Unicode C++
Unicode C++
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.
Chilkat Unicode C++ Downloads
#include <CkJsonObjectW.h>
#include <CkHttpCurlW.h>
#include <CkStringBuilderW.h>
void ChilkatSample(void)
{
bool success = false;
// 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.
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.
CkJsonObjectW jsonAuth;
// 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.put_EnableSecrets(true);
success = jsonAuth.UpdateString(L"oauth2.client_id",L"!!sharepoint|oauth2|client_id");
if (success == true) {
success = jsonAuth.UpdateString(L"oauth2.client_secret",L"!!sharepoint|oauth2|client_secret");
}
if (success == true) {
success = jsonAuth.UpdateString(L"oauth2.token_endpoint",L"!!sharepoint|oauth2|token_endpoint");
}
if (success == false) {
wprintf(L"%s\n",jsonAuth.lastErrorText());
return;
}
// Request Microsoft Graph permissions that were granted to the application.
jsonAuth.UpdateString(L"oauth2.scope",L"https://graph.microsoft.com/.default");
// ---------------------------------------------------------------------------------------------------
CkHttpCurlW curl;
// 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(L"sharepoint_hostname",L"example.sharepoint.com");
curl.SetVar(L"site_name",L"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.
curl.AddFunction(L"getSite",L"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(L"getSite",L"id",L"site_id");
// The next step is to find the Documents document library.
//
// Microsoft Graph refers to document libraries as "drives".
curl.AddFunction(L"getDrives",L"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(L"getDrives",L"value",L"name",L"Documents",true,L"id",L"document_library_id");
// Now list the contents of the Documents document library.
curl.AddFunction(L"getFiles",L"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.
curl.AddOutput2(L"getFiles",L"value",L"name",L"hamlet.json",true,L"id",L"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.
const wchar_t *curlCommand = L"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.
success = curl.DoYourThing(curlCommand);
if (success == false) {
wprintf(L"%s\n",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.
int statusCode = curl.get_StatusCode();
if (statusCode != 200) {
wprintf(L"%s\n",curl.responseBodyStr());
wprintf(L"status code = %d\n",statusCode);
return;
}
// The response body contains the contents of the downloaded file.
CkStringBuilderW sbFileContents;
curl.GetResponseSb(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.
success = sbFileContents.WriteFile(L"c:/temp/hamlet.json",L"utf-8",false);
if (success == false) {
wprintf(L"%s\n",sbFileContents.lastErrorText());
return;
}
wprintf(L"Success.\n");
}