RCORE-2115 Fix multiple backlinks created by dictionary (#7677)

* fix inserting a link multiple times to the same key in a dictionary of mixed creating multiple backlinks
realm · May 6, 2024 · 62e617b · 62e617b
1 parent 77ce9b3
commit 62e617b
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/src/realm/dictionary.cpp b/src/realm/dictionary.cpp
@@ -587,10 +587,10 @@ std::pair<Dictionary::Iterator, bool> Dictionary::insert(Mixed key, Mixed value)
     ObjLink old_link;
     if (old_entry) {
         Mixed old_value = m_values->get(ndx);
+        if (old_value.is_type(type_TypedLink)) {
+            old_link = old_value.get<ObjLink>();
+        }
         if (!value.is_same_type(old_value) || value != old_value) {
-            if (old_value.is_type(type_TypedLink)) {
-                old_link = old_value.get<ObjLink>();
-            }
             m_values->set(ndx, value);
         }
         else {

diff --git a/test/test_dictionary.cpp b/test/test_dictionary.cpp
@@ -239,16 +239,22 @@ TEST(Dictionary_TypedLinks)
         CHECK_EQUAL(lady.get_backlink_count(*persons, col_dict), 1);
         CHECK_EQUAL(lady.get_backlink(*persons, col_dict, 0), adam.get_key());
         CHECK_EQUAL(lady.get_backlink_count(), 1);
+        // make sure that inserting the same link again does nothing
+        CHECK_NOT(dict.insert("Pet", lady).second);
+        CHECK_EQUAL(lady.get_backlink_count(), 1);
         lady.remove();
         cmp(dict["Pet"], Mixed());
 
         // Reinsert lady
         lady = dogs->create_object_with_primary_key("lady");
         dict.insert("Pet", lady);
+        dict.insert("Pet", lady);
+        CHECK_EQUAL(lady.get_backlink_count(), 1);
         lady.invalidate(); // Make lady a tombstone :-(
         cmp(dict["Pet"], Mixed());
         lady = dogs->create_object_with_primary_key("lady");
         cmp(dict["Pet"], Mixed(lady.get_link()));
+        CHECK_EQUAL(lady.get_backlink_count(), 1);
 
         auto invalid_link = pluto.get_link();
         pluto.remove();