Uploading Additional Data in ASP.NET

Uploading Common Data

This section describes several approaches to uploading additional data. They are quite different but have two features in common, namely, independence of file types and upload of common data.

• To get user-provided information about a whole upload you may use an HTML form, as described in the using additional HTML form section. This approach is simple to use and understand, it is also quite flexible. Pay attention to the fact that in this case you cannot upload different data for different files, only one set of data for a whole upload.
• To add hidden data to a whole upload you can use custom fields. As opposed to the previous method, this one allows you to add data programmatically. For more information about this approach, see the using additional field section.
• To upload user-defined file descriptions you do not need to configure Image Uploader Flash beforehand, so it is the simplest way to get additional information with each uploaded file. Receiving of descriptions is examined in the using descriptions section.

Using Additional HTML Form

Using HTML forms is the most straight-forward way to upload data in web applications, thus, Image Uploader Flash supports it. All you need is just to add the desired form to the same page where the ImageUploaderFlash control is hosted and set the Metadata.AdditionalFormName property to the name of created form. Then, when a user clicks Upload, the form data will be submitted along with user-selected files. On the server side, the fields of this form are accessible through the Package.PackageFields collection by their names.

An additional form can contain HTML input elements of different types, for example, you may use:

• text for author's name
• checkbox to determine whether to send a notification about the upload completion
• select to choose keywords related to the upload

Sending Data

The following configuration makes Image Uploader Flash sending data from the addForm form along with uploaded files.

<form id="addForm" name="addForm">
   <input ID="keywords" name="keywords" type="text" />
   <input ID="addressee" name="addressee" type="text" />
</form>
<form id="form1" runat="server">
    <aur:ImageUploaderFlash ID="Uploader1" runat="server" OnAllFilesUploaded="AllFilesUploaded">
        <Metadata AdditionalFormName="addForm" />
    </aur:ImageUploaderFlash>
</form>

Receiving Sent Data

Fields of the additional form are sent in each package, though in the following example we use the first package, which number is 0, because there is always at least one package in the upload session.

protected void AllFilesUploaded(object sender, Aurigma.ImageUploaderFlash.AllFilesUploadedEventArgs e)
{
    string keywords = e.Packages[0].PackageFields["keywords"];
    string addressee = e.Packages[0].PackageFields["addressee"];
}

Using Additional Field

Additional fields can be attached to the POST request using the metadata.addCustomField(String, String, Boolean) method. It accepts the following parameters:

1. name of the additional field
2. value of the additional field
3. optional parameter telling how to deal with previous value of this field, which is overwritten by default

You may add custom fields to the upload request only at runtime using the Image Uploader Flash JavaScript API. Custom fields can use any format you like but should not conflict with the standard field names. See the POST Field Reference topic for a full list of standard Image Uploader Flash fields.

On the server side, additional fields are accessible through the Package.PackageFields collection by their names.

The following example sends and receives an additional field named authorField. Here the metadata.addCustomField(String, String, Boolean) method is called in the BeforeUpload event handler, which fires when the upload is about to be started. For more information about events, please, see the using events section.

Sending Data

<script type="text/javascript" language="javascript">
function onBeforeUpload() {
    var uploader = $au.imageUploaderFlash('Uploader1');
    uploader.metadata().addCustomField('authorField', 'Author Name');
}
</script>
<form id="form1" runat="server">
    <aur:ImageUploaderFlash ID="Uploader1" runat="server" OnAllFilesUploaded="AllFilesUploaded" >
        <ClientEvents>
            <aur:ClientEvent EventName="BeforeUpload" HandlerName="onBeforeUpload" />
        </ClientEvents>
    </aur:ImageUploaderFlash>
</form>

Receiving Sent Data

Additional fields are sent in each package, though in the following example we use the first package, which number is 0, because there is always at least one package in the upload session.

protected void AllFilesUploaded(object sender, Aurigma.ImageUploaderFlash.AllFilesUploadedEventArgs e)
{
    string author = e.Packages[0].PackageFields["authorField"];
}

Receiving Descriptions

Each file uploaded via Image Uploader Flash may have a description. There is no need to turn this possibility on, because it is enabled by default. So, let us examine how to get descriptions of uploaded files on a server using the FileUploaded Uploader.FileUploaded UploadRequest.FileUploaded UploadHandler.FileUploaded event handler:

protected void FileUploaded(object sender, Aurigma.ImageUploaderFlash.FileUploadedEventArgs e)
{
    string description = e.UploadedFile.Description;
}

Uploading Image-specific Data

Image Uploader Flash has some imaging capabilities; let us describe two of these features, which allow uploading additional data:

1. Rotating of images is enabled in Image Uploader Flash by default. So, it is a good idea to get rotation angle on a server. To get more information on how to do this, see the receiving rotation angle section.
2. Working with EXIF and IPTC Metadata provides, among other possibilities, an opportunity to extract and upload EXIF and IPTC fields for each user-selected image. EXIF metadata is a special information about the image, written into the file by the capturing device when an image was captured. These metadata may provide camera parameters during capturing, date and time of the capturing, photographer's name, and etc. IPTC is another metadata format, which is widely used in journalism to keep information about a photo, like byline, subject, location, and etc. See the handling EXIF and IPTC metadata section for detailed description on how to send and receive such metadata.

Receiving Rotation Angle

A rotation angle can be got through the Angle property of the UploadedFile class. Image Uploader Flash measures rotation angle in degrees clockwise.

As soon as rotation of images is allowed by default, there is no need to configure Image Uploader Flash to send it, so the following example shows only how to receive such data on a server.

protected void FileUploaded(object sender, Aurigma.ImageUploaderFlash.FileUploadedEventArgs e)
{
    int angle = e.UploadedFile.Angle;
}

Handling EXIF and IPTC Metadata

To upload EXIF or IPTC values, you should specify the desired fields using the Metadata.Exif and Metadata.Iptc properties. Both these properties represent semicolon separated lists of field names which should be extracted and uploaded along with images. Metadata.ValueSeparator sets a string separator for fields which can contain multiple string values, like IptcKeyword.

Sending Data

The following example sends two EXIF and two IPTC fields for each user-selected image:

<aur:ImageUploaderFlash ID="Uploader1" runat="server" OnFileUploaded="FileUploaded">
    <Converters>
        <aur:Converter Mode="*.*=SourceFile" />
    </Converters>
    <Metadata Iptc="IptcCopyrightNotice;IptcKeyword" ValueSeparator=";" 
        Exif="ExifColorSpace;ExifDateTime" />
</aur:ImageUploaderFlash>

Receiving Sent Data

The following example gets the EXIF and IPTC fields sent accordingly to the previous configuration and writes these values to the Descriptions.xml file. Here uploaded fields are contained in the Package.PackageFields collection and can be retrieved by keys named in the following way: FieldName_xx, where FieldName is a name of an EXIF or IPTC field and xx is the index of an uploaded file in this package.

protected void FileUploaded(object sender, Aurigma.ImageUploaderFlash.FileUploadedEventArgs e)
{
    string galleryPath = Server.MapPath("Gallery");
    System.Xml.XmlDocument descriptions = new System.Xml.XmlDocument();
    if (System.IO.File.Exists(galleryPath + "Descriptions.xml"))
        descriptions.Load(galleryPath + "Descriptions.xml");
    else
        descriptions.AppendChild(descriptions.CreateElement("files"));

    System.Xml.XmlElement file = descriptions.CreateElement("file");
    file.SetAttribute("name", e.UploadedFile.SourceName);
    file.SetAttribute("CopyrightNotice", e.UploadedFile.Package.PackageFields["IptcCopyrightNotice_" + e.UploadedFile.Index]);
    file.SetAttribute("IptcKeyword", e.UploadedFile.Package.PackageFields["IptcKeyword_" + e.UploadedFile.Index]);
    file.SetAttribute("ExifColorSpace", e.UploadedFile.Package.PackageFields["ExifColorSpace_" + e.UploadedFile.Index]);
    file.SetAttribute("ExifDateTime", e.UploadedFile.Package.PackageFields["ExifDateTime_" + e.UploadedFile.Index]);
    descriptions.DocumentElement.AppendChild(file);
    descriptions.Save(galleryPath + "Descriptions.xml");
}

See Also

Reference

• Metadata Class
• Package Class
• addCustomField(String, String, Boolean) Method
• UploadedFile Class
• FileUploaded Uploader.FileUploaded UploadRequest.FileUploaded UploadHandler.FileUploaded
• AllFilesUploaded Uploader.AllFilesUploaded UploadRequest.AllFilesUploaded UploadHandler.AllFilesUploaded
• BeforeUpload Event
• ActionUrl Property

Manual

• Saving Uploaded Files in ASP.NET
• Working with EXIF and IPTC Metadata