add fields 'campus' and 'party_related'

__init__.py

@@ -1,9 +1,10 @@
 from trytond.pool import Pool
-from . import (party, product, purchase, sale,
+from . import (address, party, product, purchase, sale,
                equipment, subscription, measurements)
 
 def register():
     Pool.register(
+        address.Address,
         party.Party,
         product.Template,
         product.Product,

address.py

@@ -1,9 +1,11 @@
 from trytond.pool import PoolMeta
 from trytond.model import fields
+from trytond.pyson import Eval, If
 
 
 class Address(metaclass=PoolMeta):
     __name__ = 'party.address'
 
     campus = fields.Boolean("Campus")
-    party_related = fields.One2Many('party.party', "Party related")
+    party_related = fields.Many2One('party.party', "Party Related",
+                                    states ={ 'invisible': (Eval("campus"))})

tryton.cfg

@@ -12,6 +12,7 @@ depends:
     country
     sale_subscription
 xml:
+    address.xml
     party.xml
     product.xml
     measurements.xml

view/address_form.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
+this repository contains the full copyright notices and license terms. -->
+<data>
+    <xpath expr="/form" position="inside">
+    	<label name="party_related"/>
+	<field name="party_related"/>
+    </xpath>
+    <xpath expr="/form/group[@id='checkboxes']" position="inside">
+	<label name="campus"/>
+	<field name="campus"/>
+    </xpath>
+</data>