Pascal (Lazarus/Delphi)

Find and Delete Object from JSON Array

See more JSON Examples

Demonstrates how to find an delete an object from a JSON array of objects. 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.JsonArray,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  json: TJsonObject;
  menu: TJsonObject;
  catArr: TJsonArray;
  index: Integer;

begin
  success := False;

  //  This example will delete the "Pasta" category object from Menu B.

  //  {
  //    "menus": [
  //      {
  //        "name": "Menu A",
  //        "categories": [
  //  			{
  //  			"name": "Kebabs",
  //  			"description": "blah blah blah"
  //  			},
  //  			{
  //  			"name": "Burgers",
  //  			"description": "blah blah blah"
  //  			},
  //  			{
  //  			"name": "Pasta",
  //  			"description": "blah blah blah"
  //  			},
  //  			{
  //  			"name": "Appetizers",
  //  			"description": "blah blah blah"
  //  			}
  //  		]
  //  	},
  //      {
  //        "name": "Menu B",
  //        "categories": [
  //  			{
  //  			"name": "Kebabs",
  //  			"description": "blah blah blah"
  //  			},
  //  			{
  //  			"name": "Burgers",
  //  			"description": "blah blah blah"
  //  			},
  //  			{
  //  			"name": "Pasta",
  //  			"description": "blah blah blah"
  //  			},
  //  			{
  //  			"name": "Appetizers",
  //  			"description": "blah blah blah"
  //  			}
  //  		]
  //  	  }
  //  	]
  //  }

  json := TJsonObject.Create;
  success := json.LoadFile('qa_data/json/menus.json');
  if (success = False) then
    begin
      WriteLn(json.LastErrorText);
      Exit;
    end;

  //  Find Menu B.
  menu := json.FindRecord('menus','name','Menu B',True);
  //  assume menu is found..

  //  Get the categories array, and then find the index of the "Pasta" menu category.
  catArr := menu.ArrayOf('categories');
  //  Assume it is found..

  //  Find the object where the name of the JSON member is "name", and the value is "Pasta"
  index := catArr.FindObject('name','Pasta',True);
  if (index < 0) then
    begin
      WriteLn('Pasta not found.');
    end
  else
    begin

      //  Delete the "Pasta" category record from Menu B
      success := catArr.DeleteAt(index);
      //  Assume OK..
    end;

  //  Examine the JSON to see if it worked as expected..
  json.EmitCompact := False;
  WriteLn(json.Emit());

  catArr.Free;
  menu.Free;


  json.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.