[#1838] Calculate FTS rankings only on specific columns

The bug was that when we've done a full-text query on a specific column, the
query was OK, but the rank was calculated using all text from the row. It
messed up when trying to get DISTINCT values.

ckanext/datastore/plugin.py

@@ -484,9 +484,14 @@ def _build_query_and_rank_statements(self, lang, query, plain, field=None):
             statement = u"plainto_tsquery('{lang}', '{query}') {alias}"
         else:
             statement = u"to_tsquery('{lang}', '{query}') {alias}"
-        rank_statement = u'ts_rank(_full_text, {query_alias}, 32) AS {alias}'
+        if field is None:
+            rank_field = '_full_text'
+        else:
+            rank_field = 'to_tsvector("%s")' % field
+        rank_statement = u'ts_rank({rank_field}, {query_alias}, 32) AS {alias}'
         statement = statement.format(lang=lang, query=query, alias=query_alias)
-        rank_statement = rank_statement.format(query_alias=query_alias,
+        rank_statement = rank_statement.format(rank_field=rank_field,
+                                               query_alias=query_alias,
                                                alias=rank_alias)
         return statement, rank_statement
 

ckanext/datastore/tests/test_search.py

@@ -14,11 +14,46 @@
 from ckanext.datastore.tests.helpers import extract, rebuild_all_dbs
 
 import ckan.new_tests.helpers as helpers
+import ckan.new_tests.factories as factories
 
 assert_equals = nose.tools.assert_equals
 assert_raises = nose.tools.assert_raises
 
 
+class TestDatastoreSearchNewTest(object):
+    @classmethod
+    def setup_class(cls):
+        p.load('datastore')
+
+    @classmethod
+    def teardown_class(cls):
+        p.unload('datastore')
+        helpers.reset_db()
+
+    def test_fts_on_field_calculates_ranks_only_on_that_specific_field(self):
+        resource = factories.Resource()
+        data = {
+            'resource_id': resource['id'],
+            'force': True,
+            'records': [
+                {'from': 'Brazil', 'to': 'Brazil'},
+                {'from': 'Brazil', 'to': 'Italy'}
+            ],
+        }
+        result = helpers.call_action('datastore_create', **data)
+        search_data = {
+            'resource_id': resource['id'],
+            'fields': 'from',
+            'q': {
+                'from': 'Brazil'
+            },
+        }
+        result = helpers.call_action('datastore_search', **search_data)
+        ranks = [r['rank from'] for r in result['records']]
+        assert_equals(len(result['records']), 2)
+        assert_equals(len(set(ranks)), 1)
+
+
 class TestDatastoreSearch(tests.WsgiAppCase):
     sysadmin_user = None
     normal_user = None