Merge pull request #395 from realm/al-is-valid

Add `realm.isValid()` to support checking for deleted objects

CHANGELOG.md

@@ -5,9 +5,11 @@ x.x.x Release notes (yyyy-MM-dd)
 
 ### Enhancements
 * Support for queries comparing optional properties to `null`
+* `object.isValid()` has been added to enable checking if an object has been deleted
 
 ### Bugfixes
-* None
+* When accessing an empty Results `undefined` is returned rather than throwing an exception
+* Accessing a deleted object throws a javascript exception rather than crashing
 
 0.11.1 Release notes (2016-3-29)
 =============================================================

lib/browser/index.js

@@ -23,7 +23,7 @@ import { keys, propTypes, objectTypes } from './constants';
 import Collection, * as collections from './collections';
 import List, { createList } from './lists';
 import Results, { createResults } from './results';
-import * as objects from './objects';
+import RealmObject, { createObject, registerConstructors, typeForConstructor } from './objects';
 import * as rpc from './rpc';
 import * as util from './util';
 
@@ -32,7 +32,7 @@ const listenersKey = Symbol();
 
 rpc.registerTypeConverter(objectTypes.LIST, createList);
 rpc.registerTypeConverter(objectTypes.RESULTS, createResults);
-rpc.registerTypeConverter(objectTypes.OBJECT, objects.create);
+rpc.registerTypeConverter(objectTypes.OBJECT, createObject);
 
 export default class Realm {
     constructor(config) {
@@ -62,7 +62,7 @@ export default class Realm {
 
         let realmId = rpc.createRealm(Array.from(arguments));
 
-        objects.registerConstructors(realmId, constructors);
+        registerConstructors(realmId, constructors);
 
         this[keys.id] = realmId;
         this[keys.realm] = realmId;
@@ -79,7 +79,7 @@ export default class Realm {
 
     create(type, ...args) {
         if (typeof type == 'function') {
-            type = objects.typeForConstructor(this[keys.realm], type);
+            type = typeForConstructor(this[keys.realm], type);
         }
 
         let method = util.createMethod(objectTypes.REALM, 'create', true);
@@ -88,7 +88,7 @@ export default class Realm {
 
     objects(type, ...args) {
         if (typeof type == 'function') {
-            type = objects.typeForConstructor(this[keys.realm], type);
+            type = typeForConstructor(this[keys.realm], type);
         }
 
         let method = util.createMethod(objectTypes.REALM, 'objects');
@@ -169,6 +169,9 @@ Object.defineProperties(Realm, {
     Results: {
         value: Results,
     },
+    Object: {
+        value: RealmObject,
+    },
     defaultPath: {
         get: util.getterForProperty('defaultPath'),
         set: util.setterForProperty('defaultPath'),

lib/browser/objects.js

@@ -18,15 +18,23 @@
 
 'use strict';
 
-import { keys } from './constants';
-import { getterForProperty, setterForProperty } from './util';
+import { keys, objectTypes } from './constants';
+import { getterForProperty, setterForProperty, createMethods } from './util';
 
 const registeredConstructors = {};
 
-export function create(realmId, info) {
+export default class RealmObject {
+}
+
+// Non-mutating methods:
+createMethods(RealmObject.prototype, objectTypes.OBJECT, [
+    'isValid',
+]);
+
+export function createObject(realmId, info) {
     let schema = info.schema;
     let constructor = (registeredConstructors[realmId] || {})[schema.name];
-    let object = constructor ? Object.create(constructor.prototype) : {};
+    let object = Object.create(constructor ? constructor.prototype : RealmObject.prototype);
 
     object[keys.realm] = realmId;
     object[keys.id] = info.id;

src/js_realm.hpp

@@ -231,11 +231,13 @@ inline typename T::Function Realm<T>::create_constructor(ContextType ctx) {
     FunctionType collection_constructor = ObjectWrap<T, CollectionClass<T>>::create_constructor(ctx);
     FunctionType list_constructor = ObjectWrap<T, ListClass<T>>::create_constructor(ctx);
     FunctionType results_constructor = ObjectWrap<T, ResultsClass<T>>::create_constructor(ctx);
+    FunctionType realm_object_constructor = ObjectWrap<T, RealmObjectClass<T>>::create_constructor(ctx);
 
     PropertyAttributes attributes = PropertyAttributes(ReadOnly | DontEnum | DontDelete);
     Object::set_property(ctx, realm_constructor, "Collection", collection_constructor, attributes);
     Object::set_property(ctx, realm_constructor, "List", list_constructor, attributes);
     Object::set_property(ctx, realm_constructor, "Results", results_constructor, attributes);
+    Object::set_property(ctx, realm_constructor, "Object", realm_object_constructor, attributes);
 
     return realm_constructor;
 }
@@ -469,7 +471,7 @@ void Realm<T>::write(ContextType ctx, ObjectType this_object, size_t argc, const
     }
     catch (std::exception &e) {
         realm->cancel_transaction();
-        throw e;
+        throw;
     }
 
     realm->commit_transaction();

src/js_realm_object.hpp

@@ -46,6 +46,8 @@ class RealmObject {
     static void get_property(ContextType, ObjectType, const String &, ReturnValue &);
     static bool set_property(ContextType, ObjectType, const String &, ValueType);
     static std::vector<String> get_property_names(ContextType, ObjectType);
+    
+    static void is_valid(ContextType, ObjectType, size_t, const ValueType [], ReturnValue &);
 };
 
 template<typename T>
@@ -59,8 +61,17 @@ struct RealmObjectClass : ClassDefinition<T, realm::Object> {
         wrap<RealmObject::set_property>,
         wrap<RealmObject::get_property_names>,
     };
+
+    MethodMap<T> const methods = {
+        {"isValid", wrap<RealmObject::is_valid>},
+    };
 };
 
+template<typename T>
+void RealmObject<T>::is_valid(ContextType ctx, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
+    return_value.set(get_internal<T, RealmObjectClass<T>>(this_object)->is_valid());
+}
+    
 template<typename T>
 typename T::Object RealmObject<T>::create_instance(ContextType ctx, realm::Object &realm_object) {
     static String prototype_string = "prototype";

src/js_types.hpp

@@ -104,7 +104,7 @@ struct Value {
     static return_t validated_to_##type(ContextType ctx, const ValueType &value, const char *name = nullptr) { \
         if (!is_##type(ctx, value)) { \
             std::string prefix = name ? std::string("'") + name + "'" : "JS value"; \
-            throw std::invalid_argument(prefix + " must be: " #type); \
+            throw std::invalid_argument(prefix + " must be of type: " #type); \
         } \
         return to_##type(ctx, value); \
     }

src/object-store/src/object_accessor.hpp

@@ -48,6 +48,8 @@ namespace realm {
         const ObjectSchema &get_object_schema() { return *m_object_schema; }
         Row row() { return m_row; }
 
+        bool is_valid() const { return m_row.is_attached(); }
+
     private:
         SharedRealm m_realm;
         const ObjectSchema *m_object_schema;
@@ -57,6 +59,8 @@ namespace realm {
         inline void set_property_value_impl(ContextType ctx, const Property &property, ValueType value, bool try_update);
         template<typename ValueType, typename ContextType>
         inline ValueType get_property_value_impl(ContextType ctx, const Property &property);
+        
+        inline void verify_attached();
     };
 
     //
@@ -109,6 +113,13 @@ namespace realm {
         static Mixed to_mixed(ContextType ctx, ValueType &val) { throw std::runtime_error("'Any' type is unsupported"); }
     };
 
+    class InvalidatedObjectException : public std::runtime_error
+    {
+      public:
+        InvalidatedObjectException(const std::string object_type, const std::string message) : std::runtime_error(message), object_type(object_type) {}
+        const std::string object_type;
+    };
+    
     class InvalidPropertyException : public std::runtime_error
     {
       public:
@@ -161,6 +172,8 @@ namespace realm {
     {
         using Accessor = NativeAccessor<ValueType, ContextType>;
 
+        verify_attached();
+
         if (!m_realm->is_in_transaction()) {
             throw MutationOutsideTransactionException("Can only set property values within a transaction.");
         }
@@ -225,6 +238,8 @@ namespace realm {
     {
         using Accessor = NativeAccessor<ValueType, ContextType>;
 
+        verify_attached();
+
         size_t column = property.table_column;
         if (property.is_nullable && m_row.is_null(column)) {
             return Accessor::null_value(ctx);
@@ -324,6 +339,14 @@ namespace realm {
         }
         return object;
     }
+    
+    inline void Object::verify_attached() {
+        if (!m_row.is_attached()) {
+            throw InvalidatedObjectException(m_object_schema->name,
+                "Accessing object of type " + m_object_schema->name + " which has been deleted"
+            );
+        }
+    }
 
     //
     // List implementation

tests/js/object-tests.js

@@ -431,5 +431,29 @@ module.exports = BaseTest.extend({
                 object.dataCol = [1];
             });
         });
-    }
+    },
+
+    testObjectConstructor: function() {
+        var realm = new Realm({schema: [schemas.TestObject]});
+        realm.write(function() {
+            var obj = realm.create('TestObject', {doubleCol: 1});
+            TestCase.assertTrue(obj instanceof Realm.Object);
+        });
+    },
+
+    testIsValid: function() {
+        var realm = new Realm({schema: [schemas.TestObject]});
+        var obj;
+        realm.write(function() {
+            obj = realm.create('TestObject', {doubleCol: 1});
+            TestCase.assertEqual(obj.isValid(), true);
+            realm.delete(obj);
+            TestCase.assertEqual(obj.isValid(), false);
+        });
+
+        TestCase.assertEqual(obj.isValid(), false);
+        TestCase.assertThrows(function() {
+            obj.doubleCol;
+        });
+    },
 });

tests/js/results-tests.js

@@ -50,6 +50,8 @@ module.exports = BaseTest.extend({
 
     testResultsSubscript: function() {
         var realm = new Realm({schema: [schemas.PersonObject]});
+        TestCase.assertEqual(realm.objects('PersonObject')[0], undefined);
+        
         realm.write(function() {
             realm.create('PersonObject', {name: 'name1', age: 1});
             realm.create('PersonObject', {name: 'name2', age: 2});