Lua
Get Object MetaData from Google Cloud Storage

Demonstrates how to download a Google Cloud Storage object's metadata.
Chilkat Lua Downloads

Lua
local chilkat = require("chilkat")

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

-- This example uses a previously obtained access token having permission for the
-- scope "https://www.googleapis.com/auth/cloud-platform"

-- In this example, Get Google Cloud Storage OAuth2 Access Token,
-- the service account access token was saved to a text file.  This example fetches the access token from the file..
local sbToken = chilkat.StringBuilder.new()
sbToken:load_file("qa_data/tokens/googleCloudStorageAccessToken.txt", "utf-8")

-- Send a GET equivalent to this curl command.

-- curl -X GET \
--     -H "Authorization: Bearer [OAUTH2_TOKEN]" \
--     -o "[SAVE_TO_LOCATION]" \
--     "https://www.googleapis.com/storage/v1/b/[BUCKET_NAME]/o/[OBJECT_NAME]?projection=full"

local http = chilkat.Http.new()

http.auth_token = sbToken:get_as_string()

-- Construct a URL to download the metadata for the object named "starfish.jpg" located in the "chilkat-ocean" bucket.
http:set_url_var("bucket_name", "chilkat-ocean")
http:set_url_var("object_name", "starfish.jpg")
local url = "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?projection=full"

-- If there is an error response, then we didn't actually download the metadata,
-- but instead we downloaded an error response..
local sbMetaData = chilkat.StringBuilder.new()
local success = http:download_sb(url, "utf-8", sbMetaData)
if not success then
    print(http.last_error_text)
    return
end

local responseCode = http.last_status
if responseCode == 401 then
    print("If invalid credentials, then it is likely the access token expired.")
    print("Your app should automatically fetch a new access token and re-try.")
end

if responseCode ~= 200 then
    print("Error response code = " .. responseCode)
    print("Error:")
    print(sbMetaData:get_as_string())
    return
end

print(sbMetaData:get_as_string())
print("Success.")

-- Sample output:

-- {
--  "kind": "storage#object",
--  "id": "chilkat-ocean/starfish.jpg/1502670320090292",
--  "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg",
--  "name": "starfish.jpg",
--  "bucket": "chilkat-ocean",
--  "generation": "1502670320090292",
--  "metageneration": "1",
--  "contentType": "image/jpeg",
--  "timeCreated": "2017-08-14T00:25:20.040Z",
--  "updated": "2017-08-14T00:25:20.040Z",
--  "storageClass": "MULTI_REGIONAL",
--  "timeStorageClassUpdated": "2017-08-14T00:25:20.040Z",
--  "size": "6229",
--  "md5Hash": "LpxZ2/JmI2fcl9/dqF2gSA==",
--  "mediaLink": "https://www.googleapis.com/download/storage/v1/b/chilkat-ocean/o/starfish.jpg?generation=1502670320090292&alt=media",
--  "acl": [
--   {
--    "kind": "storage#objectAccessControl",
--    "id": "chilkat-ocean/starfish.jpg/1502670320090292/project-owners-933037264567",
--    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/project-owners-933037264567",
--    "bucket": "chilkat-ocean",
--    "object": "starfish.jpg",
--    "generation": "1502670320090292",
--    "entity": "project-owners-933037264567",
--    "role": "OWNER",
--    "projectTeam": {
--     "projectNumber": "933037264567",
--     "team": "owners"
--    },
--    "etag": "CLT5kpW71dUCEAE="
--   },
--   {
--    "kind": "storage#objectAccessControl",
--    "id": "chilkat-ocean/starfish.jpg/1502670320090292/project-editors-933037264567",
--    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/project-editors-933037264567",
--    "bucket": "chilkat-ocean",
--    "object": "starfish.jpg",
--    "generation": "1502670320090292",
--    "entity": "project-editors-933037264567",
--    "role": "OWNER",
--    "projectTeam": {
--     "projectNumber": "933037264567",
--     "team": "editors"
--    },
--    "etag": "CLT5kpW71dUCEAE="
--   },
--   {
--    "kind": "storage#objectAccessControl",
--    "id": "chilkat-ocean/starfish.jpg/1502670320090292/project-viewers-933037264567",
--    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/project-viewers-933037264567",
--    "bucket": "chilkat-ocean",
--    "object": "starfish.jpg",
--    "generation": "1502670320090292",
--    "entity": "project-viewers-933037264567",
--    "role": "READER",
--    "projectTeam": {
--     "projectNumber": "933037264567",
--     "team": "viewers"
--    },
--    "etag": "CLT5kpW71dUCEAE="
--   },
--   {
--    "kind": "storage#objectAccessControl",
--    "id": "chilkat-ocean/starfish.jpg/1502670320090292/user-starfish@chilkat-176611.iam.gserviceaccount.com",
--    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/user-starfish@chilkat-176611.iam.gserviceaccount.com",
--    "bucket": "chilkat-ocean",
--    "object": "starfish.jpg",
--    "generation": "1502670320090292",
--    "entity": "user-starfish@chilkat-176611.iam.gserviceaccount.com",
--    "role": "OWNER",
--    "email": "starfish@chilkat-176611.iam.gserviceaccount.com",
--    "etag": "CLT5kpW71dUCEAE="
--   }
--  ],
--  "owner": {
--   "entity": "user-starfish@chilkat-176611.iam.gserviceaccount.com"
--  },
--  "crc32c": "9RjgwQ==",
--  "etag": "CLT5kpW71dUCEAE="
-- }
--