FileSystemProviderBase.GetLastWriteTime(FileManagerFile) Method
Override this method to implement getting the time of the last file modification.
Namespace: DevExpress.Web
Assembly: DevExpress.Web.v24.1.dll
NuGet Package: DevExpress.Web
Declaration
Parameters
| Name | Type | Description |
|---|---|---|
| file | FileManagerFile | A FileManagerFile object that is the processed file. |
Returns
| Type | Description |
|---|---|
| DateTime | A DateTime value that is the last write time. |
Remarks
If you create a custom file system provider inherited from the FileSystemProviderBase class, you can override the GetLastWriteTime method to get the time of the last file modification.
Example
using DevExpress.Web.ASPxFileManager;
using System.IO;
public class LinqFileSystemProvider : FileSystemProviderBase {
const int DbRootItemId = 1;
DbFileSystemDataContext dataContext;
Dictionary<int, DbFileSystemItem> folderCache;
string rootFolderDisplayName;
public LinqFileSystemProvider(string rootFolder)
: base(rootFolder) {
this.dataContext = new DbFileSystemDataContext();
RefreshFolderCache();
}
public DbFileSystemDataContext DataContext { get { return dataContext; } }
// Used to decrease the number of recursive LINQ to SQL queries made to a database
public Dictionary<int, DbFileSystemItem> FolderCache { get { return folderCache; } }
public override string RootFolderDisplayName { get { return rootFolderDisplayName; } }
public override IEnumerable<FileManagerFile> GetFiles(FileManagerFolder folder) {
DbFileSystemItem dbFolderItem = FindDbFolderItem(folder);
return
from dbItem in DataContext.DbFileSystemItems
where !dbItem.IsFolder && dbItem.ParentId == dbFolderItem.Id
select new FileManagerFile(this, folder, dbItem.Name);
}
public override IEnumerable<FileManagerFolder> GetFolders(FileManagerFolder parentFolder) {
DbFileSystemItem dbFolderItem = FindDbFolderItem(parentFolder);
return
from dbItem in FolderCache.Values
where dbItem.IsFolder && dbItem.ParentId == dbFolderItem.Id
select new FileManagerFolder(this, parentFolder, dbItem.Name);
}
public override bool Exists(FileManagerFile file) {
return FindDbFileItem(file) != null;
}
public override bool Exists(FileManagerFolder folder) {
return FindDbFolderItem(folder) != null;
}
public override System.IO.Stream ReadFile(FileManagerFile file) {
return new MemoryStream(FindDbFileItem(file).Data.ToArray());
}
public override DateTime GetLastWriteTime(FileManagerFile file) {
var dbFileItem = FindDbFileItem(file);
return dbFileItem.LastWriteTime.GetValueOrDefault(DateTime.Now);
}
// File/folder management operations
public override void CreateFolder(FileManagerFolder parent, string name) {
UpdateAndSubmitChanges(parent,
dbItem => DataContext.DbFileSystemItems.InsertOnSubmit(new DbFileSystemItem() {
IsFolder = true,
LastWriteTime = DateTime.Now,
Name = name,
ParentId = dbItem.Id
}));
}
public override void DeleteFile(FileManagerFile file) {
UpdateAndSubmitChanges(file, dbItem =>
DataContext.DbFileSystemItems.DeleteOnSubmit(dbItem));
}
public override void DeleteFolder(FileManagerFolder folder) {
UpdateAndSubmitChanges(folder, dbItem =>
DataContext.DbFileSystemItems.DeleteOnSubmit(dbItem));
}
public override void MoveFile(FileManagerFile file, FileManagerFolder newParentFolder) {
UpdateAndSubmitChanges(file, dbItem => dbItem.ParentId =
FindDbFolderItem(newParentFolder).Id);
}
public override void MoveFolder(FileManagerFolder folder, FileManagerFolder newParentFolder)
{
UpdateAndSubmitChanges(folder, dbItem => dbItem.ParentId =
FindDbFolderItem(newParentFolder).Id);
}
public override void RenameFile(FileManagerFile file, string name) {
UpdateAndSubmitChanges(file, dbItem => dbItem.Name = name);
}
public override void RenameFolder(FileManagerFolder folder, string name) {
UpdateAndSubmitChanges(folder, dbItem => dbItem.Name = name);
}
public override void UploadFile(FileManagerFolder folder, string fileName, Stream content) {
UpdateAndSubmitChanges(folder,
dbItem => DataContext.DbFileSystemItems.InsertOnSubmit(new DbFileSystemItem() {
Name = fileName,
Data = ReadAllBytes(content),
ParentId = dbItem.Id,
LastWriteTime = DateTime.Now,
IsFolder = false
}));
}
protected void UpdateAndSubmitChanges(FileManagerFile file, Action<DbFileSystemItem> update)
{
UpdateAndSubmitChangesCore(FindDbFileItem(file), update);
}
protected void UpdateAndSubmitChanges(FileManagerFolder folder, Action<DbFileSystemItem>
update) {
UpdateAndSubmitChangesCore(FindDbFolderItem(folder), update);
}
protected void UpdateAndSubmitChangesCore(DbFileSystemItem dbitem, Action<DbFileSystemItem>
update) {
update(dbitem);
DataContext.SubmitChanges();
RefreshFolderCache();
}
protected DbFileSystemItem FindDbFileItem(FileManagerFile file) {
DbFileSystemItem dbFolderItem = FindDbFolderItem(file.Folder);
if(dbFolderItem == null)
return null;
return
(from dbItem in DataContext.DbFileSystemItems
where dbItem.ParentId == dbFolderItem.Id && !dbItem.IsFolder && dbItem.Name ==
file.Name
select dbItem).FirstOrDefault();
}
protected DbFileSystemItem FindDbFolderItem(FileManagerFolder folder) {
return
(from dbItem in FolderCache.Values
where dbItem.IsFolder && GetRelativeName(dbItem) == folder.RelativeName
select dbItem).FirstOrDefault();
}
// Returns the path to a specified folder relative to a root folder
protected string GetRelativeName(DbFileSystemItem dbFolder) {
if(dbFolder.Id == DbRootItemId) return string.Empty;
if(dbFolder.ParentId == DbRootItemId) return dbFolder.Name;
if(!FolderCache.ContainsKey(dbFolder.ParentId)) return null;
string name = GetRelativeName(FolderCache[dbFolder.ParentId]);
return name == null ? null : Path.Combine(name, dbFolder.Name);
}
// Caches folder names in memory and obtains a root folder's name
protected void RefreshFolderCache() {
this.folderCache = (
from dbItem in DataContext.DbFileSystemItems
where dbItem.IsFolder
select dbItem
).ToDictionary(i => i.Id);
this.rootFolderDisplayName = (
from dbItem in FolderCache.Values
where dbItem.Id == DbRootItemId
select dbItem.Name).First();
}
protected static byte[] ReadAllBytes(Stream stream) {
byte[] buffer = new byte[16 * 1024];
int readCount;
using(MemoryStream ms = new MemoryStream()) {
while((readCount = stream.Read(buffer, 0, buffer.Length)) > 0) {
ms.Write(buffer, 0, readCount);
}
return ms.ToArray();
}
}
}
Related GitHub Examples
The following code snippet (auto-collected from DevExpress Examples) contains a reference to the GetLastWriteTime(FileManagerFile) method.
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See Also