Allow non-embedded links in asymmetric objects (#6981)

* Allow non-embedded links in asymmetric objects

* Update CHANGELOG

* Add test of non-embedded links in asymmetric objects

* Fix lint

Author: Kasper Overgård Nielsen

CHANGELOG.md

@@ -1,8 +1,7 @@
 # NEXT RELEASE
 
 ### Enhancements
-* <New feature description> (PR [#????](https://github.com/realm/realm-core/pull/????))
-* None.
+* Allow non-embedded links in asymmetric objects. ([PR #6981](https://github.com/realm/realm-core/pull/6981))
 
 ### Fixed
 * <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)

src/realm/object-store/object_schema.cpp

@@ -296,13 +296,6 @@ static void validate_property(Schema const& schema, ObjectSchema const& parent_o
                                 object_name, prop.name, prop.object_type);
         return;
     }
-    if (parent_object_schema.table_type == ObjectSchema::ObjectType::TopLevelAsymmetric &&
-        it->table_type != ObjectSchema::ObjectType::Embedded) {
-        exceptions.emplace_back(
-            "Asymmetric table with property '%1.%2' of type '%3' cannot have a non-embedded object type.",
-            object_name, prop.name, string_for_property_type(prop.type));
-        return;
-    }
     if (it->table_type == ObjectSchema::ObjectType::TopLevelAsymmetric) {
         exceptions.emplace_back("Property '%1.%2' of type '%3' cannot be a link to an asymmetric object.",
                                 object_name, prop.name, string_for_property_type(prop.type));

src/realm/table.cpp

@@ -415,10 +415,6 @@ ColKey Table::add_column(Table& target, StringData name)
     Group* target_group = target.get_parent_group();
     REALM_ASSERT_RELEASE(origin_group && target_group);
     REALM_ASSERT_RELEASE(origin_group == target_group);
-    // Only links to embedded objects are allowed.
-    if (is_asymmetric() && !target.is_embedded()) {
-        throw IllegalOperation("Object property not supported in asymmetric table");
-    }
     // Incoming links from an asymmetric table are not allowed.
     if (target.is_asymmetric()) {
         throw IllegalOperation("Ephemeral objects not supported");

test/object-store/schema.cpp

@@ -410,16 +410,16 @@ TEST_CASE("Schema") {
                     "Property 'object.link' of type 'object' cannot be a link to an asymmetric object."));
         }
 
-        SECTION("rejects link properties with asymmetric origin object") {
+        SECTION("allow link properties with asymmetric origin object") {
             Schema schema = {
                 {"object",
                  ObjectSchema::ObjectType::TopLevelAsymmetric,
-                 {{"link", PropertyType::Object | PropertyType::Nullable, "link target"}}},
-                {"link target", {{"value", PropertyType::Int}}},
+                 {{"_id", PropertyType::Int, Property::IsPrimary{true}},
+                  {"link", PropertyType::Object | PropertyType::Nullable, "link target"}}},
+                {"link target",
+                 {{"_id", PropertyType::Int, Property::IsPrimary{true}}, {"value", PropertyType::Int}}},
             };
-            REQUIRE_EXCEPTION(schema.validate(SchemaValidationMode::SyncFLX), SchemaValidationFailed,
-                              ContainsSubstring("Asymmetric table with property 'object.link' of type 'object' "
-                                                "cannot have a non-embedded object type."));
+            REQUIRE_NOTHROW(schema.validate(SchemaValidationMode::SyncFLX));
         }
 
         SECTION("allow embedded objects with asymmetric sync") {

test/test_table.cpp

@@ -5898,8 +5898,8 @@ TEST(Table_AsymmetricObjects)
     tr = sg->start_write();
     auto table2 = tr->add_table("target table");
     table = tr->get_table("mytable");
-    // Outgoing link from asymmetric object is not allowed.
-    CHECK_THROW(table->add_column(*table2, "link"), LogicError);
+    // Outgoing link from asymmetric object is allowed.
+    CHECK_NOTHROW(table->add_column(*table2, "link"));
     // Incoming link to asymmetric object is not allowed.
     CHECK_THROW(table2->add_column(*table, "link"), LogicError);
     tr->commit();