How to download files in Google Cloud Storage using rest api - google-cloud-storage

Question

Scenario: there are multiple folders and many files stored in storage bucket related to dcm API.(click,impression,daily aggregate files etc).
https://console.cloud.google.com/storage/browser/dcmaccountno
Is it possible to download files using rest api and currently i have service account and private key.
we dont have much exposure towards goog cloud storage hence any small help would be really appreciable.
Thank you for any help!

Answer 1

You can do calls to whichever of the two REST APIs: JSON or XML. In any case, you will need to get an authorization access token from OAuth 2.0 as detailed in the documentation and then use cURL with a GET Object Request:
JSON API:
curl -X GET \
-H "Authorization: Bearer [OAUTH2_TOKEN]" \
-o "[SAVE_TO_LOCATION]" \
"https://www.googleapis.com/storage/v1/b/[BUCKET_NAME]/o/[OBJECT_NAME]?alt=media"
XML API:
curl -X GET \
-H "Authorization: Bearer [OAUTH2_TOKEN]" \
-o "[SAVE_TO_LOCATION]" \
"https://storage.googleapis.com/[BUCKET_NAME]/[OBJECT_NAME]"
Note that for multiple files, you will have to program the requests, so if you want to easily download all the objects in a bucket or subdirectory, it's better to use gsutil instead.

Answer 2

Using rest API you can download/upload files from google storage in the following way that I already did in the below-mentioned link:
Reference: https://stackoverflow.com/a/53955058/4345389
Instead of UploadData method of WebClient, you can use DownloadData method in the following way:
// Create a new WebClient instance.
using (WebClient client= new WebClient())
{
client.Headers.Add(HttpRequestHeader.Authorization, "Bearer " + bearerToken);
client.Headers.Add(HttpRequestHeader.ContentType, "application/octet-stream");
// Download the Web resource and save it into a data buffer.
byte[] bytes = client.DownloadData(body.SourceUrl);
MemoryStream memoryStream = new MemoryStream(bytes);
// TODO write further funcitonality to write the memorystream
}
Do some tweaks as per your requirements.