I'm creating a .NET Core 3.1 web api method to download a pdf for a given filename. This method is shared across teams where their client code is generated using NSwag.
I recently changed produces attribute to Produces("Application/pdf") from json, this change is required so other teams can generate valid client code. However since this change, I haven't been able to download any files from this method. Requests to download documents return with a 406 error (in Postman) and the following error is logged to the server event viewer.
No output formatter was found for content types 'application/pdf, application/pdf' to write the response.
Reverting the produced content-type to 'application/json' does allow documents to be downloaded, but as mentioned, this value is required to be pdf.
Any suggestions would be greatly appreciated.
Method:
[HttpGet("{*filePath}")]
[ProducesResponseType(typeof(FileStreamResult), StatusCodes.Status200OK)]
[ProducesResponseType(StatusCodes.Status404NotFound)]
[ProducesResponseType(StatusCodes.Status400BadRequest)]
[ProducesResponseType(StatusCodes.Status401Unauthorized)]
[Produces("Application/pdf")]
public async Task<ActionResult> GetDocument(string fileName) {
RolesRequiredHttpContextExtensions.ValidateAppRole(HttpContext, _RequiredScopes);
var memoryStream = new MemoryStream();
var memoryStream = new MemoryStream();
using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize: 4096, useAsync: true)) {
stream.CopyTo(memoryStream);
}
memoryStream.Seek(offset: 0, SeekOrigin.Begin);
return new FileStreamResult(memoryStream, "Application/pdf");
}
I just came across the same error and after some investigation I found out that the cause of the exception was indeed in the model binding error. You already wrote about it in your answer, but on closer inspection it became obvious that the reason was not related to binding itself, rather to the response body.
Since you specified [Produces("application/pdf")] the framework assumes this content type is the only possible for this action, but when an exception is thrown, you get application/json containing error description instead.
So to make this work for both "happy path" and exceptions, you could specify multiple response types:
[Produces("application/pdf", "application/json")]
public async Task<ActionResult> GetDocument(string fileName)
{
...
}
I'am using
public asnyc Task<IActionResult> BuildPDF()
{
Stream pdfStream = _pdfService.GetData();
byte[] memoryContent = pdfStream.ToArray();
return File(memoryContent, "application/pdf");
}
and it works. Could you please try?
The issue was caused by renaming the method parameter and not updating [HttpGet("{*filePath}")] to [HttpGet("{*fileName}")]
I had the same error, it is very confusing in some cases.
I got this error after adding new parameter of type int[] to my method forgetting [FromQuery] attribute for it.
After adding [FromQuery] attribute error gone.
Related
I have a .NET Core API that I'd like to extend to save uploaded images asynchronously.
Using ImageSharp I should be able to check uploads and resize if predefined size limits are exceeded. However I can't get a simple async save working.
A simple (non-async) save to file works without problem:
My Controller extracts IFormFile from the upload and calls the following method without any problem
public static void Save(IFormFile image, string imagesFolder)
{
var fileName = Path.Combine(imagesFolder, image.FileName);
using (var stream = image.OpenReadStream())
using (var imgIS = Image.Load(stream, out IImageFormat format))
{
imgIS.Save(fileName);
}
}
ImageSharp is currently lacking async methods so a workaround is necessary.
The updated code below saves the uploaded file but the format is incorrect - when viewing the file I get the message "It appears we don't support this file format".
The format is extracted from the ImageSharp Load method. and used when saving to MemoryStream.
MemoryStream CopyToAsync method is used to save to FileStream to make the upload asynchronous.
public static async void Save(IFormFile image, string imagesFolder)
{
var fileName = Path.Combine(imagesFolder, image.FileName);
using (var stream = image.OpenReadStream())
using (var imgIS = Image.Load(stream, out IImageFormat format))
using (var memoryStream = new MemoryStream())
using (var fileStream = new FileStream(fileName, FileMode.OpenOrCreate))
{
imgIS.Save(memoryStream, format);
await memoryStream.CopyToAsync(fileStream).ConfigureAwait(false);
fileStream.Flush();
memoryStream.Close();
fileStream.Close();
}
}
I can't work out whether the issue is with ImageSharp Save to MemoryStream, or the MemoryStream.CopyToAsync.
I'm currently getting 404 on SixLabors docs - hopefully not an indication that the project has folded.
How can I make the upload async and save to file in the correct format?
CopyToAsync copies a stream starting at its current position. You must change the current position of memoryStream back to start before copying:
// ...
memoryStream.Seek(0, SeekOrigin.Begin);
await memoryStream.CopyToAsync(fileStream).ConfigureAwait(false);
// ...
I have searched high and low for this one and can't seem to find a way of accessing the Request.Content in an MVC web api. I basically am trying to create a File Service to and from Azure Blob and Table storage (table for storing metadata about the file, blob for the actual file)....
I was converting the steps in the following link, but this is where I have come unstuck
the back end I have working but can't find a way of the new unified controller passing a fileobject from json post through to the service! Any ideas would be greatly appreciated as always... or am I just going about this the wrong way?
Article here....
UPDATE: so to clarify, what I am trying to do in the new MVC 6 (where you no longer have an apicontroller to inherit from) is to access a file that has been uploaded to the api from a JSON post. That is the long and short of what I am trying to achieve.
I am trying to use the article based on the old Web API which uses the Request.Content to access it, however even if I use the WebAPIShim which they provide I still come unstuck with other objects or properties that are no longer available so I'm wondering if I need to approach it a different way, but either way, all I am trying to do is to get a file from a JSON post to a MVC 6 Web api and pass that file to my back end service....
ANY IDEAS?
Here is an example without relying on model binding.
You can always find the request data in Request.Body, or use Request.Form to get the request body as a form.
[HttpPost]
public async Task<IActionResult> UploadFile()
{
if (Request.Form.Files != null && Request.Form.Files.Count > 0)
{
var file = Request.Form.Files[0];
var contentType = file.ContentType;
using (var fileStream = file.OpenReadStream())
{
using (var memoryStream = new MemoryStream())
{
await fileStream.CopyToAsync(memoryStream);
// do what you want with memoryStream.ToArray()
}
}
}
return new JsonResult(new { });
}
If the only thing in your request is a File you can use the IFormFile class in your action:
public FileDetails UploadSingle(IFormFile file)
{
FileDetails fileDetails;
using (var reader = new StreamReader(file.OpenReadStream()))
{
var fileContent = reader.ReadToEnd();
var parsedContentDisposition = ContentDispositionHeaderValue.Parse(file.ContentDisposition);
fileDetails = new FileDetails
{
Filename = parsedContentDisposition.FileName,
Content = fileContent
};
}
return fileDetails;
}
I'm using RestSharp, and using Json.NET for serialization (see here).
Json.NET supports BSON, and since some of my requests have huge blocks of binary data, I think this would speed up my application dramatically. However, as far as I can tell, RestSharp does not seem to have any in-built support for BSON.
The use of Json.NET is implemented as a custom serializer for RestSharp, and so at first glance it looks like it would be possible to modify that custom serializer to use BSON. But, the Serialize method of the RestSharp.Serializers.ISerializer interface returns a string - which is (I assume) unsuitable for BSON. So, I assume that it would take some more significant changes to RestSharp to implement this change.
Has anyone figured out a way to do this?
Update: I looked at the RestSharp source, and discovered that the RestRequest.AddBody method that takes my object and serializes it into the request body eventually calls Request.AddParameter (with the serialized object data, and the parameter type RequestBody).
I figured that I might be able to serialize my object to BSON and then call Request.AddParameter directly - and indeed I can. However, when RestSharp then executes the RestRequest, it fails to put the binary content into the request, because there are other embedded assumptions about the request content being UTF-8 encoded.
Thus it looks like this hack would not work - there would need to be some changes made to RestSharp itself, and I'm not the man for the job...
Update 2: I decided to have a go at using the debugger to figure out how much of RestSharp I'd have to change to overcome the body-encoding issue, so I swapped out my NuGet version of RestSharp and included the RestSharp project in my solution. And... it worked.
It turns out that there has been a change to RestSharp in the last few months that isn't yet in the NuGet version.
So, you can now use AddParameter and pass in an already-BSON-encoded object, and RestSharp will send it off to the server without complaint.
Per the updates in my question, it turns out that if you have the latest RestSharp source, then instead of this:
request.AddBody(myObject);
... you can do this instead whenever you have a payload that would benefit from using BSON:
using (var memoryStream = new System.IO.MemoryStream())
{
using (var bsonWriter = new Newtonsoft.Json.Bson.BsonWriter(memoryStream))
{
var serializer = new Newtonsoft.Json.JsonSerializer();
serializer.Serialize(bsonWriter, myObject);
var bytes = memoryStream.ToArray();
request.AddParameter("application/bson", bytes, RestSharp.ParameterType.RequestBody);
}
}
Note that the first parameter to AddParameter is supposedly the parameter name, but in the case of ParameterType.RequestBody it's actually used as the content type. (Yuk).
Note that this relies on a change made to RestSharp on April 11 2013 by ewanmellor/ayoung, and this change is not in the current version on NuGet (104.1). Hence this will only work if you include the current RestSharp source in your project.
Gary's answer to his own question was incredibly useful for serializing restful calls. I wanted to answer how to deserialize restful calls using JSON.NET. I am using RestSharp version 104.4 for Silverlight. My server is using Web API 2.1 with BSON support turned on.
To accept a BSON response, create a BSON Deserializer for RestSharp like so
public class BsonDeserializer : IDeserializer
{
public string RootElement { get; set; }
public string Namespace { get; set; }
public string DateFormat { get; set; }
public T Deserialize<T>(IRestResponse response)
{
using (var memoryStream = new MemoryStream(response.RawBytes))
{
using (var bsonReader = new BsonReader(memoryStream))
{
var serializer = new JsonSerializer();
return serializer.Deserialize<T>(bsonReader);
}
}
}
}
Then, ensure your request accepts "application/bson"
var request = new RestRequest(apiUrl, verb);
request.AddHeader("Accept", "application/bson");
And add a handler for that media type
var client = new RestClient(url);
client.AddHandler("application/bson", new BsonDeserializer());
While using the Rss20FeedFormatter class in a WCF project, I was trying to wrap the content of my description elements with a <![CDATA[ ]]> section. I found that no matter what I did, the HTML content of the description elements was always encoded and the CDATA section was never added. After peering into the source code of Rss20FeedFormatter, I found that when building the Summary node, it basically creates a new TextSyndicationContent instance which wipes out whatever settings were previously specified (I think).
My Code
public class CDataSyndicationContent : TextSyndicationContent
{
public CDataSyndicationContent(TextSyndicationContent content)
: base(content)
{
}
protected override void WriteContentsTo(System.Xml.XmlWriter writer)
{
writer.WriteCData(Text);
}
}
... (The following code should wrap the Summary with a CDATA section)
SyndicationItem item = new SyndicationItem();
item.Title = new TextSyndicationContent(name);
item.Summary = new CDataSyndicationContent(
new TextSyndicationContent(
"<div>This is a test</div>",
TextSyndicationContentKind.Html));
Rss20FeedFormatter Code
(AFAIK, the above code does not work because of this logic)
...
else if (reader.IsStartElement("description", ""))
result.Summary = new TextSyndicationContent(reader.ReadElementString());
...
As a workaround, I've resorted to using the RSS20FeedFormatter to build the RSS, and then patch the RSS manually. For example:
StringBuilder buffer = new StringBuilder();
XmlTextWriter writer = new XmlTextWriter(new StringWriter(buffer));
feedFormatter.WriteTo(writer ); // feedFormatter = RSS20FeedFormatter
PostProcessOutputBuffer(buffer);
WebOperationContext.Current.OutgoingResponse.ContentType =
"application/xml; charset=utf-8";
return new MemoryStream(Encoding.UTF8.GetBytes(buffer.ToString()));
...
public void PostProcessOutputBuffer(StringBuilder buffer)
{
var xmlDoc = XDocument.Parse(buffer.ToString());
foreach (var element in xmlDoc.Descendants("channel").First()
.Descendants("item")
.Descendants("description"))
{
VerifyCdataHtmlEncoding(buffer, element);
}
foreach (var element in xmlDoc.Descendants("channel").First()
.Descendants("description"))
{
VerifyCdataHtmlEncoding(buffer, element);
}
buffer.Replace(" xmlns:a10=\"http://www.w3.org/2005/Atom\"",
" xmlns:atom=\"http://www.w3.org/2005/Atom\"");
buffer.Replace("a10:", "atom:");
}
private static void VerifyCdataHtmlEncoding(StringBuilder buffer,
XElement element)
{
if (!element.Value.Contains("<") || !element.Value.Contains(">"))
{
return;
}
var cdataValue = string.Format("<{0}><![CDATA[{1}]]></{2}>",
element.Name,
element.Value,
element.Name);
buffer.Replace(element.ToString(), cdataValue);
}
The idea for this workaround came from the following location, I just adapted it to work with WCF instead of MVC. http://localhost:8732/Design_Time_Addresses/SyndicationServiceLibrary1/Feed1/
I'm just wondering if this is simply a bug in Rss20FeedFormatter or is it by design? Also, if anyone has a better solution, I'd love to hear it!
Well #Page Brooks, I see this more as a solution then as a question :). Thanks!!! And to answer your question ( ;) ), yes, I definitely think this is a bug in the Rss20FeedFormatter (though I did not chase it as far), because had encountered precisely the same issue that you described.
You have a 'localhost:8732' referral in your post, but it wasn't available on my localhost ;). I think you meant to credit the 'PostProcessOutputBuffer' workaround to this post:
http://damieng.com/blog/2010/04/26/creating-rss-feeds-in-asp-net-mvc
Or actually it is not in this post, but in a comment to it by David Whitney, which he later put in a seperate gist here:
https://gist.github.com/davidwhitney/1027181
Thank you for providing the adaption of this workaround more to my needs, because I had found the workaround too, but was still struggling to do the adaptation from MVC. Now I only needed to tweak your solution to put the RSS feed to the current Http request in the .ashx handler that I was using it in.
Basically I'm guessing that the fix you mentioned using the CDataSyndicationContent, is from feb 2011, assuming you got it from this post (at least I did):
SyndicationFeed: Content as CDATA?
This fix stopped working in some newer ASP.NET version or something, due to the code of the Rss20FeedFormatter changing to what you put in your post. This code change might as well have been an improvement for other stuff that IS in the MVC framework, but for those using the CDataSyndicationContent fix it definitely causes a bug!
string stylesheet = #"<xsl:stylesheet version=""1.0"" xmlns:xsl=""http://www.w3.org/1999/XSL/Transform""><xsl:output cdata-section-elements=""description"" method=""xml"" indent=""yes""/></xsl:stylesheet>";
XmlReader reader = XmlReader.Create(new StringReader(stylesheet));
XslCompiledTransform t = new XslCompiledTransform(true);
t.Load(reader);
using (MemoryStream ms = new MemoryStream())
{
XmlWriter writer = XmlWriter.Create(ms, t.OutputSettings);
rssFeed.WriteTo(writer); // rssFeed is Rss20FeedFormatter
writer.Flush();
ms.Position = 0;
string niko = Encoding.UTF8.GetString(ms.ToArray());
}
I'm sure someone pointed this out already but this a stupid workaround I used.
t.OutputSettings is of type XmlWriterSettings with cdataSections being populated with a single XmlQualifiedName "description".
Hope it helps someone else.
I found the code for Cdata elsewhere
public class CDataSyndicationContent : TextSyndicationContent
{
public CDataSyndicationContent(TextSyndicationContent content)
: base(content)
{
}
protected override void WriteContentsTo(System.Xml.XmlWriter writer)
{
writer.WriteCData(Text);
}
}
Code to call it something along the lines:
item.Content = new Helpers.CDataSyndicationContent(new TextSyndicationContent("<span>TEST2</span>", TextSyndicationContentKind.Html));
However the "WriteContentsTo" function wasn't being called.
Instead of Rss20FeedFormatter I tried Atom10FeedFormatter - and it worked!
Obviously this gives Atom feed rather than traditional RSS - but worth mentioning.
Output code is:
//var formatter = new Rss20FeedFormatter(feed);
Atom10FeedFormatter formatter = new Atom10FeedFormatter(feed);
using (var writer = XmlWriter.Create(response.Output, new XmlWriterSettings { Indent = true }))
{
formatter.WriteTo(writer);
}
I'm trying to post some files using OpenRasta. I've gotten as far as getting my handler called, but by all appearances the stream in the entity is empty. Here's my handler:
public OperationResult Post( IEnumerable<IMultipartHttpEntity> entities)
{
var foo = entities.ToList();
foreach (var entity in foo)
{
if (entity.Stream != null && entity.ContentType != null)
{
var memoryStream = new MemoryStream();
entity.Stream.CopyTo(memoryStream);
}
}
return new OperationResult.Created();
}
Each time through the loop memoryStream has a length of 0. What am I doing wrong?
Nothing like posting on StackOverflow to make the answer immediately obvious. Apparently you only get one enumeration of the entities in order to grab the stream. I had added the "foo" variable above to make debugging easier, but it was causing the streaming to fail. As I stored the stream to the database, I had also failed to reset memoryStream to the beginning before writing it. Fixing these two issues got the file to upload correctly.