Dart

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.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  var success = false;

  // 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.

  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.
  final jsonAuth = 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
  jsonAuth.enableSecrets = true;

  success = true;
  try {
    jsonAuth.updateString('oauth2.client_id', '!!sharepoint|oauth2|client_id');
  } on ChilkatException {
    success = false;
  }
  if (success) {
    success = true;
    try {
      jsonAuth.updateString('oauth2.client_secret', '!!sharepoint|oauth2|client_secret');
    } on ChilkatException {
      success = false;
    }
  }

  if (success) {
    success = true;
    try {
      jsonAuth.updateString('oauth2.token_endpoint', '!!sharepoint|oauth2|token_endpoint');
    } on ChilkatException {
      success = false;
    }
  }

  if (!success) {
    print(jsonAuth.lastErrorText);
    return;
  }

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

  // ---------------------------------------------------------------------------------------------------

  final curl = 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.
  curl.setAuth(jsonAuth);

  // Define values that are already known.
  // 
  // These variables are referenced in curl commands using
  // {{variable_name}} substitution syntax.
  curl.setVar('sharepoint_hostname', 'example.sharepoint.com');
  curl.setVar('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.addFunction('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.addOutput('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.addFunction('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.addOutput2('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.
  final 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 = true;
  try {
    curl.doYourThing(curlCommand);
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print(curl.lastErrorText);
    return;
  }

  // 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.
  final statusCode = curl.statusCode;
  if (statusCode != 200) {
    print(curl.responseBodyStr);
    print('status code = $statusCode');
    return;
  }

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