Validating the file field

And for Rails applications, Carrier Wave gem provides a very simple and flexible way to achieve that.

In realistic situation, you may only allow user to be able to upload files within a limited size or with certain type.

After the files are saved, the file information that was posted is displayed in the ASP. Listing 3: Uploading multiple files to the server VB property lets you gain control over all the files that are uploaded from the page.

When the files are in this state, you can do whatever you want with them.

NET Machine Account under the Security tab, you can add it by clicking the Add button and entering ASPNET (without the period) in the text area, as illustrated in Figure 2. Looking at the code from Listing 1, you might notice some really important things right away. If the file type is not one these three choices, a Validation control throws an exception onto the screen. It wouldn't be too hard for someone to change the file extension of a file so it would be accepted and uploaded to the server, thereby bypassing this simple security model.

So far, you have seen some good examples of how to upload a file to the server without much hassle.

It is important to note that this control is called the File Field control in all versions of Microsoft Visual Studio® . NET Web Matrix, this control is called the File Upload control.NET so the file can be saved to the specified folder. NET account is not enabled to write to the folder you want, simply open up Microsoft Windows® Explorer and navigate to the folder to which you want to add this permission.Right-click on the folder (in this case, the Uploads folder), and then select Properties.This tag is used to work with file data within an HTML form.In the past when using classic ASP (ASP 3.0 or earlier), many programmers worked with third-party components to upload files from the client to the server. NET and this new control, uploading is taken care of for you—and it couldn't be simpler.