TPL Async Db w/ ServiceStack and Insight.Database

WagStackAsyncRepository.cs

    /*  WagStack
     *  
     *  TPL Async DAL using ServiceStack's Expression/SQL Building
     *  and Insight.Database's async features
     */


    public class WagStackAsyncRepository<T>:IAsyncRepository<T>
    {   
        static WagStackAsyncRepository()
        {
            OrmLiteConfig.DialectProvider = SqlServerDialect.Provider;
        }
        
        private WagStackUnitOfWork _U;
        
        public WagStackAsyncRepository(WagStackUnitOfWork u)
        {
            _U = u;
        }

        public System.Threading.Tasks.Task<IList<T>> Get()
        {
            var s = new SqlServerExpressionVisitor<T>();
            var sql = s.SelectExpression;
            return _U.Db.QueryAsync<T>(sql
                ,commandType:System.Data.CommandType.Text
                , transaction: _U.Transaction);
        }

        public Task<int> Insert(T item)
        {
            var sql = SqlServerOrmLiteDialectProvider.Instance.ToInsertRowStatement(item, null);
            return _U.Db.ExecuteAsync(sql ,commandType:System.Data.CommandType.Text
                , transaction: _U.Transaction);
        }

        public Task<int> Update(T item)
        {
            var sql = SqlServerOrmLiteDialectProvider.Instance.ToUpdateRowStatement(item);
            return _U.Db.ExecuteAsync(sql, commandType: System.Data.CommandType.Text
                , transaction: _U.Transaction);
        }

        public Task<int> Delete(T item)
        {
            var sql = SqlServerOrmLiteDialectProvider.Instance.ToDeleteRowStatement(item);
            return _U.Db.ExecuteAsync(sql ,commandType:System.Data.CommandType.Text
                , transaction: _U.Transaction);
        }

        public System.Threading.Tasks.Task<IList<T>> Where(string whereClause)
        {
            var s = new SqlServerExpressionVisitor<T>();
            var sql=string.Format("{0} {1}", s.SelectExpression, whereClause);
            return _U.Db.QueryAsync<T>(sql ,commandType:System.Data.CommandType.Text
                , transaction: _U.Transaction);
        }

        public System.Threading.Tasks.Task<IList<T>> Where(System.Linq.Expressions.Expression<Func<T, bool>> whereClause)
        {
            var s = new SqlServerExpressionVisitor<T>();
            var exp = s.Where(whereClause);
            var sql = string.Format("{0} {1}", s.SelectExpression, exp.WhereExpression);

            return _U.Db.QueryAsync<T>(sql ,commandType:System.Data.CommandType.Text
                , transaction: _U.Transaction);
        }