Merge pull request #1660 from realm/jas/backlink-queries

Preliminary work for queries over named backlinks

CHANGELOG.md

@@ -7,13 +7,15 @@
 
 ### Enhancements
 * [Sync] Reduced initial download times in Realms with long transaction histories.
-* [Sync] Wait for pending notifications to complete when removing a sync listener (1648).
+* [Sync] Wait for pending notifications to complete when removing a sync listener (#1648).
 * Enabled sort and distinct in the query string. If sort or distinct are also applied outside of the query string, the conditions are stacked.
   - Example syntax: `age > 20 SORT(name ASC, age DESC) DISTINCT(name)`
   - The ordering for sorting can be one of the following case insensitive literals: `ASC`, `ASCENDING`, `DESC`, `DESCENDING`.
   - Any number of properties can appear inside the brackets in a comma separated list.
   - Any number of sort/distinct conditions can be indicated, they will be applied in the specified order.
   - Sort or distinct cannot operate independently, these conditions must be attached to at least one query filter.
+* Added support for queries over named backlinks (#1498/#1660).
+  - Example syntax: `parents.age > 25` and `parents.@count == 2`.
 * [Sync] Added `Realm.Results.subscribe()` to subscribe to partial synced Realms.
 * [Sync] Added class `Realm.Sync.Subscription` and enum `Realm.Sync.SubscriptionState` to support partial synced Realms.
 * [Sync] Added an object-level permission subsystem. It is possible to grant fine-grained priviliges to users.

src/js_results.hpp

@@ -152,6 +152,21 @@ typename T::Object ResultsClass<T>::create_instance(ContextType ctx, SharedRealm
     return create_object<T, ResultsClass<T>>(ctx, new realm::js::Results<T>(realm, *table));
 }
 
+inline void alias_backlinks(parser::KeyPathMapping &mapping, const realm::SharedRealm &realm)
+{
+    const realm::Schema &schema = realm->schema();
+    for (auto it = schema.begin(); it != schema.end(); ++it) {
+        for (const Property &property : it->computed_properties) {
+            if (property.type == realm::PropertyType::LinkingObjects) {
+                auto target_object_schema = schema.find(property.object_type);
+                const TableRef table = ObjectStore::table_for_object_type(realm->read_group(), target_object_schema->name);
+                std::string native_name = "@links." + std::string(table->get_name()) + "." + property.link_origin_property_name;
+                mapping.add_mapping(table, property.name, native_name);
+            }
+        }
+    }
+}
+
 template<typename T>
 template<typename U>
 typename T::Object ResultsClass<T>::create_filtered(ContextType ctx, const U &collection, Arguments args) {
@@ -164,11 +179,13 @@ typename T::Object ResultsClass<T>::create_filtered(ContextType ctx, const U &co
     auto const &realm = collection.get_realm();
     auto const &object_schema = collection.get_object_schema();
     DescriptorOrdering ordering;
+    parser::KeyPathMapping mapping;
+    alias_backlinks(mapping, realm);
 
     parser::ParserResult result = parser::parse(query_string);
     NativeAccessor<T> accessor(ctx, realm, object_schema);
     query_builder::ArgumentConverter<ValueType, NativeAccessor<T>> converter(accessor, &args.value[1], args.count - 1);
-    query_builder::apply_predicate(query, result.predicate, converter);
+    query_builder::apply_predicate(query, result.predicate, converter, mapping);
     query_builder::apply_ordering(ordering, query.get_table(), result.ordering);
 
     return create_instance(ctx, collection.filter(std::move(query)).apply_ordering(std::move(ordering)));

tests/js/linkingobjects-tests.js

@@ -83,6 +83,26 @@ module.exports = {
         TestCase.assertArraysEqual(names(resultsC), ['JP']);
     },
 
+    testFilteredLinkingObjectsByName: function() {
+        var realm = new Realm({schema: [schemas.PersonObject]});
+
+        var christine, olivier;
+        realm.write(function() {
+            olivier = realm.create('PersonObject', {name: 'Olivier', age: 0});
+            christine = realm.create('PersonObject', {name: 'Christine', age: 25, children: [olivier]});
+            realm.create('PersonObject', {name: 'JP', age: 28, children: [olivier]});
+        });
+
+        let people = realm.objects('PersonObject')
+
+        TestCase.assertEqual(people.filtered('parents.age > 25').length, 1);
+        TestCase.assertEqual(people.filtered('parents.age > 25')[0].name, 'Olivier');
+        TestCase.assertEqual(people.filtered('parents.@count == 2').length, 1);
+        TestCase.assertEqual(people.filtered('parents.name CONTAINS[c] "chris"').length, 1);
+        TestCase.assertEqual(people.filtered('parents.name.@size == 2').length, 1);
+        TestCase.assertEqual(people.filtered('25 IN parents.age').length, 1);
+    },
+
     testMethod: function() {
         var realm = new Realm({schema: [schemas.PersonObject]});