Handling FileContentResult when file is not found

user_637369 0
Viewed 23919

I have a controller action that downloads a file from an azure blob based on the container reference name (i.e. full path name of the file in the blob). The code looks something like this:

public FileContentResult GetDocument(String pathName)
{
    try
    {
        Byte[] buffer = BlobStorage.DownloadFile(pathName);
        FileContentResult result = new FileContentResult(buffer, "PDF");
        String[] folders = pathName.Split(new char[] { '\\' }, StringSplitOptions.RemoveEmptyEntries);
        // get the last one as actual "file name" based on some convention
        result.FileDownloadName = folders[folders.Length - 1];

        return result;
    }
    catch (Exception ex)
    {
        // log error
    }
    // how to handle if file is not found?
    return new FileContentResult(new byte[] { }, "PDF");
}

The BlobStorage class there is my helper class to download the stream from the blob.

My question is stated in the code comment: How should I handle the scenario when the file/stream is not found? Currently, I am passing an empty PDF file, which I feel is not the best way to do it.

filecontentresult azure-blob-storage asp.net-mvc-2 c#
2 Answers

In ASP.NET Core, use NotFound()

Your controller must inherit of Controller and the method must return ActionResult

Example:

public ActionResult GetFile(string path)
{
    if (!File.Exists(path))
    {
        return NotFound();
    }
    
    try
    {
        return new FileContentResult(File.ReadAllBytes(path), "application/octet-stream");
    }
    catch (FileNotFoundException)
    {
        return NotFound();
    }
}

Note: the above code doesn't handle all cases of file operations errors as invalid chars in path or file unavailability (because it is beyond the scope of the current answer) and proper responses (like restricted file access due to permissions or else)

user_53281500
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