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FileSystemProviderBase.ReadFile(FileManagerFile) Method

Override this method to implement file reading.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v21.1.dll

Declaration

public virtual Stream ReadFile(
    FileManagerFile file
)

Parameters

Name Type Description
file FileManagerFile

A FileManagerFile object that is the processed file.

Returns

Type Description
Stream

A Stream object that points to the processed file.

Remarks

If you create a custom file system provider inherited from the FileSystemProviderBase class, you should override the ReadFile method to implement file reading.

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) {