ASP.NET WebForms: Uploading, Validating And Displaying Images

In this blog you will learn how to upload and validate and Display Images in ASP.NET Web Forms.

I wrote a series of blog posts awhile back before that demonstrates the following:

• Uploading and Storing Images to Database in ASP.NET
  
• Displaying Image to Image Control based on User Selection in ASP.NET
  
• FAQ: Displaying Image from Database to GridView Control
  
• Uploading and Storing Image Path to Database and Image to Folder - Part 1
  
• Uploading and Storing Image Path to Database and Image to Folder - Part 2 (Displaying of Images)
  
• Validate Image extensions upon Upload 

In this post I'm going to demonstrate how to upload an image to a specified folder within the root of the web application and display the image right away in the Image control after uploading. To get started let's go ahead and fire up Visual Studio and create a new Website/Web Application project. After that, create a folder under the root application for storing the uploaded images. The folder structure should look something like this below:

Solution

• Application Name 
• AppCode 
• AppData 
• ImageStorage - //we will save the images in this folder
• Default.aspx 
• web.config 

For the simplicity of this demo, I just set up the HTML form like below:

<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="Button1" runat="server" Text="Upload" onclick="Button1_Click"/>
<br />
<asp:Image ID="Image1" runat="server" />

And here's the code for uploading the image to a folder.  

protected void Button1_Click(object sender, EventArgs e) {
             StartUpLoad();
}

private void StartUpLoad() {
        //get the file name of the posted image
        string imgName = FileUpload1.FileName;
        //sets the image path
        string imgPath = "ImageStorage/" + imgName;
       //get the size in bytes that

       int imgSize = FileUpload1.PostedFile.ContentLength;

       //validates the posted file before saving
        if (FileUpload1.PostedFile != null && FileUpload1.PostedFile.FileName != "") {
           // 10240 KB means 10MB, You can change the value based on your requirement
                if (FileUpload1.PostedFile.ContentLength > 10240) {
                           Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Alert", "alert('File is too big.')", true);
                 }  else {
                           //then save it to the Folder
                           FileUpload1.SaveAs(Server.MapPath(imgPath));
                           Image1.ImageUrl = "~/" + imgPath;
                           Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Alert", "alert('Image saved!')", true);
                }

          }
}

That simple! Now you should be able to see the image in the page after uploading.