How to get the result from IObservable subscription without a blocking call?

user_7745011 0
Viewed 98

I'm trying to get filenames within a bucket of my MinIO server using the ListObjectsAsync method.

Here is the relevant code:

public async Task<string> GetFileName(string userID, string datasetID) 
{
    ListObjectsArgs args = new ListObjectsArgs()
        .WithBucket(userID)
        .WithPrefix(datasetID)
        .WithRecursive(true);

    var files = _minio.ListObjectsAsync(args);

    List<string> fileNames = new();
    
    IDisposable subscription = files
        .Subscribe(item => 
            fileNames.Add(item.Key),
            () => Console.WriteLine(fileNames.Count)
        );
      
    // I want to return one of the filenames here!
    return ""; 
}

The code above fills the list fileNames as expected and prints out the correct number of files within the respective locations. However, I would like to user the data within the function above. I know I could do the following:

files.ToList().Wait();

However, this is a blocking call. Should I simply wrap this call into Task or is there some other (better) way to get the required data?

observable minio system.reactive idisposable c#
2 Answers

Instead of doing the subscribe, return files.ToTask().

EDIT

As you mention in the comments, first use .ToList() in order to gather all the next events into one event. If you are looking for a specific file, like another answer implies, then use .Filter.

Also I think your return type should be a Task with an array of strings rather than a single string... (Unless you only want one file and have filtered out all the others.)

user_5064410

I think you can check the files you received one by one and stop processing the rest of them when the current file meets a specific condition. Like:

CancellationTokenSource source = new CancellationTokenSource();
CancellationToken token = source.Token;
Item file = null;
files.Subscribe(
        item => {
            if (item.Key=="MyFile")
            {
                file=item; 
                source.Cancel();
            }
        },
        () => Console.WriteLine(fileNames.Count),
        token );
user_18175740
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