C#

Download a SharePoint File by Path using HttpCurl

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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.

C#

bool 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.
Chilkat.JsonObject jsonAuth = new Chilkat.JsonObject();

//  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 = jsonAuth.UpdateString("oauth2.client_id","!!sharepoint|oauth2|client_id");
if (success == true) {
    success = jsonAuth.UpdateString("oauth2.client_secret","!!sharepoint|oauth2|client_secret");
}

if (success == true) {
    success = jsonAuth.UpdateString("oauth2.token_endpoint","!!sharepoint|oauth2|token_endpoint");
}

if (success == false) {
    Debug.WriteLine(jsonAuth.LastErrorText);
    return;
}

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

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

Chilkat.HttpCurl curl = new Chilkat.HttpCurl();

//  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.
string 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.DoYourThing(curlCommand);
if (success == false) {
    Debug.WriteLine(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.StatusCode;
if (statusCode != 200) {
    Debug.WriteLine(curl.ResponseBodyStr);
    Debug.WriteLine("status code = " + Convert.ToString(statusCode));
    return;
}

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