FileUpload control in ASP.NET web form using c# Samples and examples

FileUpload is very simple control allows user to select file and upload.
You can easily handle that with very little coding and ease. I have given the full code behind for this functionality.

First create a aspx page with 3 controls

FileUpload: rename it to FileUpload1
Label: rename it to lblMsg
Button: rename it to btnAdd

Copy this code in your code behind file inside the class declaration. As you can see we are simply calling the
SaveUploadedFile() function to save the uploaded file. you can check for the particular extension within the function
right now we are checking for only 3 extensions. You can change it in sAllowedExt string.

Here is the code behing stuff:


String UPLOAD_PATH = "";
int MAXSIZE = 5 * 1024 * 1024; // max 5 MB

String sAllowedExt = ",.doc,.pdf,.xls,";  // make sure whatever extension you enter, string ends with comma

protected void Page_Load(object sender, EventArgs e)
{
    btnUpload.Attributes.Add("onclick", "return checkFile();");
    UPLOAD_PATH = Server.MapPath("~/UploadedDocs") + "/";
}

private void setMsg(String sMsg)
{
    lblMsg.Text = sMsg;
}

protected void btnAdd_Click(object sender, EventArgs e)
{
    try
    {
        SaveUploadedFile();            
    }
    catch (Exception ex)
    {
        //Response.Write("Error: " + ex.Message);
        setMsg("File could not be uploaded successfully.");        
    }
}

private void SaveUploadedFile()
{
    
    if (FileUpload1.HasFile)
    {
        String fileExtension =  System.IO.Path.GetExtension(FileUpload1.FileName).ToLower();
        String validExt = ;
        if (validExt.IndexOf("," + fileExtension + ",") != -1)
        {                
            if (FileUpload1.FileBytes.Length <= MAXSIZE)
            {
                FileUpload1.PostedFile.SaveAs(UPLOAD_PATH + FileUpload1.FileName);
                setMsg("File uploaded successfully.");
            }
            else
            {
                setMsg("File size exceeded the permitted limit.");
            }
        }
        else 
        {
            setMsg("This file type is not accepted.");
        }
    }        

}

Once the user uploads the file, it's availabe using FileUpload.PostedFile.SaveAs() method.
You can then directly save that file to particular folder with new name. We are checking FileUpload1.HasFile
to make sure we only process if a file is uploaded.

Make sure to change the max. request length attribute in web.config file to handle large files. here is the example
which can handle quite large files. Change as per your need.


< system.web >
  < httpRuntime maxRequestLength="2048576" executionTimeout="54000" / >
< /system.web >

The javascript function is added in Load event just to validate the FileUpload1 control. Here is the same.


function checkFile()
{
    if( document.getElementById("FileUpload1").value == "" || document.getElementById("FileUpload1").value == null )
    {
        alert("Please select a file.");
        return false;            
    }
    else return true;                   
}

Hope this easy to use solution will be useful in your web application.

Go Upload...

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