CODEWITHSUNDEEP
c#.netasp.net-mvcamazon-s3stream
Matias Cicero
Matias Cicero

Reputation: 26281

Unable to return image stream from action in ASP.NET MVC

I have the following action:

public async Task<ActionResult> Get(string path)
{
     StaticImage image = await _images.UseRepositoryAsync(repo => repo.ReadAsync(path));
     return image != null ? new FileStreamResult(image.Stream, "image/jpeg") : (ActionResult)HttpNotFound();
}

I have a generic persistence strategy (uses Amazon S3) that retrieves StaticImage as follows:

//E is StaticImage in this case
//The returned entity is not disposed, it leaves that responsability to the controller
//However, the response IS disposed, that's why I need to copy the stream
public async Task<E> SelectAsync(params object[] keys)
{
     using(GetObjectResponse response = await MakeGetObjectRequestAsync(keys.First().ToString()))
     {
           if(response == null) return default(E);

           E entity = CreateEntity();
           entity.Key = response.Key;

           Stream entityStream = new MemoryStream(Convert.ToInt32(response.ResponseStream.Length));
           await response.ResponseStream.CopyToAsync(entityStream);
           entity.Stream = entityStream; 

           return entity;
     }
}

response.ResponseStream contains the image's content:

enter image description here

And it is being copied just fine to the new stream (see Length):

enter image description here

However, 0 bytes are returned from my controller:

enter image description here

Upvotes: 1

Views: 1232

Answers (1)

Dave Zych
Dave Zych

Reputation: 21887

If you look at your second image, the stream's position is 197397. My assumption is that when you're passing it to the constructor of FileStreamResult, it's not copying it because the position is at the end of the stream. Before you pass it to the constructor of FileStreamResult, set the position back to 0:

StaticImage image = await _images.UseRepositoryAsync(repo => repo.ReadAsync(path));     
image.Stream.Position = 0;
return image != null ? new FileStreamResult(image.Stream, "image/jpeg") : (ActionResult)HttpNotFound();

Upvotes: 4

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