Addition of time filtering to postgresql.py provider. (#1629)

* Addition of time filtering to postgresql.py provider.

* Consistency update: single quotes + filter renamed to datetime_filter.

* Update to datetime filter to use <= upper bound for consistency for CQL implementation.

pygeoapi/provider/postgresql.py

@@ -140,6 +140,7 @@ def query(self, offset=0, limit=10, resulttype='results',
         property_filters = self._get_property_filters(properties)
         cql_filters = self._get_cql_filters(filterq)
         bbox_filter = self._get_bbox_filter(bbox)
+        time_filter = self._get_datetime_filter(datetime_)
         order_by_clauses = self._get_order_by_clauses(sortby, self.table_model)
         selected_properties = self._select_properties_clause(select_properties,
                                                              skip_geometry)
@@ -151,6 +152,7 @@ def query(self, offset=0, limit=10, resulttype='results',
                        .filter(property_filters)
                        .filter(cql_filters)
                        .filter(bbox_filter)
+                       .filter(time_filter)
                        .options(selected_properties))
 
             matched = results.count()
@@ -455,6 +457,29 @@ def _get_bbox_filter(self, bbox):
 
         return bbox_filter
 
+    def _get_datetime_filter(self, datetime_):
+        if datetime_ in (None, '../..'):
+            return True
+        else:
+            if self.time_field is None:
+                LOGGER.error('time_field not enabled for collection')
+                raise ProviderQueryError()
+
+            time_column = getattr(self.table_model, self.time_field)
+
+            if '/' in datetime_:  # envelope
+                LOGGER.debug('detected time range')
+                time_begin, time_end = datetime_.split('/')
+                if time_begin == '..':
+                    datetime_filter = time_column <= time_end
+                elif time_end == '..':
+                    datetime_filter = time_column >= time_begin
+                else:
+                    datetime_filter = time_column.between(time_begin, time_end)
+            else:
+                datetime_filter = time_column == datetime_
+        return datetime_filter
+
     def _select_properties_clause(self, select_properties, skip_geometry):
         # List the column names that we want
         if select_properties: