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using System;
using System.Data;
using System.Globalization;
namespace DotNetDataProviderTemplate
{
public class TemplateDataReader : IDataReader
{
// The DataReader should always be open when
returned to the user.
private bool m_fOpen = true;
// Keep track of the results and position
// within the resultset (starts prior to first
record).
private SampleDb.SampleDbResultSet
m_resultset;
private static int m_STARTPOS = -1;
private int m_nPos
= m_STARTPOS;
/*
* Keep track of the connection in order to
implement the
* CommandBehavior.CloseConnection flag. A
null reference means
* normal behavior (do not automatically
close).
*/
private TemplateConnection m_connection = null;
/*
* Because the user should not be able to
directly create a
* DataReader object, the constructors are
* marked as internal.
*/
internal
TemplateDataReader(SampleDb.SampleDbResultSet resultset)
{
m_resultset = resultset;
}
internal
TemplateDataReader(SampleDb.SampleDbResultSet resultset,
TemplateConnection connection)
{
m_resultset =
resultset;
m_connection = connection;
}
/****
* METHODS / PROPERTIES FROM IDataReader.
****/
public int Depth
{
/*
* Always return a value of zero
if nesting is not supported.
*/
get { return 0; }
}
public bool IsClosed
{
/*
* Keep track of the reader state
- some methods should be
* disallowed if the reader is
closed.
*/
get { return !m_fOpen; }
}
public int RecordsAffected
{
/*
* RecordsAffected is only
applicable to batch statements
* that include
inserts/updates/deletes. The sample always
* returns -1.
*/
get { return -1; }
}
public void Close()
{
/*
* Close the reader. The sample
only changes the state,
* but an actual implementation
would also clean up any
* resources used by the
operation. For example,
* cleaning up any resources
waiting for data to be
* returned by the server.
*/
m_fOpen = false;
}
public bool NextResult()
{
// The sample only returns a single
resultset. However,
// DbDataAdapter expects NextResult to
return a value.
return false;
}
public bool Read()
{
// Return true if it is possible to
advance and if you are still positioned
// on a valid row. Because the data
array in the resultset
// is two-dimensional, you must divide
by the number of columns.
if (++m_nPos >=
m_resultset.data.Length / m_resultset.metaData.Length)
return false;
else
return true;
}
public DataTable GetSchemaTable()
{
//$
throw new NotSupportedException();
}
/****
* METHODS / PROPERTIES FROM IDataRecord.
****/
public int FieldCount
{
// Return the count of the number of
columns, which in
// this case is the size of the column
metadata
// array.
get { return
m_resultset.metaData.Length; }
}
public String GetName(int i)
{
return m_resultset.metaData[i].name;
}
public String GetDataTypeName(int i)
{
/*
* Usually this would return the
name of the type
* as used on the back end, for
example 'smallint' or 'varchar'.
* The sample returns the simple
name of the .NET Framework type.
*/
return
m_resultset.metaData[i].type.Name;
}
public Type GetFieldType(int i)
{
// Return the actual Type class for the
data type.
return m_resultset.metaData[i].type;
}
public Object GetValue(int i)
{
return m_resultset.data[m_nPos, i];
}
public int GetValues(object[] values)
{
for (int i = 0; i < values.Length
&& i < m_resultset.metaData.Length; i++)
{
values[i] =
m_resultset.data[m_nPos, i];
}
return i;
}
public int GetOrdinal(string name)
{
// Look for the ordinal of the column
with the same name and return it.
for (int i = 0; i <
m_resultset.metaData.Length; i++)
{
if (0 == _cultureAwareCompare(name,
m_resultset.metaData[i].name))
{
return i;
}
}
// Throw an exception if the ordinal
cannot be found.
throw new
IndexOutOfRangeException("Could not find specified column in
results");
}
public object this [ int i ]
{
get { return m_resultset.data[m_nPos, i];
}
}
public object this [ String name ]
{
// Look up the ordinal and return
// the value at that position.
get { return this[GetOrdinal(name)]; }
}
public bool GetBoolean(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (bool)m_resultset.data[m_nPos, i];
}
public byte GetByte(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (byte)m_resultset.data[m_nPos, i];
}
public long GetBytes(int i, long fieldOffset,
byte[] buffer, int bufferoffset, int length)
{
// The sample does not support this
method.
throw new
NotSupportedException("GetBytes not supported.");
}
public char GetChar(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (char)m_resultset.data[m_nPos, i];
}
public long GetChars(int i, long fieldoffset,
char[] buffer, int bufferoffset, int length)
{
// The sample does not support this
method.
throw new
NotSupportedException("GetChars not supported.");
}
public Guid GetGuid(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (Guid)m_resultset.data[m_nPos, i];
}
public Int16 GetInt16(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (Int16)m_resultset.data[m_nPos,
i];
}
public Int32 GetInt32(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (Int32)m_resultset.data[m_nPos,
i];
}
public Int64 GetInt64(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (Int64)m_resultset.data[m_nPos,
i];
}
public float GetFloat(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (float)m_resultset.data[m_nPos,
i];
}
public double GetDouble(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (double)m_resultset.data[m_nPos,
i];
}
public String GetString(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (String)m_resultset.data[m_nPos,
i];
}
public Decimal GetDecimal(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (Decimal)m_resultset.data[m_nPos,
i];
}
public DateTime GetDateTime(int i)
{
/*
* Force the cast to return the
type. InvalidCastException
* should be thrown if the data is
not already of the correct type.
*/
return (DateTime)m_resultset.data[m_nPos,
i];
}
public IDataReader GetData(int i)
{
/*
* The sample code does not
support this method. Normally,
* this would be used to expose
nested tables and
* other hierarchical data.
*/
throw new
NotSupportedException("GetData not supported.");
}
public bool IsDBNull(int i)
{
return m_resultset.data[m_nPos, i] ==
DBNull.Value;
}
/*
* Implementation specific methods.
*/
private int _cultureAwareCompare(string strA,
string strB)
{
return
CultureInfo.CurrentCulture.CompareInfo.Compare(strA, strB,
CompareOptions.IgnoreKanaType | CompareOptions.IgnoreWidth |
CompareOptions.IgnoreCase);
}
}
}
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