Accessing the Request.Content in the new ASP.NET vnext web api way of doing things? - asp.net-web-api2

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;
}

Related

Easy way to retrieve image source in abp

I'm pretty new to ABP Framework and probably this question has a really simple answer, but I haven't managed to find it. Images are an important part of any app and handling them the best way (size, caching) is mandatory.
Scenario
setup a File System Blob Storing provider. This means that the upload file will be stored in the file system as an image file
make a service that uses a Blob container to save and retrieve the image. So, after saving it, I use the unique file name as a blob name. This name is used to retrieve it back.
the user is logged in, so authorization is required
I can easily obtain the byte[]s of the image by calling blobContainer.GetAllBytesOrNullAsync(blobName)
I want to easily display the image in <img> or in datatable row directly.
So, here is my question: is there an easy way to use a blob stored image as src of a <img> directly in a razor page? What I've managed to achieve is setting in the model, a source as a string made from image type + bytes converted to base 64 string (as here) however in this case I need to do it in the model and also I don't know if caching is used by the browser. I don't see how caching would work in this case.
I am aware that this may be a question more related to asp.net core, but I was thinking that maybe in abp there is some way via a link to access the image.
If you have the ID of the blob then it is easy to do. Just create a Endpoint to get the Image based on the blob id.
Here is the sample AppService
public class DocumentAppService : FileUploadAppService
{
private readonly IBlobContainer<DocumentContainer> _blobContainer;
private readonly IRepository<Document, Guid> _repository;
public DocumentAppService(IRepository<Document, Guid> repository, IBlobContainer<DocumentContainer> blobContainer)
{
_repository = repository;
_blobContainer = blobContainer;
}
public async Task<List<DocumentDto>> Upload([FromForm] List<IFormFile> files)
{
var output = new List<DocumentDto>();
foreach (var file in files)
{
using var memoryStream = new MemoryStream();
await file.CopyToAsync(memoryStream).ConfigureAwait(false);
var id = Guid.NewGuid();
var newFile = new Document(id, file.Length, file.ContentType, CurrentTenant.Id);
var created = await _repository.InsertAsync(newFile);
await _blobContainer.SaveAsync(id.ToString(), memoryStream.ToArray()).ConfigureAwait(false);
output.Add(ObjectMapper.Map<Document, DocumentDto>(newFile));
}
return output;
}
public async Task<FileResult> Get(Guid id)
{
var currentFile = _repository.FirstOrDefault(x => x.Id == id);
if (currentFile != null)
{
var myfile = await _blobContainer.GetAllBytesOrNullAsync(id.ToString());
return new FileContentResult(myfile, currentFile.MimeType);
}
throw new FileNotFoundException();
}
}
Upload function will upload the files and Get function will get the file.
Now set the Get route as a src for the image.
Here is the blog post: https://blog.antosubash.com/posts/dotnet-file-upload-with-abp
Repo: https://github.com/antosubash/FileUpload

.NET Core pdf downloader "No output formatter was found for content types 'application/pdf'..."

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.

Power App - generate PDF

I got an assignment to see if I can make power app that will generate some PDF file for end user to see.
After through research on this topic I found out that this is not an easy to achieve :)
In order to make power app generate and download/show generated pdf I made these steps:
Created power app with just one button :) to call Azure function from step 2
Created Azure function that will generate and return pdf as StreamContent
Due to power app limitations (or I just could not find the way) there was no way for me to get pdf from response inside power app.
After this, I changed my Azure function to create new blob entry but know I have problem to get URL for that new entry inside Azure function in order to return this to power app and then use inside power app Download function
My Azure function code is below
using System;
using System.Net;
using System.Net.Http.Headers;
using System.Runtime.InteropServices;
using Aspose.Words;
public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log, Stream outputBlob)
{
log.Info($"C# HTTP trigger function processed a request. RequestUri={req.RequestUri}");
var dataDir = #"D:/home";
var docFile = $"{dataDir}/word-templates/WordAutomationTest.docx";
var uid = Guid.NewGuid().ToString().Replace("-", "");
var pdfFile = $"{dataDir}/pdf-export/WordAutomationTest_{uid}.pdf";
var doc = new Document(docFile);
doc.Save(pdfFile);
var result = new HttpResponseMessage(HttpStatusCode.OK);
var stream = new FileStream(pdfFile, FileMode.Open);
stream.CopyTo(outputBlob);
// result.Content = new StreamContent(stream);
// result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
// result.Content.Headers.ContentDisposition.FileName = Path.GetFileName(pdfFile);
// result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
// result.Content.Headers.ContentLength = stream.Length;
return result;
}
I left old code (the one that streams pdf back under comments just as reference of what I tried)
Is there any way to get download URL for newly generated blob entry inside Azure function?
Is there any better way to make power app generate and download/show generated PDF?
P.S. I tried to use PDFViewer control inside power app, but this control is completely useless cause U can not set Document value via function
EDIT: Response from #mathewc helped me a lot to finally wrap this up. All details are below.
New Azure function that works as expected
#r "Microsoft.WindowsAzure.Storage"
using System;
using System.Net;
using System.Net.Http.Headers;
using System.Runtime.InteropServices;
using Aspose.Words;
using Microsoft.WindowsAzure.Storage.Blob;
public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log, CloudBlockBlob outputBlob)
{
log.Info($"C# HTTP trigger function processed a request. RequestUri={req.RequestUri}");
var dataDir = #"D:/home";
var docFile = $"{dataDir}/word-templates/WordAutomationTest.docx";
var uid = Guid.NewGuid().ToString().Replace("-", "");
var pdfFile = $"{dataDir}/pdf-export/WordAutomationTest_{uid}.pdf";
var doc = new Document(docFile);
doc.Save(pdfFile);
var result = new HttpResponseMessage(HttpStatusCode.OK);
var stream = new FileStream(pdfFile, FileMode.Open);
outputBlob.UploadFromStream(stream);
return req.CreateResponse(HttpStatusCode.OK, outputBlob.Uri);
}
REMARKS:
Wee need to add "WindowsAzure.Storage" : "7.2.1" inside project.json. This package MUST be the same version as one with same name that is in %USERPROFILE%\AppData\Local\Azure.Functions.Cli
If you change your blob output binding type from Stream to CloudBlockBlob you will have access to CloudBlockBlob.Uri which is the blob path you require (documentation here). You can then return that Uri back to your Power App. You can use CloudBlockBlob.UploadFromStreamAsync to upload your PDF Stream to the blob.

Sending Commands from an MVC4 site to Another

I have two sites: one of them controls the other sending some commands through Web API. The idea is: the action of the controller site sends a command to the other site, gets the response and perform some business rules, without redirecting to the other site.
I have tons of examples explaining how to implement this via jQuery, but I want to make the controller post the data to the other site, instead of the view.
I found an approach at this answer: How to use System.Net.HttpClient to post a complex type?, but I want the answer for an JSON approach.
Can someone post a simple example using JSON showing how to do this?
As I didn't find a brief answer to my question, I'll post the solution I've made.
As the method uses an HttpClient method that requires async statements, the action below was implemented retuning a Task<ActionResult>. Another modification is if you're saving an object in context.
Instead of using:
context.SaveChanges();
You'll have to use:
await context.SaveChangesAsync();
The code below implements an Action from an ASP.NET MVC4 Controller:
[HttpPost]
public async Task<ActionResult> Create(MyModel model)
{
if (ModelState.IsValid)
{
// Logic to save the model.
// I usually reload saved data using something kind of the statement below:
var inserted = context.MyModels
.AsNoTracking()
.Where(m => m.SomeCondition == someVariable)
.SingleOrDefault();
// Send Command.
// APIMyModel is a simple class with public properties.
var apiModel = new APIMyModel();
apiModel.AProperty = inserted.AProperty;
apiModel.AnotherProperty = inserted.AnotherProperty;
DataContractJsonSerializer jsonSer = new DataContractJsonSerializer(typeof(APIMyModel));
// use the serializer to write the object to a MemoryStream
MemoryStream ms = new MemoryStream();
jsonSer.WriteObject(ms, apiModel);
ms.Position = 0;
//use a Stream reader to construct the StringContent (Json)
StreamReader sr = new StreamReader(ms);
// Note if the JSON is simple enough you could ignore the 5 lines above that do the serialization and construct it yourself
// then pass it as the first argument to the StringContent constructor
StringContent theContent = new StringContent(sr.ReadToEnd(), System.Text.Encoding.UTF8, "application/json");
HttpClient aClient = new HttpClient();
Uri theUri = new Uri("http://yoursite/api/TheAPIAction");
HttpResponseMessage aResponse = await aClient.PostAsync(theUri, theContent);
if (aResponse.IsSuccessStatusCode)
{
// Success Logic. Yay!
}
else
{
// show the response status code
String failureMsg = "HTTP Status: " + aResponse.StatusCode.ToString() + " - Reason: " + aResponse.ReasonPhrase;
}
return RedirectToAction("Index");
}
// if Model is not valid, you can put your logic to reload ViewBag properties here.
}

Returning Azure BLOB from WCF service as a Stream - Do we need to close it?

I have a simple WCF service that exposes a REST endpoint, and fetches files from a BLOB container. The service returns the file as a stream. i stumbled this post about closing the stream after the response has been made :
http://devdump.wordpress.com/2008/12/07/disposing-return-values/
This is my code:
public class FileService
{
[OperationContract]
[WebGet(UriTemplate = "{*url}")]
public Stream ServeHttpRequest(string url)
{
var fileDir = Path.GetDirectoryName(url);
var fileName = Path.GetFileName(url);
var blobName = Path.Combine(fileDir, fileName);
return getBlob(blobName);
}
private Stream getBlob(string blobName)
{
var account = CloudStorageAccount.FromConfigurationSetting("ConnectingString");
var client = account.CreateCloudBlobClient();
var container = client.GetContainerReference("data");
var blob = container.GetBlobReference(blobName);
MemoryStream ms = new MemoryStream();
blob.DownloadToStream(ms);
ms.Seek(0, SeekOrigin.Begin);
return ms;
}
}
So I have two question :
Should I follow the pattern mentioned in the post ?
If I change my return type to Byte[], what are Cons/Pros ?
( My client is Silverlight 4.0, just in case it has any effect )
I'd consider changing your return type to byte[]. It's tidier.
Stream implements IDisposable, so in theory the consumer of your method will need to call your code in a using block:
using (var receivedStream = new FileService().ServeHttpRequest(someUrl))
{
// do something with the stream
}
If your client definitely needs access to something that Stream provides, then by all means go ahead and return that, but by returning a byte[] you keep control of any unmanaged resources that are hidden under the covers.
OperationBehaviorAttribute.AutoDisposeParameters is set to TRUE by default which calls dispose on all the inputs/outputs that are disposable. So everything just works.
This link :
http://devdump.wordpress.com/2008/12/07/disposing-return-values/
explains how to manually control the process.