Is it possible to get the browser to popup its Save As... dialog when doing a POST (rather than GET) request?
Using the Spring framework, I'm trying to build a service that will receive some data (a two-dimensional json array), and produce an Excel file that the user is prompted to download.
By doing a GET request, eg by browsing directly to my URL, I can get the browser to display the popup by setting headers similar to this:
response.setHeader("Content-Disposition", "attachment; filename=" + fileName)
response.setContentType("application/vnd.ms-excel")
I need to allow the client to post the data that will be used to build the Excel file though, which implies a POST request. The same headers are returned, but no popup.
Is there a way to achieve this, or does the popup appear only for GET requests?
I'm thinking I could do a two-step process; 1) allow the client to POST the data, and return some sort of reference key, 2) allow the client to do a GET request and include the key, and return the relevant headers to cause the browser to popup the dialog.
Any other thoughts on how to do this?
Thanks
It's possible. I'm not sure what I did wrong the first time I tried it out.
Related
I need to reuse value which is generated for my previous request.
For example, at first request, I make a POST to the URL /api/products/{UUID} and get HTTP response with code 201 (Created) with an empty body.
And at second request I want to get that product by request GET /api/products/{UUID}, where UUID should be from the first request.
So, the question is how to store that UUID between requests and reuse it?
You can use the Request Sent Dynamic values https://paw.cloud/extensions?extension_type=dynamic_value&q=request+send these will get the value used last time you sent a requst for a given request.
In your case you will want to combine the URLSentValue with the RegExMatch (https://paw.cloud/extensions/RegExMatch) to first get the url as it was last sent for a request and then extract the UUID from the url.
e.g
REQUEST A)
REQUEST B)
The problem is in your first requests answer. Just dont return "[...] an empty body."
If you are talking about a REST design, you will return the UUID in the first request and the client will use it in his second call: GET /api/products/{UUID}
The basic idea behind REST is, that the server doesn't store any informations about previous requests and is "stateless".
I would also adjust your first query. In general the server should generate the UUID and return it (maybe you have reasons to break that, then please excuse me). Your server has (at least sometimes) a better random generator and you can avoid conflicts. So you would usually design it like this:
CLIENT: POST /api/products/ -> Server returns: 201 {product_id: UUID(1234...)}
Client: GET /api/products/{UUID} -> Server returns: 200 {product_detail1: ..., product_detail2: ...}
If your client "loses" the informations and you want him to be later able to get his products, you would usually implement an API endpoint like this:
Client: GET /api/products/ -> Server returns: 200 [{id:UUID(1234...), title:...}, {id:UUID(5678...),, title:...}]
Given something like this, presuming the {UUID} is your replacement "variable":
It is probably so simple it escaped you. All you need to do is create a text file, say UUID.txt:
(with sample data say "12345678U910" as text in the file)
Then all you need to do is replace the {UUID} in the URL with a dynamic token for a file. Delete the {UUID} portion, then right click in the URL line where it was and select
Add Dynamic Value -> File -> File Content :
You will get a drag-n-drop reception widget:
Either press the "Choose File..." or drop the file into the receiver widget:
Don't worry that the dynamic variable token (blue thing in URL) doesn't change yet... Then click elsewhere to let the drop receiver go away and you will have exactly what you want, a variable you can use across URLs or anywhere else for that matter (header fields, form fields, body, etc):
Paw is a great tool that goes asymptotic to awesome when you explore the dynamic value capability. The most powerful yet I have found is the regular expression parsing that can parse raw reply HTML and capture anything you want for the next request... For example, if you UUID came from some user input and was ingested into the server, then returned in a html reply, you could capture that from the reply HTML and re-inject it to the URL, or any field or even add it to the cookies using the Dynamic Value capabilities of Paw.
#chickahoona's answer touches on the more normal way of doing it, with the first request posting to an endpoint without a UUID and the server returning it. With that in place then you can use the RegExpMatch extension to extract the value from the servers's response and use it in subsequent requests.
Alternately, if you must generate the UUID on the client side, then again the RegExpMatch extension can help, simply choose the create request's url for the source and provide a regexp that will strip the UUID off the end of it, such as /([^/]+)$.
A third option I'll throw out to you, put the UUID in an environment variable and just have all of your requests reference it from there.
i am sending a large amount of excel content data to the browser using Page.Response.Write("") in a for loop.
before starting the loop i am changing the conetnt type of the reponse.context property to "ms-excel".
if i have an exception during that for loop , i try to popup an error message to the browser by registering an HTML startup script block and Write it to the browser. before the write i change back the content type to be text/html.
but i get an error that say that is not possible to change the content type after sending the HTTP Headers.
How to notify the browser about an error that occured during that for loop?
Is it possible to have more that one respone to the same browser tab?
by the way,right now i don't want to use ASP.NET AJAX.
Did you try Response.ClearHeaders(); before changing the context type?
If that doesn't work because your Response.Write is causing problems, you might think about going the route of building a string before deciding your content type and then setting the headers.
Loop trough the content and add to a StringBuilder
If no error, set contenttype to ms-excel and write out SB
If there is an error, leave contenttype as it is write out your error message as needed.
Page.Response.Write("") will send data to the browser. When you do that the browser needs to know the type of content it gets in order to render it correct. If you already told the browser what kind of content you have(and even if you don't, you are already sening data with Response.Write, it will use the default value which I think is text/html) then you can't take it back. Whatever you are saying to the client is said and you can't take it back.
The way to solve your problem is to cache the reply as suggested by Doozer.
/Tibi
Current situation
I have ASP.NET web application that render PDF for users using MS Report Viewer. The PDF is rendered with this method:
Byte pdfByte = Byte();
pdfByte = ReportViewer.LocalReport.Render("PDF", Nothing, mimeType, encoding, extensions, stream, warning)
And send to browser as an attachment with response object:
Response.Clear()
Response.ContentType = mimeType
Response.AddHeader("content-disposition", "attachment; filename=myfile." + extension)
Response.BinaryWrite(pdfByte)
Response.Flush()
Response.End()
This work great! The user browser will get the PDF as download-able attachment.
What I am trying to achieve
Render multiple PDF and send all of them separately to user's browser. User will get separate PDF documents. It doesn't matter whether they will get them all at once or one by one.
The problem
The problem is after Response.End() the next line of code is not executed. I have tried to store the pdfByte object in session, looping through it and send them to user's browser with Response object but after the first PDF get sent then it stop.
I have also tried removing Response.End() thinking the code will keep running but still it stop after the first PDF get sent.
Please advice any workaround or tips. Thanks!
You cannot send multiple files (as separate entities) in a single HTTP response (the protocol does not support it. However, what you can do is to archive all files together and send the that single zip (or whatever format you want) to the client.
You can use libraries such as DotNetZip/SharpZipLib to combine (and compress) files together. Based on library API, you may need to save PDF files to disk before adding to zip file. Also do not forget to change your content type appropriate while sending the zip file to client.
Yet another alternative is to provide user with a page having multiple links to download files. It may mean that you either have to store your PDFs for some time so that they can served later (via links) or make link point to a handler that will re-run the report again to get the PDF out of it.
Admittedly the method I'm using doesn't feel very elegant, but here's what I'm doing:
create one IFRAME on the page for each document you want to send to the client (maybe create the IFRAMEs dynamically in server-side code if the number of documents is variable);
create a HttpHandler that generates the PDF documents, depending on a parameter you're passing in through the QueryString, just like you're doing above;
set the src on all IFRAMES to the URL of the HttpHandler with the appropriate parameters attached.
Of course the HttpHandler needs to do implement security logic, if required.
This works quite beautifully: If I want to send 3 documents, I create 3 IFRAMEs, set their src, and the user will see 3 "Save As..." dialogs pop up.
Simply put, I'd like someone to be able to click a link, and get a one-time-use pdf. We have the library to create PDF files, so that's not an issue.
We could generate a link to an aspx page, have that page generate the pdf, save the pdf to the filesystem, and then Response.Redirect to the saved pdf. Then we'd somehow have to keep track of and clean up the PDF file.
Since we don't ever need to keep this data, what I'd like to do instead, if possible, is to have the aspx page generate the pdf, and serve it directly back as a response to the original request. Is this possible?
(In our case, we're using C#, and we want to serve a pdf back, but it seems like any solution would probably work for various .NET languages and returned filetypes.)
Assuming you can get a byte[] representing your PDF:
Response.Clear();
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition",
"attachment;filename=\"FileName.pdf\"");
Response.BinaryWrite(yourPdfAsByteArray);
Response.Flush();
Response.End();
Look at how HTTP works. The client (=browser) doesn't rely on extensions, it only wants the server to return some metadata along with the document.
Metadata can be added with Response.AddHeader, and one 'metadata line' consists of Name and Value.
Content-Type is the property you are interested in, and the value is MIME type of the data (study: RFC1945 for HTTP headers, google for MIME type).
For ordinal aspx pages (html, ....) the property is 'text/html' (not so trivial, but for this example it is enough.). If you return JPG image, it can have name 'image.gif', but as long as you send 'image/jpeg' in Content-Type, it is processed as JPG image.
Content-type for pdf is 'application/pdf'.
The browser will act according to default behaviour, for example, with Adobe plugin, it will display the PDF in it's window, if you don't have any plugin for PDF, it should download the file, etc..
Content-Disposition header says, what you should do with the data. If you want explicitly the client to 'download' some HTML/PDF/whatever, and not display it by default, value 'attachment' is what you want. It should have another parameter, (as suggested by Justin Niessner), which is used in case of something like:
http://server/download.aspx?file=11 -> Content-Disposition: attachment;filename=file.jpg says, how the file should be by default named.
I am doing an e-commerce solution in ASP.NET which uses PayPal's Website Payments Standard service. Together with that I use a service they offer (Payment Data Transfer) that sends you back order information after a user has completed a payment. The final thing I need to do is to parse the POST request from them and persist the info in it. The HTTP request's content is in this form :
SUCCESS
first_name=Jane+Doe
last_name=Smith
payment_status=Completed
payer_email=janedoesmith%40hotmail.com
payment_gross=3.99
mc_currency=USD
custom=For+the+purchase+of+the+rare+book+Green+Eggs+%26+Ham
Basically I want to parse this information and do something meaningful, like send it through e-mail or save it in DB. My question is what is the right approach to do parsing raw HTTP data in ASP.NET, not how the parsing itself is done.
Something like this placed in your onload event.
if (Request.RequestType == "POST")
{
using (StreamReader sr = new StreamReader(Request.InputStream))
{
if (sr.ReadLine() == "SUCCESS")
{
/* Do your parsing here */
}
}
}
Mind you that they might want some special sort of response to (ie; not your full webpage), so you might do something like this after you're done parsing.
Response.Clear();
Response.ContentType = "text/plain";
Response.Write("Thanks!");
Response.End();
Update: this should be done in a Generic Handler (.ashx) file in order to avoid a great deal of overhead from the page model. Check out this article for more information about .ashx files
Use an IHttpHandler and avoid the Page model overhead (which you don't need), but use Request.Form to get the values so you don't have to parse name value pairs yourself. Just pretend you're in PHP or Classic ASP (or ASP.NET MVC, for that matter). ;)
I'd strongly recommend saving each request to some file.
This way, you can always go back to the actual contents of it later. You can thank me later, when you find that hostile-endian, koi-8 encoded, [...], whatever it was that stumped your parser...
Well if the incoming data is in a standard form encoded POST format, then using the Request.Form array will give you all the data in a nice to handle manner.
If not then I can't see any way other than using Request.InputStream.
If I'm reading your question right, I think you're looking for the InputStream property on the Request object. Keep in mind that this is a firehose stream, so you can't reset it.