Indexeddb添加新值，而不是更新现有值

当尝试使用put方法更新indexeddb中的记录时，似乎创建了一个新值而不是更改。根据MDN这是更新记录的方法，但我没有得到预期的结果。什么好主意吗?下面是我的代码示例。

/*
    @keys initalisation
*/
extension.onupgradeneeded = function (event) {
    database = event.target.result;
    if (!database.objectStoreNames.contains('profile')) {
        var _profile = database.createObjectStore('profile', { autoIncrement: true });
        _profile.createIndex('default', 'default', { unique: true });
        _profile.createIndex('username', 'username', { unique: true });
        _profile.transaction.oncomplete = function (_oncompleteEvent) {
             app.database.store(database, 'profile', {
                default: true,
                username: 'my name', 
                image: 'images/svg/menu.svg' 
             });
        };
}
var app = {
    database: {
        update: function (_database, _datakeys, _key, _value, _function) {
            /*
                @pass database object, array / string, string, object, callback
            */
            var _updateRequest = _database.transaction(_datakeys, "readwrite").objectStore(_key).put(_value);
            _updateRequest.onerror = function (event) {
                try {
                    _function.error(event);
                } catch(err) {
                    console.log('An error was encountered', event.target.error.name);
                }
            };
            _updateRequest.onsuccess = function (event) {
                try {
                    _function.success(event);
                } catch (error) {
                    _function(event);
                }
            };
        }
    }
};
/*
    @how I call the function
*/
app.database.update(database, 'profile', 'profile', {default: false, username: 'hello world', image: 'http://imagepath.com' }, {
    error: function () {
        alert('failed');
    },
    success: function (returnedData) {
        console.log(returnedData);
    }
);