# HG changeset patch
# User Denis Laxalde <denis.laxalde@logilab.fr>
# Date 1424678561 -3600
# Node ID 4b8253fb31257ad067f82bfdf99da650ac63ddb5
# Parent  ea73a949e8023302e6a390477872456cc966b674
[web/facet] Use an Exists node in HasRelationFacet

The generated RQL now includes an EXISTS clause. For instance, one gets:
::

    DISTINCT Any  WHERE X is CWUser, EXISTS(X in_group A)

instead of:

::

    DISTINCT Any  WHERE X is CWUser, X in_group A

for a HasRelationFacet with ``rtype = 'in_group'``, which is more appropriate
for testing the existence of the relation.

Add a test for this facet along the way.

diff -r ea73a949e802 -r 4b8253fb3125 web/facet.py
--- a/web/facet.py	Wed Apr 01 13:39:30 2015 +0200
+++ b/web/facet.py	Mon Feb 23 09:02:41 2015 +0100
@@ -1465,15 +1465,17 @@
 
     def add_rql_restrictions(self):
         """add restriction for this facet into the rql syntax tree"""
-        self.select.set_distinct(True) # XXX
         value = self._cw.form.get(self.__regid__)
         if not value: # no value sent for this facet
             return
+        exists = nodes.Exists()
+        self.select.add_restriction(exists)
         var = self.select.make_variable()
         if self.role == 'subject':
-            self.select.add_relation(self.filtered_variable, self.rtype, var)
+            subj, obj = self.filtered_variable, var
         else:
-            self.select.add_relation(var, self.rtype, self.filtered_variable)
+            subj, obj = var, self.filtered_variable
+        exists.add_relation(subj, self.rtype, obj)
 
 
 class BitFieldFacet(AttributeFacet):
diff -r ea73a949e802 -r 4b8253fb3125 web/test/unittest_facet.py
--- a/web/test/unittest_facet.py	Wed Apr 01 13:39:30 2015 +0200
+++ b/web/test/unittest_facet.py	Mon Feb 23 09:02:41 2015 +0100
@@ -129,8 +129,6 @@
             self.assertEqual(f.select.as_string(),
                               'DISTINCT Any  WHERE X is CWUser')
 
-
-
     def test_relationattribute(self):
         with self.admin_access.web_request() as req:
             f, (guests, managers) = self._in_group_facet(req, cls=facet.RelationAttributeFacet)
@@ -150,6 +148,20 @@
             self.assertEqual(f.select.as_string(),
                               "DISTINCT Any  WHERE X is CWUser, X in_group E, E name 'guests'")
 
+    def test_hasrelation(self):
+        with self.admin_access.web_request() as req:
+            rset, rqlst, filtered_variable = self.prepare_rqlst(req)
+            f = facet.HasRelationFacet(req, rset=rset,
+                                       select=rqlst.children[0],
+                                       filtered_variable=filtered_variable)
+            f.__regid__ = 'has_group'
+            f.rtype = 'in_group'
+            f.role = 'subject'
+            f._cw.form[f.__regid__] = 'feed me'
+            f.add_rql_restrictions()
+            self.assertEqual(f.select.as_string(),
+                             'DISTINCT Any  WHERE X is CWUser, EXISTS(X in_group A)')
+
     def test_daterange(self):
         with self.admin_access.web_request() as req:
             rset, rqlst, filtered_variable = self.prepare_rqlst(req)