[ADD] doc: model inheritance stuff

doc/howtos/backend.rst

@@ -615,7 +615,7 @@ The second inheritance mechanism (delegation) allows to link every record of a
 model to a record in a parent model, and provides transparent access to the
 fields of the parent record.
 
-.. image:: backend/inheritance_methods.png
+.. image:: ../images/inheritance_methods.png
     :align: center
 
 .. seealso::

doc/reference/orm.rst

@@ -34,6 +34,8 @@ Model
         * If :attr:`._name` is unset, name of a single model to extend
           in-place
 
+        See :ref:`reference/orm/inheritance`.
+
     .. attribute:: _order
 
         Ordering field when searching without an ordering specified (default:
@@ -140,6 +142,8 @@ Model
     .. automethod:: name_get
     .. automethod:: name_create
 
+    .. _reference/orm/model/automatic:
+
     .. rubric:: Automatic fields
 
     .. attribute:: id
@@ -297,6 +301,110 @@ Relational fields
 .. autoclass:: openerp.fields.Reference
     :show-inheritance:
 
+.. _reference/orm/inheritance:
+
+Inheritance and extension
+=========================
+
+Odoo provides three different mechanisms to extend models in a modular way:
+
+* creating a new model from an existing one, adding new information to the
+  copy but leaving the original module as-is
+* extending models defined in other modules in-place, replacing the previous
+  version
+* delegating some of the model's fields to records it contains
+
+.. image:: ../images/inheritance_methods.png
+    :align: center
+
+Classical inheritance
+---------------------
+
+When using the :attr:`~openerp.models.Model._inherit` and
+:attr:`~openerp.models.Model._name` attributes together, Odoo creates a new
+model using the existing one (provided via
+:attr:`~openerp.models.Model._inherit`) as a base. The new model gets all the
+fields, methods and meta-information (defaults & al) from its base.
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/inheritance.py
+    :language: python
+    :lines: 5-
+
+and using them:
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_inheritance.py
+    :language: python
+    :lines: 8,12,9,19
+
+will yield:
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_inheritance.py
+    :language: text
+    :lines: 15,22
+
+the second model has inherited from the first model's ``check`` method and its
+``name`` field, but overridden the ``call`` method, as when using standard
+:ref:`Python inheritance <python:tut-inheritance>`.
+
+Extension
+---------
+
+When using :attr:`~openerp.models.Model._inherit` but leaving out
+:attr:`~openerp.models.Model._name`, the new model replaces the existing one,
+essentially extending it in-place. This is useful to add new fields or methods
+to existing models (created in other modules), or to customize or reconfigure
+them (e.g. to change their default sort order):
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/extension.py
+    :language: python
+    :lines: 5-
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_extension.py
+    :language: python
+    :lines: 8,13
+
+will yield:
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_extension.py
+    :language: text
+    :lines: 11
+
+.. note:: it will also yield the various :ref:`automatic fields
+          <reference/orm/model/automatic>` unless they've been disabled
+
+Delegation
+----------
+
+The third inheritance mechanism provides more flexibility (it can be altered
+at runtime) but less power: using the :attr:`~openerp.models.Model._inherits`
+a model *delegates* the lookup of any field not found on the current model
+to "children" models. The delegation is performed via
+:class:`~openerp.fields.Reference` fields automatically set up on the parent
+model:
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/delegation.py
+    :language: python
+    :lines: 5-
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_delegation.py
+    :language: python
+    :lines: 9-12,21,26
+
+will result in:
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_delegation.py
+    :language: text
+    :lines: 23,28
+
+and it's possible to write directly on the delegated field:
+
+.. literalinclude:: ../../openerp/addons/test_documentation_examples/tests/test_delegation.py
+    :language: python
+    :lines: 47
+
+.. warning:: when using delegation inheritance, methods are *not* inherited,
+             only fields
+
 .. _reference/orm/domains:
 
 Domains

openerp/addons/test_documentation_examples/__init__.py

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+import inheritance
+import extension
+import delegation

openerp/addons/test_documentation_examples/__openerp__.py

@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*-
+{
+    'name': "Documentation examples test",
+    'description': """
+    Contains pieces of code to be used as technical documentation examples
+    (via the ``literalinclude`` directive) in situations where they can be
+    syntax-checked and tested.
+    """,
+
+    'author': "Odoo",
+    'website': "http://odoo.com",
+
+    'category': 'Tests',
+    'version': '0.1',
+    'data': [
+        'ir.model.access.csv',
+    ],
+}

openerp/addons/test_documentation_examples/delegation.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+
+from openerp import models, fields
+
+class Child0(models.Model):
+    _name = 'delegation.child0'
+
+    field_0 = fields.Integer()
+
+class Child1(models.Model):
+    _name = 'delegation.child1'
+
+    field_1 = fields.Integer()
+
+class Delegating(models.Model):
+    _name = 'delegation.parent'
+
+    _inherits = {
+        'delegation.child0': 'child0_id',
+        'delegation.child1': 'child1_id',
+    }
+
+    child0_id = fields.Many2one('delegation.child0', required=True, ondelete='cascade')
+    child1_id = fields.Many2one('delegation.child1', required=True, ondelete='cascade')

openerp/addons/test_documentation_examples/extension.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+
+from openerp import models, fields
+
+class Extension0(models.Model):
+    _name = 'extension.0'
+
+    name = fields.Char(default="A")
+
+class Extension1(models.Model):
+    _inherit = 'extension.0'
+
+    description = fields.Char(default="Extended")

openerp/addons/test_documentation_examples/inheritance.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+
+from openerp import models, fields
+
+class Inheritance0(models.Model):
+    _name = 'inheritance.0'
+
+    name = fields.Char()
+
+    def call(self):
+        return self.check("model 0")
+
+    def check(self, s):
+        return "This is {} record {}".format(s, self.name)
+
+class Inheritance1(models.Model):
+    _name = 'inheritance.1'
+    _inherit = 'inheritance.0'
+
+    def call(self):
+        return self.check("model 1")

openerp/addons/test_documentation_examples/ir.model.access.csv

@@ -0,0 +1,7 @@
+id,name,model_id:id,group_id:id,perm_read,perm_write,perm_create,perm_unlink
+access_inheritance_0,access_inheritance_0,model_inheritance_0,,1,1,1,1
+access_inheritance_1,access_inheritance_1,model_inheritance_1,,1,1,1,1
+access_extension_0,access_extension_0,model_extension_0,,1,1,1,1
+access_delegation_child0,access_delegation_child0,model_delegation_child0,,1,1,1,1
+access_delegation_child1,access_delegation_child1,model_delegation_child1,,1,1,1,1
+access_delegation_parent,access_delegation_parent,model_delegation_parent,,1,1,1,1

openerp/addons/test_documentation_examples/tests/__init__.py

@@ -0,0 +1,12 @@
+# -*- coding: utf-8 -*-
+
+from . import test_inheritance, test_extension, test_delegation
+
+fast_suite = [
+]
+
+checks = [
+    test_inheritance,
+    test_extension,
+    test_delegation,
+]

openerp/addons/test_documentation_examples/tests/test_delegation.py

@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+from openerp.tests import common
+
+class TestDelegation(common.TransactionCase):
+
+    def setUp(self):
+        super(TestDelegation, self).setUp()
+        env = self.env
+        record = env['delegation.parent'].create({
+            'child0_id': env['delegation.child0'].create({'field_0': 0}).id,
+            'child1_id': env['delegation.child1'].create({'field_1': 1}).id,
+        })
+        self.record = record
+
+    def test_delegating_record(self):
+        env = self.env
+        record = self.record
+
+        # children fields can be looked up on the parent record directly
+        self.assertEqual(
+        record.field_0
+        ,
+        0
+        )
+        self.assertEqual(
+        record.field_1
+        ,
+        1
+        )
+
+    def test_swap_child(self):
+        env = self.env
+        record = self.record
+
+        record.write({
+            'child0_id': env['delegation.child0'].create({'field_0': 42}).id
+        })
+        self.assertEqual(
+        record.field_0
+        ,
+        42
+        )
+
+    def test_write(self):
+        record = self.record
+
+        record.write({'field_1': 4})
+        self.assertEqual(
+        record.field_1
+        ,
+        4
+        )
+        self.assertEqual(
+        record.child1_id.field_1
+        ,
+        4
+        )

openerp/addons/test_documentation_examples/tests/test_extension.py

@@ -0,0 +1,14 @@
+# -*- coding: utf-8 -*-
+from openerp.tests import common
+
+class TestBasicInheritance(common.TransactionCase):
+    def test_extend_fields(self):
+        env = self.env
+
+        record = env['extension.0'].create({})
+
+        self.assertDictContainsSubset(
+        {'name': "A", 'description': "Extended"}
+        ,
+        record.read()[0]
+        )

openerp/addons/test_documentation_examples/tests/test_inheritance.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+from openerp.tests import common
+
+class TestBasicInheritance(common.TransactionCase):
+    def test_inherit_method(self):
+        env = self.env
+
+        a = env['inheritance.0'].create({'name': 'A'})
+        b = env['inheritance.1'].create({'name': 'B'})
+
+        self.assertEqual(
+        a.call()
+            ,
+        """
+        This is model 0 record A
+        """.strip()
+        )
+        self.assertEqual(
+        b.call()
+            ,
+        """
+        This is model 1 record B
+        """.strip()
+        )