System.ObjectDisposedException: 'Cannot access a disposed object. ObjectDisposed_ObjectName_Name', al momento de guardar mi lista de imagenes

Andrea Evelyn Mejia Rubio 0

My View in vue.js sends me the image arrangement to my api, which I want to save in a folder asynchronously and when I do the second round in my foreach to the second image it gives me the error.

foreach (var imagen in imagenes)
{
    ImagenesProducto imagenesProducto = new ImagenesProducto();

 using (var stream = new FileStream(concFile, FileMode.Create))
 {
     await imagen.CopyToAsync(stream);
 }
}

Lan Huang-MSFT 25,636 Reputation points Microsoft Vendor

2024-04-10T01:22:23.8066667+00:00

Hi @Andrea Evelyn Mejia Rubio,

The current forum is in English, could you please edit your question in English? Then we can help solve your problem, thank you for your understanding.

2 answers

Michael Taylor 48,576 Reputation points

2024-04-10T16:42:11.8233333+00:00

I think we're missing some information here to be helpful. It looks like you have a list of streams(?) in imagenes. You enumerate through and for each one you are creating an instance of ImagenesProducto but that doesn't seem to be used elsewhere so we'll ignore it. You then create a new file using a stream and copy the current item (stream?) into it. By itself this code is fine so I think something else is going on here.

Look at the callstack and tell us what specifically is getting disposed too early. My gut instinct is that it is your imagen variable which means whatever is passing you that set of items might be bad.

Step through your code and when you get to the CopyToAsync line look at both objects in the debugger and see which one is marked as disposed.
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Andrea Evelyn Mejia Rubio 0 Reputation points

2024-04-10T17:42:07.8966667+00:00

Everything is within my asynchronous method, imagenes has the list of images that I am going to save in the established folder but when I do the second round of the foreach it seends me the error.

public async void CargarImagenesAsync(IList<IFormFile> imagenes, Producto producto) { int index = 0; foreach (var imagen in imagenes) { ImagenesProducto imagenesP = new ImagenesProducto(); string concFile = directorioRaiz + rutaImagen + nombreImagen; using (var stream = new FileStream(concFile, FileMode.Create)) { await imagen.CopyToAsync(stream); index++; } imagenesP.IdProducto = producto.Id; imagenesP.SrcImagen = rutaImagenDb; producto.ImagenesProducto.Add(imagenesP); } }

After analyzing the variables, image every time it goes through the foreach the image object is brought, the problem arises when I enter the using and it sends me this error.

+ $exception {"Cannot access a disposed object.\r\nObject name: 'FileBufferingReadStream'."} System.ObjectDisposedException

Michael Taylor 48,576 Reputation points

2024-04-10T18:32:21.4233333+00:00

Please respond to answers using the Add Comment button, don't create your own answer.

Notice the exception is talking about FileBufferingReadStream. You aren't creating an instance of that but of FileStream. The type in question is part of ASPNET Core which leads me to believe that the problem is with accessing imagenes items and not this code. Please show us how you're calling this method.

AgaveJoe 26,136 Reputation points

2024-04-10T19:41:48.19+00:00

Returning void from an async method is troublesome because the caller cannot await the response. The caller will continue without waiting for CargarImagenesAsync to complete. Plus the caller cannot catch any exception thrown in the asyns method.

Change void to Task and see if that helps or you get a different error.

Lan Huang-MSFT 25,636 Reputation points Microsoft Vendor

2024-04-11T07:40:43.6066667+00:00

Hi @Andrea Evelyn Mejia Rubio,

Is your project ASP.NET or ASP.NET Core?

Michael Taylor 48,576 Reputation points

2024-04-11T13:38:53.01+00:00

My gut instinct is that the calling controller looks like this.

public void DoSomething ( ... ) { CargarImagenesAsync(...); }

Since the method is async it executes outside the request thread of the ASPNET request. The form files that are being passed to the function are getting disposed by the runtime (because the ASPNET thread completed) while the async method is executing. It is arbitrary that it fails on the second iteration of the loop.

To fix you need to wait for the work to complete before letting the ASPNET request finish and the files get cleaned up.

public async Task DoSomething ( ... ) { //Wait for the work to complete await CargarImagenesAsync(...); }

As @AgaveJoe mentioned, to do that you need to ensure your async method (all of them generally) has a return type of Task or Task<T>. Otherwise there is nothing to await on.
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Bruce (SqlWork.com) 56,686 Reputation points

2024-04-21T15:24:05.29+00:00

I assume imagenes is posted by the vue app. Your api code is probably returning a response to the vue.js code before the sample code completes. The api must await the copy before returning. If you don’t want wait for the file copy, the postback image streams must be copied to new buffers before calling the code.
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