Lua

Download a SharePoint File by Path using HttpCurl

See more SharePoint Examples

This example shows how to use Chilkat's HttpCurl class to download a file from SharePoint when the file path within the document library is already known. The example uses Microsoft Graph to automatically resolve the SharePoint site name to a site ID, find the drive ID for the Documents document library, and then download the file directly by path using the Graph root:/path:/content syntax.

Lua

local chilkat = require("chilkat")

-- This example downloads a file from a SharePoint Documents document library
-- when the file's path within the library is already known.
--
-- The file downloaded in this example is:
--
--   images/sea_creatures/starfish.jpg
--
-- Unlike the previous example  that searched for a file by name and obtained
-- its Microsoft Graph item ID, this example uses the Graph path-based API.
--
-- The example demonstrates how HttpCurl automatically resolves:
--
--   site_name  -> site_id
--   site_id    -> document_library_id
--
-- and then uses the known file path to download the file directly.

local success = false

-- --------------------------------------------------------------------------------------------------------
-- Before running this example, create an Azure App Registration and grant it
-- the Microsoft Graph permissions required to access SharePoint.
--
-- The application will authenticate using OAuth2 Client Credentials.
-- See:
-- How to Create SharePoint App Registration for OAuth 2.0 Client Credentials
-- --------------------------------------------------------------------------------------------------------

-- Build a JSON authentication configuration.
-- HttpCurl will use this information to automatically obtain OAuth2 access tokens.
local jsonAuth = chilkat.JsonObject.new()

-- Enable secret lookup.
--
-- Instead of hard-coding sensitive values such as the client ID,
-- client secret, and token endpoint, secret specification strings
-- are used.  Chilkat automatically retrieves the actual values from
-- Windows Credential Manager (Windows) or Apple Keychain (macOS).
--
-- See:
-- Secret Specification Strings
jsonAuth.enable_secrets = true

success = jsonAuth:update_string("oauth2.client_id", "!!sharepoint|oauth2|client_id")
if success then
    success = jsonAuth:update_string("oauth2.client_secret", "!!sharepoint|oauth2|client_secret")
end

if success then
    success = jsonAuth:update_string("oauth2.token_endpoint", "!!sharepoint|oauth2|token_endpoint")
end

if not success then
    print(jsonAuth.last_error_text)
    return
end

-- Request Microsoft Graph permissions that were granted to the application.
jsonAuth:update_string("oauth2.scope", "https://graph.microsoft.com/.default")

-- ---------------------------------------------------------------------------------------------------

local curl = chilkat.HttpCurl.new()

-- Associate the OAuth2 configuration with HttpCurl.
--
-- When the request is executed, Chilkat automatically obtains an access token
-- if needed and adds the Authorization: Bearer header to the HTTP request.
curl:set_auth(jsonAuth)

-- Define values that are already known.
--
-- These variables are referenced in curl commands using
-- {{variable_name}} substitution syntax.
curl:set_var("sharepoint_hostname", "example.sharepoint.com")
curl:set_var("site_name", "test")

-- The download request requires a Microsoft Graph site ID.
--
-- Because the application only knows the SharePoint site name,
-- define a helper function that can retrieve the site information.
curl:add_function("getSite", "GET https://graph.microsoft.com/v1.0/sites/root:/sites/{{site_name}}")

-- Extract the site's ID and store it in the HttpCurl variable named site_id.
curl:add_output("getSite", "id", "site_id")

-- The download request also requires the drive ID of the Documents
-- document library.
--
-- Microsoft Graph refers to document libraries as "drives".
curl:add_function("getDrives", "GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives")

-- Search the returned drives for the one named "Documents"
-- and save its drive ID in the document_library_id variable.
curl:add_output2("getDrives", "value", "name", "Documents", true, "id", "document_library_id")

-- This is the target Microsoft Graph request.
--
-- GET /sites/{site-id}/drives/{drive-id}/root:/{path-to-file}:/content
--
-- The path-based API allows a file to be downloaded directly when its
-- location within the document library is known.
--
-- The -L option causes HttpCurl to follow redirects.
-- Microsoft Graph typically returns a redirect to the actual download URL.
--
-- The -o option specifies the output filename.
-- The --output-dir option specifies the directory where the downloaded
-- file will be saved.
local curlCommand = "GET -L --output-dir c:/temp/qa_output -o starfish.jpg https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives/{{document_library_id}}/root:/images/sea_creatures/starfish.jpg:/content"

-- Execute the request.
--
-- HttpCurl examines the target request and determines that both
-- site_id and document_library_id are required.
--
-- To obtain these values, it automatically builds and executes
-- the following dependency chain:
--
--   1) getSite    -> site_id
--   2) getDrives  -> document_library_id
--   3) download   -> file content
--
-- The file is streamed directly to the output file specified by
-- the curl command.
success = curl:do_your_thing(curlCommand)
if not success then
    print(curl.last_error_text)
    return
end

-- A successful Graph response should return HTTP 200.
-- Any other status code typically indicates an authentication,
-- permission, site lookup, document library lookup, or file lookup error.
local statusCode = curl.status_code
if statusCode ~= 200 then
    print(curl.response_body_str)
    print("status code = " .. statusCode)
    return
end

-- The file has been downloaded successfully and written to:
--
--   c:/temp/qa_output/starfish.jpg
--
print("Success.")