Skip to main content
Tab

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

public virtual DateTime GetLastWriteTime(
    FileManagerFile file
)

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();
        }
    }
}

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the GetLastWriteTime(FileManagerFile) method.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

See Also