Lua

Download Object from Google Cloud Storage

See more Google Cloud Storage Examples

Demonstrates how to download an object from Google Cloud Storage to a file. 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]?alt=media"

local http = chilkat.Http.new()

http.auth_token = sbToken:get_as_string()

-- Construct a URL to download an object named "starfish.jpg" from 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}?alt=media"

-- If there is an error response, then we didn't actually download the file data,
-- but instead we downloaded an error response..
local fileData = chilkat.BinData.new()
local success = http:download_bd(url, fileData)
if not success then
    print(http.last_error_text)
    return
end

local sbErrorResponse = chilkat.StringBuilder.new()
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
    -- Get the error response
    sbErrorResponse:append_bd(fileData, "utf-8", 0, 0)
    print("Error response code = " .. responseCode)
    print("Error:")
    print(sbErrorResponse:get_as_string())
    return
end

print("Success.")

-- Save the downloaded data to a file.
success = fileData:write_file("qa_output/starfish.jpg")