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FileManager Events

This article explains the events available in the Telerik FileManager for Blazor. They are grouped logically.

CUD Events

The OnCreate, OnUpdate and OnDelete events let you get the data item that the user changed so you can transfer the user action to the actual data source.

The OnEdit event let you respond to user actions - when they want to edit an item. See the example.

OnCreate

The OnCreate event fires when a new item is created (new folder). Its event handler receives the updated FileManagerCreateEventArgs as an argument.

OnUpdate

The OnUpdate event fires when a file is updated (rename finishes). Its event handler receives the updated FileManagerUpdateEventArgs as an argument.

OnEdit

The OnEdit event fires when the user is about to enter edit mode for an existing item. Its event handler receives the updated FileManagerEditEventArgs as an argument.

OnDelete

The OnDelete event fires when a file is deleted. Its event handler receives the updated FileManagerDeleteEventArgs as an argument.

Read Event

In the common case, all the data is provided to the filemanager's Data collection and the FileManager performs the operations on it for you. In some cases, you may want to do this programmatically (for example, to retrieve only a small number of items to improve the backend performance). Attach the OnRead event to perform all the data read operations programmatically in the FileManager.

The OnRead event fires when the data source is read. Its event handler receives the updated FileManagerReadEventArgs as an argument.

Handle OnRead.

<TelerikFileManager Data="@Data"
                    @bind-Path="@DirectoryPath"
                    Height="400px"
                    IdField="MyModelId"
                    NameField="Name"
                    SizeField="Size"
                    PathField="Path"
                    ExtensionField="Extension"
                    IsDirectoryField="IsDirectory"
                    HasDirectoriesField="HasDirectories"
                    ParentIdField="ParentId"
                    DateCreatedField="DateCreated"
                    DateCreatedUtcField="DateCreatedUtc"
                    DateModifiedField="DateModified"
                    DateModifiedUtcField="DateModifiedUtc"
                    OnRead="@OnRead"
                    OnUpdate="@OnUpdateHandler"
                    OnModelInit="@OnModelInitHandler"
                    OnDownload="@OnDownloadHandler"
                    OnDelete="@OnDeleteHandler">
</TelerikFileManager>

@code {
    public List<FlatFileEntry> Data = new List<FlatFileEntry>();
    public string DirectoryPath { get; set; } = string.Empty;

    public async Task OnRead(FileManagerReadEventArgs args)
    {
        await GetFlatFileEntries();

        args.Data = Data;
        args.Total = Data.Count;

        await Task.Yield();
    }

    async Task OnUpdateHandler(FileManagerUpdateEventArgs args)
    {
        var item = args.Item as FlatFileEntry;

        if (item.IsDirectory)
        {
            // prevent renaming of directories. If you allow that, make sure
            //to also update the Path of the children
        }
        else
        {
            // simulate update of the file name and path
            var name = item.Name ?? string.Empty;
            var extension = item.Extension ?? string.Empty;
            var fullName = extension.Length > 0 && name.EndsWith(extension) ?
                name : $"{name}{extension}";

            var updatedItem = Data.FirstOrDefault(x => x.MyModelId == item.MyModelId);

            updatedItem.Name = item.Name;
            updatedItem.Path = Path.Combine(DirectoryPath, fullName);
        }
    }

    async Task OnDownloadHandler(FileManagerDownloadEventArgs args)
    {
        var selectedItem = args.Item as FlatFileEntry;

        //the FileManager does not have the actual file.
        //To download it, find the actual file in the datasource  
        //based on the selected file (args.Item) and
        //assign the following data to the argument:

        //args.Stream = the file stream of the actual selected file;
        //args.MimeType = the mime type of the actual file, so it can be downloaded;
        //args.FileName = allows overriding the name of the downloaded file;
    }


    async Task OnDeleteHandler(FileManagerDeleteEventArgs args)
    {
        var currItem = args.Item as FlatFileEntry;

        var itemToDelete = Data.FirstOrDefault(x => x.MyModelId == currItem.MyModelId);

        //simulate item deletion
        Data.Remove(itemToDelete);

        RefreshData();
    }

    private FlatFileEntry OnModelInitHandler()
    {
        var item = new FlatFileEntry();
        item.Name = $"New folder";
        item.Size = 0;
        item.Path = Path.Combine(DirectoryPath, item.Name);
        item.IsDirectory = true;
        item.HasDirectories = false;
        item.DateCreated = DateTime.Now;
        item.DateCreatedUtc = DateTime.Now;
        item.DateModified = DateTime.Now;
        item.DateModifiedUtc = DateTime.Now;

        return item;
    }

    private void RefreshData()
    {
        Data = new List<FlatFileEntry>(Data);
    }

    // fetch the FileManager data
    protected override async Task OnInitializedAsync()
    {
        Data = await GetFlatFileEntries();
    }

    // a model to bind the FileManager. Should usually be in its own separate location.
    public class FlatFileEntry
    {
        public string MyModelId { get; set; }
        public string ParentId { get; set; }
        public string Name { get; set; }
        public long Size { get; set; }
        public string Path { get; set; }
        public string Extension { get; set; }
        public bool IsDirectory { get; set; }
        public bool HasDirectories { get; set; }
        public DateTime DateCreated { get; set; }
        public DateTime DateCreatedUtc { get; set; }
        public DateTime DateModified { get; set; }
        public DateTime DateModifiedUtc { get; set; }
    }

    // the next lines are hardcoded data generation so you can explore the FileManager freely

    async Task<List<FlatFileEntry>> GetFlatFileEntries()
    {

        var workFiles = new FlatFileEntry()
            {
                MyModelId = "1",
                ParentId = null,
                Name = "Work Files",
                IsDirectory = true,
                HasDirectories = true,
                DateCreated = new DateTime(2022, 1, 2),
                DateCreatedUtc = new DateTime(2022, 1, 2),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine("files"),
                Size = 3 * 1024 * 1024
            };

        var Documents = new FlatFileEntry()
            {
                MyModelId = "2",
                ParentId = workFiles.MyModelId,
                Name = "Documents",
                IsDirectory = true,
                HasDirectories = false,
                DateCreated = new DateTime(2022, 1, 2),
                DateCreatedUtc = new DateTime(2022, 1, 2),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine(workFiles.Path, "documents"),
                Size = 1024 * 1024
            };

        var Images = new FlatFileEntry()
            {
                MyModelId = "3",
                ParentId = workFiles.MyModelId,
                Name = "Images",
                IsDirectory = true,
                HasDirectories = false,
                DateCreated = new DateTime(2022, 1, 2),
                DateCreatedUtc = new DateTime(2022, 1, 2),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine(workFiles.Path, "images"),
                Size = 2 * 1024 * 1024
            };

        var specification = new FlatFileEntry()
            {
                MyModelId = "4",
                ParentId = Documents.MyModelId,
                Name = "Specification",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".docx",
                DateCreated = new DateTime(2022, 1, 5),
                DateCreatedUtc = new DateTime(2022, 1, 5),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine(Documents.Path, "specification.docx"),
                Size = 462 * 1024
            };

        var report = new FlatFileEntry()
            {
                MyModelId = "5",
                ParentId = Documents.MyModelId,
                Name = "Monthly report",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".xlsx",
                DateCreated = new DateTime(2022, 1, 20),
                DateCreatedUtc = new DateTime(2022, 1, 20),
                DateModified = new DateTime(2022, 1, 25),
                DateModifiedUtc = new DateTime(2022, 1, 25),
                Path = Path.Combine(Documents.Path, "monthly-report.xlsx"),
                Size = 538 * 1024
            };

        var dashboardDesign = new FlatFileEntry()
            {
                MyModelId = "6",
                ParentId = Images.MyModelId,
                Name = "Dashboard Design",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".png",
                DateCreated = new DateTime(2022, 1, 10),
                DateCreatedUtc = new DateTime(2022, 1, 10),
                DateModified = new DateTime(2022, 2, 13),
                DateModifiedUtc = new DateTime(2022, 2, 13),
                Path = Path.Combine(Images.Path, "dashboard-design.png"),
                Size = 1024
            };

        var gridDesign = new FlatFileEntry()
            {
                MyModelId = "7",
                ParentId = Images.MyModelId,
                Name = "Grid Design",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".jpg",
                DateCreated = new DateTime(2022, 1, 12),
                DateCreatedUtc = new DateTime(2022, 1, 12),
                DateModified = new DateTime(2022, 2, 13),
                DateModifiedUtc = new DateTime(2022, 2, 13),
                Path = Path.Combine(Images.Path, "grid-design.jpg"),
                Size = 1024
            };

        var files = new List<FlatFileEntry>()
            {
                workFiles,

                Documents,
                specification,
                report,

                Images,
                dashboardDesign,
                gridDesign
            };

        return await Task.FromResult(files);
    }
}

Other Events

OnModelInit

The OnModelInit event fires when a new instance of the model is about to be created. See the example.

OnDownload

The OnDownload event fires before a file is to be downloaded, cancellable. Its event handler receives the updated FileManagerDownloadEventArgs as an argument. See the example.

Example

Handle FileManager events.

<TelerikFileManager Data="@Data"
                    @bind-Path="@DirectoryPath"
                    Height="400px"
                    OnCreate="@OnCreateHandler"
                    OnUpdate="@OnUpdateHandler"
                    OnModelInit="@OnModelInitHandler"
                    OnDownload="@OnDownloadHandler"
                    OnDelete="@OnDeleteHandler">
</TelerikFileManager>

@code {
    public List<FlatFileEntry> Data = new List<FlatFileEntry>();
    public string DirectoryPath { get; set; } = string.Empty;

    async Task OnCreateHandler(FileManagerCreateEventArgs args)
    {
        var newFolder = args.Item as FlatFileEntry;

        var parent = GetParent(newFolder, DirectoryPath);

        newFolder.Id = "20";
        newFolder.ParentId = parent.Id;
        newFolder.Name = "New folder";
        newFolder.IsDirectory = true;
        newFolder.HasDirectories = false;
        newFolder.DateCreated = DateTime.Now;
        newFolder.DateCreatedUtc = DateTime.Now;
        newFolder.DateModified = DateTime.Now;
        newFolder.DateModifiedUtc = DateTime.Now;
        newFolder.Path = Path.Combine(DirectoryPath, newFolder.Name);
        newFolder.Extension = null;

        var parentDirectory = GetDirectory(DirectoryPath) ?? GetParent(newFolder, DirectoryPath);

        if (parentDirectory != null)
        {
            // simulate add in file system
            newFolder.ParentId = parentDirectory.Id;
            Data.Add(newFolder);
            parentDirectory.HasDirectories = Data.Count(x => x.ParentId == parentDirectory.Id) > 0;
        }
        else
        {
            // create a folder in the root dir
            Data.Add(newFolder);
        }

        RefreshData();
    }

    private FlatFileEntry GetDirectory(string path)
    {
        var directory = Data.FirstOrDefault(x => x.IsDirectory && x.Path == path);

        return directory;
    }

    private FlatFileEntry GetParent(FlatFileEntry currItem, string currDirectory)
    {
        var parentItem = Data
            .FirstOrDefault(x => x.IsDirectory && x.Path == currDirectory);

        return parentItem;
    }


    async Task OnUpdateHandler(FileManagerUpdateEventArgs args)
    {
        var item = args.Item as FlatFileEntry;

        if (item.IsDirectory)
        {
            // prevent renaming of directories. If you allow that, make sure
            //to also update the Path of the children
        }
        else
        {
            // the name prop is updated, but update the path to the file as well
            var name = item.Name ?? string.Empty;
            var extension = item.Extension ?? string.Empty;
            var fullName = extension.Length > 0 && name.EndsWith(extension) ?
                name : $"{name}{extension}";

            var updatedItem = Data.FirstOrDefault(x => x.Id == item.Id);

            updatedItem.Name = item.Name;
            updatedItem.Path = Path.Combine(DirectoryPath, fullName);
            Console.WriteLine(updatedItem.Path);
        }
    }

    async Task OnDownloadHandler(FileManagerDownloadEventArgs args)
    {
        var selectedItem = args.Item as FlatFileEntry;

        //the Filemanager does not have the actual file.
        //To download it, find the selected file through args.Item and
        //assign the actual file to the argument as follows:

        //args.Stream = the file stream of the actual selected file;
        //args.MimeType = the mime type of the actual file, so it can be downloaded;
        //args.FileName = allows overriding the name of the downloaded file;

    }


    async Task OnDeleteHandler(FileManagerDeleteEventArgs args)
    {
        var currItem = args.Item as FlatFileEntry;

        var itemToDelete = Data.FirstOrDefault(x => x.Id == currItem.Id);

        Data.Remove(itemToDelete);

        RefreshData();
    }

    private FlatFileEntry OnModelInitHandler()
    {
        var item = new FlatFileEntry();
        item.Name = $"New folder";
        item.Size = 0;
        item.Path = Path.Combine(DirectoryPath, item.Name);
        item.IsDirectory = true;
        item.HasDirectories = false;
        item.DateCreated = DateTime.Now;
        item.DateCreatedUtc = DateTime.Now;
        item.DateModified = DateTime.Now;
        item.DateModifiedUtc = DateTime.Now;

        return item;
    }

    private void RefreshData()
    {
        Data = new List<FlatFileEntry>(Data);
    }

    // fetch the FileManager data
    protected override async Task OnInitializedAsync()
    {
        Data = await GetFlatFileEntries();
    }

    // a model to bind the FileManager. Should usually be in its own separate location.
    public class FlatFileEntry
    {
        public string Id { get; set; }
        public string ParentId { get; set; }
        public string Name { get; set; }
        public long Size { get; set; }
        public string Path { get; set; }
        public string Extension { get; set; }
        public bool IsDirectory { get; set; }
        public bool HasDirectories { get; set; }
        public DateTime DateCreated { get; set; }
        public DateTime DateCreatedUtc { get; set; }
        public DateTime DateModified { get; set; }
        public DateTime DateModifiedUtc { get; set; }
    }

    // the next lines are hardcoded data generation so you can explore the FileManager freely

    async Task<List<FlatFileEntry>> GetFlatFileEntries()
    {

        var workFiles = new FlatFileEntry()
            {
                Id = "1",
                ParentId = null,
                Name = "Work Files",
                IsDirectory = true,
                HasDirectories = true,
                DateCreated = new DateTime(2022, 1, 2),
                DateCreatedUtc = new DateTime(2022, 1, 2),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine("files"),
                Size = 3 * 1024 * 1024
            };

        var Documents = new FlatFileEntry()
            {
                Id = "2",
                ParentId = workFiles.Id,
                Name = "Documents",
                IsDirectory = true,
                HasDirectories = false,
                DateCreated = new DateTime(2022, 1, 2),
                DateCreatedUtc = new DateTime(2022, 1, 2),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine(workFiles.Path, "documents"),
                Size = 1024 * 1024
            };

        var Images = new FlatFileEntry()
            {
                Id = "3",
                ParentId = workFiles.Id,
                Name = "Images",
                IsDirectory = true,
                HasDirectories = false,
                DateCreated = new DateTime(2022, 1, 2),
                DateCreatedUtc = new DateTime(2022, 1, 2),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine(workFiles.Path, "images"),
                Size = 2 * 1024 * 1024
            };

        var specification = new FlatFileEntry()
            {
                Id = "4",
                ParentId = Documents.Id,
                Name = "Specification",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".docx",
                DateCreated = new DateTime(2022, 1, 5),
                DateCreatedUtc = new DateTime(2022, 1, 5),
                DateModified = new DateTime(2022, 2, 3),
                DateModifiedUtc = new DateTime(2022, 2, 3),
                Path = Path.Combine(Documents.Path, "specification.docx"),
                Size = 462 * 1024
            };

        var report = new FlatFileEntry()
            {
                Id = "5",
                ParentId = Documents.Id,
                Name = "Monthly report",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".xlsx",
                DateCreated = new DateTime(2022, 1, 20),
                DateCreatedUtc = new DateTime(2022, 1, 20),
                DateModified = new DateTime(2022, 1, 25),
                DateModifiedUtc = new DateTime(2022, 1, 25),
                Path = Path.Combine(Documents.Path, "monthly-report.xlsx"),
                Size = 538 * 1024
            };

        var dashboardDesign = new FlatFileEntry()
            {
                Id = "6",
                ParentId = Images.Id,
                Name = "Dashboard Design",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".png",
                DateCreated = new DateTime(2022, 1, 10),
                DateCreatedUtc = new DateTime(2022, 1, 10),
                DateModified = new DateTime(2022, 2, 13),
                DateModifiedUtc = new DateTime(2022, 2, 13),
                Path = Path.Combine(Images.Path, "dashboard-design.png"),
                Size = 1024
            };

        var gridDesign = new FlatFileEntry()
            {
                Id = "7",
                ParentId = Images.Id,
                Name = "Grid Design",
                IsDirectory = false,
                HasDirectories = false,
                Extension = ".jpg",
                DateCreated = new DateTime(2022, 1, 12),
                DateCreatedUtc = new DateTime(2022, 1, 12),
                DateModified = new DateTime(2022, 2, 13),
                DateModifiedUtc = new DateTime(2022, 2, 13),
                Path = Path.Combine(Images.Path, "grid-design.jpg"),
                Size = 1024
            };

        var files = new List<FlatFileEntry>()
            {
                workFiles,

                Documents,
                specification,
                report,

                Images,
                dashboardDesign,
                gridDesign
            };

        return await Task.FromResult(files);

    }
}
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