/// <summary>
/// Sets the enumerator to its initial position, which is before the first element in the collection.
/// </summary>
public void Reset()
{
if (this.database != null)
{
lock (this.database.IsamSession)
{
if (this.cleanup)
{
if (!this.database.IsamSession.Disposed)
{
// BUGBUG: we will try to close an already closed tableid
// if it was already closed due to a rollback. this could
// cause us to crash in ESENT due to lack of full validation
// in small config. we should use cursor LS to detect when
// our cursor gets closed and thus avoid closing it again
Api.JetCloseTable(this.database.IsamSession.Sesid, this.columnList.tableid);
}
}
this.cleanup = false;
this.moved = false;
this.current = false;
this.columnDefinition = null;
}
}
else
{
this.enumerator.Reset();
}
}
/// <summary>
/// Adds the specified column definition.
/// </summary>
/// <param name="columnDefinition">The column definition.</param>
public void Add(ColumnDefinition columnDefinition)
{
Dictionary.Add(columnDefinition.Name.ToLower(CultureInfo.InvariantCulture), columnDefinition);
}
/// <summary>
/// Advances the enumerator to the next element of the collection.
/// </summary>
/// <returns>
/// true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection.
/// </returns>
public bool MoveNext()
{
if (this.database != null)
{
lock (this.database.IsamSession)
{
JET_SESID sesid = this.database.IsamSession.Sesid;
if (!this.moved)
{
Api.JetGetColumnInfo(sesid, this.database.Dbid, this.tableName, null, out this.columnList);
this.cleanup = true;
this.current = Api.TryMoveFirst(sesid, this.columnList.tableid);
}
else if (this.current)
{
this.current = Api.TryMoveNext(sesid, this.columnList.tableid);
if (!this.current)
{
Api.JetCloseTable(sesid, this.columnList.tableid);
this.cleanup = false;
}
}
this.moved = true;
this.columnDefinition = null;
return this.current;
}
}
else
{
return this.enumerator.MoveNext();
}
}
/// <summary>
/// Fetches the Column Definition for the specified columnid.
/// </summary>
/// <value>
/// The <see cref="ColumnDefinition"/> for the specifed column identifier
/// </value>
/// <param name="columnid">The columnid.</param>
/// <returns>The <see cref="ColumnDefinition"/> for the specified column identifier.</returns>
public ColumnDefinition this[Columnid columnid]
{
get
{
if (this.database != null)
{
lock (this.database.IsamSession)
{
if (this.cachedColumnDefinition != columnid.Name.ToLower(CultureInfo.InvariantCulture)
|| this.columnUpdateID != DatabaseCommon.SchemaUpdateID)
{
JET_COLUMNBASE columnBase;
Api.JetGetColumnInfo(
this.database.IsamSession.Sesid,
this.database.Dbid,
this.tableName,
columnid.Name,
out columnBase);
this.columnDefinition = ColumnDefinition.Load(this.database, this.tableName, columnBase);
this.cachedColumnDefinition = columnid.Name.ToLower(CultureInfo.InvariantCulture);
this.columnUpdateID = DatabaseCommon.SchemaUpdateID;
}
return this.columnDefinition;
}
}
else
{
return (ColumnDefinition)this.Dictionary[columnid.Name.ToLower(CultureInfo.InvariantCulture)];
}
}
}
/// <summary>
/// Creates a <see cref="ColumnDefinition"/> object representing the column passed in by <paramref name="columnBase"/>.
/// </summary>
/// <param name="database">The database.</param>
/// <param name="tableName">Name of the table.</param>
/// <param name="columnBase">The <see cref="JET_COLUMNBASE"/> object that represents this particular column.</param>
/// <returns>
/// A <see cref="ColumnDefinition"/> object based on the <paramref name="columnBase"/> object.
/// </returns>
internal static ColumnDefinition Load(IsamDatabase database, string tableName, JET_COLUMNBASE columnBase)
{
lock (database.IsamSession)
{
using (IsamTransaction trx = new IsamTransaction(database.IsamSession))
{
JET_SESID sesid = database.IsamSession.Sesid;
// load info for the column
ColumnDefinition columnDefinition = new ColumnDefinition();
columnDefinition.columnid = new Columnid(columnBase);
columnDefinition.name = columnDefinition.columnid.Name;
columnDefinition.type = columnDefinition.columnid.Type;
columnDefinition.flags = ColumnFlagsFromGrbits(columnBase.grbit);
columnDefinition.maxLength = (int)columnBase.cbMax;
columnDefinition.IsAscii = columnBase.cp == JET_CP.ASCII;
// there is currently no efficient means to retrieve the
// default value of a specific column from JET. so, we are
// going to reach into the catalog and fetch it directly
JET_TABLEID tableidCatalog;
Api.JetOpenTable(
sesid,
database.Dbid,
"MSysObjects",
null,
0,
OpenTableGrbit.ReadOnly,
out tableidCatalog);
Api.JetSetCurrentIndex(sesid, tableidCatalog, "RootObjects");
Api.MakeKey(sesid, tableidCatalog, true, MakeKeyGrbit.NewKey);
Api.MakeKey(
sesid,
tableidCatalog,
Converter.BytesFromObject(JET_coltyp.Text, true, columnBase.szBaseTableName),
MakeKeyGrbit.None);
Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ);
JET_COLUMNBASE columnbaseCatalog;
Api.JetGetTableColumnInfo(sesid, tableidCatalog, "ObjidTable", out columnbaseCatalog);
uint objidTable = Api.RetrieveColumnAsUInt32(sesid, tableidCatalog, columnbaseCatalog.columnid).GetValueOrDefault();
Api.JetSetCurrentIndex(sesid, tableidCatalog, "Name");
Api.MakeKey(sesid, tableidCatalog, objidTable, MakeKeyGrbit.NewKey);
Api.MakeKey(sesid, tableidCatalog, (short)2, MakeKeyGrbit.None);
Api.MakeKey(sesid, tableidCatalog, columnBase.szBaseColumnName, Encoding.ASCII, MakeKeyGrbit.None);
Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ);
Api.JetGetTableColumnInfo(sesid, tableidCatalog, "DefaultValue", out columnbaseCatalog);
byte[] defaultValueBytes = Api.RetrieveColumn(sesid, tableidCatalog, columnbaseCatalog.columnid);
Columnid isamColumnid = columnDefinition.columnid;
columnDefinition.defaultValue = Converter.ObjectFromBytes(
isamColumnid.Coltyp,
columnDefinition.IsAscii,
defaultValueBytes);
columnDefinition.ReadOnly = true;
return columnDefinition;
}
}
}
/// <summary>
/// Creates a <see cref="ColumnDefinition"/> object representing the column passed in by <paramref name="columnList"/>.
/// </summary>
/// <param name="database">The database.</param>
/// <param name="tableName">Name of the table.</param>
/// <param name="columnList">The <see cref="JET_COLUMNLIST"/> object that represents the row in
/// the temptable for this particular column.</param>
/// <returns>
/// A <see cref="ColumnDefinition"/> object based on the current row in the temptable
/// represented by <paramref name="columnList"/>.
/// </returns>
internal static ColumnDefinition Load(IsamDatabase database, string tableName, JET_COLUMNLIST columnList)
{
lock (database.IsamSession)
{
using (IsamTransaction trx = new IsamTransaction(database.IsamSession))
{
// load info for the column
ColumnDefinition columnDefinition = new ColumnDefinition();
JET_SESID sesid = database.IsamSession.Sesid;
// If we use the wide API (Vista+), then the temp table will be in UTF-16.
// Technically, this should have worked in Vista. But there was a bug, and
// it was fixed after Windows 7.
Encoding encodingOfTextColumns = EsentVersion.SupportsWindows8Features
? Encoding.Unicode
: Encoding.ASCII;
string columnName = Api.RetrieveColumnAsString(
database.IsamSession.Sesid,
columnList.tableid,
columnList.columnidcolumnname,
encodingOfTextColumns);
JET_COLUMNBASE columnbase;
Api.JetGetColumnInfo(database.IsamSession.Sesid, database.Dbid, tableName, columnName, out columnbase);
columnDefinition.columnid = new Columnid(columnbase);
columnDefinition.name = columnDefinition.columnid.Name;
columnDefinition.type = columnDefinition.columnid.Type;
ColumndefGrbit grbitColumn = (ColumndefGrbit)Api.RetrieveColumnAsUInt32(sesid, columnList.tableid, columnList.columnidgrbit).GetValueOrDefault();
columnDefinition.flags = ColumnFlagsFromGrbits(grbitColumn);
columnDefinition.maxLength = Api.RetrieveColumnAsInt32(sesid, columnList.tableid, columnList.columnidcbMax).GetValueOrDefault();
columnDefinition.IsAscii = columnbase.cp == JET_CP.ASCII;
byte[] defaultValueBytes = Api.RetrieveColumn(sesid, columnList.tableid, columnList.columnidDefault);
Columnid isamColumnid = columnDefinition.columnid;
columnDefinition.defaultValue = Converter.ObjectFromBytes(
isamColumnid.Coltyp,
columnDefinition.IsAscii,
defaultValueBytes);
columnDefinition.ReadOnly = true;
return columnDefinition;
}
}
}
/// <summary>
/// Sets the column.
/// </summary>
/// <param name="columnDefinition">The column definition.</param>
/// <param name="index">The index.</param>
/// <param name="obj">The object.</param>
private void SetColumn(ColumnDefinition columnDefinition, int index, object obj)
{
lock (this.isamSession)
{
this.cursor.CheckDisposed();
using (IsamTransaction trx = new IsamTransaction(this.isamSession, true))
{
Columnid columnid = columnDefinition.Columnid;
this.SetColumn(columnid.InteropColumnid, columnid.Coltyp, columnid.IsAscii, index, obj);
trx.Commit();
}
}
}
/// <summary>
/// Retrieves the column.
/// </summary>
/// <param name="columnDefinition">The column definition.</param>
/// <param name="index">The index.</param>
/// <returns>The value stored within.</returns>
private object RetrieveColumn(ColumnDefinition columnDefinition, int index)
{
lock (this.isamSession)
{
this.cursor.CheckDisposed();
using (IsamTransaction trx = new IsamTransaction(this.isamSession, true))
{
Columnid columnid = columnDefinition.Columnid;
return this.RetrieveColumn(columnid.InteropColumnid, columnid.Coltyp, columnid.IsAscii, index);
}
}
}
