Delphi DLL

curl with Variable Substitution in the Request Body

See more CURL Examples

This example demonstrates using variables located in the request body with the {{variable_name}} syntax. Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sbCurl: HCkStringBuilder;
curl: HCkHttpCurl;
sbRawRequest: HCkStringBuilder;

begin
success := False;

// Variables can also be used within the HTTP request body.
// Variable names are enclosed between {{ and }}

// Here is a curl command with two variables {{name}} and {{age}} located in the data.

// curl -X POST https://api.example.com/data \
//   -H "Content-Type: application/json" \
//   -d '{"name":"{{name}}","age":{{age}}}'

sbCurl := CkStringBuilder_Create();
CkStringBuilder_AppendLn(sbCurl,'curl -X POST https://api.example.com/data \");
CkStringBuilder_AppendLn(sbCurl,'  -H "Content-Type: application/json" \");
CkStringBuilder_AppendLn(sbCurl,'  -d ''{"name":"{{name}}","age":{{age}}}''');

curl := CkHttpCurl_Create();

// Provide values for variables.
CkHttpCurl_SetVar(curl,'name','Alice');
CkHttpCurl_SetVar(curl,'age','30');

// To demonstrate how the variables are replaced, this example does not execute the curl command. 
// Instead, it generates the raw HTTP request that would be sent if the curl command were run.
sbRawRequest := CkStringBuilder_Create();
success := CkHttpCurl_ToRawRequest(curl,CkStringBuilder__getAsString(sbCurl),sbRawRequest);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttpCurl__lastErrorText(curl));
    Exit;
  end;

Memo1.Lines.Add(CkStringBuilder__getAsString(sbRawRequest));

// Output:

// POST /data HTTP/1.1
// Host: api.example.com
// Content-Type: application/json
// Content-Length: 25
// 
// {"name":"Alice","age":30}

// --------------------------------------------------------------------------------------------------
// Note: Variable substitution in the request body can be turned off by 
// setting the EnableBodyVars property equal to False

CkHttpCurl_putEnableBodyVars(curl,False);

success := CkHttpCurl_ToRawRequest(curl,CkStringBuilder__getAsString(sbCurl),sbRawRequest);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttpCurl__lastErrorText(curl));
    Exit;
  end;

Memo1.Lines.Add(CkStringBuilder__getAsString(sbRawRequest));

// The raw request with body variable substitution disable:

// Host: api.example.com
// Content-Type: application/json
// Content-Length: 33
// 
// {"name":"{{name}}","age":{{age}}}

CkStringBuilder_Dispose(sbCurl);
CkHttpCurl_Dispose(curl);
CkStringBuilder_Dispose(sbRawRequest);

end;