After a series of twists and turns, it is still convenient for delphi to read and modify json files;

Find a delphi tripartite library ISuperObject on the network, add it to the project and reference it directly;

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Several commonly used functions in ISuperObject:

• Function SO(const s: SOString = '{}'): ISuperObject; overload; this function passes in json data string and returns an ISuperObject object, which is generally the first function we use when parsing json, such as jboj: = so (jsonstr).
• property O[const path: SOString]: ISuperObject read GetO write PutO; default; for example: jobj.O ['username'], this function is called by an ISuperObject object, the string in square brackets is the field name in json, and an ISuperObject object is returned.
• property S[const path: SOString]: SOString read GetS write PutS; this function is called by an ISuperObject object. Unlike O ['username'], it returns A SoString, that is, A string, using STR: = jobj. S ['username']; similarly, there are several other similar functions, such as I ['age'] returns an integer, B ['isenable'] returns A Boolean Type A ['users'] returns an array of tsuperarrays
• The functions of AsString, AsBoolean, AsInteger,AsArray and ISuperObject are used to convert ISuperObject to the corresponding data type.

Demo code:

//read json file
procedure TForm2.Button1Click(Sender: TObject);
var
  rText: TextFile;
  tmp: UTF8String;
begin
  AssignFile(rText, 'C:\Users\admin\Desktop\F.txt');
  reset(rText);
  while not EOF(rText) do
  begin
    readln(rText, tmp);
    Res := Res + tmp;
  end;
  closefile(rText);
  Memo1.Lines.Add(Res);
  application.MessageBox('Loading succeeded!', 'Tips', MB_OK);
end;

//Handle JSON String, reading according to fixed structure
procedure TForm2.Button2Click(Sender: TObject);
var
  jRet, jUsers: ISuperObject;
  aryUsers: TSuperArray;
  gridStartTime, gridEndTime, resultStartTime, resultEndTime, WindSpeedBorder,
    WindDirectBorder: string;
  po, pof, poh, posp: Tpoint;
  num, count, I, J: integer;
  aryers, arrline, arrbar, arrspeed: TSuperArray;
  Tlist: TStringlist;
begin
  jRet:=TSuperObject.Create(stObject);
  Tlist := TStringlist.Create;
  Tlist.Delimiter := ',';
  jRet := SO(Res);
  gridStartTime := jRet.O['gridStartTime'].AsString();
  Memo1.Lines.Add(gridStartTime);
  gridEndTime := jRet.O['gridEndTime'].AsString();
  Memo1.Lines.Add(gridEndTime);
  resultStartTime := jRet.O['resultStartTime'].AsString();
  Memo1.Lines.Add(resultStartTime);
  resultEndTime := jRet.O['resultEndTime'].AsString();
  Memo1.Lines.Add(resultEndTime);
  WindSpeedBorder := jRet.O['WindSpeedBorder'].AsString();
  Memo1.Lines.Add(WindSpeedBorder);
  WindDirectBorder := jRet.O['WindDirectBorder'].AsString();
  Memo1.Lines.Add(WindDirectBorder);

  aryers := jRet.O['WindDirectLine'].O['coordinates'].AsArray();
  count := aryers.Length;
  for I := 0 to count - 1 do
  begin
    arrline := aryers[I].O['mWindDirectBaseLine'].AsArray();
    for J := 0 to arrline.Length - 1 do
    begin
      // Tlist.DelimitedText := arrline[J].O['p'].AsString();
      // po:=point(strtoint(Tlist[0]),strtoint(Tlist[1]));
      Memo1.Lines.Add(arrline[J].O['p'].AsString());
    end;
    arrbar := aryers[I].O['mWindDirectBars'].AsArray();
    for J := 0 to arrbar.Length - 1 do
    begin
      // Tlist.DelimitedText := arrbar[J].O['f'].O['p'].AsString();
      // pof:=point(strtoint(Tlist[0]),strtoint(Tlist[1]));
      // Tlist.DelimitedText := arrbar[J].O['h'].O['p'].AsString();
      // poh:=point(strtoint(Tlist[0]),strtoint(Tlist[1]));
      Memo1.Lines.Add('f: ' + arrbar[J].O['f'].O['p'].AsString()
          + ' h: ' + arrbar[J].O['h'].O['p'].AsString());
    end;
  end;

  aryers := jRet.O['WindSpeedLine'].O['coordinates'].AsArray();
  count := aryers.Length;
  for I := 0 to count - 1 do
  begin
    arrspeed := aryers[I].AsArray();
    for J := 0 to arrspeed.Length - 1 do
    begin
      // Tlist.DelimitedText := arrspeed[J].O['p'].AsString();
      // posp:=point(strtoint(Tlist[0]),strtoint(Tlist[1]));
      Memo1.Lines.Add(arrspeed[J].O['p'].AsString());
    end;
  end;
  application.MessageBox('Processing complete!', 'Tips', MB_OK);
end;

//modify JSON File and save
procedure TForm2.Button3Click(Sender: TObject);
var
  jfields, jitems, jo, jRet: ISuperObject;
  date: string;
  num, count, I, J: integer;
  txt:TextFile;
  aryers, arrline, arrbar, arrspeed: TSuperArray;
begin
  jRet := SO(Res);
  if jRet = nil then
       application.MessageBox('Read failed!', 'Tips', MB_OK);
//  date := FormatDateTime('yyyy-MM-dd hh:nn:ss', Now());
  jRet.S['gridStartTime'] := date;
  jRet.S['gridEndTime'] := date;
  jRet.S['resultStartTime'] := date;
  jRet.S['resultEndTime'] := date;
  jRet.S['WindSpeedBorder'] := date;
  jRet.S['WindDirectBorder'] := date;
  jRet.I['gridMethod']:=2;
  count:=jRet.O['WindDirectLine'].A['coordinates'].Length;
  for I := 0 to count - 1 do
  begin
      num:= jRet.O['WindDirectLine'].A['coordinates'][I].A['mWindDirectBaseLine'].Length;
      for J := 0 to num - 1 do
      begin
        jRet.O['WindDirectLine'].A['coordinates'][I].A['mWindDirectBaseLine'][J].S['p']:=inttostr(I)+' ,'+inttostr(J);
      end;
  end;
  Assignfile(txt,'E:\p.gal');  //specify the path to a file
  rewrite(txt);               //Create and open a new file (or overwrite the old one)
  Writeln(txt,jRet.AsString());
  Closefile(txt);            //Close open file

  application.MessageBox(Pchar(jRet.O['gridStartTime'].AsString()), 'Tips', MB_OK);
end;

Be careful:

• When reading the file, if the json file contains Chinese format, it must be ensured that the get field is of UTF8String type.
• jRet.O['WindSpeedLine'].A['coordinates'][0].AsArray().add(jo); / / you can add json nested with array in this way.
• Jo read or declared: = so(); cannot be cleared with clear(), otherwise add(jo) will become empty data.