// Executes a query with a scalar result, i.e. a query that ends with a result operator such as Count, Sum, or Average.
public T ExecuteScalar <T>(QueryModel queryModel)
{
var visitor = new QueryVisitor(_collectionName, _collectionSchema);
visitor.VisitQueryModel(queryModel);
var expression = visitor.RootExpression;
_customAction?.Invoke(expression);
Dbg.Trace($"linq provider produced expression {expression}");
if (expression.CountOnly)
{
return((T)(object)_client.EvalQuery(expression).Item2);
}
throw new NotSupportedException("Only Count scalar method is implemented");
}
internal override IDataClient TryExecute(IDataClient client)
{
if (!CanExecute)
{
return(client);
}
Dbg.CheckThat(Params.Count == 2 || Params.Count == 1);
var result = new Tuple <bool, int>(false, 0);
try
{
Dbg.CheckThat(Query != null);
Profiler.IsActive = true;
Profiler.Start("COUNT");
result = client.EvalQuery(Query);
}
catch (CacheException ex)
{
Logger.WriteEror("Can not execute COUNT : {0} {1}", ex.Message, ex.ServerMessage);
}
catch (Exception ex)
{
Logger.WriteEror("Can not execute COUNT : {0}", ex.Message);
return(client);
}
finally
{
Profiler.End();
Logger.Write("Found {0} items. The call took {1:F4} miliseconds", result.Item2,
Profiler.TotalTimeMilliseconds);
}
return(client);
}
public static bool IsComplete <T>(this IDataClient @this, Expression <Func <T, bool> > where)
{
var query = PredicateToQuery(where);
return(@this.EvalQuery(query).Item1);
}
public static int Count <T>(this IDataClient @this, Expression <Func <T, bool> > where)
{
var query = PredicateToQuery(where);
return(@this.EvalQuery(query).Item2);
}
