Better SQL database performance / memory usage.

Rows accessible incrementally.
Rows.forwardOnly for optimization.

5 files changed, 109 insertions, 16 deletions

diff --git a/examples/declarative/sql/README b/examples/declarative/sql/README
new file mode 100644
index 0000000..a7baab2
--- /dev/null
+++ b/examples/declarative/sql/README
@@ -0,0 +1,7 @@
+Simple demonstration of HTML5-compatible SQL database interface.
+Adds another "hello, world" every time you run it.
+Database is stored in:
+ - %APPDATA%/Nokia/Qt/QML/Databases/ (Windows)
+ - ~/.local/share/Nokia/Qt/QML/Databases/ (Unix)
+ - ~/Library/Application Support/Nokia/Qt/QML/Databases/ (Mac OS X)
+No quota management.
diff --git a/examples/declarative/sql/hello.qml b/examples/declarative/sql/hello.qml
index fb6d21c..e43d320 100644
--- a/examples/declarative/sql/hello.qml
+++ b/examples/declarative/sql/hello.qml
@@ -2,10 +2,9 @@ import Qt 4.6
 
 Text {
     Script {
-        function test()
+        function allGreetings()
         {
             var db = openDatabase("QmlExampleDB", "", "The Example QML SQL!", 1000000);
-            print(db)
             var r = ""
 
             db.transaction(function(tx) {
@@ -13,9 +12,16 @@ Text {
                 tx.executeSql('INSERT INTO Greeting VALUES(?, ?)', [ 'hello', 'world' ]);
                 tx.executeSql('SELECT * FROM Greeting', [],
                     function(tx, rs) {
+                        /* Inefficient HTML5-compatible way
                         for(var i = 0; i < rs.rows.length; i++) {
                             r += rs.rows[i][0] + ", " + rs.rows[i][1] + "\n"
                         }
+                        */
+                        /* Efficient way: forward only, not "length" query */
+                        rs.rows.forwardOnly = true;
+                        for(var i = 0; rs.rows[i]; i++) {
+                            r += rs.rows[i][0] + ", " + rs.rows[i][1] + "\n"
+                        }
                     },
                     function(tx, error) {
                         print("ERROR:", error.message)
@@ -26,5 +32,5 @@ Text {
             return r
         }
     }
-    text: test()
+    text: allGreetings()
 }
diff --git a/src/declarative/qml/qmlengine.cpp b/src/declarative/qml/qmlengine.cpp
index efe1a89..c0dd1a8 100644
--- a/src/declarative/qml/qmlengine.cpp
+++ b/src/declarative/qml/qmlengine.cpp
@@ -111,7 +111,7 @@ QScriptValue desktopOpenUrl(QScriptContext *ctxt, QScriptEngine *e)
 QmlEnginePrivate::QmlEnginePrivate(QmlEngine *e)
 : rootContext(0), currentExpression(0),
   isDebugging(false), contextClass(0), objectClass(0), valueTypeClass(0),
-  nodeListClass(0), namedNodeMapClass(0), scriptEngine(this), rootComponent(0),
+  nodeListClass(0), namedNodeMapClass(0), sqlQueryClass(0), scriptEngine(this), rootComponent(0),
   networkAccessManager(0), typeManager(e), uniqueId(1)
 {
     QScriptValue qtObject =
@@ -156,6 +156,8 @@ QmlEnginePrivate::~QmlEnginePrivate()
     nodeListClass = 0;
     delete namedNodeMapClass;
     namedNodeMapClass = 0;
+    delete sqlQueryClass;
+    sqlQueryClass = 0;
 
     for(int ii = 0; ii < bindValues.count(); ++ii)
         clear(bindValues[ii]);
diff --git a/src/declarative/qml/qmlengine_p.h b/src/declarative/qml/qmlengine_p.h
index 15ab40d..0eeae0c 100644
--- a/src/declarative/qml/qmlengine_p.h
+++ b/src/declarative/qml/qmlengine_p.h
@@ -154,6 +154,8 @@ public:
     // Used by DOM Core 3 API
     QScriptClass *nodeListClass;
     QScriptClass *namedNodeMapClass;
+    // Used by SQL database API
+    QScriptClass *sqlQueryClass;
 
     struct QmlScriptEngine : public QScriptEngine
     {
diff --git a/src/declarative/qml/qmlsqldatabase.cpp b/src/declarative/qml/qmlsqldatabase.cpp
index 90d6e3e..4a7c3a3 100644
--- a/src/declarative/qml/qmlsqldatabase.cpp
+++ b/src/declarative/qml/qmlsqldatabase.cpp
@@ -65,6 +65,84 @@
 #endif
 
 Q_DECLARE_METATYPE(QSqlDatabase)
+Q_DECLARE_METATYPE(QSqlQuery)
+
+class QmlSqlQueryScriptClass: public QScriptClass {
+public:
+    QmlSqlQueryScriptClass(QScriptEngine *engine) : QScriptClass(engine)
+    {
+        str_length = engine->toStringHandle(QLatin1String("length"));
+        str_forwardOnly = engine->toStringHandle(QLatin1String("forwardOnly")); // not in HTML5 (optimization)
+    }
+
+    QueryFlags queryProperty(const QScriptValue &object,
+                             const QScriptString &name,
+                             QueryFlags flags, uint *id)
+    {
+        if (flags & HandlesReadAccess) {
+            if (name == str_length) {
+                return HandlesReadAccess;
+            } else if (name == str_forwardOnly) {
+                return flags;
+            } else {
+                bool ok;
+                qint32 pos = name.toString().toInt(&ok);
+                if (pos < 0 || !ok)
+                    return 0;
+                QSqlQuery query = qscriptvalue_cast<QSqlQuery>(object.data());
+                *id = pos;
+                if (*id < (uint)query.size())
+                    return HandlesReadAccess;
+            }
+        }
+        if (flags & HandlesWriteAccess)
+            if (name == str_forwardOnly)
+                return flags;
+        return 0;
+    }
+
+    QScriptValue property(const QScriptValue &object,
+                          const QScriptString &name, uint id)
+    {
+        QSqlQuery query = qscriptvalue_cast<QSqlQuery>(object.data());
+        if (name == str_length) {
+            int s = query.size();
+            if (s<0) {
+                // Inefficient.
+                query.last();
+                return query.at()+1;
+            } else {
+                return s;
+            }
+        } else if (name == str_forwardOnly) {
+            return query.isForwardOnly();
+        } else {
+            if (query.at() == id || query.seek(id)) { // Qt 4.6 doesn't optimize at()==id
+                QSqlRecord r = query.record();
+                QScriptValue row = engine()->newArray(r.count());
+                for (int j=0; j<r.count(); ++j) {
+                    // XXX only strings
+                    row.setProperty(j, QScriptValue(engine(),r.value(j).toString()));
+                }
+                return row;
+            }
+        }
+        return engine()->undefinedValue();
+    }
+
+    void setProperty(QScriptValue &object,
+                      const QScriptString &name, uint, const QScriptValue & value)
+    {
+        if (name == str_forwardOnly) {
+            QSqlQuery query = qscriptvalue_cast<QSqlQuery>(object.data());
+            query.setForwardOnly(value.toBool());
+        }
+    }
+
+private:
+    QScriptString str_length;
+    QScriptString str_forwardOnly;
+};
 
 static QScriptValue qmlsqldatabase_executeSql(QScriptContext *context, QScriptEngine *engine)
 {
@@ -85,18 +163,14 @@ static QScriptValue qmlsqldatabase_executeSql(QScriptContext *context, QScriptEn
             query.bindValue(0,values.toVariant());
         }
         if (query.exec()) {
-            QScriptValue rows = engine->newArray();
-            int i=0;
-            for (; query.next(); ++i) {
-                QSqlRecord r = query.record();
-                QScriptValue row = engine->newArray(r.count());
-                for (int j=0; j<r.count(); ++j) {
-                    row.setProperty(j, QScriptValue(engine,r.value(j).toString()));
-                }
-                rows.setProperty(i, row);
-            }
             QScriptValue rs = engine->newObject();
-            rs.setProperty(QLatin1String("rows"), rows);
+            if (!QmlEnginePrivate::get(engine)->sqlQueryClass)
+                QmlEnginePrivate::get(engine)->sqlQueryClass= new QmlSqlQueryScriptClass(engine);
+            QScriptValue rows = engine->newObject(QmlEnginePrivate::get(engine)->sqlQueryClass);
+            rows.setData(engine->newVariant(qVariantFromValue(query)));
+            rs.setProperty(QLatin1String("rows"),rows);
+            rs.setProperty(QLatin1String("rowsAffected"),query.numRowsAffected());
+            rs.setProperty(QLatin1String("insertId"),query.lastInsertId().toString()); // XXX only string
             cb.call(QScriptValue(), QScriptValueList() << context->thisObject() << rs);
         } else {
             err = true;
@@ -142,7 +216,7 @@ static QScriptValue qmlsqldatabase_transaction(QScriptContext *context, QScriptE
     return engine->undefinedValue();
 }
 
-// XXX Something like this belongs in Qt.
+// XXX Something like this should be exported by Qt.
 static QString userLocalDataPath(const QString& app)
 {
     QString result;
@@ -196,6 +270,8 @@ static QScriptValue qmlsqldatabase_open(QScriptContext *context, QScriptEngine *
     md5.addData(dbversion.utf8());
     QString dbid(QLatin1String(md5.result().toHex()));
 
+    // Uses SQLLITE (like HTML5), but any could be used.
+
     if (QSqlDatabase::connectionNames().contains(dbid)) {
         database = QSqlDatabase::database(dbid);
     } else {