// Internals
DbCommand CreateCommand(DbCommandDescriptor descriptor)
{
var cmd = _connection.CreateCommand();
var parameters = descriptor.Parameters;
if (parameters.Length > 0)
{
var paramNames = new string[parameters.Length];
for (var i = 0; i < parameters.Length; i++)
{
var name = _details.GetParamName(i);
paramNames[i] = name;
var p = cmd.CreateParameter();
p.ParameterName = name;
p.Value = parameters[i] ?? DBNull.Value;
cmd.Parameters.Add(p);
}
cmd.CommandText = String.Format(descriptor.Sql, paramNames);
}
else
{
cmd.CommandText = descriptor.Sql;
}
if (InTransaction)
{
cmd.Transaction = _txStack.Peek();
}
return(cmd);
}
IEnumerable <T> EnumerateRecords <T>(DbCommandDescriptor descriptor, Func <DbDataReader, T> converter)
{
using (var cmd = CreateCommand(descriptor)) {
QueryWillExecute(cmd);
using (var reader = cmd.ExecuteReader()) {
while (reader.Read())
{
yield return(converter(reader));
}
}
}
}
T CacheableRead <T>(bool singleCell, bool singleRow, bool useCache, string sql, object[] parameters, Func <DbCommandDescriptor, T> factory)
{
var descriptor = new DbCommandDescriptor((singleCell ? 1 : 0) + (singleRow ? 2 : 0), sql, parameters);
if (useCache && _cache.Contains(descriptor))
{
return((T)_cache.Get(descriptor));
}
var fresh = factory(descriptor);
if (useCache)
{
_cache.Put(descriptor, fresh);
}
else
{
_cache.Remove(descriptor);
}
return(fresh);
}
IDictionary <string, object> Row(DbCommandDescriptor descriptor)
{
return(EnumerateRecords(descriptor, RecordToDict).FirstOrDefault());
}
T[] Col <T>(DbCommandDescriptor descriptor)
{
return(EnumerateRecords(descriptor, GetFirstCellValue <T>).ToArray());
}
T Cell <T>(DbCommandDescriptor descriptor)
{
return(EnumerateRecords(descriptor, GetFirstCellValue <T>).FirstOrDefault());
}
IDictionary <string, object>[] Rows(DbCommandDescriptor descriptor)
{
return(EnumerateRecords(descriptor, RecordToDict).ToArray());
}