I'm building a file upload web application using ASP.NET Core 6 and I would like the user to be able to confirm whether or not to overwrite an existing file. The application allows for multiple file uploads
Questions:
where to check if the file exists? (i.e. client-side or on the server)
if on the client-side how to check if file exists on the server?
how to handle the POST request so that it can "wait" for user confirmation?
is this kind of "communication" with the user even possible in ASP.NET Core 6? or should I be using Blazor or Signal R (I'm really new to .NET)
This is my form:
<form method="POST" enctype="multipart/form-data">
<input type="file" multiple name="files">
<button type="submit" class="btn custom-button">Upload Files</button>
</form>
This is the controller action:
[HttpPost]
public async Task<IActionResult> UploadFiles(IEnumerable<IFormFile> files, string folders)
{
foreach (var file in files)
{
string trimmedFileName = String.Concat(file.FileName.Where(c =>!Char.IsWhiteSpace(c)));
var filePath = Path.Combine(folders, trimmedFileName);
if (System.IO.File.Exists(filePath))
{
ViewBag.Error = $"File {trimmedFileName} already exists on the server";
this.Redirect("UploadFiles");
}
using var filestream = System.IO.File.Create(filePath);
await file.CopyToAsync(filestream);
}
}
I have simplified the above code so as not too add too much detail
Attempts
I have tried AJAX calls to stop the POST request and add some logic but I don't seem to be able to access the folder on the server to even check if the file already exists
$("#uploadForm").submit(function(e){
e.preventDefault();
let files = $(".form-control-file")[0].files;
for (let i = 0; i < files.length; i++){
let url = $("#filePathUrl").val() + "/" + files[i].name;
if(url){
$.ajax({
url: url,
type: 'HEAD',
error: function(){
alert(files[i].name + " exists!");
},
success: function(){
alert(files[i].name + " does not exist on server");
I have simplified and removed closing braces from the above code to keep things simple
Here's what you can do,
Use AjaxRequest to submit the form (by preventing default)
In Controller Action save files if all the files are new
Dont save files if there is any duplicate. Send a message to the client stating that these files are duplicate, Do you want to overwrite these files?
if user says "Yes", send the same AjaxRequest again with an additional parameter and Save all the files (with overwriting duplicate files)
If user says "No", then nothing needs to be done
Lets move to code
JS
function processFiles(confirmOverwrite = false){
const files = $(".form-control-file")[0].files;
const formData = new FormData();
files.forEach(file => formData,append('files[]', file));
const folderName = 'Uploads';
const url = $("#filePathUrl").val();
$.ajax({
url: url+'?folders='+folderName+'&confirmOverwrite='+confirmOverwrite,
type: 'POST',
data: formData,
processData: false,
success: (response) =>{
if(response.Status){
alert('Files uploadedn successfully');
}
else{
if(response.Message){
if(confirm(response.Message + ' files already exist. Do you want to overwrite these?')){
processFiles(true);
}
else{
alert('Files not uploaded');
}
}
}
},
error: (a,b,c) => {
console.error({a,b,c});
}
});
}
$("#uploadForm").submit(function(e){
e.preventDefault();
processFiles(false);
});
Controller
[HttpPost]
public async Task<IActionResult> UploadFiles(IEnumerable<IFormFile> files, string folders, bool confirmOverwrite = false)
{
var existingFiles = new List<string>();
var filesToBeSaved = new List<(IFormFile file, string filePath)>();
foreach (var file in files)
{
string trimmedFileName = file.FileName.Replace(" ", "");
var filePath = Path.Combine(folders, trimmedFileName);
if (System.IO.File.Exists(filePath) && !confirmOverwrite)
{
existingFiles.Add(file.FileName + "("+ trimmedFileName + ")");
}
else
{
filesToBeSaved.Add((file, filePath));
}
}
if (existingFiles.Any())
{
return Json(new { Status = false, Message = string.Join(", ", existingFiles) });
}
else
{
foreach (var (file, filePath) in filesToBeSaved)
{
using var filestream = System.IO.File.Create(filePath);
await file.CopyToAsync(filestream);
}
return Json(new { Status = true, Message = "Success" });
}
}
Your POST to upload the file could return a 409 Conflict status if a file already exists. The UI would then detect this on first posting, and show a popup. If the user selects 'continue', then the POST could include a query parameter to say the user has confirmed the OK is allowed. Something like this:
[HttpPost]
public async Task<IActionResult> UploadFiles(bool? allowOverwrite, IEnumerable<IFormFile> files, string folders)
{
foreach (var file in files)
{
string trimmedFileName = String.Concat(file.FileName.Where(c => !Char.IsWhiteSpace(c)));
var filePath = Path.Combine(folders, trimmedFileName);
if (!allowOverwrite.GetDefaultValue() && System.IO.File.Exists(filePath)) < ---
{
ViewBag.Error = $"File {trimmedFileName} already exists on the server";
return Conflict(); < ---
}
using var filestream = System.IO.File.Create(filePath);
await file.CopyToAsync(filestream);
}
}
I'm a little lost on what should I do. I'm trying to upload a file along with its form data in one click, but I can't get the file. I tried to check the file in client and it's okay, but when receiving the file in the Controller, it's empty.
Problem
How do I upload the file along its formData using jQuery?
View
Assuming the other fields
<form id="_RegisterProduct" enctype="multipart/form-data">
<div>
<label>Product Description</label>
<textarea id="product_description" name="_product_description"></textarea>
<input type="file"
id="product_file"
name="product_file"
class="dropify" />
</div>
<button type="submit" id="snippet_new_save">Register Product</button>
</form>
<script>
$(function() {
rules: {
text: { required: true, minlength: 5 },
number: { required: true, minlength: 1 }
},
submitHandler: function (form) {
var fileUpload = $("#product_file").val();
var formData = $("#_RegisterForm").serialize();
var url = "#Url.Action("RegisterProduct", "Product")";
$.get(url, { fileUpload: fileUpload, formData }, function (e) {
if (e >= 1) {
console.log("success");
} else {
console.log("error");
}
});
}
})
</script>
Controller
public string RegisterProduct(HttpPostedFileBase fileUpload, AB_ProductModel formData)
{
var data = "";
using (var con = new SqlConnection(Conn.MyConn()))
{
var path = Server.MapPath("~/Content/uploads/products");
var Extension = "";
var fileName = "";
try
{
if(fileUpload.ContentLength > 0)
{
Extension = Path.GetExtension(fileUpload.FileName);
fileName = Path.GetFileName(fileUpload.FileName);
var com = new SqlCommand("dbo.sp_some_stored_procedure_for_saving_data",
con);
con.Open
data = Convert.ToString(com.ExecuteScalar());
var file_path = Path.Combine(path, data + Extension);
fileUpload.SaveAs(file_path);
}
}
catch (Exception ex)
{
data = ex.Message;
}
// data returns id if success or error message
}
return data;
}
Why serialize the form? This method creates a string that can be sent over to the server, but that is not what you want to do... In case of a file upload; see .serialize() function description here.
FormData type automatically manages the enctype for your forms (see here on MDN), so you can omit that—although you should consider using it, because it helps other members on the team understand the intent. If you want to use plain jQuery, you can simply attach the formData variable to the data field of the $.ajax call. See like here,
/*
* i know id-based selection should only have 1 element,
* otherwise HTML is invalid for containing multiple elements
* with the same id, but this is the exact code i used back then, so using it again.
**/
var formData = new FormData($('#form')[0]);
$.ajax({
type: 'POST',
processData: false,
contentType: false,
data: formData,
success: function (data) {
// The file was uploaded successfully...
$('.result').text('File was uploaded.');
},
error: function (data) {
// there was an error.
$('.result').text('Whoops! There was an error in the request.');
}
});
This of course requires that your HTML DOM contains these elements—I used the code I wrote for my article quite a few years back. Secondly, for my other part of the feature, I used Request.Files to capture the files that might have been uploaded with the request.
files = Request.Files.Count;
if(files > 0) {
// Files are sent!
for (int i = 0; i < files; i++) {
var file = Request.Files[i];
// Got the image...
string fileName = Path.GetFileName(file.FileName);
// Save the file...
file.SaveAs(Server.MapPath("~/" + fileName));
}
}
This way, I uploaded the files using jQuery and FormData.
You can check out the complete article I posted here, Uploading the files — HTML5 and jQuery Way!
Oh, and do not forget the suggestion made in the comment,
using (var com = new SqlCommand("dbo.sp_some_stored_procedure_for_saving_data", con))
{
con.Open(); // missed call?
data = Convert.ToString(com.ExecuteScalar());
// although, using should close here!
var file_path = Path.Combine(path, data + Extension);
fileUpload.SaveAs(file_path);
}
So, this was pretty much how you can do this.
I have a large(ish) form in MVC.
I need to be able to generate an excel file containing data from a subset of that form.
The tricky bit is that this shouldn't affect the rest of the form and so I want to do it via AJAX. I've come across a few questions on SO that seem to be related, but I can't quite work out what the answers mean.
This one seems the closest to what I'm after: asp-net-mvc-downloading-excel - but I'm not sure I understand the response, and it is a couple years old now. I also came across another article (can't find it anymore) about using an iframe to handle the file download, but I'm not sure how to get this working with MVC.
My excel file returns fine if I'm doing a full post back but I can't get it working with AJAX in mvc.
You can't directly return a file for download via an AJAX call so, an alternative approach is to to use an AJAX call to post the related data to your server. You can then use server side code to create the Excel File (I would recommend using EPPlus or NPOI for this although it sounds as if you have this part working).
UPDATE September 2016
My original answer (below) was over 3 years old, so I thought I would update as I no longer create files on the server when downloading files via AJAX however, I have left the original answer as it may be of some use still depending on your specific requirements.
A common scenario in my MVC applications is reporting via a web page that has some user configured report parameters (Date Ranges, Filters etc.). When the user has specified the parameters they post them to the server, the report is generated (say for example an Excel file as output) and then I store the resulting file as a byte array in the TempData bucket with a unique reference. This reference is passed back as a Json Result to my AJAX function that subsequently redirects to separate controller action to extract the data from TempData and download to the end users browser.
To give this more detail, assuming you have a MVC View that has a form bound to a Model class, lets call the Model ReportVM.
First, a controller action is required to receive the posted model, an example would be:
public ActionResult PostReportPartial(ReportVM model){
// Validate the Model is correct and contains valid data
// Generate your report output based on the model parameters
// This can be an Excel, PDF, Word file - whatever you need.
// As an example lets assume we've generated an EPPlus ExcelPackage
ExcelPackage workbook = new ExcelPackage();
// Do something to populate your workbook
// Generate a new unique identifier against which the file can be stored
string handle = Guid.NewGuid().ToString();
using(MemoryStream memoryStream = new MemoryStream()){
workbook.SaveAs(memoryStream);
memoryStream.Position = 0;
TempData[handle] = memoryStream.ToArray();
}
// Note we are returning a filename as well as the handle
return new JsonResult() {
Data = new { FileGuid = handle, FileName = "TestReportOutput.xlsx" }
};
}
The AJAX call that posts my MVC form to the above controller and receives the response looks like this:
$ajax({
cache: false,
url: '/Report/PostReportPartial',
data: _form.serialize(),
success: function (data){
var response = JSON.parse(data);
window.location = '/Report/Download?fileGuid=' + response.FileGuid
+ '&filename=' + response.FileName;
}
})
The controller action to handle the downloading of the file:
[HttpGet]
public virtual ActionResult Download(string fileGuid, string fileName)
{
if(TempData[fileGuid] != null){
byte[] data = TempData[fileGuid] as byte[];
return File(data, "application/vnd.ms-excel", fileName);
}
else{
// Problem - Log the error, generate a blank file,
// redirect to another controller action - whatever fits with your application
return new EmptyResult();
}
}
One other change that could easily be accommodated if required is to pass the MIME Type of the file as a third parameter so that the one Controller action could correctly serve a variety of output file formats.
This removes any need for any physical files to created and stored on the server, so no housekeeping routines required and once again this is seamless to the end user.
Note, the advantage of using TempData rather than Session is that once TempData is read the data is cleared so it will be more efficient in terms of memory usage if you have a high volume of file requests. See TempData Best Practice.
ORIGINAL Answer
You can't directly return a file for download via an AJAX call so, an alternative approach is to to use an AJAX call to post the related data to your server. You can then use server side code to create the Excel File (I would recommend using EPPlus or NPOI for this although it sounds as if you have this part working).
Once the file has been created on the server pass back the path to the file (or just the filename) as the return value to your AJAX call and then set the JavaScript window.location to this URL which will prompt the browser to download the file.
From the end users perspective, the file download operation is seamless as they never leave the page on which the request originates.
Below is a simple contrived example of an ajax call to achieve this:
$.ajax({
type: 'POST',
url: '/Reports/ExportMyData',
data: '{ "dataprop1": "test", "dataprop2" : "test2" }',
contentType: 'application/json; charset=utf-8',
dataType: 'json',
success: function (returnValue) {
window.location = '/Reports/Download?file=' + returnValue;
}
});
url parameter is the Controller/Action method where your code will create the Excel file.
data parameter contains the json data that would be extracted from the form.
returnValue would be the file name of your newly created Excel file.
The window.location command redirects to the Controller/Action method that actually returns your file for download.
A sample controller method for the Download action would be:
[HttpGet]
public virtual ActionResult Download(string file)
{
string fullPath = Path.Combine(Server.MapPath("~/MyFiles"), file);
return File(fullPath, "application/vnd.ms-excel", file);
}
My 2 cents - you don't need to store the excel as a physical file on the server - instead, store it in the (Session) Cache. Use a uniquely generated name for your Cache variable (that stores that excel file) - this will be the return of your (initial) ajax call. This way you don't have to deal with file access issues, managing (deleting) the files when not needed, etc. and, having the file in the Cache, is faster to retrieve it.
I was recently able to accomplish this in MVC (although there was no need to use AJAX) without creating a physical file and thought I'd share my code:
Super simple JavaScript function (datatables.net button click triggers this):
function getWinnersExcel(drawingId) {
window.location = "/drawing/drawingwinnersexcel?drawingid=" + drawingId;
}
C# Controller code:
public FileResult DrawingWinnersExcel(int drawingId)
{
MemoryStream stream = new MemoryStream(); // cleaned up automatically by MVC
List<DrawingWinner> winnerList = DrawingDataAccess.GetWinners(drawingId); // simple entity framework-based data retrieval
ExportHelper.GetWinnersAsExcelMemoryStream(stream, winnerList, drawingId);
string suggestedFilename = string.Format("Drawing_{0}_Winners.xlsx", drawingId);
return File(stream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml", suggestedFilename);
}
In the ExportHelper class I do use a 3rd party tool (GemBox.Spreadsheet) to generate the Excel file and it has a Save to Stream option. That being said, there are a number of ways to create Excel files that can easily be written to a memory stream.
public static class ExportHelper
{
internal static void GetWinnersAsExcelMemoryStream(MemoryStream stream, List<DrawingWinner> winnerList, int drawingId)
{
ExcelFile ef = new ExcelFile();
// lots of excel worksheet building/formatting code here ...
ef.SaveXlsx(stream);
stream.Position = 0; // reset for future read
}
}
In IE, Chrome, and Firefox, the browser prompts to download the file and no actual navigation occurs.
First Create the controller action that will create the Excel File
[HttpPost]
public JsonResult ExportExcel()
{
DataTable dt = DataService.GetData();
var fileName = "Excel_" + DateTime.Now.ToString("yyyyMMddHHmm") + ".xls";
//save the file to server temp folder
string fullPath = Path.Combine(Server.MapPath("~/temp"), fileName);
using (var exportData = new MemoryStream())
{
//I don't show the detail how to create the Excel, this is not the point of this article,
//I just use the NPOI for Excel handler
Utility.WriteDataTableToExcel(dt, ".xls", exportData);
FileStream file = new FileStream(fullPath, FileMode.Create, FileAccess.Write);
exportData.WriteTo(file);
file.Close();
}
var errorMessage = "you can return the errors in here!";
//return the Excel file name
return Json(new { fileName = fileName, errorMessage = "" });
}
then create the Download action
[HttpGet]
[DeleteFileAttribute] //Action Filter, it will auto delete the file after download,
//I will explain it later
public ActionResult Download(string file)
{
//get the temp folder and file path in server
string fullPath = Path.Combine(Server.MapPath("~/temp"), file);
//return the file for download, this is an Excel
//so I set the file content type to "application/vnd.ms-excel"
return File(fullPath, "application/vnd.ms-excel", file);
}
if you want to delete the file after downloaded create this
public class DeleteFileAttribute : ActionFilterAttribute
{
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
filterContext.HttpContext.Response.Flush();
//convert the current filter context to file and get the file path
string filePath = (filterContext.Result as FilePathResult).FileName;
//delete the file after download
System.IO.File.Delete(filePath);
}
}
and finally ajax call from you MVC Razor view
//I use blockUI for loading...
$.blockUI({ message: '<h3>Please wait a moment...</h3>' });
$.ajax({
type: "POST",
url: '#Url.Action("ExportExcel","YourController")', //call your controller and action
contentType: "application/json; charset=utf-8",
dataType: "json",
}).done(function (data) {
//console.log(data.result);
$.unblockUI();
//get the file name for download
if (data.fileName != "") {
//use window.location.href for redirect to download action for download the file
window.location.href = "#Url.RouteUrl(new
{ Controller = "YourController", Action = "Download"})/?file=" + data.fileName;
}
});
I used the solution posted by CSL but I would recommend you dont store the file data in Session during the whole session. By using TempData the file data is automatically removed after the next request (which is the GET request for the file). You could also manage removal of the file data in Session in download action.
Session could consume much memory/space depending on SessionState storage and how many files are exported during the session and if you have many users.
I've updated the serer side code from CSL to use TempData instead.
public ActionResult PostReportPartial(ReportVM model){
// Validate the Model is correct and contains valid data
// Generate your report output based on the model parameters
// This can be an Excel, PDF, Word file - whatever you need.
// As an example lets assume we've generated an EPPlus ExcelPackage
ExcelPackage workbook = new ExcelPackage();
// Do something to populate your workbook
// Generate a new unique identifier against which the file can be stored
string handle = Guid.NewGuid().ToString()
using(MemoryStream memoryStream = new MemoryStream()){
workbook.SaveAs(memoryStream);
memoryStream.Position = 0;
TempData[handle] = memoryStream.ToArray();
}
// Note we are returning a filename as well as the handle
return new JsonResult() {
Data = new { FileGuid = handle, FileName = "TestReportOutput.xlsx" }
};
}
[HttpGet]
public virtual ActionResult Download(string fileGuid, string fileName)
{
if(TempData[fileGuid] != null){
byte[] data = TempData[fileGuid] as byte[];
return File(data, "application/vnd.ms-excel", fileName);
}
else{
// Problem - Log the error, generate a blank file,
// redirect to another controller action - whatever fits with your application
return new EmptyResult();
}
}
using ClosedXML.Excel;
public ActionResult Downloadexcel()
{
var Emplist = JsonConvert.SerializeObject(dbcontext.Employees.ToList());
DataTable dt11 = (DataTable)JsonConvert.DeserializeObject(Emplist, (typeof(DataTable)));
dt11.TableName = "Emptbl";
FileContentResult robj;
using (XLWorkbook wb = new XLWorkbook())
{
wb.Worksheets.Add(dt11);
using (MemoryStream stream = new MemoryStream())
{
wb.SaveAs(stream);
var bytesdata = File(stream.ToArray(), "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "myFileName.xlsx");
robj = bytesdata;
}
}
return Json(robj, JsonRequestBehavior.AllowGet);
}
$.ajax({
type: "GET",
url: "/Home/Downloadexcel/",
contentType: "application/json; charset=utf-8",
data: null,
success: function (Rdata) {
debugger;
var bytes = new Uint8Array(Rdata.FileContents);
var blob = new Blob([bytes], { type: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "myFileName.xlsx";
link.click();
},
error: function (err) {
}
});
The accepted answer didn't quite work for me as I got a 502 Bad Gateway result from the ajax call even though everything seemed to be returning fine from the controller.
Perhaps I was hitting a limit with TempData - not sure, but I found that if I used IMemoryCache instead of TempData, it worked fine, so here is my adapted version of the code in the accepted answer:
public ActionResult PostReportPartial(ReportVM model){
// Validate the Model is correct and contains valid data
// Generate your report output based on the model parameters
// This can be an Excel, PDF, Word file - whatever you need.
// As an example lets assume we've generated an EPPlus ExcelPackage
ExcelPackage workbook = new ExcelPackage();
// Do something to populate your workbook
// Generate a new unique identifier against which the file can be stored
string handle = Guid.NewGuid().ToString();
using(MemoryStream memoryStream = new MemoryStream()){
workbook.SaveAs(memoryStream);
memoryStream.Position = 0;
//TempData[handle] = memoryStream.ToArray();
//This is an equivalent to tempdata, but requires manual cleanup
_cache.Set(handle, memoryStream.ToArray(),
new MemoryCacheEntryOptions().SetSlidingExpiration(TimeSpan.FromMinutes(10)));
//(I'd recommend you revise the expiration specifics to suit your application)
}
// Note we are returning a filename as well as the handle
return new JsonResult() {
Data = new { FileGuid = handle, FileName = "TestReportOutput.xlsx" }
};
}
AJAX call remains as with the accepted answer (I made no changes):
$ajax({
cache: false,
url: '/Report/PostReportPartial',
data: _form.serialize(),
success: function (data){
var response = JSON.parse(data);
window.location = '/Report/Download?fileGuid=' + response.FileGuid
+ '&filename=' + response.FileName;
}
})
The controller action to handle the downloading of the file:
[HttpGet]
public virtual ActionResult Download(string fileGuid, string fileName)
{
if (_cache.Get<byte[]>(fileGuid) != null)
{
byte[] data = _cache.Get<byte[]>(fileGuid);
_cache.Remove(fileGuid); //cleanup here as we don't need it in cache anymore
return File(data, "application/vnd.ms-excel", fileName);
}
else
{
// Something has gone wrong...
return View("Error"); // or whatever/wherever you want to return the user
}
}
...
Now there is some extra code for setting up MemoryCache...
In order to use "_cache" I injected in the constructor for the controller like so:
using Microsoft.Extensions.Caching.Memory;
namespace MySolution.Project.Controllers
{
public class MyController : Controller
{
private readonly IMemoryCache _cache;
public LogController(IMemoryCache cache)
{
_cache = cache;
}
//rest of controller code here
}
}
And make sure you have the following in ConfigureServices in Startup.cs:
services.AddDistributedMemoryCache();
$.ajax({
global: false,
url: SitePath + "/User/ExportTeamMembersInExcel",
"data": { 'UserName': UserName, 'RoleId': RoleId, UserIds: AppraseeId },
"type": "POST",
"dataType": "JSON",
"success": function (result) {
var bytes = new Uint8Array(result.FileContents);
var blob = new Blob([bytes], { type: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "myFileName.xlsx";
link.click();
},
"error": function () {
alert("error");
}
})
[HttpPost]
public JsonResult ExportTeamMembersInExcel(string UserName, long? RoleId, string[] UserIds)
{
MemoryStream stream = new MemoryStream();
FileContentResult robj;
DataTable data = objuserservice.ExportTeamToExcel(UserName, RoleId, UserIds);
using (XLWorkbook wb = new XLWorkbook())
{
wb.Worksheets.Add(data, "TeamMembers");
using (stream)
{
wb.SaveAs(stream);
}
}
robj = File(stream.ToArray(), System.Net.Mime.MediaTypeNames.Application.Octet, "TeamMembers.xlsx");
return Json(robj, JsonRequestBehavior.AllowGet);
}
I may sound quite naive, and may attract quite a criticism, but here's how I did it,
(It doesn't involve ajax for export, but it doesn't do a full postback either )
Thanks for this post and this answer.
Create a simple controller
public class HomeController : Controller
{
/* A demo action
public ActionResult Index()
{
return View(model);
}
*/
[HttpPost]
public FileResult ExportData()
{
/* An example filter
var filter = TempData["filterKeys"] as MyFilter;
TempData.Keep(); */
var someList = db.GetDataFromDb(/*filter*/) // filter as an example
/*May be here's the trick, I'm setting my filter in TempData["filterKeys"]
in an action,(GetFilteredPartial() illustrated below) when 'searching' for the data,
so do not really need ajax here..to pass my filters.. */
//Some utility to convert list to Datatable
var dt = Utility.ConvertToDataTable(someList);
// I am using EPPlus nuget package
using (ExcelPackage pck = new ExcelPackage())
{
ExcelWorksheet ws = pck.Workbook.Worksheets.Add("Sheet1");
ws.Cells["A1"].LoadFromDataTable(dt, true);
using (var memoryStream = new MemoryStream())
{
pck.SaveAs(memoryStream);
return File(memoryStream.ToArray(),
"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
"ExportFileName.xlsx");
}
}
}
//This is just a supporting example to illustrate setting up filters ..
/* [HttpPost]
public PartialViewResult GetFilteredPartial(MyFilter filter)
{
TempData["filterKeys"] = filter;
var filteredData = db.GetConcernedData(filter);
var model = new MainViewModel();
model.PartialViewModel = filteredData;
return PartialView("_SomePartialView", model);
} */
}
And here are the Views..
/*Commenting out the View code, in order to focus on the imp. code
#model Models.MainViewModel
#{Layout...}
Some code for, say, a partial View
<div id="tblSampleBody">
#Html.Partial("_SomePartialView", Model.PartialViewModel)
</div>
*/
//The actual part.. Just **posting** this bit of data from the complete View...
//Here, you are not posting the full Form..or the complete View
#using (Html.BeginForm("ExportData", "Home", FormMethod.Post))
{
<input type="submit" value="Export Data" />
}
//...
//</div>
/*And you may require to pass search/filter values.. as said in the accepted answer..
That can be done while 'searching' the data.. and not while
we need an export..for instance:-
<script>
var filterData = {
SkipCount: someValue,
TakeCount: 20,
UserName: $("#UserName").val(),
DepartmentId: $("#DepartmentId").val(),
}
function GetFilteredData() {
$("#loader").show();
filterData.SkipCount = 0;
$.ajax({
url: '#Url.Action("GetFilteredPartial","Home")',
type: 'POST',
dataType: "html",
data: filterData,
success: function (dataHTML) {
if ((dataHTML === null) || (dataHTML == "")) {
$("#tblSampleBody").html('<tr><td>No Data Returned</td></tr>');
$("#loader").hide();
} else {
$("#tblSampleBody").html(dataHTML);
$("#loader").hide();
}
}
});
}
</script>*/
The whole point of the trick seems that, we are posting a form (a part of the Razor View ) upon which we are calling an Action method, which returns: a FileResult, and this FileResult returns the Excel File..
And for posting the filter values, as said, ( and if you require to), I am making a post request to another action, as has been attempted to describe..
This thread helped me create my own solution that I will share here. I was using a GET ajax request at first without issues but it got to a point where the request URL length was exceeded so I had to swith to a POST.
The javascript uses JQuery file download plugin and consists of 2 succeeding calls. One POST (To send params) and one GET to retreive the file.
function download(result) {
$.fileDownload(uri + "?guid=" + result,
{
successCallback: onSuccess.bind(this),
failCallback: onFail.bind(this)
});
}
var uri = BASE_EXPORT_METADATA_URL;
var data = createExportationData.call(this);
$.ajax({
url: uri,
type: 'POST',
contentType: 'application/json',
data: JSON.stringify(data),
success: download.bind(this),
fail: onFail.bind(this)
});
Server side
[HttpPost]
public string MassExportDocuments(MassExportDocumentsInput input)
{
// Save query for file download use
var guid = Guid.NewGuid();
HttpContext.Current.Cache.Insert(guid.ToString(), input, null, DateTime.Now.AddMinutes(5), Cache.NoSlidingExpiration);
return guid.ToString();
}
[HttpGet]
public async Task<HttpResponseMessage> MassExportDocuments([FromUri] Guid guid)
{
//Get params from cache, generate and return
var model = (MassExportDocumentsInput)HttpContext.Current.Cache[guid.ToString()];
..... // Document generation
// to determine when file is downloaded
HttpContext.Current
.Response
.SetCookie(new HttpCookie("fileDownload", "true") { Path = "/" });
return FileResult(memoryStream, "documents.zip", "application/zip");
}
CSL's answer was implemented in a project I'm working on but the problem I incurred was scaling out on Azure broke our file downloads. Instead, I was able to do this with one AJAX call:
SERVER
[HttpPost]
public FileResult DownloadInvoice(int id1, int id2)
{
//necessary to get the filename in the success of the ajax callback
HttpContext.Response.Headers.Add("Access-Control-Expose-Headers", "Content-Disposition");
byte[] fileBytes = _service.GetInvoice(id1, id2);
string fileName = "Invoice.xlsx";
return File(fileBytes, System.Net.Mime.MediaTypeNames.Application.Octet, fileName);
}
CLIENT
(modified version of Handle file download from ajax post)
$("#downloadInvoice").on("click", function() {
$("#loaderInvoice").removeClass("d-none");
var xhr = new XMLHttpRequest();
var params = [];
xhr.open('POST', "#Html.Raw(Url.Action("DownloadInvoice", "Controller", new { id1 = Model.Id1, id2 = Model.Id2 }))", true);
xhr.responseType = 'arraybuffer';
xhr.onload = function () {
if (this.status === 200) {
var filename = "";
var disposition = xhr.getResponseHeader('Content-Disposition');
if (disposition && disposition.indexOf('attachment') !== -1) {
var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
var matches = filenameRegex.exec(disposition);
if (matches != null && matches[1]) filename = matches[1].replace(/['"]/g, '');
}
var type = xhr.getResponseHeader('Content-Type');
var blob = typeof File === 'function'
? new File([this.response], filename, { type: type })
: new Blob([this.response], { type: type });
if (typeof window.navigator.msSaveBlob !== 'undefined') {
// IE workaround for "HTML7007: One or more blob URLs were revoked by closing the blob for which they were created. These URLs will no longer resolve as the data backing the URL has been freed."
window.navigator.msSaveBlob(blob, filename);
} else {
var URL = window.URL || window.webkitURL;
var downloadUrl = URL.createObjectURL(blob);
if (filename) {
// use HTML5 a[download] attribute to specify filename
var a = document.createElement("a");
// safari doesn't support this yet
if (typeof a.download === 'undefined') {
window.location = downloadUrl;
} else {
a.href = downloadUrl;
a.download = filename;
document.body.appendChild(a);
a.click();
}
} else {
window.location = downloadUrl;
}
setTimeout(function() {
URL.revokeObjectURL(downloadUrl);
$("#loaderInvoice").addClass("d-none");
}, 100); // cleanup
}
}
};
xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xhr.send($.param(params));
});
This works for me. Make sure you return a File from your controller action with contentType as "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" and file name as e.g. "List.xlsx" which should be the same as in the AJAX success call. I have used ClosedXML NuGet package to generate the excel file.
$.ajax({
url: "Home/Export",
type: 'GET',
contentType: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
xhrFields: { responseType: 'blob' },
success: function (data) {
var a = document.createElement('a');
var url = window.URL.createObjectURL(data);
a.href = url;
a.download = 'List.xlsx';
a.click();
window.URL.revokeObjectURL(url);
}
});
I am using Asp.Net WebForm and just I wanna to download a file from server side. There is a lot article but I cannot find just basic answer.
Now, I tried a basic way and got it.
That's my problem.
I have to create a lot of input button dynamically on runtime. And I want to add each button to download button with giving an unique fileNumber.
I create each button like this:
fragment += "<div><input type=\"button\" value=\"Create Excel\" onclick=\"CreateExcelFile(" + fileNumber + ");\" /></div>";
Each button call this ajax method.
$.ajax({
type: 'POST',
url: 'index.aspx/CreateExcelFile',
data: jsonData,
contentType: 'application/json; charset=utf-8',
dataType: 'json',
success: function (returnValue) {
window.location = '/Reports/Downloads/' + returnValue.d;
}
});
Then I wrote a basic simple method.
[WebMethod]
public static string CreateExcelFile2(string fileNumber)
{
string filePath = string.Format(#"Form_{0}.xlsx", fileNumber);
return filePath;
}
I am generating this Form_1, Form_2, Form_3.... And I am going to delete this old files with another program. But if there is a way to just sending byte array to download file like using Response. I wanna to use it.
I hope this will be usefull for anyone.
On Submit form
public ActionResult ExportXls()
{
var filePath="";
CommonHelper.WriteXls(filePath, "Text.xls");
}
public static void WriteXls(string filePath, string targetFileName)
{
if (!String.IsNullOrEmpty(filePath))
{
HttpResponse response = HttpContext.Current.Response;
response.Clear();
response.Charset = "utf-8";
response.ContentType = "text/xls";
response.AddHeader("content-disposition", string.Format("attachment; filename={0}", targetFileName));
response.BinaryWrite(File.ReadAllBytes(filePath));
response.End();
}
}
Good day!
I am working on a ASP.NET Web API 2 project. At a certain point there is a need to upload some files. The files need to be linked to a certain FileModel (our own class). So, the client needs to send IEnumerable as parameter and the files as content. Because it's a RESTful API, both have to be sent in the same request.
The best we could come up with is the follow Controller action:
public async Task<HttpResponseMessage> Add([FromUri] IEnumerable<FileModel> fileModels)
{
// REQUEST INTEGRITY TESTING
var streamProvider = new CustomMultipartFormDataStreamProvider(fileSavePath, fileModels);
// Read the MIME multipart content using the stream provider we just created.
var work = await Request.Content.ReadAsMultipartAsync(streamProvider).ContinueWith(async t =>
{
// SOME WORK DONE AFTER SAVING THE FILES TO THE HARD DRIVE
}
}
The problem is following: the files are being uploaded with a 'multipart/form-data' Content-Type header. We need to know the contents of the FileModels before manipulating the files on the server side. If we use the MultipartFormDataStreamProvider, we can only access the non file parameters after the files have already been saved to the hard drive.
The only workaround for this we could find is to send the IEnumerable< FileModel > parameter in the URL. But given that the URL has a limited max length, this is not a reliable method.
The question is: Is there a way to submit both the IEnumerable< FileModel > fileModels parameter and the files in the body of the request and get access to the fileModels parameter before accessing the files? We also want to be able to use HttpContext.Current.Request.Files.Count;
Our current jQuery for file upload looks like this (for early testing purposes, it only supports one file upload):
$('#Upload').click(function(e) {
e.preventDefault();
var headers = new Array();
headers["SessionId"] = sessionId;
var files = $('#fileInput').get(0).files;
var formData = new FormData();
formData.append("files", files[0]);
var fileModel = $('#fileSubmission').serialize();
$.ajax({
url: "api/Submissions/Add/?" + fileModel,
headers: headers,
type: 'POST',
data: formData,
cache: false,
contentType: false,
processData: false,
dataType: 'json'
});
});
Thank you very much!
I am sorry for the late answer, but we solved the problem (I forgot that I didn't upload the answer here). Basically what we did is that we called the ReadAsMultiPartAsync method on a temporary location and then we extracted the other parameters from the request. Afterwards, we validated the input and moved the files from the temporary to the permanent location.
If you want to see the code, this is what worked for our particular example and I believe it's pretty straight-forward to adapt to any work case scenario:
On the client side, we have the following form (yes, this implementation is for demo purposes and only supports sending one file ... also, the input type="file" field is indeed outside of the form; the fileId text input is completed manually in our case, just for testing purposes)
<input type="file" name="data" id="fileInput" multiple="multiple" />
<form id="fileSubmission">
<input type="text" width="10" onchange="getFileDetails()" autocomplete="off" placeholder="FileId" name="files[0].Id" id="fileId" />
<input type="hidden" name="files[0].FileName" id="FileName"/>
<input type="hidden" name="files[0].Extension" id="Extension"/>
<input type="hidden" name="files[0].EntityId" id="EntityId"/>
<br /><br />
<input type="submit" id="Upload" value="Upload" />
</form>
where getFileDetails() populates the other input fields. Also, the form is being sent to the server by using the following jQuery/Javascript:
$('#Upload').click(function(e) {
e.preventDefault();
var courseId = $('#courseId').val();
var fileId = $('#fileId').val();
if (!courseId || !fileId) {
return;
}
var headers = new Array();
headers["SessionId"] = sessionId;
headers["contentType"] = "application/json; charset=UTF-8";
var formData = new FormData();
var opmlFile = $('#fileInput').get(0).files;
// this is like the model we're expecting on the server
var files = [];
files.push({ 'Id': $('#fileId').val(), 'OriginalFileName': opmlFile[0].name, 'FileName': $('#FileName').val(), 'Extension': $('#Extension').val(), 'EntityId': $('#EntityId').val() });
formData.append("fileModels", JSON.stringify(files));
formData.append("File_0", opmlFile[0]);
$.ajax({
url: "api/Courses/" + courseId + "/Submissions/Add/",
headers: headers,
type: 'POST',
data: formData,
cache: false,
contentType: false,
processData: false,
dataType: 'json'
});
});
On the server side, we have the following :
// POST: api/Courses/{courseId}/Submissions/Add
[HttpPost]
[ValidateModelState]
[ValidateMimeMultipartContent]
[PermissionsAuthorize(CoursePermissions.CanCreateSubmissions)]
public async Task<HttpResponseMessage> Add(int courseId)
{
// the same as in the jQuery part
const string paramName = "fileModels";
// Put the files in a temporary location
// this way we call ReadAsMultiPartAsync and we get access to the other data submitted
var tempPath = HttpContext.Current.Server.MapPath("~/App_Data/Temp/" + Guid.NewGuid());
Directory.CreateDirectory(tempPath);
var streamProvider = new MultipartFormDataStreamProvider(tempPath);
var readResult = await Request.Content.ReadAsMultipartAsync(streamProvider);
if (readResult.FormData[paramName] == null)
{
// We don't have the FileModels ... delete the TempFiles and return BadRequest
Directory.Delete(tempPath, true);
return Request.CreateResponse(HttpStatusCode.BadRequest);
}
// The files have been successfully saved in a TempLocation and the FileModels are not null
// Validate that everything else is fine with this command
var fileModels = JsonConvert.DeserializeObject<IEnumerable<FileModelExtension>>(readResult.FormData[paramName]).ToList();
// AT THIS POINT, ON THE SERVER, WE HAVE ALL THE FILE MODELS
// AND ALL THE FILES ARE SAVED IN A TEMPORARY LOCATION
// NEXT STEPS ARE VALIDATION OF THE INPUT AND THEN
// MOVING THE FILE FROM THE TEMP TO THE PERMANENT LOCATION
// YOU CAN ACCESS THE INFO ABOUT THE FILES LIKE THIS:
foreach (var tempFile in readResult.FileData)
{
var originalFileName = tempFile.Headers.ContentDisposition.FileName.Replace("\"", string.Empty);
var localTempPath = tempFile.LocalFileName;
}
}
I hope this will help anyone out there trying to submit files and other parameters at once to the server by using Post requests! :)
NOTE: Some of the attributes used on the server are custom. PermissionAuthorize, ValidateModelState and ValidateMimeMultiPartContent are custom Filters we have used. The implementation of the latter two has been inspired by http://benfoster.io/blog/automatic-modelstate-validation-in-aspnet-mvc
The multipartcontent attribute just does a check on actionContext.Request.Content.IsMimeMultipartContent(), like this:
public class ValidateMimeMultipartContent : ActionFilterAttribute
{
public override void OnActionExecuting(HttpActionContext actionContext)
{
if (!actionContext.Request.Content.IsMimeMultipartContent())
{
actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.UnsupportedMediaType, Messages.UnsupportedMediaType);
}
}
}