Merge pull request #110 from timrichardson/computed_fields

allow compute fields to depend on compute fields defined earlier

gluon/dal.py

@@ -8542,10 +8542,12 @@ class Table(object):
                 # try compute it
                 try:
                     new_fields[name] = (ofield,ofield.compute(row))
+                    __,fields[name] = new_fields[name]  #the value is the second element of the tuple
+                    row = Row(fields)  #allow later compute fields to refer to this value
                 except (KeyError, AttributeError):
-                    # error sinlently unless field is required!
+                    # error silently unless field is required!
                     if ofield.required:
-                        raise SyntaxError('unable to comput field: %s' % name)
+                        raise SyntaxError('unable to compute field: %s' % name)
         return new_fields.values()
 
     def _attempt_upload(self, fields):

gluon/tests/test_dal.py

@@ -599,6 +599,19 @@ class TestComputedFields(unittest.TestCase):
         self.assertEqual(db.tt[id].cc,'zx')
         db.tt.drop()
         db.commit()
+        
+        # test checking that a compute field can refer to earlier-defined computed fields
+        db.define_table('tt',
+                        Field('aa'),
+                        Field('bb',default='x'),
+                        Field('cc',compute=lambda r: r.aa+r.bb),
+                        Field('dd',compute=lambda r: r.bb + r.cc))
+        db.commit()
+        id = db.tt.insert(aa="z")
+        self.assertEqual(db.tt[id].dd,'xzx')  
+        db.tt.drop()
+        db.commit()
+        
 
 class TestCommonFilters(unittest.TestCase):