Update README with the new custom operator feature

README.rst

@@ -101,10 +101,6 @@ Enable autocompletion tool (work in progress, not enabled yet)::
 
   QBE_AUTOCOMPLETE = True
 
-Enable an Exhibit faceted navigation for results (not yet implemented)::
-
-  QBE_EXHIBIT = False
-
 Admin module name to add admin urls in results::
 
   QBE_ADMIN = "admin"
@@ -121,58 +117,70 @@ Path to QBE formats export file, in order to add custom export formats::
 
   QBE_FORMATS_EXPORT = "qbe_formats"
 
+Path to custom QBE operators for the criteria::
+
+  QBE_CUSTOM_OPERATORS = "qbe_operators"
+
 Custom Operators
 --------
 
 Use Custom Operators only if you know what you are doing and at your own risks!
 
-If you need to define custom operators, in one of your ``models.py``, you need to create a new class that extends ``django_qbe.operators.CustomOperator``::
+If you need to define custom operators, in a file ``qbe_operators.py`` in your
+project root, you need to create a new class that extends
+``django_qbe.operators.CustomOperator``::
 
   import datetime
   from django.utils import timezone
   from django_qbe.operators import CustomOperator
-  
+
+
   class SinceDaysAgo(CustomOperator):
-      slug = 'since-days-ago' # REQUIRED and must be unique
-      label = 'Since Days Ago' # REQUIRED
-  
+      slug = 'since-days-ago'  # REQUIRED and must be unique
+      label = 'Since Days Ago'  # REQUIRED
+
       def get_params(self):
           if len(self.params):
               return self.params
-  
+
           now = timezone.now()
           today = now.replace(hour=0, minute=0, second=0, microsecond=0)
           tomorrow = today + datetime.timedelta(days=1)
-  
+
           date_since = today - datetime.timedelta(days=int(self.value))
-  
+
           operator = "gt"
           lookup_since = self._get_lookup(operator, str(date_since))
           lookup_until = self._get_lookup(operator, str(tomorrow))
-  
+
           self.params.append(lookup_since)
           self.params.append(lookup_until)
-  
+
           return self.params
-  
+
       def get_wheres(self):
           if len(self.wheres):
               return self.wheres
-  
+
           lookup_cast = self._db_operations.lookup_cast
           for operator in ["gte", "lt"]:
               db_operator = self._db_operators[operator]
-              self.wheres.append(u"%s %s" \
-                  % (lookup_cast(operator) % self.db_field,
-                     db_operator))
-  
+              self.wheres.append(u"%s %s" % (
+                  lookup_cast(operator) % self.db_field,
+                  db_operator)
+              )
+
           return self.wheres
 
-Your custom operator must have 2 attributes, ``slug`` and ``label`` in order to be displayed in the Criteria dropdown.
+Your custom operator must have 2 attributes, ``slug`` and ``label`` in order
+to be displayed in the Criteria dropdown.
 
-The ``get_params`` and ``get_wheres`` methods must return an iterable instance (eg. list), otherwise it gets converted to a list.
+The ``get_params`` and ``get_wheres`` methods must return an iterable instance
+(eg. list), otherwise it gets converted to a list.
 
-If you dont want to write it in your ``models.py`` make sure that it is imported in one of the files that are evaluated at runtime (eg. ``models.py`` or ``urls.py``) in order to register your Custom Operator.
+If you dont want to write it in your ``models.py`` make sure that it is
+imported in one of the files that are evaluated at runtime (eg. ``models.py``
+or ``urls.py``) in order to register your Custom Operator.
 
 .. _QBE: http://www.google.com/url?sa=t&source=web&ct=res&cd=2&ved=0CB4QFjAB&url=http%3A%2F%2Fpages.cs.wisc.edu%2F~dbbook%2FopenAccess%2FthirdEdition%2Fqbe.pdf&ei=_UD5S5WSBYP5-Qb-18i8CA&usg=AFQjCNHMv-Pua285zhWT8DevuZFj2gfYKA&sig2=-sTEDWjJhnTaixh2iJfsAw
 .. _PyPI: http://pypi.python.org/pypi/django_qbe/