A constraint to use a simple boolean TALES expression.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@11097 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Constraint/TALESConstraint.py

+##############################################################################
+#
+# Copyright (c) 2006 Nexedi SARL and Contributors. All Rights Reserved.
+#                    Jerome Perrin <jerome@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# guarantees and support are strongly advised to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import sys
+
+from Products.CMFCore.Expression import Expression
+from ZODB.POSException import ConflictError
+from Products.PageTemplates.TALES import CompilerError
+from zLOG import LOG, PROBLEM
+
+from Constraint import Constraint
+
+class TALESConstraint(Constraint):
+  """This constraint uses an arbitrary TALES expression on the context of the
+  object; if this expression is evaluated as False, the object will be
+  considered in an inconsistent state.
+    
+    Configuration example:
+    { 'id'            : 'tales_constraint',
+      'description'   : 'Title should not be equals to foo',
+      'type'          : 'TALESConstraint',
+      'expression'    : 'python: object.getTitle() != 'foo',
+    },
+
+  For readability, please don't abuse this constraint to evaluate complex
+  things. If necessary, write your own constraint class.
+  """
+
+  def checkConsistency(self, obj, fixit=0):
+    """See Interface """
+    # import this later to prevent circular import
+    from Products.ERP5Type.Utils import createExpressionContext
+    if not self._checkConstraintCondition(obj):
+      return []
+    errors = []
+    expression_text = self.constraint_definition['expression']
+    expression = Expression(expression_text)
+    econtext = createExpressionContext(obj)
+    try:
+      if not expression(econtext):
+        errors.append(self._generateError(obj, 'Expression was false')
+    except (ConflictError, CompilerError):
+      raise
+    except Exception, e:
+      LOG('ERP5Type', PROBLEM, 'TALESConstraint error on "%s" on %s' %
+         (self.constraint_definition['expression'], obj), error=sys.exc_info())
+      errors.append(self._generateError(obj,
+                    'Error while evaluating expression: %s' % str(e)))
+    return errors
+

product/ERP5Type/Constraint/__init__.py

@@ -7,3 +7,4 @@ from PropertyExistence import PropertyExistence
 from CategoryExistence import CategoryExistence
 from PortalTypeClass import PortalTypeClass
 from CategoryAcquiredMembershipArity import CategoryAcquiredMembershipArity
+from TALESConstraint import TALESConstraint

product/ERP5Type/tests/testConstraint.py

@@ -219,6 +219,7 @@ class TestConstraint(ERP5TypeTestCase):
     sequence.edit(
         constraint=constraint,
     )
+    return constraint
 
   def stepCallCheckConsistency(self, sequence=None, 
                                sequence_list=None, **kw):
@@ -1074,6 +1075,44 @@ class TestConstraint(ERP5TypeTestCase):
     # should be fixed now
     self.assertEquals([], obj.checkConsistency())
     self.failUnless(obj.getPropertyType(prop_name))
+  
+  def test_TALESConstraint(self):
+    """Tests TALESConstraint
+    """
+    constraint = self._createGenericConstraint(Sequence(),
+                   klass_name='TALESConstraint',
+                   id='tales_constraint',
+                   expression='python: object.getTitle() != "foo"')
+    obj = self._makeOne()
+    self.assertEquals([], constraint.checkConsistency(obj))
+    obj.setTitle('foo')
+    self.assertEquals(1, len(constraint.checkConsistency(obj)))
+    
+  def test_TALESConstraintInvalidExpression(self):
+    """Tests TALESConstraint with an invalid expression
+    """
+    constraint = self._createGenericConstraint(Sequence(),
+                   klass_name='TALESConstraint',
+                   id='tales_constraint',
+                   expression='python: None / 3') # ValueError
+    obj = self._makeOne()
+    # an error during expression evaluation simply makes a consistency error
+    self.assertEquals(1, len(constraint.checkConsistency(obj)))
+
+    # an error during expression compilation is reraised to the programmer
+    constraint = self._createGenericConstraint(Sequence(),
+                   klass_name='TALESConstraint',
+                   id='tales_constraint',
+                   expression='python: None (" ')
+    from Products.PageTemplates.TALES import CompilerError
+    self.assertRaises(CompilerError, constraint.checkConsistency, obj)
+
+    constraint = self._createGenericConstraint(Sequence(),
+                   klass_name='TALESConstraint',
+                   id='tales_constraint',
+                   expression='error: " ')
+    self.assertRaises(CompilerError, constraint.checkConsistency, obj)
+
 
 if __name__ == '__main__':
     framework()