Pascal (Lazarus/Delphi)

REST with Query Params

See more REST Examples

Demonstrates how to add query params for a REST request. 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.Rest;

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

procedure RunDemo;
var
  success: Boolean;
  rest: TRest;
  bTls: Boolean;
  port: Integer;
  bAutoReconnect: Boolean;
  responseJson: string;

begin
  success := False;

  //  This example requires the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  //  Let's say we want to send a GET request to 
  //  https://example.com/search?query=hello%20world&category=books&sortBy=price&filterBy=inStock

  //  Notice that the query parameter values must be URL encoded.

  //  Let's also explain the parts of the above URL:

  //      Scheme: https
  //          The scheme specifies the protocol used to access the resource. 
  //          In this case, it is "https," which indicates that the resource is accessed using the Hypertext Transfer Protocol Secure (HTTPS).
  //  
  //      Host: example.com
  //          The host part of the URL identifies the domain name or IP address of the server hosting the resource. In this case, "example.com" is the host.
  //  
  //      Path: /search
  //          The path is the specific location or resource on the server that the client wants to access. 
  //          In this URL, the path is "/search," indicating that the client is requesting the "search" resource on the server.
  //  
  //      Query Parameters:
  //          Query parameters are used to send additional data to the server as key-value pairs. 
  //          They are separated from the path by a question mark ? and each parameter is separated by an ampersand &.
  //  
  //          The above URL has four query parameters:
  //              query=hello%20world: The "query" parameter with the value "hello world". The %20 represents the URL-encoded space character in the value.
  //              category=books: The "category" parameter with the value "books".
  //              sortBy=price: The "sortBy" parameter with the value "price".
  //              filterBy=inStock: The "filterBy" parameter with the value "inStock".

  rest := TRest.Create;

  //  Connect to the REST server.

  //  The Host part of the URL is passed in the 1st argument.
  //  The Scheme part of the URL ("https") is indicated by the 2nd and 3rd arguments (port and bTls).
  bTls := True;
  port := 443;
  bAutoReconnect := True;
  success := rest.Connect('example.com',port,bTls,bAutoReconnect);

  //  There are 3 ways to send the above GET request.

  //  1) Send the request with path and query params pre-built, where the query param values are URL encoded.
  responseJson := rest.FullRequestNoBody('GET','/search?query=hello%20world&category=books&sortBy=price&filterBy=inStock');
  if (rest.LastMethodSuccess <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  2) Pass only the Path part of the URL, and specify the query params separately by calling AddQueryParams beforehand.
  //     Again, the query params must be already URL encoded when passed to AddQueryParams
  rest.ClearAllQueryParams();
  rest.AddQueryParams('query=hello%20world&category=books&sortBy=price&filterBy=inStock');
  responseJson := rest.FullRequestNoBody('GET','/search');
  //  ...
  //  ...

  //  3) Pass each query parameter separately by calling AddQueryParam.  In this case, the query param value should be passed without URL encoding.
  //     (ClearAllQueryParams ensures any params set for previous request are cleared.)
  rest.ClearAllQueryParams();
  rest.AddQueryParam('query','hello world');
  rest.AddQueryParam('category','books');
  rest.AddQueryParam('sortBy','price');
  rest.AddQueryParam('filterBy','inStock');
  responseJson := rest.FullRequestNoBody('GET','/search');
  //  ...
  //  ...


  rest.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.