Programming ASP.NET 3.5, 4th Edition

The FileUpload Control

Often an application needs to allow users to upload files to the web server. The FileUpload control makes it easy for the user to browse for and select the file to transfer, providing a Browse button and a text box for entering the filename. Once the user has entered a fully qualified filename in the text box, either by typing it directly or by using the Browse button, the SaveAs method of the FileUpload control can be called to save the file to disk.

In addition to the normal complement of members inherited from the WebControl class, the FileUpload control also exposes several read-only properties of particular interest, listed in Tables Table 5-15 and Table 5-16.

Figure 5-18. WizardDemo.aspx after some navigation

Table 5-15. FileUpload properties (read-only)

Name	Type	Description
FileContent	Stream	Returns a Stream object that points to the file to upload.
FileName	String	Returns the name of the file to be uploaded, without any qualifying path information.
HasFile	Boolean	If true, indicates the control has a file to upload.
PostedFile	HttpPostedFile	Returns a reference to the file which has been uploaded. Exposes the read-only properties listed in Table 5-16.

Table 5-16. HttpPostedFile properties (read-only)

Name	Type	Description
ContentLength	Integer	Returns the size of the file, in bytes, of an uploaded file.
ContentType	String	Returns the MIME content type of the uploaded file (e.g., ...