[REF] Merge a refactoring of the workflow (lp:~openerp-dev/openobject-server/trunk-refactor-workflow-stw)

bzr revid: stw@openerp.com-20140109095017-xakyapswp8b5eed5

openerp/workflow/__init__.py

@@ -2,7 +2,7 @@
 ##############################################################################
 #
 #    OpenERP, Open Source Management Solution
-#    Copyright (C) 2004-2009 Tiny SPRL (<http://tiny.be>).
+#    Copyright (C) 2004-2014 Tiny SPRL (<http://tiny.be>).
 #
 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU Affero General Public License as
@@ -19,12 +19,13 @@
 #
 ##############################################################################
 
-import instance
+from openerp.workflow.service import WorkflowService
 
-wkf_on_create_cache = {}
+# The new API is in openerp.workflow.workflow_service
+# OLD API of the Workflow
 
 def clear_cache(cr, uid):
-    wkf_on_create_cache[cr.dbname]={}
+    WorkflowService.clear_cache(cr.dbname)
 
 def trg_write(uid, res_type, res_id, cr):
     """
@@ -36,10 +37,7 @@ def trg_write(uid, res_type, res_id, cr):
     :param res_id: the model instance id the workflow belongs to
     :param cr: a database cursor
     """
-    ident = (uid,res_type,res_id)
+    return WorkflowService.new(cr, uid, res_type, res_id).write()
-    cr.execute('select id from wkf_instance where res_id=%s and res_type=%s and state=%s', (res_id or None,res_type or None, 'active'))
-    for (id,) in cr.fetchall():
-        instance.update(cr, id, ident)
 
 def trg_trigger(uid, res_type, res_id, cr):
     """
@@ -52,12 +50,7 @@ def trg_trigger(uid, res_type, res_id, cr):
     :param res_id: the model instance id the workflow belongs to
     :param cr: a database cursor
     """
-    cr.execute('select instance_id from wkf_triggers where res_id=%s and model=%s', (res_id,res_type))
+    return WorkflowService.new(cr, uid, res_type, res_id).trigger()
-    res = cr.fetchall()
-    for (instance_id,) in res:
-        cr.execute('select %s,res_type,res_id from wkf_instance where id=%s', (uid, instance_id,))
-        ident = cr.fetchone()
-        instance.update(cr, instance_id, ident)
 
 def trg_delete(uid, res_type, res_id, cr):
     """
@@ -67,8 +60,7 @@ def trg_delete(uid, res_type, res_id, cr):
     :param res_id: the model instance id the workflow belongs to
     :param cr: a database cursor
     """
-    ident = (uid,res_type,res_id)
+    return WorkflowService.new(cr, uid, res_type, res_id).delete()
-    instance.delete(cr, ident)
 
 def trg_create(uid, res_type, res_id, cr):
     """
@@ -78,16 +70,7 @@ def trg_create(uid, res_type, res_id, cr):
     :param res_id: the model instance id to own the created worfklow instance
     :param cr: a database cursor
     """
-    ident = (uid,res_type,res_id)
+    return WorkflowService.new(cr, uid, res_type, res_id).create()
-    wkf_on_create_cache.setdefault(cr.dbname, {})
-    if res_type in wkf_on_create_cache[cr.dbname]:
-        wkf_ids = wkf_on_create_cache[cr.dbname][res_type]
-    else:
-        cr.execute('select id from wkf where osv=%s and on_create=True', (res_type,))
-        wkf_ids = cr.fetchall()
-        wkf_on_create_cache[cr.dbname][res_type] = wkf_ids
-    for (wkf_id,) in wkf_ids:
-        instance.create(cr, ident, wkf_id)
 
 def trg_validate(uid, res_type, res_id, signal, cr):
     """
@@ -98,14 +81,8 @@ def trg_validate(uid, res_type, res_id, signal, cr):
     :signal: the signal name to be fired
     :param cr: a database cursor
     """
-    result = False
+    assert isinstance(signal, basestring)
-    ident = (uid,res_type,res_id)
+    return WorkflowService.new(cr, uid, res_type, res_id).validate(signal)
-    # ids of all active workflow instances for a corresponding resource (id, model_nam)
-    cr.execute('select id from wkf_instance where res_id=%s and res_type=%s and state=%s', (res_id, res_type, 'active'))
-    for (id,) in cr.fetchall():
-        res2 = instance.validate(cr, id, ident, signal)
-        result = result or res2
-    return result
 
 def trg_redirect(uid, res_type, res_id, new_rid, cr):
     """
@@ -120,22 +97,7 @@ def trg_redirect(uid, res_type, res_id, new_rid, cr):
     :param new_rid: the model instance id to own the worfklow instance
     :param cr: a database cursor
     """
-    # get ids of wkf instances for the old resource (res_id)
+    assert isinstance(new_rid, (long, int))
-#CHECKME: shouldn't we get only active instances?
+    return WorkflowService.new(cr, uid, res_type, res_id).redirect(new_rid)
-    cr.execute('select id, wkf_id from wkf_instance where res_id=%s and res_type=%s', (res_id, res_type))
-    for old_inst_id, wkf_id in cr.fetchall():
-        # first active instance for new resource (new_rid), using same wkf
-        cr.execute(
-            'SELECT id '\
-            'FROM wkf_instance '\
-            'WHERE res_id=%s AND res_type=%s AND wkf_id=%s AND state=%s', 
-            (new_rid, res_type, wkf_id, 'active'))
-        new_id = cr.fetchone()
-        if new_id:
-            # select all workitems which "wait" for the old instance
-            cr.execute('select id from wkf_workitem where subflow_id=%s', (old_inst_id,))
-            for (item_id,) in cr.fetchall():
-                # redirect all those workitems to the wkf instance of the new resource
-                cr.execute('update wkf_workitem set subflow_id=%s where id=%s', (new_id[0], item_id))
 
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:

openerp/workflow/helpers.py

@@ -0,0 +1,22 @@
+import openerp.sql_db
+
+class Session(object):
+    def __init__(self, cr, uid):
+        assert isinstance(cr, openerp.sql_db.Cursor)
+        assert isinstance(uid, (int, long))
+        self.cr = cr
+        self.uid = uid
+
+class Record(object):
+    def __init__(self, model, record_id):
+        assert isinstance(model, basestring)
+        assert isinstance(record_id, (int, long))
+        self.model = model
+        self.id = record_id
+
+class WorkflowActivity(object):
+    KIND_FUNCTION = 'function'
+    KIND_DUMMY = 'dummy'
+    KIND_STOPALL = 'stopall'
+    KIND_SUBFLOW = 'subflow'
+

openerp/workflow/instance.py

@@ -2,7 +2,7 @@
 ##############################################################################
 #
 #    OpenERP, Open Source Management Solution
-#    Copyright (C) 2004-2009 Tiny SPRL (<http://tiny.be>).
+#    Copyright (C) 2004-2014 Tiny SPRL (<http://tiny.be>).
 #
 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU Affero General Public License as
@@ -19,59 +19,116 @@
 #
 ##############################################################################
 import workitem
+from openerp.workflow.helpers import Session
+from openerp.workflow.helpers import Record
+from openerp.workflow.workitem import WorkflowItem
 
-def create(cr, ident, wkf_id):
+class WorkflowInstance(object):
-    (uid,res_type,res_id) = ident
+    def __init__(self, session, record, values):
-    cr.execute('insert into wkf_instance (res_type,res_id,uid,wkf_id) values (%s,%s,%s,%s) RETURNING id', (res_type,res_id,uid,wkf_id))
+        assert isinstance(session, Session)
-    id_new = cr.fetchone()[0]
+        assert isinstance(record, Record)
-    cr.execute('select * from wkf_activity where flow_start=True and wkf_id=%s', (wkf_id,))
+        self.session = session
-    res = cr.dictfetchall()
+        self.record = record
-    stack = []
-    workitem.create(cr, res, id_new, ident, stack=stack)
-    update(cr, id_new, ident)
-    return id_new
 
-def delete(cr, ident):
+        if not values:
-    (uid,res_type,res_id) = ident
+            values = {}
-    cr.execute('delete from wkf_instance where res_id=%s and res_type=%s', (res_id,res_type))
 
-def validate(cr, inst_id, ident, signal, force_running=False):
+        assert isinstance(values, dict)
-    cr.execute("select * from wkf_workitem where inst_id=%s", (inst_id,))
+        self.instance = values
+
+    @classmethod
+    def create(cls, session, record, workflow_id):
+        assert isinstance(session, Session)
+        assert isinstance(record, Record)
+        assert isinstance(workflow_id, (int, long))
+
+        cr = session.cr
+        cr.execute('insert into wkf_instance (res_type,res_id,uid,wkf_id) values (%s,%s,%s,%s) RETURNING id', (record.model, record.id, session.uid, workflow_id))
+        instance_id = cr.fetchone()[0]
+
+        cr.execute('select * from wkf_activity where flow_start=True and wkf_id=%s', (workflow_id,))
         stack = []
-    for witem in cr.dictfetchall():
+
+        activities = cr.dictfetchall()
+        for activity in activities:
+            WorkflowItem.create(session, record, activity, instance_id, stack)
+
+        cr.execute('SELECT * FROM wkf_instance WHERE id = %s', (instance_id,))
+        values = cr.dictfetchone()
+        wi = WorkflowInstance(session, record, values)
+        wi.update()
+
+        return wi
+
+    def delete(self):
+        self.session.cr.execute('delete from wkf_instance where res_id=%s and res_type=%s', (self.record.id, self.record.model))
+
+    def validate(self, signal, force_running=False):
+        assert isinstance(signal, basestring)
+        assert isinstance(force_running, bool)
+
+        cr = self.session.cr
+        cr.execute("select * from wkf_workitem where inst_id=%s", (self.instance['id'],))
         stack = []
-        workitem.process(cr, witem, ident, signal, force_running, stack=stack)
+        for work_item_values in cr.dictfetchall():
+            wi = WorkflowItem(self.session, self.record, work_item_values)
+            wi.process(signal=signal, force_running=force_running, stack=stack)
             # An action is returned
-    _update_end(cr, inst_id, ident)
+        self._update_end()
         return stack and stack[0] or False
 
-def update(cr, inst_id, ident):
+    def update(self):
-    cr.execute("select * from wkf_workitem where inst_id=%s", (inst_id,))
+        cr = self.session.cr
-    for witem in cr.dictfetchall():
-        stack = []
-        workitem.process(cr, witem, ident, stack=stack)
-    return _update_end(cr, inst_id, ident)
 
-def _update_end(cr, inst_id, ident):
+        cr.execute("select * from wkf_workitem where inst_id=%s", (self.instance['id'],))
-    cr.execute('select wkf_id from wkf_instance where id=%s', (inst_id,))
+        for work_item_values in cr.dictfetchall():
+            stack = []
+            WorkflowItem(self.session, self.record, work_item_values).process(stack=stack)
+        return self._update_end()
+
+    def _update_end(self):
+        cr = self.session.cr
+        instance_id = self.instance['id']
+        cr.execute('select wkf_id from wkf_instance where id=%s', (instance_id,))
         wkf_id = cr.fetchone()[0]
-    cr.execute('select state,flow_stop from wkf_workitem w left join wkf_activity a on (a.id=w.act_id) where w.inst_id=%s', (inst_id,))
+        cr.execute('select state,flow_stop from wkf_workitem w left join wkf_activity a on (a.id=w.act_id) where w.inst_id=%s', (instance_id,))
         ok=True
         for r in cr.fetchall():
             if (r[0]<>'complete') or not r[1]:
                 ok=False
                 break
         if ok:
-        cr.execute('select distinct a.name from wkf_activity a left join wkf_workitem w on (a.id=w.act_id) where w.inst_id=%s', (inst_id,))
+            cr.execute('select distinct a.name from wkf_activity a left join wkf_workitem w on (a.id=w.act_id) where w.inst_id=%s', (instance_id,))
             act_names = cr.fetchall()
-        cr.execute("update wkf_instance set state='complete' where id=%s", (inst_id,))
+            cr.execute("update wkf_instance set state='complete' where id=%s", (instance_id,))
-        cr.execute("update wkf_workitem set state='complete' where subflow_id=%s", (inst_id,))
+            cr.execute("update wkf_workitem set state='complete' where subflow_id=%s", (instance_id,))
-        cr.execute("select i.id,w.osv,i.res_id from wkf_instance i left join wkf w on (i.wkf_id=w.id) where i.id IN (select inst_id from wkf_workitem where subflow_id=%s)", (inst_id,))
+            cr.execute("select i.id,w.osv,i.res_id from wkf_instance i left join wkf w on (i.wkf_id=w.id) where i.id IN (select inst_id from wkf_workitem where subflow_id=%s)", (instance_id,))
-        for i in cr.fetchall():
+            for cur_instance_id, cur_model_name, cur_record_id in cr.fetchall():
+                cur_record = Record(cur_model_name, cur_record_id)
                 for act_name in act_names:
-                validate(cr, i[0], (ident[0],i[1],i[2]), 'subflow.'+act_name[0])
+                    WorkflowInstance(self.session, cur_record, {'id':cur_instance_id}).validate('subflow.{}'.format(act_name[0]))
+
         return ok
 
 
+
+
+
+def create(session, record, workflow_id):
+    return WorkflowInstance(session, record).create(workflow_id)
+
+def delete(session, record):
+    return WorkflowInstance(session, record).delete()
+
+def validate(session, record, instance_id, signal, force_running=False):
+    return WorkflowInstance(session, record).validate(instance_id, signal, force_running)
+
+def update(session, record, instance_id):
+    return WorkflowInstance(session, record).update(instance_id)
+
+def _update_end(session, record, instance_id):
+    return WorkflowInstance(session, record)._update_end(instance_id)
+
+
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
 

openerp/workflow/service.py

@@ -0,0 +1,115 @@
+# -*- coding: utf-8 -*-
+##############################################################################
+#
+#    OpenERP, Open Source Management Solution
+#    Copyright (C) 2004-TODAY OpenERP S.A. (<http://openerp.com>).
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU Affero General Public License as
+#    published by the Free Software Foundation, either version 3 of the
+#    License, or (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU Affero General Public License for more details.
+#
+#    You should have received a copy of the GNU Affero General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+##############################################################################
+from helpers import Session
+from helpers import Record
+
+from openerp.workflow.instance import WorkflowInstance
+# import instance
+
+
+class WorkflowService(object):
+    CACHE = {}
+
+    @classmethod
+    def clear_cache(cls, dbname):
+        cls.CACHE[dbname] = {}
+
+    @classmethod
+    def new(cls, cr, uid, model_name, record_id):
+        return cls(Session(cr, uid), Record(model_name, record_id))
+
+    def __init__(self, session, record):
+        assert isinstance(session, Session)
+        assert isinstance(record, Record)
+
+        self.session = session
+        self.record = record
+
+        self.cr = self.session.cr
+
+    def write(self):
+        self.cr.execute('select id from wkf_instance where res_id=%s and res_type=%s and state=%s',
+            (self.record.id or None, self.record.model or None, 'active')
+        )
+        for (instance_id,) in self.cr.fetchall():
+            WorkflowInstance(self.session, self.record, {'id': instance_id}).update()
+
+    def trigger(self):
+        self.cr.execute('select instance_id from wkf_triggers where res_id=%s and model=%s', (self.record.id, self.record.model))
+        res = self.cr.fetchall()
+        for (instance_id,) in res:
+            self.cr.execute('select %s,res_type,res_id from wkf_instance where id=%s', (self.session.uid, instance_id,))
+            current_uid, current_model_name, current_record_id = self.cr.fetchone()
+
+            current_session = Session(self.session.cr, current_uid)
+            current_record = Record(current_model_name, current_record_id)
+
+            WorkflowInstance(current_session, current_record, {'id': instance_id}).update()
+
+    def delete(self):
+        WorkflowInstance(self.session, self.record, {}).delete()
+
+    def create(self):
+        WorkflowService.CACHE.setdefault(self.cr.dbname, {})
+
+        wkf_ids = WorkflowService.CACHE[self.cr.dbname].get(self.record.model, None)
+
+        if not wkf_ids:
+            self.cr.execute('select id from wkf where osv=%s and on_create=True', (self.record.model,))
+            wkf_ids = self.cr.fetchall()
+            WorkflowService.CACHE[self.cr.dbname][self.record.model] = wkf_ids
+
+        for (wkf_id, ) in wkf_ids:
+            WorkflowInstance.create(self.session, self.record, wkf_id)
+
+    def validate(self, signal):
+        result = False
+        # ids of all active workflow instances for a corresponding resource (id, model_nam)
+        self.cr.execute('select id from wkf_instance where res_id=%s and res_type=%s and state=%s', (self.record.id, self.record.model, 'active'))
+        # TODO: Refactor the workflow instance object
+        for (instance_id,) in self.cr.fetchall():
+            wi = WorkflowInstance(self.session, self.record, {'id': instance_id})
+
+            res2 = wi.validate(signal)
+
+            result = result or res2
+        return result
+
+    def redirect(self, new_rid):
+        # get ids of wkf instances for the old resource (res_id)
+        # CHECKME: shouldn't we get only active instances?
+        self.cr.execute('select id, wkf_id from wkf_instance where res_id=%s and res_type=%s', (self.record.id, self.record.model))
+
+        for old_inst_id, workflow_id in self.cr.fetchall():
+            # first active instance for new resource (new_rid), using same wkf
+            self.cr.execute(
+                'SELECT id '\
+                'FROM wkf_instance '\
+                'WHERE res_id=%s AND res_type=%s AND wkf_id=%s AND state=%s',
+                (new_rid, self.record.model, workflow_id, 'active'))
+            new_id = self.cr.fetchone()
+            if new_id:
+                # select all workitems which "wait" for the old instance
+                self.cr.execute('select id from wkf_workitem where subflow_id=%s', (old_inst_id,))
+                for (item_id,) in self.cr.fetchall():
+                    # redirect all those workitems to the wkf instance of the new resource
+                    self.cr.execute('update wkf_workitem set subflow_id=%s where id=%s', (new_id[0], item_id))
+

openerp/workflow/wkf_expr.py

@@ -1,114 +0,0 @@
-# -*- coding: utf-8 -*-
-##############################################################################
-#    
-#    OpenERP, Open Source Management Solution
-#    Copyright (C) 2004-2009 Tiny SPRL (<http://tiny.be>).
-#
-#    This program is free software: you can redistribute it and/or modify
-#    it under the terms of the GNU Affero General Public License as
-#    published by the Free Software Foundation, either version 3 of the
-#    License, or (at your option) any later version.
-#
-#    This program is distributed in the hope that it will be useful,
-#    but WITHOUT ANY WARRANTY; without even the implied warranty of
-#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#    GNU Affero General Public License for more details.
-#
-#    You should have received a copy of the GNU Affero General Public License
-#    along with this program.  If not, see <http://www.gnu.org/licenses/>.     
-#
-##############################################################################
-
-"""
-Evaluate workflow code found in activity actions and transition conditions.
-"""
-
-import openerp
-from openerp.tools.safe_eval import safe_eval as eval
-
-class Env(dict):
-    """
-    Dictionary class used as an environment to evaluate workflow code (such as
-    the condition on transitions).
-
-    This environment provides sybmols for cr, uid, id, model name, model
-    instance, column names, and all the record (the one obtained by browsing
-    the provided ID) attributes.
-    """
-    def __init__(self, cr, uid, model, id):
-        self.cr = cr
-        self.uid = uid
-        self.model = model
-        self.id = id
-        self.ids = [id]
-        self.obj = openerp.registry(cr.dbname)[model]
-        self.columns = self.obj._columns.keys() + self.obj._inherit_fields.keys()
-
-    def __getitem__(self, key):
-        if (key in self.columns) or (key in dir(self.obj)):
-            res = self.obj.browse(self.cr, self.uid, self.id)
-            return res[key]
-        else:
-            return super(Env, self).__getitem__(key)
-
-def _eval_expr(cr, ident, workitem, lines):
-    """
-    Evaluate each line of ``lines`` with the ``Env`` environment, returning
-    the value of the last line.
-    """
-    assert lines, 'You used a NULL action in a workflow, use dummy node instead.'
-    uid, model, id = ident
-    result = False
-    for line in lines.split('\n'):
-        line = line.strip()
-        if not line:
-            continue
-        if line == 'True':
-            result = True
-        elif line == 'False':
-            result = False
-        else:
-            env = Env(cr, uid, model, id)
-            result = eval(line, env, nocopy=True)
-    return result
-
-def execute_action(cr, ident, workitem, activity):
-    """
-    Evaluate the ir.actions.server action specified in the activity.
-    """
-    uid, model, id = ident
-    ir_actions_server = openerp.registry(cr.dbname)['ir.actions.server']
-    context = { 'active_model': model, 'active_id': id, 'active_ids': [id] }
-    result = ir_actions_server.run(cr, uid, [activity['action_id']], context)
-    return result
-
-def execute(cr, ident, workitem, activity):
-    """
-    Evaluate the action specified in the activity.
-    """
-    return _eval_expr(cr, ident, workitem, activity['action'])
-
-def check(cr, workitem, ident, transition, signal):
-    """
-    Test if a transition can be taken. The transition can be taken if:
-    
-    - the signal name matches,
-    - the uid is SUPERUSER_ID or the user groups contains the transition's
-      group,
-    - the condition evaluates to a truish value.
-    """
-    if transition['signal'] and signal != transition['signal']:
-        return False
-
-    uid = ident[0]
-    if uid != openerp.SUPERUSER_ID and transition['group_id']:
-        registry = openerp.registry(cr.dbname)
-        user_groups = registry['res.users'].read(cr, uid, [uid], ['groups_id'])[0]['groups_id']
-        if transition['group_id'] not in user_groups:
-            return False
-
-    return _eval_expr(cr, ident, workitem, transition['condition'])
-
-
-# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
-

openerp/workflow/workitem.py

@@ -1,8 +1,8 @@
-# -*- coding: utf-8 -*-
+
 ##############################################################################
 #
 #    OpenERP, Open Source Management Solution
-#    Copyright (C) 2004-2009 Tiny SPRL (<http://tiny.be>).
+#    Copyright (C) 2004-2014 OpenERP S.A. (<http://openerp.com).
 #
 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU Affero General Public License as
@@ -24,159 +24,238 @@
 # cr.execute('delete from wkf_triggers where model=%s and res_id=%s', (res_type,res_id))
 #
 import logging
-
 import instance
 
-import wkf_expr
+from openerp.workflow.helpers import Session
+from openerp.workflow.helpers import Record
+from openerp.workflow.helpers import WorkflowActivity
 
 logger = logging.getLogger(__name__)
 
-def create(cr, act_datas, inst_id, ident, stack):
+import openerp
-    for act in act_datas:
+from openerp.tools.safe_eval import safe_eval as eval
+
+class Environment(dict):
+    """
+    Dictionary class used as an environment to evaluate workflow code (such as
+    the condition on transitions).
+
+    This environment provides sybmols for cr, uid, id, model name, model
+    instance, column names, and all the record (the one obtained by browsing
+    the provided ID) attributes.
+    """
+    def __init__(self, session, record):
+        self.cr = session.cr
+        self.uid = session.uid
+        self.model = record.model
+        self.id = record.id
+        self.ids = [record.id]
+        self.obj = openerp.registry(self.cr.dbname)[self.model]
+        self.columns = self.obj._columns.keys() + self.obj._inherit_fields.keys()
+
+    def __getitem__(self, key):
+        if (key in self.columns) or (key in dir(self.obj)):
+            res = self.obj.browse(self.cr, self.uid, self.id)
+            return res[key]
+        else:
+            return super(Environment, self).__getitem__(key)
+
+
+class WorkflowItem(object):
+    def __init__(self, session, record, work_item_values):
+        assert isinstance(session, Session)
+        assert isinstance(record, Record)
+        self.session = session
+        self.record = record
+
+        if not work_item_values:
+            work_item_values = {}
+
+        assert isinstance(work_item_values, dict)
+        self.workitem = work_item_values
+
+    @classmethod
+    def create(cls, session, record, activity, instance_id, stack):
+        assert isinstance(session, Session)
+        assert isinstance(record, Record)
+        assert isinstance(activity, dict)
+        assert isinstance(instance_id, (long, int))
+        assert isinstance(stack, list)
+
+        cr = session.cr
         cr.execute("select nextval('wkf_workitem_id_seq')")
         id_new = cr.fetchone()[0]
-        cr.execute("insert into wkf_workitem (id,act_id,inst_id,state) values (%s,%s,%s,'active')", (id_new, act['id'], inst_id))
+        cr.execute("insert into wkf_workitem (id,act_id,inst_id,state) values (%s,%s,%s,'active')", (id_new, activity['id'], instance_id))
         cr.execute('select * from wkf_workitem where id=%s',(id_new,))
-        res = cr.dictfetchone()
+        work_item_values = cr.dictfetchone()
         logger.info('Created workflow item in activity %s',
-                    act['id'], extra={'ident': ident})
+                    activity['id'],
-        process(cr, res, ident, stack=stack)
+                    extra={'ident': (session.uid, record.model, record.id)})
 
-def process(cr, workitem, ident, signal=None, force_running=False, stack=None):
+        workflow_item = WorkflowItem(session, record, work_item_values)
+        workflow_item.process(stack=stack)
+
+    @classmethod
+    def create_all(cls, session, record, activities, instance_id, stack):
+        assert isinstance(activities, list)
+
+        for activity in activities:
+            cls.create(session, record, activity, instance_id, stack)
+
+    def process(self, signal=None, force_running=False, stack=None):
+        assert isinstance(force_running, bool)
         assert stack is not None
 
-    cr.execute('select * from wkf_activity where id=%s', (workitem['act_id'],))
+        cr = self.session.cr
+
+        cr.execute('select * from wkf_activity where id=%s', (self.workitem['act_id'],))
         activity = cr.dictfetchone()
 
         triggers = False
-    if workitem['state'] == 'active':
+        if self.workitem['state'] == 'active':
             triggers = True
-        if not _execute(cr, workitem, activity, ident, stack):
+            if not self._execute(activity, stack):
                 return False
 
-    if force_running or workitem['state'] == 'complete':
+        if force_running or self.workitem['state'] == 'complete':
-        ok = _split_test(cr, workitem, activity['split_mode'], ident, signal, stack)
+            ok = self._split_test(activity['split_mode'], signal, stack)
             triggers = triggers and not ok
 
         if triggers:
-        cr.execute('select * from wkf_transition where act_from=%s', (workitem['act_id'],))
+            cr.execute('select * from wkf_transition where act_from=%s', (self.workitem['act_id'],))
             for trans in cr.dictfetchall():
                 if trans['trigger_model']:
-                ids = wkf_expr._eval_expr(cr,ident,workitem,trans['trigger_expr_id'])
+                    ids = self.wkf_expr_eval_expr(trans['trigger_expr_id'])
                     for res_id in ids:
                         cr.execute('select nextval(\'wkf_triggers_id_seq\')')
                         id =cr.fetchone()[0]
-                    cr.execute('insert into wkf_triggers (model,res_id,instance_id,workitem_id,id) values (%s,%s,%s,%s,%s)', (trans['trigger_model'],res_id,workitem['inst_id'], workitem['id'], id))
+                        cr.execute('insert into wkf_triggers (model,res_id,instance_id,workitem_id,id) values (%s,%s,%s,%s,%s)', (trans['trigger_model'],res_id, self.workitem['inst_id'], self.workitem['id'], id))
 
         return True
 
-
+    def _execute(self, activity, stack):
-# ---------------------- PRIVATE FUNCS --------------------------------
+        """Send a signal to parenrt workflow (signal: subflow.signal_name)"""
-
-def _state_set(cr, workitem, activity, state, ident):
-    cr.execute('update wkf_workitem set state=%s where id=%s', (state,workitem['id']))
-    workitem['state'] = state
-    logger.info("Changed state of work item %s to \"%s\" in activity %s",
-                workitem['id'], state, activity['id'], extra={'ident': ident})
-
-def _execute(cr, workitem, activity, ident, stack):
         result = True
-    #
+        cr = self.session.cr
-    # send a signal to parent workflow (signal: subflow.signal_name)
-    #
         signal_todo = []
-    if (workitem['state']=='active') and activity['signal_send']:
-        cr.execute("select i.id,w.osv,i.res_id from wkf_instance i left join wkf w on (i.wkf_id=w.id) where i.id IN (select inst_id from wkf_workitem where subflow_id=%s)", (workitem['inst_id'],))
-        for i in cr.fetchall():
-            signal_todo.append((i[0], (ident[0],i[1],i[2]), activity['signal_send']))
 
-    if activity['kind']=='dummy':
+        if (self.workitem['state']=='active') and activity['signal_send']:
-        if workitem['state']=='active':
+            # signal_send']:
-            _state_set(cr, workitem, activity, 'complete', ident)
+            cr.execute("select i.id,w.osv,i.res_id from wkf_instance i left join wkf w on (i.wkf_id=w.id) where i.id IN (select inst_id from wkf_workitem where subflow_id=%s)", (self.workitem['inst_id'],))
+            for instance_id, model_name, record_id in cr.fetchall():
+                record = Record(model_name, record_id)
+                signal_todo.append((instance_id, record, activity['signal_send']))
+
+
+        if activity['kind'] == WorkflowActivity.KIND_DUMMY:
+            if self.workitem['state']=='active':
+                self._state_set(activity, 'complete')
                 if activity['action_id']:
-                res2 = wkf_expr.execute_action(cr, ident, workitem, activity)
+                    res2 = self.wkf_expr_execute_action(activity)
                     if res2:
                         stack.append(res2)
                         result=res2
-    elif activity['kind']=='function':
+
-        if workitem['state']=='active':
+        elif activity['kind'] == WorkflowActivity.KIND_FUNCTION:
-            _state_set(cr, workitem, activity, 'running', ident)
+
-            returned_action = wkf_expr.execute(cr, ident, workitem, activity)
+            if self.workitem['state']=='active':
+                self._state_set(activity, 'running')
+                returned_action = self.wkf_expr_execute(activity)
                 if type(returned_action) in (dict,):
                     stack.append(returned_action)
                 if activity['action_id']:
-                res2 = wkf_expr.execute_action(cr, ident, workitem, activity)
+                    res2 = self.wkf_expr_execute_action(activity)
                     # A client action has been returned
                     if res2:
                         stack.append(res2)
                         result=res2
-            _state_set(cr, workitem, activity, 'complete', ident)
+                self._state_set(activity, 'complete')
-    elif activity['kind']=='stopall':
+
-        if workitem['state']=='active':
+        elif activity['kind'] == WorkflowActivity.KIND_STOPALL:
-            _state_set(cr, workitem, activity, 'running', ident)
+            if self.workitem['state']=='active':
-            cr.execute('delete from wkf_workitem where inst_id=%s and id<>%s', (workitem['inst_id'], workitem['id']))
+                self._state_set(activity, 'running')
+                cr.execute('delete from wkf_workitem where inst_id=%s and id<>%s', (self.workitem['inst_id'], self.workitem['id']))
                 if activity['action']:
-                wkf_expr.execute(cr, ident, workitem, activity)
+                    self.wkf_expr_execute(activity)
-            _state_set(cr, workitem, activity, 'complete', ident)
+                self._state_set(activity, 'complete')
-    elif activity['kind']=='subflow':
+
-        if workitem['state']=='active':
+        elif activity['kind'] == WorkflowActivity.KIND_SUBFLOW:
-            _state_set(cr, workitem, activity, 'running', ident)
+
+            if self.workitem['state']=='active':
+
+                self._state_set(activity, 'running')
                 if activity.get('action', False):
-                id_new = wkf_expr.execute(cr, ident, workitem, activity)
+                    id_new = self.wkf_expr_execute(activity)
                     if not id_new:
-                    cr.execute('delete from wkf_workitem where id=%s', (workitem['id'],))
+                        cr.execute('delete from wkf_workitem where id=%s', (self.workitem['id'],))
                         return False
                     assert type(id_new)==type(1) or type(id_new)==type(1L), 'Wrong return value: '+str(id_new)+' '+str(type(id_new))
                     cr.execute('select id from wkf_instance where res_id=%s and wkf_id=%s', (id_new, activity['subflow_id']))
                     id_new = cr.fetchone()[0]
                 else:
-                id_new = instance.create(cr, ident, activity['subflow_id'])
+                    inst = instance.WorkflowInstance(self.session, self.record)
-            cr.execute('update wkf_workitem set subflow_id=%s where id=%s', (id_new, workitem['id']))
+                    id_new = inst.create(activity['subflow_id'])
-            workitem['subflow_id'] = id_new
+
-        if workitem['state']=='running':
+                cr.execute('update wkf_workitem set subflow_id=%s where id=%s', (id_new, self.workitem['id']))
-            cr.execute("select state from wkf_instance where id=%s", (workitem['subflow_id'],))
+                self.workitem['subflow_id'] = id_new
+
+            if self.workitem['state']=='running':
+                cr.execute("select state from wkf_instance where id=%s", (self.workitem['subflow_id'],))
                 state = cr.fetchone()[0]
                 if state=='complete':
-                _state_set(cr, workitem, activity, 'complete', ident)
+                    self._state_set(activity, 'complete')
-    for t in signal_todo:
+
-        instance.validate(cr, t[0], t[1], t[2], force_running=True)
+        for instance_id, record, signal_send in signal_todo:
+            wi = instance.WorkflowInstance(self.session, record, {'id': instance_id})
+            wi.validate(signal_send, force_running=True)
 
         return result
 
-def _split_test(cr, workitem, split_mode, ident, signal=None, stack=None):
+    def _state_set(self, activity, state):
-    cr.execute('select * from wkf_transition where act_from=%s', (workitem['act_id'],))
+        self.session.cr.execute('update wkf_workitem set state=%s where id=%s', (state, self.workitem['id']))
+        self.workitem['state'] = state
+        logger.info('Changed state of work item %s to "%s" in activity %s',
+                    self.workitem['id'], state, activity['id'],
+                    extra={'ident': (self.session.uid, self.record.model, self.record.id)})
+
+    def _split_test(self, split_mode, signal, stack):
+        cr = self.session.cr
+        cr.execute('select * from wkf_transition where act_from=%s', (self.workitem['act_id'],))
         test = False
         transitions = []
         alltrans = cr.dictfetchall()
-    if split_mode=='XOR' or split_mode=='OR':
+
+        if split_mode in ('XOR', 'OR'):
             for transition in alltrans:
-            if wkf_expr.check(cr, workitem, ident, transition,signal):
+                if self.wkf_expr_check(transition,signal):
                     test = True
-                transitions.append((transition['id'], workitem['inst_id']))
+                    transitions.append((transition['id'], self.workitem['inst_id']))
                     if split_mode=='XOR':
                         break
         else:
             test = True
             for transition in alltrans:
-            if not wkf_expr.check(cr, workitem, ident, transition,signal):
+                if not self.wkf_expr_check(transition, signal):
                     test = False
                     break
-            cr.execute('select count(*) from wkf_witm_trans where trans_id=%s and inst_id=%s', (transition['id'], workitem['inst_id']))
+                cr.execute('select count(*) from wkf_witm_trans where trans_id=%s and inst_id=%s', (transition['id'], self.workitem['inst_id']))
                 if not cr.fetchone()[0]:
-                transitions.append((transition['id'], workitem['inst_id']))
+                    transitions.append((transition['id'], self.workitem['inst_id']))
-    if test and len(transitions):
+
+        if test and transitions:
             cr.executemany('insert into wkf_witm_trans (trans_id,inst_id) values (%s,%s)', transitions)
-        cr.execute('delete from wkf_workitem where id=%s', (workitem['id'],))
+            cr.execute('delete from wkf_workitem where id=%s', (self.workitem['id'],))
             for t in transitions:
-            _join_test(cr, t[0], t[1], ident, stack)
+                self._join_test(t[0], t[1], stack)
             return True
         return False
 
-def _join_test(cr, trans_id, inst_id, ident, stack):
+    def _join_test(self, trans_id, inst_id, stack):
+        cr = self.session.cr
         cr.execute('select * from wkf_activity where id=(select act_to from wkf_transition where id=%s)', (trans_id,))
         activity = cr.dictfetchone()
         if activity['join_mode']=='XOR':
-        create(cr,[activity], inst_id, ident, stack)
+            WorkflowItem.create(self.session, self.record, activity, inst_id, stack=stack)
             cr.execute('delete from wkf_witm_trans where inst_id=%s and trans_id=%s', (inst_id,trans_id))
         else:
             cr.execute('select id from wkf_transition where act_to=%s', (activity['id'],))
@@ -191,7 +270,68 @@ def _join_test(cr, trans_id, inst_id, ident, stack):
             if ok:
                 for (id,) in trans_ids:
                     cr.execute('delete from wkf_witm_trans where trans_id=%s and inst_id=%s', (id,inst_id))
-            create(cr, [activity], inst_id, ident, stack)
+                WorkflowItem.create(self.session, self.record, activity, inst_id, stack=stack)
+
+    def wkf_expr_eval_expr(self, lines):
+        """
+        Evaluate each line of ``lines`` with the ``Environment`` environment, returning
+        the value of the last line.
+        """
+        assert lines, 'You used a NULL action in a workflow, use dummy node instead.'
+        result = False
+        for line in lines.split('\n'):
+            line = line.strip()
+            if not line:
+                continue
+            if line == 'True':
+                result = True
+            elif line == 'False':
+                result = False
+            else:
+                env = Environment(self.session, self.record)
+                result = eval(line, env, nocopy=True)
+        return result
+
+    def wkf_expr_execute_action(self, activity):
+        """
+        Evaluate the ir.actions.server action specified in the activity.
+        """
+        context = {
+            'active_model': self.record.model,
+            'active_id': self.record.id,
+            'active_ids': [self.record.id]
+        }
+
+        ir_actions_server = openerp.registry(self.session.cr.dbname)['ir.actions.server']
+        result = ir_actions_server.run(self.session.cr, self.session.uid, [activity['action_id']], context)
+
+        return result
+
+    def wkf_expr_execute(self, activity):
+        """
+        Evaluate the action specified in the activity.
+        """
+        return self.wkf_expr_eval_expr(activity['action'])
+
+    def wkf_expr_check(self, transition, signal):
+        """
+        Test if a transition can be taken. The transition can be taken if:
+
+        - the signal name matches,
+        - the uid is SUPERUSER_ID or the user groups contains the transition's
+          group,
+        - the condition evaluates to a truish value.
+        """
+        if transition['signal'] and signal != transition['signal']:
+            return False
+
+        if self.session.uid != openerp.SUPERUSER_ID and transition['group_id']:
+            registry = openerp.registry(self.session.cr.dbname)
+            user_groups = registry['res.users'].read(self.session.cr, self.session.uid, [self.session.uid], ['groups_id'])[0]['groups_id']
+            if transition['group_id'] not in user_groups:
+                return False
+
+        return self.wkf_expr_eval_expr(transition['condition'])
 
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4: