Skip to main content

.NET Core MVC Application File Upload To Physical Location With Streaming Technique(Useful For Large Files) - Part 2


In Part 1 we have explored how to upload large files to a server using Streaming Technique. A complete .Net Core sample application has been developed from scratch to understand the file upload. Also discussed on custom model binding manually from the raw form data as well as triggering model validation. I recommend understanding Part 1 is essential before jumping here. 

AJAX Call To File Upload(MVC or Web API):

Let's develop an action method that displays a form with a file upload field.
Controller/AjaxFileUploadController.cs:
using Microsoft.AspNetCore.Mvc;

namespace StreamFileUpload.App.Controllers
{
    [Route("ajax-file-upload")]
    public class AjaxFileUplaodController : Controller
    {
        [Route("add-file")]
        public IActionResult AddFile()
        {
            return View();
        }
    }
}
Let's develop the form that posts the data using the AJAX call.
Views/AjaxFileUpload/AddFile.cshtml:
<div>
    <form action="add-file" 
        enctype="multipart/form-data" 
        method="POST"
        onsubmit="AJAXSubmit(this);return false;">
        <div class="form-group">
            <label for="txtName">Name</label>
            <input type="text" class="form-control" id="txtName" name="Name">
        </div>
        <div class="form-group">
            <label for="txtAge">Age</label>
            <input type="text" class="form-control" id="txtAge" name="Age">
        </div>
        <div class="form-group">
            <label for="fileUpload">Upload Files</label>
            <input type="file" class="form-control-file" id="fileUpload"  name="FileUpload">
        </div>
        <button type="submit" class="btn btn-primary">Save</button>
    </form>
</div>
In the form 'action' attribute specified with the action route value of MVC post action method. 'onsubmit' is the form method executed on form submission. 'AJAXSubmit(this)' method is our javascript method which sends form data using ajax. 'return false;' is to stop the form to get reload.

Now implement 'AJAXSubmit()' method as follows.
Views/AjaxFileUpload/AddFile.cshtml:
<script>
    async function AJAXSubmit(formElement){
        var formData = new FormData(formElement);

        try{
            var response = await fetch(formElement.action,{
                method: 'POST',
                body: formData
            });
            if(response.status == 200){
                alert("file uploaded success fully")
            }else{
                alert("failed to upload file")
            }
        }catch(e){

        }
    }
</script>
Reading form data and assigning to AJAX post body.

Let's add an MVC post action method as follows.
Controller/AjaxFileUploadController.cs:
using System;
using System.Globalization;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Net.Http.Headers;
using StreamFileUpload.App.Models;

namespace StreamFileUpload.App.Controllers
{
    [Route("ajax-file-upload")]
    public class AjaxFileUploadController : Controller
    {
        private readonly IWebHostEnvironment _webHostEnvironment;

        public AjaxFileUploadController(IWebHostEnvironment webHostEnvironment)
        {
            _webHostEnvironment = webHostEnvironment;
        }
        
        [Route("add-file")]
        [HttpPost]
        public async Task SaveFileToPhysicalFolder()
        {
            var boundary = HeaderUtilities.RemoveQuotes(
                MediaTypeHeaderValue.Parse(Request.ContentType).Boundary
            ).Value;

            var reader = new MultipartReader(boundary, Request.Body);

            var section = await reader.ReadNextSectionAsync();

             var formAccumelator = new KeyValueAccumulator();

            while (section != null)
            {
                var hasContentDisposition = ContentDispositionHeaderValue.TryParse(
                    section.ContentDisposition, out var contentDisposition
                );

                if (hasContentDisposition)
                {
                    if (contentDisposition.DispositionType.Equals("form-data") &&
                    (!string.IsNullOrEmpty(contentDisposition.FileName.Value) ||
                    !string.IsNullOrEmpty(contentDisposition.FileNameStar.Value)))
                    {
                        string fileStoragePath = $"{_webHostEnvironment.WebRootPath}/images/";
                        string fileName = Path.GetRandomFileName() + ".jpg";
                        // uploaded files form fileds
                        byte[] fileByteArray;
                        using (var memoryStream = new MemoryStream())
                        {
                            await section.Body.CopyToAsync(memoryStream);
                            fileByteArray = memoryStream.ToArray();
                        }
                        using (var fileStream = System.IO.File.Create(Path.Combine(fileStoragePath,fileName)))
                        {
                            await fileStream.WriteAsync(fileByteArray);
                        }
                    }
                    else
                    {
                        var key = HeaderUtilities.RemoveQuotes(contentDisposition.Name).Value;

                        using(var streamReader = new StreamReader(section.Body,
                        encoding: Encoding.UTF8,
                        detectEncodingFromByteOrderMarks:true,
                        bufferSize:1024,
                        leaveOpen:true)){
                            var value = await streamReader.ReadToEndAsync();
                            if(string.Equals(value, "undefined",StringComparison.OrdinalIgnoreCase)){
                                value = string.Empty;
                            }
                            formAccumelator.Append(key, value);
                        }
                    }
                }
                section = await reader.ReadNextSectionAsync();
            }
            var profile = new Profile();
            var formValueProvidere = new FormValueProvider(
                BindingSource.Form,
                new FormCollection(formAccumelator.GetResults()),
                CultureInfo.CurrentCulture
            );

            var bindindSuccessfully = await TryUpdateModelAsync(profile,"",formValueProvidere);
            if(ModelState.IsValid){
                // write log to save profile data to database
            }
            

            return Content("Uploaded successfully");
        }
    }
}
Here post action method code explained in detail in Part 1.

Now run the application and check ajax call posting data as below.

Uploading Multiple Files:

Using the 'multiple' attribute on the file input element will support uploading multiple files.
Views/AjaxFileUpload/AddFile.cshtml:
<input type="file" class="form-control-file" id="fileUpload"  name="FileUpload" multiple>
You can test multiple file upload by updating the input element as above.

Why Can't We Use Model Binding Or Partial Model Binding In-Stream Upload?:

We discussed that in the streaming technique we read the file from the request object, so we can't use model binding for streaming technique. 

But we mostly think like reading uploading fields from request object and then all other form fields like 'textbox', 'checkbox', 'select', etc can be used Model Binding so that we can get rid custom model binding which we discussed Part 1. That kind of technique won't possible, the reason behind will be explored in the coming steps.

Let's update the post action method to use model binding as below:
public async Task<IActionResult> SaveFileToPhysicalFolder(Profile profile)
{
	var boundary = HeaderUtilities.RemoveQuotes(
		MediaTypeHeaderValue.Parse(Request.ContentType).Boundary
	).Value;

	var reader = new MultipartReader(boundary, Request.Body);

	var section = await reader.ReadNextSectionAsync();
	while (section != null)
	{
		var hasContentDisposition = ContentDispositionHeaderValue.TryParse(
			section.ContentDisposition, out var contentDisposition
		);

		if (hasContentDisposition)
		{
			if (contentDisposition.DispositionType.Equals("form-data") &&
			(!string.IsNullOrEmpty(contentDisposition.FileName.Value) ||
			!string.IsNullOrEmpty(contentDisposition.FileNameStar.Value)))
			{
				string fileStoragePath = $"{_webHostEnvironment.WebRootPath}/images/";
				string fileName = Path.GetRandomFileName() + ".jpg";
				// uploaded files form fileds
				byte[] fileByteArray;
				using (var memoryStream = new MemoryStream())
				{
					await section.Body.CopyToAsync(memoryStream);
					fileByteArray = memoryStream.ToArray();
				}
				using (var fileStream = System.IO.File.Create(Path.Combine(fileStoragePath,fileName)))
				{
					await fileStream.WriteAsync(fileByteArray);
				}
			}
		}  
		section = await reader.ReadNextSectionAsync();
	}
   
	return Content("Uploaded successfully");
}
Here implemented model binding of model type 'Profile' and trying to fetch upload fields from the request object.

Now run the application on the debug mode and check form fields bind to model as below.
Further debugging we encounter an exception as below

Hint:

Exception occured in code:-

var section = await reader.ReadNextSectionAsync();


Exception Message:
Unexpected end of stream, the content may have already read by another component.
An exception occurs because model binding reading the form of body stream before the action method starts executing. On the reading the entire stream of data, it removed from the request body, but in code, we are trying to read the stream from the empty object which results in an error.

This sample of implement explains we can not use the model binding for uploading forms.

Wrapping Up:

Hopefully, this article will help to understand the additional information like Ajax call file upload, why can't be model binding, etc using the streaming technique in a file upload. I love to have your feedback, suggestions, and better techniques in the comment section.

Refer:

Follow Me:


Labels:

Comments

Post a Comment

Popular posts from this blog

Angular 14 Reactive Forms Example

In this article, we will explore the Angular(14) reactive forms with an example. Reactive Forms: Angular reactive forms support model-driven techniques to handle the form's input values. The reactive forms state is immutable, any form filed change creates a new state for the form. Reactive forms are built around observable streams, where form inputs and values are provided as streams of input values, which can be accessed synchronously. Some key notations that involve in reactive forms are like: FormControl - each input element in the form is 'FormControl'. The 'FormControl' tracks the value and validation status of form fields. FormGroup - Track the value and validate the state of the group of 'FormControl'. FormBuilder - Angular service which can be used to create the 'FormGroup' or FormControl instance quickly. Form Array - That can hold infinite form control, this helps to create dynamic forms. Create An Angular(14) Application: Let'
3 comments
Read more

.NET 7 Web API CRUD Using Entity Framework Core

In this article, we are going to implement a sample .NET 7 Web API CRUD using the Entity Framework Core. Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, and desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains programming functions that can be requested via HTTP calls either to fetch or update data for their respective clients. Some of the Key Characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build the REST full services. Install The SQL Server And SQL Management Studio: Let's install the SQL server on our l
3 comments
Read more

.NET6 Web API CRUD Operation With Entity Framework Core

In this article, we are going to do a small demo on AspNetCore 6 Web API CRUD operations. What Is Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains a programming function that can be requested via HTTP calls to save or fetch the data for their respective clients. Some of the key characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build REST full services. Create A .NET6 Web API Application: Let's create a .Net6 Web API sample application to accomplish our
6 comments
Read more

ReactJS(v18) JWT Authentication Using HTTP Only Cookie

In this article, we will implement the ReactJS application authentication using the HTTP-only cookie. HTTP Only Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing the JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-ONly cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use the authentication with HTTP-only JWT cookie then we no need to implement the custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To authenticate our client application with JWT HTTP-only cookie, I developed a NetJS(which is a node) Mock API. Check the GitHub link and read the document on G
2 comments
Read more

Angular 14 State Management CRUD Example With NgRx(14)

In this article, we are going to implement the Angular(14) state management CRUD example with NgRx(14) NgRx Store For State Management: In an angular application to share consistent data between multiple components, we use NgRx state management. Using NgRx state helps to avoid unwanted API calls, easy to maintain consistent data, etc. The main building blocks for the NgRx store are: Actions - NgRx actions represents event to trigger the reducers to save the data into the stores. Reducer - Reducer's pure function, which is used to create a new state on data change. Store - The store is the model or entity that holds the data. Selector - Selector to fetch the slices of data from the store to angular components. Effects - Effects deals with external network calls like API. The effect gets executed based the action performed Ngrx State Management flow: The angular component needs data for binding.  So angular component calls an action that is responsible for invoking the API call.  Aft
8 comments
Read more

Unit Testing Asp.NetCore Web API Using xUnit[.NET6]

In this article, we are going to write test cases to an Asp.NetCore Web API(.NET6) application using the xUnit. xUnit For .NET: The xUnit for .Net is a free, open-source, community-focused unit testing tool for .NET applications. By default .Net also provides a xUnit project template to implement test cases. Unit test cases build upon the 'AAA' formula that means 'Arrange', 'Act' and 'Assert' Arrange - Declaring variables, objects, instantiating mocks, etc. Act - Calling or invoking the method that needs to be tested. Assert - The assert ensures that code behaves as expected means yielding expected output. Create An API And Unit Test Projects: Let's create a .Net6 Web API and xUnit sample applications to accomplish our demo. We can use either Visual Studio 2022 or Visual Studio Code(using .NET CLI commands) to create any.Net6 application. For this demo, I'm using the 'Visual Studio Code'(using the .NET CLI command) editor. Create a fo
7 comments
Read more

Part-1 Angular JWT Authentication Using HTTP Only Cookie[Angular V13]

In this article, we are going to implement a sample angular application authentication using HTTP only cookie that contains a JWT token. HTTP Only JWT Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-Only cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use authentication with HTTP only JWT cookie then we no need to implement custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To implement JWT cookie authentication we need to set up an API. For that, I had created a mock authentication API(Using the NestJS Se
Post a Comment
Read more

Angular 14 Crud Example

In this article, we will implement CRUD operation in the Angular 14 application. Angular: Angular is a framework that can be used to build a single-page application. Angular applications are built with components that make our code simple and clean. Angular components compose of 3 files like TypeScript File(*.ts), Html File(*.html), CSS File(*.cs) Components typescript file and HTML file support 2-way binding which means data flow is bi-directional Component typescript file listens for all HTML events from the HTML file. Create Angular(14) Application: Let's create an Angular(14) application to begin our sample. Make sure to install the Angular CLI tool into our local machine because it provides easy CLI commands to play with the angular application. Command To Install Angular CLI npm install -g @angular/cli Run the below command to create the angular application. Command To Create Angular Application ng new name_of_your_app Note: While creating the app, you will see a noti
4 comments
Read more

ReactJS(v18) Authentication With JWT AccessToken And Refresh Token

In this article, we are going to do ReactJS(v18) application authentication using the JWT Access Token and Refresh Token. JSON Web Token(JWT): JSON Web Token is a digitally signed and secured token for user validation. The JWT is constructed with 3 important parts: Header Payload Signature Create ReactJS Application: Let's create a ReactJS application to accomplish our demo. npx create-react-app name-of-your-app Configure React Bootstrap Library: Let's install the React Bootstrap library npm install react-bootstrap bootstrap Now add the bootstrap CSS reference in 'index.js'. src/index.js: import 'bootstrap/dist/css/bootstrap.min.css' Create A React Component 'Layout': Let's add a React component like 'Layout' in 'components/shared' folders(new folders). src/components/shared/Layout.js: import Navbar from "react-bootstrap/Navbar"; import { Container } from "react-bootstrap"; import Nav from "react-boot
Post a Comment
Read more

A Small Guide On NestJS Queues

NestJS Application Queues helps to deal with application scaling and performance challenges. When To Use Queues?: API request that mostly involves in time taking operations like CPU bound operation, doing them synchronously which will result in thread blocking. So to avoid these issues, it is an appropriate way to make the CPU-bound operation separate background job.  In nestjs one of the best solutions for these kinds of tasks is to implement the Queues. For queueing mechanism in the nestjs application most recommended library is '@nestjs/bull'(Bull is nodejs queue library). The 'Bull' depends on Redis cache for data storage like a job. So in this queueing technique, we will create services like 'Producer' and 'Consumer'. The 'Producer' is used to push our jobs into the Redis stores. The consumer will read those jobs(eg: CPU Bound Operations) and process them. So by using this queues technique user requests processed very fastly because actually
8 comments
Read more