private void viewBtn_Click(object sender, EventArgs e)
{
ClearDisplay();
// open database and read records back - the database is transactional
Env env = new Env(EnvCreateFlags.None);
try {
DbBTree btree;
Env.OpenFlags envFlags =
Env.OpenFlags.Create |
Env.OpenFlags.InitLock |
Env.OpenFlags.InitLog |
Env.OpenFlags.InitMPool |
Env.OpenFlags.InitTxn |
Env.OpenFlags.Recover;
env.Open(homeDir, envFlags, 0);
Db db = env.CreateDatabase(DbCreateFlags.None);
Txn txn = env.TxnBegin(null, Txn.BeginFlags.None);
DbFile tmpDb =
db.Open(txn, Path.Combine(homeDir, myDb), null, DbType.Unknown, Db.OpenFlags.None, 0);
txn.Commit(Txn.CommitMode.None);
if (tmpDb.DbType == DbType.BTree)
{
btree = (DbBTree)tmpDb;
}
else
{
throw new ApplicationException("Unexpected database type.");
}
List <Customer> custList = new List <Customer>();
// DbBTreeCursor implements IDisposable - will be closed through "using"
using (DbBTreeCursor cursor = btree.OpenCursor(null, DbFileCursor.CreateFlags.None)) {
Customer cust = null;
while (GetNextRecord(cursor, ref cust))
{
custList.Add(cust);
}
}
db.Close();
DataGridViewColumn nameCol = new DataGridViewTextBoxColumn();
nameCol.Name = "NameCol";
nameCol.HeaderText = "Name";
nameCol.DataPropertyName = "Name";
dataGridView.Columns.Add(nameCol);
dataGridView.DataSource = custList;
tabControl.SelectTab("dataPage");
}
catch (Exception ex) {
errBox.Text = ex.ToString();
tabControl.SelectTab("errorPage");
}
finally {
env.Close();
}
}
private List <StockItem> ReadStockItems(Vendor vendor)
{
Databases dbs = Databases.Instance;
List <StockItem> items = new List <StockItem>();
DbBTreeCursor cursor = dbs.VendorNameIdx.OpenCursor(null, DbFileCursor.CreateFlags.None);
try {
DbEntry secKeyEntry = dbs.Fmt.ToDbEntry <string>(vendor.Name);
#if false
// same as below, but using standard cursor methods
DbEntry keyEntry = DbEntry.Out(keyBuffer);
DbEntry dataEntry = DbEntry.Out(dataBuffer);
ReadStatus status;
status = cursor.PGetAt(ref secKeyEntry, ref keyEntry, ref dataEntry,
DbcFile.GetAtMode.Set, DbcFile.ReadFlags.None);
// we are not checking for ReadStatus.BufferSmall, but maybe we should
while (status == ReadStatus.Success)
{
StockItem item = null;
index = dataEntry.Start;
dbs.Formatter.Deserialize <StockItem>(ref item, dataEntry.Buffer, ref index);
items.Add(item);
status = cursor.PGet(ref secKeyEntry, ref keyEntry, ref dataEntry,
DbcFile.GetMode.NextDup, DbcFile.ReadFlags.None);
}
#endif
#if true
// same as above, but using a foreach loop (which closes the cursor automatically)
foreach (KeyDataPair entry in cursor.ItemsAt(ref secKeyEntry, DbFileCursor.ReadFlags.None))
{
StockItem item = null;
dbs.Fmt.FromDbEntry <StockItem>(ref item, ref entry.Data);
items.Add(item);
}
#endif
}
finally {
cursor.Close();
}
inventoryView.DataSource = null;
DataGridViewColumn col = new DataGridViewTextBoxColumn();
col.Name = "NameCol";
col.HeaderText = "Name";
col.DataPropertyName = "Name";
inventoryView.Columns.Add(col);
inventoryView.DataSource = items;
return(items);
}
private bool GetNextRecord(DbBTreeCursor cursor, ref Customer cust)
{
ReadStatus status;
// If we need to call SetLength further down, and that causes its value to
// increase, then it will clear all buffer content between the old and the
// new length, overwriting some of our data. So we set it to the maximum here.
keyStream.SetLength(keyStream.Capacity);
dataStream.SetLength(dataStream.Capacity);
// we base our DbEntry instances on the serialization stream buffers
DbEntry key = DbEntry.Out(keyStream.GetBuffer());
DbEntry data = DbEntry.Out(dataStream.GetBuffer());
do
{
status = cursor.Get(ref key, ref data, DbFileCursor.GetMode.Next, DbFileCursor.ReadFlags.None);
switch (status)
{
case ReadStatus.NotFound: return(false);
case ReadStatus.KeyEmpty: continue; // skip deleted records
case ReadStatus.BufferSmall:
if (key.Buffer.Length < key.Size)
{
keyStream.SetLength(key.Size);
key = DbEntry.Out(keyStream.GetBuffer());
}
if (data.Buffer.Length < data.Size)
{
dataStream.SetLength(data.Size);
data = DbEntry.Out(dataStream.GetBuffer());
}
continue;
case ReadStatus.Success:
dataStream.Position = 0;
dataStream.SetLength(data.Size);
cust = (Customer)formatter.Deserialize(dataStream);
return(true);
default:
return(false);
}
} while (true);
}
public IList <T> Lookup <T>(ICondition condition) where T : class
{
dbName = typeof(T).FullName;
initDatabase();
List <T> result = new List <T>( );
Txn trans = env.TxnBegin(null, Txn.BeginFlags.None);
switch (condition.Name)
{
case "SELECT_ALL":
using (DbBTreeCursor cursor = dbInstance.OpenCursor(null, DbFileCursor.CreateFlags.None)) {
T cust = null;
IEnumerable <KeyDataPair> lst = cursor.ItemsForward(false, DbFileCursor.ReadFlags.None);
foreach (KeyDataPair pair in lst)
{
using (MemoryStream mem = new MemoryStream(pair.Data.Buffer)) {
T t = (T)formatter.Deserialize(mem);
result.Add(t);
}
}
}
break;
case "SELECT_BY_CODE":
SelectByCodeCondition cond = condition as SelectByCodeCondition;
if (cond == null)
{
throw new InvalidDataException(String.Format("Invalid {0} condition", condition.Name));
}
foreach (int i in cond.HashCodes)
{
T t = null;
byte[] buf = new byte[1024];
MemoryStream key = new MemoryStream( );
MemoryStream value = new MemoryStream();
formatter.Serialize(key, i);
DbEntry dbKey = DbEntry.InOut(key.ToArray());
DbEntry dbVal = DbEntry.Out(buf);
while (true)
{
ReadStatus status =
dbInstance.GetExact(trans, ref dbKey, ref dbVal, DbFile.ReadFlags.None);
switch (status)
{
case ReadStatus.BufferSmall:
if (dbVal.Buffer.Length < dbVal.Size)
{
value.SetLength(dbVal.Size);
dbVal = DbEntry.Out(value.GetBuffer());
}
continue;
case ReadStatus.KeyEmpty:
goto brk;
case ReadStatus.NotFound:
goto brk;
case ReadStatus.Success:
value.Position = 0;
value.SetLength(dbVal.Size);
value.Write(dbVal.Buffer, 0, dbVal.Size);
value.Flush();
value.Seek(0, SeekOrigin.Begin);
t = (T)formatter.Deserialize(value);
result.Add(t);
key.Dispose();
value.Dispose();
break;
}
}
brk :;
}
break;
default:
throw new NotImplementedException(String.Format("Condition {0} is not implemented", condition.Name));
}
trans.Commit(Txn.CommitMode.Sync);
env.Close();
return(result);
}
