Pascal (Lazarus/Delphi)

curl Dependency Engine Simple Example

See more CURL Examples

This example demonstrates a simple way to define curl commands with declared inputs and outputs, and then execute a target command by automatically resolving its dependencies.

When the DoYourThing method is called with the target curl command, the following occurs:

• Scans the curl command for required inputs using the {{variable}} syntax
• Determines which of those inputs already have values
• For any missing inputs:
  • Locates another curl command that can produce the needed value
  • Recursively resolves that command’s own inputs in the same way
• Constructs an execution plan so that each curl command runs only after all of its required inputs are available

The execution plan is then carried out, with the final step being the target curl command originally passed to DoYourThing.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.JsonObject,
  Chilkat.HttpCurl;

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

procedure RunDemo;
var
  success: Boolean;
  httpCurl: THttpCurl;
  targetCurl: string;
  fnName: string;
  jsonPath: string;
  jsonOAuth2: TJsonObject;
  statusCode: Integer;
  responseJson: TJsonObject;

begin
  success := False;

  httpCurl := THttpCurl.Create;

  //  The target curl command we ultimately want to execute.
  //  It requires a {{site_id}} value, which is not yet known.
  targetCurl := 'GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives';

  //  Because site_id is unknown, we define a helper function (curl command)
  //  that can retrieve it.
  fnName := 'getSite';
  httpCurl.AddFunction(fnName,'GET https://graph.microsoft.com/v1.0/sites/root:/sites/{{site_name}}');

  //  Define the outputs produced by the helper function.
  //  Outputs are extracted from the JSON response using JSON paths.
  //  Here, the "id" field from the response is mapped to the variable "site_id".
  jsonPath := 'id';
  httpCurl.AddOutput(fnName,jsonPath,'site_id');

  //  Provide a value for site_name, which is required by the getSite function.
  httpCurl.SetVar('site_name','test');

  //  ----------------------------------------------------------------------------------------------------------------------
  //  Build the OAuth2 configuration used for authentication.
  //  This uses the client credentials flow, with secrets retrieved
  //  from the local secrets manager (because EnableSecrets = true).
  jsonOAuth2 := TJsonObject.Create;
  jsonOAuth2.EnableSecrets := True;
  jsonOAuth2.UpdateString('oauth2.client_id','!!sharepoint|oauth2|client_id');
  jsonOAuth2.UpdateString('oauth2.client_secret','!!sharepoint|oauth2|client_secret');
  jsonOAuth2.UpdateString('oauth2.scope','https://graph.microsoft.com/.default');
  jsonOAuth2.UpdateString('oauth2.token_endpoint','!!sharepoint|oauth2|token_endpoint');
  //  ----------------------------------------------------------------------------------------------------------------------

  httpCurl.SetAuth(jsonOAuth2);

  //  Execute the target curl command.
  //  Internally, the system will:
  //  1) Detect that {{site_id}} is required but not yet defined.
  //  2) Find that the "getSite" function can produce site_id.
  //  3) Verify that getSite's input (site_name) is already available.
  //  4) Build an execution plan: first run getSite, then run the target curl.
  success := httpCurl.DoYourThing(targetCurl);
  if (success = False) then
    begin
      WriteLn(httpCurl.LastErrorText);
      Exit;
    end;

  //  Retrieve and display the HTTP response status code.
  statusCode := httpCurl.StatusCode;
  WriteLn('response status code: ' + statusCode);

  //  Load and display the JSON response from the final curl command.
  responseJson := TJsonObject.Create;
  responseJson.EmitCompact := False;
  httpCurl.GetResponseJson(responseJson);
  WriteLn(responseJson.Emit());


  httpCurl.Free;
  jsonOAuth2.Free;
  responseJson.Free;

end;

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

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.