius. We preferred to keep the engine simple and light since current approach is not limiting, the suggested approach just behaves as a "wizard", but do not add a new feature, exactly.


5

Hi!

Did I understand it correctly. It's possible with aurelius to build such behaviour.
Wagner you mention it this functionality is already there, are there any plans to build a 'wizard' for
the TMS Data modeler?


greets

6

René, there is no need of such wizard. If there is a table, for example, named "ClassStudent" that relates class and student, such table will be converted to a class TClassStudent and you can use it from Aurelius normally.


7

Hello!

That's clear. But it would be nice as mentioned above is you have for example a class TStucent and a class TRooms and the m-n-Table TStudentRooms.
Then it would be nice to have a property generated in TStudent to get a list of TRooms and in TRooms a property to get a list of TStudents.



greets

     -René

8

You just enable the ManyValuedAssociation (which is also available for 1:n relationships) that will give you a list of TStudentRoom in both Student and TRoom classes and you can get the other side from there.

9

Hello!

You're right. Sorry sometimes I don't see the wood for the trees!


regards

        -René