Lua

Streaming Download Large File to the Local Filesystem

See more Azure Cloud Storage Examples

Downloads a large file in a streaming fashion to the local filesystem. Lua

local chilkat = require("chilkat")

-- Azure File Service Example: Downloads a large file to the local filesystem using a Chilkat stream.
-- See:  https://docs.microsoft.com/en-us/rest/api/storageservices/get-file

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

local rest = chilkat.Rest.new()

-- Connect to the Azure Storage Blob Service
local bTls = true
local port = 443
local bAutoReconnect = true
-- In this example, the storage account name is "chilkat".
local success = rest:connect("chilkat.file.core.windows.net", port, bTls, bAutoReconnect)
if not success then
    print(rest.last_error_text)
    return
end

-- Provide Azure Cloud credentials for the REST calls.
local azAuth = chilkat.AuthAzureStorage.new()
azAuth.access_key = "AZURE_ACCESS_KEY"
-- The account name used here should match the 1st part of the domain passed in the call to Connect (above).
azAuth.account = "chilkat"
azAuth.scheme = "SharedKey"
azAuth.service = "File"
-- This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.xms_version = "2021-08-06"
success = rest:set_auth_azure_storage(azAuth)

-- Note: The application does not need to explicitly set the following
-- headers: x-ms-date, Authorization.  These headers
-- are automatically set by Chilkat.

-- When streaming a download to the local filesystem or directed elsewhere,
-- the complete HTTP GET operation must be broken into parts.
-- For example, an HTTP GET consists of sending the request, followed by reading the response header,
-- and then finally the response body.  We'll want to read the response header, and then based
-- on the information received (such as success or failure), either read the response body
-- as an error message, or as the file data.

-- Send the HTTP GET request to download the file.
-- The share is named "pip".
success = rest:send_req_no_body("GET", "/pip/somethingBig.zip")
if not success then
    print(rest.last_error_text)
    return
end

-- Read the response header.
local responseStatusCode = rest:read_response_header()
if responseStatusCode < 0 then
    print(rest.last_error_text)
    return
end

print("Response status code = " .. responseStatusCode)

-- We expect a 200 response status if the file data is coming.
-- Otherwise, we'll get a string response body with an error message(or no response body).
if responseStatusCode == 200 then
    local bodyStream = chilkat.Stream.new()

    -- The stream's sink will be a file.
    bodyStream.sink_file = "qa_output/somethingBig.zip"

    -- Read the response body to the stream.  Given that we've
    -- set the stream's sink to a file, it will stream directly
    -- to the file.
    success = rest:read_resp_body_stream(bodyStream, true)
    if not success then
        print(rest.last_error_text)
        return
    end

    print("Successfully received the large file.")
else
    local errResponse = rest:read_resp_body_string()
    if not rest.last_method_success then
        print(rest.last_error_text)
    else
        print(errResponse)
    end
end