| public UpdateIncrement ( string table, string column, int increment ) : string | ||
| table | string | The table. |
| column | string | The column to update. |
| increment | int | The increment or decrement value. |
| return | string | |
/// <summary>
/// Retrieves a Page Attachment.
/// </summary>
/// <param name="pageInfo">The Page Info that owns the Attachment.</param>
/// <param name="name">The name of the Attachment, for example "myfile.jpg".</param>
/// <param name="destinationStream">A Stream object used as <b>destination</b> of a byte stream,
/// i.e. the method writes to the Stream the file content.</param>
/// <param name="countHit">A value indicating whether or not to count this retrieval in the statistics.</param>
/// <returns><c>true</c> if the Attachment is retrieved, <c>false</c> otherwise.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="pageInfo"/>, <paramref name="name"/> or <paramref name="destinationStream"/> are <c>null</c>.</exception>
/// <exception cref="ArgumentException">If <paramref name="name"/> is empty or if <paramref name="destinationStream"/> does not support writing,
/// or if the page does not have attachments or if the attachment does not exist.</exception>
public bool RetrievePageAttachment(PageInfo pageInfo, string name, System.IO.Stream destinationStream, bool countHit)
{
if(pageInfo == null) throw new ArgumentNullException("pageInfo");
if(name == null) throw new ArgumentNullException("name");
if(name.Length == 0) throw new ArgumentException("Name cannot be empty", "name");
if(destinationStream == null) throw new ArgumentNullException("destinationStream");
if(!destinationStream.CanWrite) throw new ArgumentException("Cannot write into Destination Stream", "destinationStream");
ICommandBuilder builder = GetCommandBuilder();
DbConnection connection = builder.GetConnection(connString);
DbTransaction transaction = BeginTransaction(connection);
if(!AttachmentExists(transaction, pageInfo, name)) {
RollbackTransaction(transaction);
throw new ArgumentException("Attachment does not exist", "name");
}
QueryBuilder queryBuilder = new QueryBuilder(builder);
string query = queryBuilder.SelectFrom("Attachment", new string[] { "Size", "Data" });
query = queryBuilder.Where(query, "Name", WhereOperator.Equals, "Name");
query = queryBuilder.AndWhere(query, "Page", WhereOperator.Equals, "Page");
List<Parameter> parameters = new List<Parameter>(2);
parameters.Add(new Parameter(ParameterType.String, "Name", name));
parameters.Add(new Parameter(ParameterType.String, "Page", pageInfo.FullName));
DbCommand command = builder.GetCommand(transaction, query, parameters);
DbDataReader reader = ExecuteReader(command);
if(reader != null) {
bool done = false;
if(reader.Read()) {
int read = ReadBinaryColumn(reader, "Data", destinationStream);
done = (long)read == (long)reader["Size"];
}
CloseReader(reader);
if(!done) {
RollbackTransaction(transaction);
return false;
}
}
else {
RollbackTransaction(transaction);
return false;
}
if(countHit) {
// Update download count
query = queryBuilder.UpdateIncrement("Attachment", "Downloads", 1);
query = queryBuilder.Where(query, "Name", WhereOperator.Equals, "Name");
query = queryBuilder.AndWhere(query, "Page", WhereOperator.Equals, "Page");
parameters = new List<Parameter>(2);
parameters.Add(new Parameter(ParameterType.String, "Name", name));
parameters.Add(new Parameter(ParameterType.String, "Page", pageInfo.FullName));
command = builder.GetCommand(transaction, query, parameters);
int rows = ExecuteNonQuery(command, false);
if(rows != 1) {
RollbackTransaction(transaction);
return false;
}
}
CommitTransaction(transaction);
return true;
}
/// <summary>
/// Deletes the Backups of a Page, up to a specified revision.
/// </summary>
/// <param name="page">The Page to delete the backups of.</param>
/// <param name="revision">The newest revision to delete (newer revision are kept) o -1 to delete all the Backups.</param>
/// <returns><c>true</c> if the deletion succeeded, <c>false</c> otherwise.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="page"/> is <c>null</c>.</exception>
/// <exception cref="ArgumentOutOfRangeException">If <paramref name="revision"/> is less than -1.</exception>
public bool DeleteBackups(PageInfo page, int revision)
{
if(page == null) throw new ArgumentNullException("page");
if(revision < -1) throw new ArgumentOutOfRangeException("revision", "Invalid Revision");
// 1. Retrieve target content (revision-1 = first kept revision)
// 2. Replace the current content (delete, store)
// 3. Delete all older revisions up to the specified on (included) "N-m...N"
// 4. Re-number remaining revisions starting from FirstRevision (zero) to revision-1 (don't re-number revs -1, -100)
ICommandBuilder builder = GetCommandBuilder();
DbConnection connection = builder.GetConnection(connString);
DbTransaction transaction = BeginTransaction(connection);
if(GetPage(transaction, page.FullName) == null) {
RollbackTransaction(transaction);
return false;
}
int[] baks = GetBackups(transaction, page);
if(baks.Length > 0 && revision > baks[baks.Length - 1]) {
RollbackTransaction(transaction);
return true;
}
string nspace, name;
NameTools.ExpandFullName(page.FullName, out nspace, out name);
if(nspace == null) nspace = "";
QueryBuilder queryBuilder = new QueryBuilder(builder);
string query = queryBuilder.DeleteFrom("PageContent");
query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
if(revision != -1) query = queryBuilder.AndWhere(query, "Revision", WhereOperator.LessThanOrEqualTo, "Revision");
query = queryBuilder.AndWhere(query, "Revision", WhereOperator.GreaterThanOrEqualTo, "FirstRevision");
List<Parameter> parameters = new List<Parameter>(4);
parameters.Add(new Parameter(ParameterType.String, "Page", name));
parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));
if(revision != -1) parameters.Add(new Parameter(ParameterType.Int16, "Revision", revision));
parameters.Add(new Parameter(ParameterType.Int16, "FirstRevision", FirstRevision));
DbCommand command = builder.GetCommand(transaction, query, parameters);
int rows = ExecuteNonQuery(command, false);
if(rows == -1) {
RollbackTransaction(transaction);
return false;
}
if(revision != -1) {
int revisionDelta = revision + 1;
query = queryBuilder.UpdateIncrement("PageContent", "Revision", -revisionDelta);
query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
query = queryBuilder.AndWhere(query, "Revision", WhereOperator.GreaterThanOrEqualTo, "FirstRevision");
parameters = new List<Parameter>(3);
parameters.Add(new Parameter(ParameterType.String, "Page", name));
parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));
parameters.Add(new Parameter(ParameterType.Int16, "FirstRevision", FirstRevision));
command = builder.GetCommand(transaction, query, parameters);
rows = ExecuteNonQuery(command, false);
if(rows > 0) CommitTransaction(transaction);
else RollbackTransaction(transaction);
return rows >= 0;
}
else {
CommitTransaction(transaction);
return true;
}
}
