CODEWITHSUNDEEP
c#ienumerable
Kaja
Kaja

Reputation: 3057

using an IEnumerable list outside of foreach loop

I am using IEnumerable in a for each loop as follows:

foreach (IListBlobItem blobItem in container.ListBlobs())
{        
    if (blobItem is CloudBlobDirectory)
    {
        CloudBlobDirectory directory = (CloudBlobDirectory)blobItem;
        IEnumerable<IListBlobItem> blobs = directory.ListBlobs(true);
    }                
}
await ProcessBlobs(blobs);

I would like to use blobsvariable outside of this foreach loop but I get this message: blobs doesnot exist in the current context

I decided to define blobs outside of the foreach loop:

IEnumerable<IListBlobItem> blobs = new IEnumerable<IListBlobItem>;

foreach (IListBlobItem blobItem in container.ListBlobs())
{           
    if (blobItem is CloudBlobDirectory)
    {
        //Console.WriteLine(blobItem.Uri);
        CloudBlobDirectory directory = (CloudBlobDirectory)blobItem;
        IEnumerable<IListBlobItem> blobs = directory.ListBlobs(true);                    
    }
}

but I get the error: can not create an instance of the abstract class or interface IEnumerable<IListBlobItem>

Do you have any idea how can I solve this problem?

Upvotes: 1

Views: 524

Answers (5)

Farhad Rahmanifard
Farhad Rahmanifard

Reputation: 688

You are trying to create an object of an interface which is impossible. Instead, declare blobs as object an then convert it to IEnumerable<IListBlobItem>.

object blobs = null;

foreach (IListBlobItem blobItem in container.ListBlobs())
{           
    if (blobItem is CloudBlobDirectory)
    {
        //Console.WriteLine(blobItem.Uri);
        CloudBlobDirectory directory = (CloudBlobDirectory)blobItem;
        blobs = directory.ListBlobs(true);                    
    }
}
///usage:
///(IEnumerable<IListBlobItem>)blobs

Also, you can declare blobs as IEnumerable<IListBlobItem> which other answers cover.

Upvotes: 2

Ray Krungkaew
Ray Krungkaew

Reputation: 6977

Use default to get default value. This will return null for reference type

IEnumerable<IListBlobItem> blobs = default(IEnumerable<IListBlobItem>);

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/default

Upvotes: 1

BASKA
BASKA

Reputation: 399

Set IEnumerable blobs like property in this way:

IEnumerable<IListBlobItem> blobs{get;set;}

Upvotes: 1

Jakob M&#246;ll&#229;s
Jakob M&#246;ll&#229;s

Reputation: 4379

Try using Enumerable.Empty<TResult>, like so:

IEnumerable<IListBlobItem> blobs = Enumerable.Empty<IListBlobItem>();

This will return an empty, non-null enumerable.

See .NET API Documentation

Upvotes: 2

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186833

You can declare blobs being an empty collection, say, array:

   // Empty
   IEnumerable<IListBlobItem> blobs = new IListBlobItem[0];

   foreach (IListBlobItem blobItem in container.ListBlobs())
   {
      if (blobItem is CloudBlobDirectory)
      {
          CloudBlobDirectory directory = (CloudBlobDirectory)blobItem;
          blobs = directory.ListBlobs(true);                    
      }            
   }

   // process either blobs from foreach or an empty collection
   await ProcessBlobs(blobs);

Upvotes: 2

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