Blazorise FileInput component

The FileInput component is a specialized input that provides a clean interface for selecting files.

Customized, cross-browser consistent, file input control that supports single file and multiple files upload.

Examples

Single file (default)

On single file mode, when file is selected or user does not cancel Browse dialog, Changed event will be raised. The return value will be a FileChangedEventArgs that will contain only one item in the Files property.

Choose file

<Field>
    <FileInput Changed="@OnChanged" />
</Field>

@code {
    Task OnChanged( FileChangedEventArgs e )
    {
        return Task.CompletedTask;
    }
}

Multiple files

Multiple file uploading is supported by enabling Multiple attribute to component. In this case Files property of FileChangedEventArgs can contain multiple files.

Choose files

<Field>
    <FileInput Changed="@OnChanged" Multiple />
</Field>

@code {
    Task OnChanged( FileChangedEventArgs e )
    {
        return Task.CompletedTask;
    }
}

Directories

Directory uploading is supported by enabling Directory attribute to component. In this case Files property of FileChangedEventArgs can contain multiple files within a directory.

Choose folder

<Field>
    <FileInput Changed="@OnChanged" Directory />
</Field>

@code {
    Task OnChanged( FileChangedEventArgs e )
    {
        return Task.CompletedTask;
    }
}

Multiple Directories

Multiple Directory uploading is supported by enabling Directory and Multiple attribute to component. In this case Files property of FileChangedEventArgs can contain multiple files within a directory.

Choose folders

<Field>
    <FileInput Changed="@OnChanged" Directory Multiple />
</Field>

@code {
    Task OnChanged( FileChangedEventArgs e )
    {
        return Task.CompletedTask;
    }
}

Limiting to certain file types

You can limit the file types by setting the Filter attribute to a string containing the allowed file type(s). To specify more than one type, separate the values with a comma.

To accept any file type, leave Filter as null (default).

Note: Not all browsers support or respect the accept attribute on file inputs.

Choose file

<!-- Accept all image formats by IANA media type wildcard-->
<Field>
    <FileInput Filter="image/*" />
</Field>

<!-- Accept specific image formats by IANA type -->
<Field>
    <FileInput Filter="image/jpeg, image/png, image/gif" />
</Field>

<!-- Accept specific image formats by extension -->
<Field>
    <FileInput Filter=".jpg, .png, .gif" />
</Field>

Events

Changed

This is the main event that will be called every time a user selects a single or multiple files. Depending on the mode in which the FileInput currently operates. In all cases the event argument is the same. Only difference is that Files array will contain single or multiple items.

Written

This event will be called on every buffer of data that has being written to the destination stream. It is directly related to the MaxMessageSize attribute found on FileInput component and will contain the information about currently processed file, it's offset and data array.

Progressed

Similar to the Written, this event will also be called while file is writing to the destination stream but it will contain only the progress and percentage on how much the file is being uploaded.

Note: If Progressed and Written events aren't important to you, we highly advise you the usage of the DisableProgressReport Parameter, as it will improve file transfer significantly.

Started

This event will be called each time one of the selected file(s) has started the upload process.

Ended

This event is fired after the file has ended the upload process. If there was no error it will have Success property set to true.

Examples

WriteToStreamAsync

In this example you can see the usage of all events, including the Written and Progressed. For your own use case you can just focus on Changed event.

Choose file

@using System.IO

<Field>
    <FileInput Changed="@OnChanged" Written="@OnWritten" Progressed="@OnProgressed" />
</Field>

@code {
    string fileContent;

    async Task OnChanged( FileChangedEventArgs e )
    {
        try
        {
            foreach ( var file in e.Files )
            {
                // A stream is going to be the destination stream we're writing to.
                using ( var stream = new MemoryStream() )
                {
                    // Here we're telling the FileInput where to write the upload result
                    await file.WriteToStreamAsync( stream );

                    // Once we reach this line it means the file is fully uploaded.
                    // In this case we're going to offset to the beginning of file
                    // so we can read it.
                    stream.Seek( 0, SeekOrigin.Begin );

                    // Use the stream reader to read the content of uploaded file,
                    // in this case we can assume it is a textual file.
                    using ( var reader = new StreamReader( stream ) )
                    {
                        fileContent = await reader.ReadToEndAsync();
                    }
                }
            }
        }
        catch ( Exception exc )
        {
            Console.WriteLine( exc.Message );
        }
        finally
        {
            this.StateHasChanged();
        }
    }

    void OnWritten( FileWrittenEventArgs e )
    {
        Console.WriteLine( $"File: {e.File.Name} Position: {e.Position} Data: {Convert.ToBase64String( e.Data )}" );
    }

    void OnProgressed( FileProgressedEventArgs e )
    {
        Console.WriteLine( $"File: {e.File.Name} Progress: {e.Percentage}" );
    }
}

OpenReadStream

Using OpenReadStream on the file you can process the file as it is streamed from the browser to your code, this is mirrors the API found in ASP.NET Core Input File component, for example

Note: We highly advise the usage of this api on Blazor WebAssembly as it is very performant.

Choose file

@using System.IO

<Field>
    <FileInput Changed="@OnChanged" Written="@OnWritten" Progressed="@OnProgressed" />
</Field>

@code {
    string fileContent;

    async Task OnChanged( FileChangedEventArgs e )
    {
        try
        {
            foreach ( var file in e.Files )
            {
                // A stream is going to be the destination stream we're writing to.
                using ( var stream = new MemoryStream() )
                {
                    // Here we're telling the FileInput where to write the upload result
                    await file.WriteToStreamAsync( stream );

                    // Once we reach this line it means the file is fully uploaded.
                    // In this case we're going to offset to the beginning of file
                    // so we can read it.
                    stream.Seek( 0, SeekOrigin.Begin );

                    // Use the stream reader to read the content of uploaded file,
                    // in this case we can assume it is a textual file.
                    using ( var reader = new StreamReader( stream ) )
                    {
                        fileContent = await reader.ReadToEndAsync();
                    }
                }
            }
        }
        catch ( Exception exc )
        {
            Console.WriteLine( exc.Message );
        }
        finally
        {
            this.StateHasChanged();
        }
    }

    void OnWritten( FileWrittenEventArgs e )
    {
        Console.WriteLine( $"File: {e.File.Name} Position: {e.Position} Data: {Convert.ToBase64String( e.Data )}" );
    }

    void OnProgressed( FileProgressedEventArgs e )
    {
        Console.WriteLine( $"File: {e.File.Name} Progress: {e.Percentage}" );
    }
}

Reset

By default after each file upload has finished, file input will automatically reset to it's initial state. If you want this behavior disabled and control it manually you need to first set AutoReset to false. After that you can call Reset() every time you want the file input to be reset.

Choose file

<Field>
    <FileInput @ref="@fileInput" AutoReset="false" Changed="@OnChanged" />
</Field>
<Field>
    <Button Color="Color.Primary" Clicked="Reset">Reset</Button>
</Field>

@code {
    FileInput fileInput;

    Task OnChanged(FileChangedEventArgs e)
    {
        return Task.CompletedTask;
    }

    Task Reset()
    {
        return fileInput.Reset().AsTask();
    }
}

Show Picker

If you want to show the default picker that comes with the file input element you can make it by using the ShowPicker() function.

Note: Keep in mind that not all browser will support the ShowPicker() function.

Choose file

<Field>
    <Button Color="Color.Primary" Clicked="@(() => fileInput.ShowPicker())">
        Show Picker
    </Button>
</Field>
<Field>
    <FileInput @ref="@fileInput" />
</Field>

@code {
    FileInput fileInput;
}

API

Parameters

Parameter	Description	Type	Default
`AriaDescribedBy`	Gets or sets the aria-describedby attribute value. Remarks When set, this value is rendered as-is and overrides help and validation message ids generated by Field and Validation.	`string`
`AriaInvalid`	Gets or sets the aria-invalid attribute value. Remarks When set, this value is rendered as-is and overrides the validation-derived aria-invalid state.	`string`
`Autofocus`	Set's the focus to the component after the rendering is done.	`bool`	`false`
`AutoReset`	If true file input will be automatically reset after it has being uploaded.	`bool`	`true`
`BrowseButtonLocalizer`	Function used to handle custom localization that will override a default ITextLocalizer.	`TextLocalizerHandler`	`null`
`ChildContent`	Specifies the content to be rendered inside this FileInput.	`RenderFragment`	`null`
`Classes`	Custom CSS class names for component elements.	`TClasses`	`null`
`Directory`	Gets or Sets whether file picker should upload directories.	`bool`	`false`
`Disabled`	Add the disabled boolean attribute on an input to prevent user interactions and make it appear lighter.	`bool`	`false`
`DisableProgressReport`	Gets or sets whether report progress should be disabled. By enabling this setting, Progressed and Written callbacks won't be called. Internal file progress won't be tracked. This setting can speed up file transfer considerably.	`bool`	`false`
`Feedback`	Placeholder for validation messages.	`RenderFragment`	`null`
`Filter`	Specifies the types of files that the input accepts. See w3schools.com.	`string`
`MaxChunkSize`	Gets or sets the max chunk size when uploading the file. Take note that if you're using IFileEntry,CancellationToken) you're provided with a stream and should configure the chunk size when handling with the stream. Remarks See docs.microsoft.com.	`int`	`20 * 1024`
`MaxFileSize`	Maximum file size in bytes, checked before starting upload (note: never trust client, always check file size at server-side). Defaults to long.MaxValue.	`long`	`long.MaxValue`
`Multiple`	Enables the multiple file selection.	`bool`	`false`
`Placeholder`	Sets the placeholder for the empty file input.	`string`
`ReadOnly`	Add the readonly boolean attribute on an input to prevent modification of the input’s value.	`bool`	`false`
`SegmentFetchTimeout`	Gets or sets the Segment Fetch Timeout when uploading the file.	`TimeSpan`	`TimeSpan.FromMinutes( 1 )`
`Size`	Sets the size of the input control.	`Size?`	`null`
`Styles`	Custom inline styles for component elements.	`TStyles`	`null`
`TabIndex`	If defined, indicates that its element can be focused and can participates in sequential keyboard navigation.	`int?`	`null`
`Value`	Gets or sets the value inside the input field.	`TValue`	`null`
`ValueExpression`	Gets or sets an expression that identifies the input value.	`Expression<Func<TValue>>`	`null`

Events

Event	Description	Type
`Blur`	The blur event fires when an element has lost focus.	`EventCallback<FocusEventArgs>`
`Changed`	Occurs every time the selected file has changed, including when the reset operation is executed.	`EventCallback<FileChangedEventArgs>`
`CustomValidationValue`	Used to provide custom validation value on which the validation will be processed with the Validator handler. Remarks Should be used carefully as it's only meant for some special cases when input is used in a wrapper component, like Autocomplete or SelectList.	`Func<TValue>`
`Ended`	Occurs when an individual file upload has ended.	`EventCallback<FileEndedEventArgs>`
`FocusIn`	Occurs when the input box gains focus.	`EventCallback<FocusEventArgs>`
`FocusOut`	Occurs when the input box loses focus.	`EventCallback<FocusEventArgs>`
`KeyDown`	Occurs when a key is pressed down while the control has focus.	`EventCallback<KeyboardEventArgs>`
`KeyPress`	Occurs when a key is pressed while the control has focus.	`EventCallback<KeyboardEventArgs>`
`KeyUp`	Occurs when a key is released while the control has focus.	`EventCallback<KeyboardEventArgs>`
`OnFocus`	Occurs when the input box gains or loses focus.	`EventCallback<FocusEventArgs>`
`Progressed`	Notifies the progress of file being written to the destination stream.	`EventCallback<FileProgressedEventArgs>`
`Started`	Occurs when an individual file upload has started.	`EventCallback<FileStartedEventArgs>`
`ValueChanged`	Occurs after value has changed.	`EventCallback<TValue>`
`Written`	Occurs every time the part of file has being written to the destination stream.	`EventCallback<FileWrittenEventArgs>`

Methods

Method	Description	Return	Parameters
`NotifyChange`	Notifies the component that file input value has changed.	`Task`	`FileEntry[] files`
`UpdateFileStartedAsync`	Notifies the component that file upload is about to start.	`Task`	`IFileEntry fileEntry`
`UpdateFileEndedAsync`	Notifies the component that file upload has ended.	`Task`	`IFileEntry fileEntry, bool success, FileInvalidReason fileInvalidReason`
`UpdateFileWrittenAsync`	Updates component with the latest file data.	`Task`	`IFileEntry fileEntry, long position, byte[] data`
`UpdateFileProgressAsync`	Updated the component with the latest upload progress.	`Task`	`IFileEntry fileEntry, long progressProgress`
`WriteToStreamAsync`	Writes the file data to the target stream.	`Task`	`IFileEntry fileEntry, Stream stream, CancellationToken cancellationToken`
`OpenReadStream`	Opens the stream for reading the uploaded file.	`Stream`	`IFileEntry fileEntry, CancellationToken cancellationToken`
`RemoveFileEntry`	Removes the file entry from js dictionary.	`Task`	`IFileEntry fileEntry, CancellationToken cancellationToken`
`Reset`	Manually resets the input file value.	`ValueTask`
`RemoveFile`	Removes a file from the current file selection.	`ValueTask`	`int fileId`
`ShowPicker`	Show a browser picker for the file input.	`Task`
`Focus`	Sets the focus on the underline element.	`Task`	`bool scrollToElement`
`Revalidate`	Forces the Validation (if any is used) to re-validate with the new custom or internal value.	`Task`

Blazorise FileInput component

Examples

Single file (default)

Multiple files

Directories

Multiple Directories

Limiting to certain file types

Events

Changed

Written

Progressed

Started

Ended

Examples

WriteToStreamAsync

OpenReadStream

Reset

Show Picker

API

Parameters

Events

Methods

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