In this article I will explain with an example, how to upload files using Web API in ASP.Net Core Razor Pages.
This article will illustrate how to send (upload) files by calling the Web API using jQuery AJAX in ASP.Net Core Razor Pages.
Note: For beginners in Web API, please refer my article ASP.Net Core Razor Pages: Step by Step Web API Tutorial for Beginners.
 
 
Namespaces
You will need to import the following namespaces.
using System.IO;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Hosting;
 
 
Web API Controller
In order to add a Web API Controller, you will need to Right Click the Project in the Solution Explorer and click on Add and then New Item.
Now from the Add New Item window, choose the API Controller – Empty option as shown below.
ASP.Net Core Razor Pages: Upload Files using Web API
 
Then give it a suitable name and click Add.
 
Action method for uploading the Files
The next step is to add an Action Method to the Web API Controller.
Inside this Action method, first the Folder (Directory) where the Files will be saved is created inside the www Folder using IHostingEnvironment interface if it does not exists.
Note: For more details about IHostingEnvironment interface, please refer Using IHostingEnvironment in ASP.Net Core.
 
Then the Name of the File is read from Request.Form collection and the File is read from the Request.Form.Files collection and saved in the Folder (Directory) created earlier using the FileStream class.
Finally, an OK response along with the name of the File is returned to the Client which confirms successful upload of the File.
[Route("api/[controller]")]
[ApiController]
public class FileAPIController : ControllerBase
{
    private IHostingEnvironment Environment;
 
    public FileAPIController(IHostingEnvironment _environment)
    {
        Environment = _environment;
    }
 
    [Route("UploadFiles")]
    [HttpPost]
    public IActionResult UploadFiles()
    {
        //Create the Directory.
        string path = Path.Combine(this.Environment.WebRootPath, "Uploads\\");
        if (!Directory.Exists(path))
        {
            Directory.CreateDirectory(path);
        }
 
        //Fetch the File.
        IFormFile postedFile = Request.Form.Files[0];
 
        //Fetch the File Name.
        string fileName = Request.Form["fileName"] + Path.GetExtension(postedFile.FileName);
 
        //Save the File.
        using (FileStream stream = new FileStream(Path.Combine(path, fileName), FileMode.Create))
        {
            postedFile.CopyTo(stream);
        }
 
        //Send OK Response to Client.
        return Ok(fileName);
    }
}
 
 
Razor PageModel (Code-Behind)
The PageModel consists of following Handler method.
This Handler method handles the GET calls, for this particular example it is not required and hence left empty.
public class IndexModel : PageModel
{
    public void OnGet()
    {
    }
}
 
 
Razor Page (HTML)
Razor HTML Page consists of an HTML TextBox, an HTML FileUpload element, a Button and an HTML5 Progress element for displaying the progress of the uploading File and an HTML SPAN element.
The Upload Button has been assigned a jQuery Click event handler.
When the Upload Button is clicked, the File is read from the HTML FileUpload element and added to an HTML5 FormData JavaScript object and then the File is uploaded using XmlHttpRequest (XHR).
A Progress event handler is attached to the XmlHttpRequest (XHR), which displays the progress of the File being uploaded using the HTML5 Progress element.
The Name of the File is fetched from the TextBox and is added to the FormData object along with the File.
Finally, the received Name of the uploaded File is displayed in an HTML SPAN element.
@page
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <table>
        <tr>
            <td>Name:</td>
            <td><input type="text" id="fileName" /></td>
        </tr>
        <tr>
            <td>File:</td>
            <td><input type="file" id="file" /></td>
        </tr>
        <tr>
            <td></td>
            <td><input type="button" id="btnUpload" value="Upload" /></td>
        </tr>
        <tr>
            <td colspan="2"><progress id="fileProgress" style="display: none"></progress></td>
        </tr>
    </table>
    <hr/>
    <span id="lblMessage" style="color: green"></span>
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <script type="text/javascript">
        $("body").on("click", "#btnUpload", function () {
            var formData = new FormData();
            formData.append("fileName", $("#fileName").val());
            formData.append("file", $("#file")[0].files[0]);
            $.ajax({
                url: '/api/FileAPI/UploadFiles',
                type: 'POST',
                data: formData,
                cache: false,
                contentType: false,
                processData: false,
                success: function (fileName) {
                    $("#fileProgress").hide();
                    $("#lblMessage").html("<b>" + fileName + "</b> has been uploaded.");
                },
                xhr: function () {
                    var fileXhr = $.ajaxSettings.xhr();
                    if (fileXhr.upload) {
                        $("progress").show();
                        fileXhr.upload.addEventListener("progress", function (e) {
                            if (e.lengthComputable) {
                                $("#fileProgress").attr({
                                    value: e.loaded,
                                    max: e.total
                                });
                            }
                        }, false);
                    }
                    return fileXhr;
                }
            });
        });
    </script>
</body>
</html>
 
 
Screenshot
ASP.Net Core Razor Pages: Upload Files using Web API
 
 
Browser Compatibility

The above code has been tested in the following browsers only in versions that support HTML5.

Internet Explorer  FireFox  Chrome  Safari  Opera 

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