列出存储桶目录中的对象

Question

Several days ago, I was working with Google Cloud Storage listing and downloading objects inside buckets but now I am struggling to read only objects inside the specific directory because I want only iterate over the objects inside this directory. My bucket is "pubsite_prod_rev_12345" but I try to read-only elements inside "/earnings/":

 string bucketId = "pubsite_prod_rev_12345/earnings";

So now I turn to the help of experts in this matter, this is my code:

 string[] scopes = new string[] { "https://www.googleapis.com/auth/devstorage.read_only" };
var credential = GoogleCredential.FromFile(@"C:\Data\Jorgesys\jorgesys-8aa7ab2343daa.json").CreateScoped(scopes);
            var storage = StorageClient.Create(credential);
      
            var bucket_name = "jorgesys.appspot.com";            
            //string bucketId = "pubsite_prod_rev_12345";

            //Trying to make a list only inside earnings directoy!
            string bucketId = "pubsite_prod_rev_12345/earnings";

            StringBuilder sb = new StringBuilder();
            try
            {
                var bucketObjects = storage.ListObjects(bucketId);
                foreach (var bucketObject in bucketObjects)
                {
                    sb.AppendLine("Object Name: " + bucketObject.Name);
                    sb.AppendLine("Id: " + bucketObject.Id);
                }
            }
            catch (Exception ex)
            {             
                sb.AppendLine("Exception: " + ex.Message);
            }

I don´t want to filter, just get the elements inside /earnings/ directory, how could achieve this task.

> miroslava/earnings_202102_2138916436889858-1.zip
> miroslava/earnings_202103_2138916436889858-2.zip
> miroslava/earnings_202104_2138916436889858-3.zip
> miroslava/earnings_202105_2138916436889858-4.zip
> earning/earnings_202102_2138916436889858-1.zip
> earnings/earnings_202103_2138916436889858-2.zip
> earnings/earnings_202104_2138916436889858-3.zip
> earnings/earnings_202105_2138916436889858-4.zip
> financial-stats/subscriptions/subscriptions_com.jorgesys_mensual1_201607_country.csv
> financial-stats/subscriptions/subscriptions_com.jorgesys_mensual1_201607_device.csv
> financial-stats/subscriptions/subscriptions_com.jorgesys_mensual1_201607_country.csv
> financial-stats/subscriptions/subscriptions_com.jorgesys_week1_201607_device.csv

Answer 1

Google Cloud Storage does not have directories. The directory portion of the filename is called a prefix .

For example the object name: tmp/log.txt has the prefix tmp/ .

The next concept is the delimiter . This is typically the / character.

To specify the directory path tmp use a prefix of tmp/ and a delimiter of / . Any objects that start with tmp/ and do not contain the delimiter (excluding the prefix) are returned as names. Any objects that start with tmp/ and contain a delimiter are returned as prefixes. Example tmp/subdirectory/123 would be returned as the prefix tmp/subdirectory/ with nothing additional as a name.

With that complicated explanation here is an example:

Note: Your line with bucketId is not correct. The bucket name does not include any part of the object name.

var bucketName = "pubsite_prod_rev_12345";

// Specify the delimter.
var delimeter = "/";

// Specify the prefix
var prefix = "earnings/";

var storage = StorageClient.Create();

var options = new ListObjectsOptions { Delimiter = delimiter };

var storageObjects = storage.ListObjects(bucketName, prefix, options);

foreach (var storageObject in storageObjects)
{
    sb.AppendLine("Object Name: " + storageObject.Name);
}

Class StorageClient

Class ListObjectOptions