Validating file upload control


Bill Evjen Reuters December 2005 Applies to: Microsoft ASP.NET 2.0 Microsoft Visual Web Developer 2005 Express Edition Summary: Learn how to use the new File Upload server control in Microsoft ASP. (18 printed pages) Introduction An Example of the File Upload Server Control Conclusion Ever since Microsoft ASP.If you want to allow 10 megabyte (MB) files to be uploaded to the server, set the max Request Length value to 11264, meaning that the application allows files that are up to 11000 KB to be uploaded to the server. After the user clicks the Submit button and the files are posted to the server, the code behind takes the files and saves them to a specific location on the server. Uploading multiple files to the server Visual Basic Protected Sub Button1_Click(By Val sender As Object, _ By Val e As System. NET technologies and community-based learning initiatives for . He is a technical director for Reuters, the international news and financial services company based in St. Bill is the founder and executive director of the International .

Combined with yii\widgets\Active Form and models, you can easily implement a secure file uploading mechanism.

Like working with plain text inputs, to upload a single file you would create a model class and use an attribute of the model to keep the uploaded file instance.

The file input field in our HTML form above is named "file To Upload". If the file is larger than 500KB, an error message is displayed, and $upload Ok is set to 0: 500000) // Allow certain file formatsif($image File Type !

= "gif" ) // Check if $upload Ok is set to 0 by an errorif ($upload Ok == 0) else ?

You cannot upload anything that is larger than this limit. NET, however, is that it usually provides a way around limitations. Text = "You have not specified a file." End If End Sub Now, by using the Get Extension method from the System. Path namespace, you can perform basically the same operation. The result of this action is illustrated in Figure 5. Uploading four files at once to the server from a single ASP. NET, the state of the file-input text boxes cannot be saved because doing so might pose a security risk. NET is a powerful control that was quite difficult to achieve in the days of Active Server Pages 3.0.