C# Asp.net write file to client - c#

I hope this is a quick question I hope. I need to write some reports and then have the user prompted to save it to his/her local machine. The last time I did this I wrote a file to the webserver and then sent it to the client via Response object.
to create on the webserver
TextWriter tw = new StreamWriter(filePath);
to send to client
page.Response.WriteFile(path);
The question is, Is there a way to skip the writing of the physical file to to the webserver and go right from an object that represent the document to the response?

You could use the Response.ContentType like this
Response.ContentType = "text/plain";
Response.OutputStream.Write(buffer, 0, buffer.Length);
Response.AddHeader("Content-Disposition", "attachment;filename=yourfile.txt");
This of course works if you want to write a text file. In case you want to write a .doc for example you change the ContentType to "application/msword" etc...

You can.
Try this:
Table oTable = new Table();
//Add data to table.
Response.Clear();
Response.Buffer = true;
Response.ContentType = "application/vnd.ms-excel";
Response.AddHeader("Content-Disposition", "attachment;filename="test.xls"");
Response.Charset = "";
this.EnableViewState = false;
System.IO.StringWriter oStringWriter = new System.IO.StringWriter();
System.Web.UI.Html32TextWriter oHtmlTextWriter = new System.Web.UI.Html32TextWriter(oStringWriter);
0Table.RenderControl(oHtmlTextWriter);
Response.Write(oStringWriter.ToString());
Response.End();
This will give prompt the user to open or save test.xls file.
similarly you can provide other ASP.NET objects in place of Table.

Yes.
page.Response.WriteFile(yourData, 0, yourData.Length);

The exact answer to the question depends on how do you have your report organized (i.e. what is the "object" you're referring to). If you have a single string, you can use Response.Write to just write it. If you need a TextWriter, Response.Output is what you want - that way you can skip writing to the disk and then using WriteFile. Also, if your content happened to be binary, you could use Response.OutputStream for that.
You may also want to set Response.AddHeader("Content-Disposition", "attachment"), if you want the user to see a save file dialog. However, Content-Disposition is not necessarily honored, so the user may still get the report opened directly in the browser. Remember to set headers before you output the actual content!
Also, depending on the format of the report, you may want to set Response.ContentType to something appropriate such as text/plain, text/csv or whatever have you. The correct mime types are listed at the IANA site.

Related

I can't send a file from my server filesystem to the client (downloading with the Save As dialog box)

I am working with some calculations and the product of my business logic is the creation of a PDF report (C# ASP.NET). So far, I have managed to create the report. The convention of my company is storing all the data in .gz format somewhere in the filesystem. At the click of some button, I need to send the file to the client, with the opening of the dialog box for downloading and saving the file to the desired destination.
I have tried a lot of options, including .TransmitFile, .OutputStream.Write as they are the methods that the Response object has. However, I'm not getting any feedback back. There doesn't seem to be any errors and the code is running as the methods never happened. If I set a try catch block, the code runs into an exception with description "Thread was aborted", though I heard that Response.End always throws an exception.
var file = new FileInfo(integrityCheckInfo.ReportPath);
var buffer = integrityCheckInfo.ReportData;
//Code for downloading the report, doesn't work, and I don't know how to fix this.
if (File.Exists(integrityCheckInfo.ReportPath))
{
Response.Clear();
//Response.AddHeader("Accept-encoding", "gzip, deflate");
Response.AddHeader("content-length", buffer.Length.ToString());
Response.ContentType = "application/x-gzip";
Response.Buffer = true;
Response.Expires = -1000;
Response.AddHeader("content-disposition", "attachment; filename=report.gz");
//Response.BinaryWrite(buffer);
Response.OutputStream.Write(buffer, 0, buffer.Length);
//Response.Flush();
//Response.TransmitFile(integrityCheckInfo.ReportPath);
//Response.Flush();
Response.End();
}
The code that starts with // are comments and they are not included in this iteration where I wanted to download the .gz instead of the PDF but also got nothing for feedback.

How do I export a C#/asp.net datagrid to Excel and avoid the new security preventing opening Excel files?

I have a C#/asp.net program that stores data in a datagrid and then uses HttpResponse to create an Excel file from it. This worked well until Microsoft made security changes. Here's some information on that change: http://www.networksteve.com/exchange/topic.php/XLS_file_will_not_open_in_Excel_2016,_only_gray_view/?TopicId=77375&Posts=3. The solutions such as turning off Excel security and uninstalling the patch the caused the problem are not acceptable for my client. The official Microsoft answer is "The best option is to move away from using HTML wrapped as .XLS. If you use native formats (e.g. XLS, XLSX, XLSB) which will open in protected view when untrusted, this will provide some level of protection from the documents being opened." http://answers.microsoft.com/en-us/office/forum/office_2010-excel/windows-installed-updates-and-now-downloaded-excel/069b0fdf-d085-4322-b298-5976d0efa9ce?rtAction=1468539460673
My question is, how do I do that? I tried using the Microsoft.Interop and found multiple people saying this is not a good solution. I could never get that working anyway; see that discussion here: How can I download an Excel file to the user's download folder?
See my code below. I'm hoping that I can change the header or content type and get this to work. I'm open to any coding suggestions. As I said, our client is not going to change security options on their and their clients' machines; this needs to be something I can do in the code so the client doesn't have to do anything. Also, my boss is very hesitant to give me time to learn 3rd party controls so those are probably out as well.
var grid = new DataGrid();
grid.HeaderStyle.Font.Bold = true;
grid.AlternatingItemStyle.BackColor = System.Drawing.Color.DarkGray;
grid.DataSource = GetTable(storerId, bSunday, bMonday, bTuesday, bWednesday, bThursday, bFriday, bSaturday, beginDate, endDate);
grid.DataBind();
response.Clear();
//response.AddHeader("content-disposition", string.Format("{0}{1}{2}{3}{4}", "attachment;filename=", storerId, "KpiExport", DateTime.Today.ToShortDateString(), ".xls"));
//response.AddHeader("Content-Disposition", string.Format("{0}{1}{2}{3}{4}", "attachment;filename=", storerId, "KpiExport", DateTime.Today.ToShortDateString(), ".xls"));
HttpContext.Current.Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", "sample.xls"));
response.Charset = "";
// response.ContentType = "application/vnd.xls";
response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
var writer = new StringWriter();
var htmlWriter = new HtmlTextWriter(writer);
grid.RenderControl(htmlWriter);
response.Write(writer.ToString());
response.End();

How to show Save As Dialog on ASP.net

I'm newbie on asp.net, i am developing Online Report Generator, i want to let the client to choose where he/she want to put his/her files so this is my code but didn't seems to work, it returning to my ajax error statement my ConfigurationManager.AppSettings["ExtractFolder"] is equal to "c:\temp\": just want to ask what's wrong with the code?
context.Response.ContentType = "application/vnd.ms-excel";
context.Response.AddHeader("content-disposition", "attachment;filename="+filename);
context.Response.WriteFile(ConfigurationManager.AppSettings["ExtractFolder"]+filename);
context.Response.Flush();
context.Response.End();
Try this
String FileName = "FileName.txt";
String FilePath = "C:/...."; //Replace this
System.Web.HttpResponse response = System.Web.HttpContext.Current.Response;
response.ClearContent();
response.Clear();
response.ContentType = "text/plain";
response.AddHeader("Content-Disposition", "attachment; filename=" + FileName + ";");
response.TransmitFile(FilePath);
response.Flush();
response.End();
For more content types check our http://en.wikipedia.org/wiki/MIME_type#List_of_common_media_types
Basically you can't do what you want to do the way you are trying to do it.
The ASP.net code that you have is dependant on being part of a full http Request/Response cycle. The part where it is setting headers is where it telling the browser to download stuff.
An AJAX request is looking for a specific return with its request, generally javascript passable data. You are not returning this but rather the contents of a file.
Here's an article the explains the concepts and problems a little more. It also provides you an alternate solution. Basically the solution revolves around using an iFrame to handle the file download request.
First, check that your source file you want to send to the user is in c:\temp\ and that you have set filename to the name of the file you are sending. Next you will want to make sure that your .net process has permission to c:\temp on your server. It probably doesn't.
Also, make sure you understand that response.writefile actually reads a file from the server and writes it out to the browser. You can't specify where the user saves the file to locally, this is handled by the browser not by your code.
Using Coders sample code make sure you change the following (see my comments)
String FileName = "FileName.xlsx"; //MAKE SURE THIS IS YOUR EXCEL FILENAME ON YOUR SERVER
String FilePath = "C:/...."; //SET THIS TO THE FOLDER THE FILE IS IN (put your file in your root folder of your website for now, you can move it later once you get the download code working)
System.Web.HttpResponse response = System.Web.HttpContext.Current.Response;
response.ClearContent();
response.Clear();
response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"; //MAKE SURE YOU HAVE CHANGED THIS TOO
response.AddHeader("Content-Disposition", "attachment; filename=" + FileName + ";");
response.TransmitFile(FilePath);
response.Flush();
response.End();
I also suggest trying the above in a standalone page first then incorporate it into your AJAX page once you know its working.

Download Document in the right format without MIME

I have got this WebService that allows uploading/downloading any docs (mostly .docx, .doc, .pdf) and all it returns is byte[] when querying for downloading.
I have written this code
string ContractGUID = dtContract.Rows[0]["ContractGUID"].ToString();
//Get Bytes from WebService
byte[] fileData = BLL.Contract.GetDocument(new Guid(ContractGUID));
Response.Clear();
Response.BinaryWrite(fileData);
Response.AddHeader("Content-Disposition", "Attachment");
Response.Flush();
The other methods that the WebService exposed are GetDocumentName and GetDocumentLen
Is it possible to determine the Mime-Type or force the browser to download it in the right format? Currently it is downloading as .htm in Chrome and when open, I see funny characters. Any better advice?
Thanks.
No, it's not possible to force the browser to download in the right format without you telling it via the Content-Type header.
Response.ContentType = "application/pdf"; //or whatever appropriate
If the web service exposes a GetDocumentName() method you can probably infer the appropriate format by looking at the name, assuming the name has a file extension. This, obviously, is not bullet proof since you can change the extension of a file to anything you want.
Another alternative would be to try and guess the file format by peeking at the first bytes. For example, if the first 4 bytes of the file are 25 50 44 46 then it's very likely that this is a PDF file. On this website, they have a pretty extensive list.
Here's the list of possible content-type headers.
I think, the browser does it through filename.
e.g.:
response.Clear();
response.AddHeader("Content-Disposition", "attachment; filename=" + dbFile.filename.Replace(" ", "_"));
response.AddHeader("Content-Length", dbFile.data.Length.ToString());
response.ContentType = "application/octet-stream";
response.OutputStream.Write(dbFile.data, 0, dbFile.data.Length);
response.End();
dbFile.filename is a string
dbFile.data is a byte[]

save as dialog in asp.net

I have some data in the form of a string. I want to write this data to a file and save the file to the specified path. The path would be specified by opening a save as dialog on the button click. How can this be achieved??
The file is saved into the server initially with this code
string getnote = txtdisplay.Text.Trim();
String filepath = Server.MapPath(#"img\new1.txt");
System.IO.FileStream ab = new System.IO.FileStream(filepath, System.IO.FileMode.Create);
System.IO.StreamWriter Write101 = new System.IO.StreamWriter(ab);
Write101.WriteLine(getnote);
Write101.Close();
Response.ClearContent();
From the server get the file as attachment.Use the following code for save as dialog box for downloading or saving the file. The file will save by default in the download folder. To save to the specified location change the browser settings.
Response.ContentType = "text";
Response.AppendHeader("Content-Disposition", "attachment; filename=new1.txt");
Response.TransmitFile(Server.MapPath("~/img/new1.txt"));
Response.End();
Response.ContentType = "application/octet-stream" (or content type of your file).
Response.AppendHeader("content-disposition", "attachment;filename=" & strFileName)
There is no Save As dialog in ASP.NET.
Remember, your ASP.NET application is running in a browser on a user's computer. You have no access to the user's file system, including the Save As dialog.
However, if you send the user a file, as an attachment, most browsers will display a dialog asking the user whether to save the file or open it. Maybe the user will choose to save it. That's what the example from phoenix does.
You could use a LinkButton (or regular link) and have the url point to a handler (ASHX) that retrieves the data and sends back a response with content disposition set to attachment. Write the data to the response. You'll also need to set up some other headers in the response -- such as content type and length. This would give the document (file) a regular link that could perhaps be bookmarked (if a regular link) in the future so that it can be retrieved again. You'd need to pass enough data in the query string to be able to identify which data is to be downloaded.
if I userstand you correctly, here -
saveFileDialog1.DefaultExt = "*.file";
saveFileDialog1.Filter = "File|*.file|Other File|*.OFile|";
if (saveFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK &&
saveFileDialog1.FileName.Length > 0)
{
WebClient wc = new WebClient();
wc.DownloadFile("http://www.exaple.com/exaplefile", saveFileDialog1.FileName);;
}

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