[Modeling-cvs] ProjectModeling/Modeling/doc/UserGuide DefiningaModel.tex,1.36,1.37

[<sbi...@us...>]

Update of /cvsroot/modeling/ProjectModeling/Modeling/doc/UserGuide
In directory sc8-pr-cvs1:/tmp/cvs-serv18199/Modeling/doc/UserGuide

Modified Files:
	DefiningaModel.tex 
Log Message:
Modeling many-to-many relationships

Index: DefiningaModel.tex
===================================================================
RCS file: /cvsroot/modeling/ProjectModeling/Modeling/doc/UserGuide/DefiningaModel.tex,v
retrieving revision 1.36
retrieving revision 1.37
diff -C2 -d -r1.36 -r1.37
*** DefiningaModel.tex	31 Aug 2003 17:22:50 -0000	1.36
--- DefiningaModel.tex	31 Aug 2003 17:32:25 -0000	1.37
***************
*** 1999,2009 ****
--- 1999,2079 ----
  \end{verbatim}
  
+ We just defined a new entity, \class{PersonAddress}, and two associations
+ modeling the relationships between the correlation table and the correlated
+ ones.
  
+ Last, we'll need to add some code in classes \class{Person} and \code{Address}
+ to directly manipulate the many-to-many relationships. Since relating an
+ object to an other one is just a matter of adding a object/a row to the
+ correlation table, the code is pretty straightforward.
+ 
+ In \class{Person}, you'll add the following methods:
+ \begin{verbatim}
+   # Relationship: addresses
+   def getAddresses(self):
+     return self.valueForKeyPath('personAddresses.address')
+     
+   def addToAddresses(self, address):
+     if address in self.getAddresses():
+       return
+     from PersonAddress import PersonAddress
+     _pa=PersonAddress()  # Create an object in the correlation table
+     self.editingContext().insert(_pa)
+     self.addToPersonAddresses(_pa)
+     _pa.setPerson(self)
+     _pa.setAddress(address)
+     address.addToPersonAddresses(_pa)
+ 
+   def removeFromAddresses(self, address):
+     _pa=[pa for pa in self.getPersonAddresses() if address == pa.getAddress()]
+     if not _pa:
+       raise ValueError, 'Cannot find address'
+     # Here we simply need to remove the corresponding object in the
+     # correlation table
+     _pa=_pa[0]
+     self.removeFromPersonAddresses(_pa)
+     _pa.getAddress().removeFromPersonAddresses(_pa)
+     _pa.setAddress(None)
+     _pa.setPerson(None)
+     self.editingContext().delete(_pa)
+ \end{verbatim}
  
+ And you'll add the equivalent methods in \class{Address}:
+ \begin{verbatim}
+   # Relationship: persons
+   def getPersons(self):
+     return self.valueForKeyPath('personAddresses.person')
+     
+   def addToPersons(self, person):
+     if person in self.getPersons():
+       return
+     from PersonAddress import PersonAddress
+     _pa=PersonAddress()  # Create an object in the correlation table
+     self.editingContext().insert(_pa)
+     self.addToPersonAddresses(_pa)
+     _pa.setPerson(person)
+     _pa.setAddress(self)
+     person.addToPersonAddresses(_pa)
  
+   def removeFromPersons(self, person):
+     _pa=[pa for pa in self.getPersonAddresses() if person == pa.getPerson()]
+     if not _pa:
+       raise ValueError, 'Cannot find person'
+     # Here we simply need to remove the corresponding object in the
+     # correlation table
+     _pa=_pa[0]
+     self.removeFromPersonAddresses(_pa)
+     _pa.getPerson().removeFromPersonAddresses(_pa)
+     _pa.setAddress(None)
+     _pa.setPerson(None)
+     self.editingContext().delete(_pa)
+ \end{verbatim}
  \makeatletter
  \def\verbatim@font{\normalsize\ttfamily}
  \makeatother
  
+ Now we can normally call e.g. \method{getAddresses} or \method{addToAddresses}
+ on a \class{Person} object, passing a \class{Address} object, without caring
+ about the details anymore.
  
  \subsection{How to model inheritance \label{design-inheritance}}