(Tcl) Download a File from a SharePoint Documents Library

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This example shows how to use Chilkat's HttpCurl class to download a file from the root of a SharePoint Documents document library. The example demonstrates how HttpCurl automatically resolves the SharePoint site name to a site ID, finds the drive ID for the Documents library, locates the file by name, and then downloads the file content using Microsoft Graph.

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load ./chilkat.dll

set success 0

# This example downloads a file named "hamlet.json" from the root of the SharePoint
# Documents document library.
# 
# The example demonstrates how HttpCurl can automatically resolve all of the
# information needed to locate and download a file:
# 
#   site_name            -> site_id
#   site_id              -> document_library_id
#   document_library_id  -> file_id
#   file_id              -> file content
# 
# The application only provides the SharePoint site name and the desired
# filename.  HttpCurl automatically executes the required Microsoft Graph
# requests to obtain the remaining values.

set success 0

# --------------------------------------------------------------------------------------------------------
# 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.
set jsonAuth [new_CkJsonObject]

# 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
CkJsonObject_put_EnableSecrets $jsonAuth 1

set success [CkJsonObject_UpdateString $jsonAuth "oauth2.client_id" "!!sharepoint|oauth2|client_id"]
if {$success == 1} then {
    set success [CkJsonObject_UpdateString $jsonAuth "oauth2.client_secret" "!!sharepoint|oauth2|client_secret"]
}

if {$success == 1} then {
    set success [CkJsonObject_UpdateString $jsonAuth "oauth2.token_endpoint" "!!sharepoint|oauth2|token_endpoint"]
}

if {$success == 0} then {
    puts [CkJsonObject_lastErrorText $jsonAuth]
    delete_CkJsonObject $jsonAuth
    exit
}

# Request Microsoft Graph permissions that were granted to the application.
CkJsonObject_UpdateString $jsonAuth "oauth2.scope" "https://graph.microsoft.com/.default"

# ---------------------------------------------------------------------------------------------------

set curl [new_CkHttpCurl]

# 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.
CkHttpCurl_SetAuth $curl $jsonAuth

# Define values that are already known.
# 
# These variables are referenced in curl commands using
# {{variable_name}} substitution syntax.
CkHttpCurl_SetVar $curl "sharepoint_hostname" "example.sharepoint.com"
CkHttpCurl_SetVar $curl "site_name" "test"

# The first step is to obtain the Microsoft Graph site ID.
# 
# The application only knows the SharePoint site name, so define
# a function that can retrieve the site information.
CkHttpCurl_AddFunction $curl "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.
CkHttpCurl_AddOutput $curl "getSite" "id" "site_id"

# The next step is to find the Documents document library.
# 
# Microsoft Graph refers to document libraries as "drives".
CkHttpCurl_AddFunction $curl "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.
CkHttpCurl_AddOutput2 $curl "getDrives" "value" "name" "Documents" 1 "id" "document_library_id"

# Now list the contents of the Documents document library.
CkHttpCurl_AddFunction $curl "getFiles" "GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives/{{document_library_id}}/root/children"

# Search the returned files for an item named "hamlet.json"
# and save its Microsoft Graph item ID in the file_id variable.
CkHttpCurl_AddOutput2 $curl "getFiles" "value" "name" "hamlet.json" 1 "id" "file_id"

# This is the target request.
# 
# GET -L https://graph.microsoft.com/v1.0/drives/{{document_library_id}}/items/{{file_id}}/content
# 
# The /content endpoint returns the actual contents of the file.
# 
# The -L option instructs HttpCurl to follow the redirect returned by
# Microsoft Graph.  The Graph API typically responds with a redirect
# to the actual file download URL.
set curlCommand "GET -L https://graph.microsoft.com/v1.0/drives/{{document_library_id}}/items/{{file_id}}/content"

# Execute the request.
# 
# HttpCurl examines the target request and determines that both
# document_library_id and file_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) getFiles     -> file_id
#   4) download     -> file content
# 
# The final response returned by DoYourThing is the downloaded
# file content from the target request.
set success [CkHttpCurl_DoYourThing $curl $curlCommand]
if {$success == 0} then {
    puts [CkHttpCurl_lastErrorText $curl]
    delete_CkJsonObject $jsonAuth
    delete_CkHttpCurl $curl
    exit
}

# 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.
set statusCode [CkHttpCurl_get_StatusCode $curl]
if {$statusCode != 200} then {
    puts [CkHttpCurl_responseBodyStr $curl]
    puts "status code = $statusCode"
    delete_CkJsonObject $jsonAuth
    delete_CkHttpCurl $curl
    exit
}

# The response body contains the contents of the downloaded file.
set sbFileContents [new_CkStringBuilder]

CkHttpCurl_GetResponseSb $curl $sbFileContents

# Optionally save the downloaded content to a local file.
# 
# The third argument controls whether the file is appended.
# Passing ckfalse causes the file to be overwritten if it already exists.
set success [CkStringBuilder_WriteFile $sbFileContents "c:/temp/hamlet.json" "utf-8" 0]
if {$success == 0} then {
    puts [CkStringBuilder_lastErrorText $sbFileContents]
    delete_CkJsonObject $jsonAuth
    delete_CkHttpCurl $curl
    delete_CkStringBuilder $sbFileContents
    exit
}

puts "Success."

delete_CkJsonObject $jsonAuth
delete_CkHttpCurl $curl
delete_CkStringBuilder $sbFileContents