(Delphi DLL) 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 for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, HttpCurl, StringBuilder, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
jsonAuth: HCkJsonObject;
curl: HCkHttpCurl;
curlCommand: PWideChar;
statusCode: Integer;
sbFileContents: HCkStringBuilder;

begin
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.
jsonAuth := CkJsonObject_Create();

// 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_putEnableSecrets(jsonAuth,True);

success := CkJsonObject_UpdateString(jsonAuth,'oauth2.client_id','!!sharepoint|oauth2|client_id');
if (success = True) then
  begin
    success := CkJsonObject_UpdateString(jsonAuth,'oauth2.client_secret','!!sharepoint|oauth2|client_secret');
  end;
if (success = True) then
  begin
    success := CkJsonObject_UpdateString(jsonAuth,'oauth2.token_endpoint','!!sharepoint|oauth2|token_endpoint');
  end;
if (success = False) then
  begin
    Memo1.Lines.Add(CkJsonObject__lastErrorText(jsonAuth));
    Exit;
  end;

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

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

curl := CkHttpCurl_Create();

// 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',True,'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',True,'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.
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.
success := CkHttpCurl_DoYourThing(curl,curlCommand);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttpCurl__lastErrorText(curl));
    Exit;
  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.
statusCode := CkHttpCurl_getStatusCode(curl);
if (statusCode <> 200) then
  begin
    Memo1.Lines.Add(CkHttpCurl__responseBodyStr(curl));
    Memo1.Lines.Add('status code = ' + IntToStr(statusCode));
    Exit;
  end;

// The response body contains the contents of the downloaded file.
sbFileContents := CkStringBuilder_Create();
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.
success := CkStringBuilder_WriteFile(sbFileContents,'c:/temp/hamlet.json','utf-8',False);
if (success = False) then
  begin
    Memo1.Lines.Add(CkStringBuilder__lastErrorText(sbFileContents));
    Exit;
  end;

Memo1.Lines.Add('Success.');

CkJsonObject_Dispose(jsonAuth);
CkHttpCurl_Dispose(curl);
CkStringBuilder_Dispose(sbFileContents);

end;