Abrufen von Aktienkursen über eine GET-Anfrage im JSON-Format und deren Verbindung mit FastReport VCL 6

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 frxReport1: TfrxReport;
 JSON_DS: TfrxUserDataSet;
 ButtonConnectToJSON: TButton;
 Label1: TLabel;
 Label2: TLabel;
 Label3: TLabel;
 ComboBoxName: TComboBox;
 ComboBoxResolution: TComboBox;
 DateTimePickerFrom: TDateTimePicker;
 Label4: TLabel;
 DateTimePickerTo: TDateTimePicker;
 ButtonShowReport: TButton;
 Image1: TImage;
 Label5: TLabel;
 StatusBar1: TStatusBar;
 ButtonDesign: TButton;
 frxDesigner1: TfrxDesigner;
 frxChartObject1: TfrxChartObject;
 frxPDFExport1: TfrxPDFExport;

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ComboBoxName.Items := 'GAZP SBER BRENT MOEX ROSN YNDX RUAL';
ComboBoxResolution.Items := '1 5 15 30 45 60 120 180 240 D W M';

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var
 tHTTP: TfrxTransportHTTP;
 frxJSON: TfrxJSON;
 Res: String;
 Symbol,Resolution,FromCandlesHistory,ToCandlesHistory : String;
 frxJSONArrayT,frxJSONArrayC,frxJSONArrayO,
 frxJSONArrayH,frxJSONArrayL,frxJSONArrayV: TfrxJSONArray;
 S: TStringStream;

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procedure TFormJSON.ButtonConnectToJSONClick(Sender: TObject);
begin
 frxReport1.LoadFromFile('ChartJSON.fr3');
 JSON_DS.RangeEnd := reCount;
 Symbol := ComboBoxName.Items[ComboBoxName.ItemIndex];
 Resolution := ComboBoxResolution.Items[ComboBoxResolution.ItemIndex];
 FromCandlesHistory := DateTimeToUnix(DateTimePickerFrom.DateTime).ToString;
 ToCandlesHistory := DateTimeToUnix(DateTimePickerTo.DateTime).ToString;
 
//Creating a TfrxTransportHTTP Object for a GET Request over HTTPS
 
 tHTTP := TfrxTransportHTTP.Create(nil);
 try
 
//We form a GET request string and get a response in JSON format
 
 Res := tHTTP.Get('https://api.bcs.ru/udfdatafeed/v1/history?symbol='
 +Symbol+
 '&resolution='+Resolution +
 '&from='+ FromCandlesHistory+
 '&to='+ToCandlesHistory);
 
// if JSON is received incorrectly, then load it from the file and display a message in StatusBarr
 
 if (Res = '') or (pos('"s":"ok"',Res) = 0) then
 begin
 StatusBar1.SimpleText := 'Error loading JSON';
 S := TStringStream.Create('', TEncoding.UTF8);
 try
 S.LoadFromFile('JSON/'+Symbol+'.json');
 finally
 Res:= S.DataString;
 FreeAndNil(S);
 end;
 StatusBar1.SimpleText := 'Successful JSON loading from file '+Symbol+'.json';
 end
 else
 begin
 StatusBar1.SimpleText := 'Successful JSON('+Symbol+') loading';
 end;
 
// We load the received JSON from the Res line into the frxJSON object: TfrxJSON
 
 frxJSON := TfrxJSON.Create(Res);
 try
 if frxJSON.IsValid then
 begin
 StatusBar1.SimpleText :=StatusBar1.SimpleText +' /JSON is Valid';
 
// Read arrays
 
 if frxJSON.IsNameExists('t') then
 frxJSONArrayT := TfrxJSONArray.Create(frxJSON.ObjectByName('t'));
 frxJSONArrayC := TfrxJSONArray.Create(frxJSON.ObjectByName('c'));
 frxJSONArrayO := TfrxJSONArray.Create(frxJSON.ObjectByName('o'));
 frxJSONArrayH := TfrxJSONArray.Create(frxJSON.ObjectByName('h'));
 frxJSONArrayL := TfrxJSONArray.Create(frxJSON.ObjectByName('l'));
 frxJSONArrayV := TfrxJSONArray.Create(frxJSON.ObjectByName('v'));
// Prepare JSON_DS by clearing and adding fields
 JSON_DS.Fields.Clear;
 JSON_DS.Fields.Add('Ticker');
 JSON_DS.Fields.Add('Date');
 JSON_DS.Fields.Add('Time');
 JSON_DS.Fields.Add('Open');
 JSON_DS.Fields.Add('Close');
 JSON_DS.Fields.Add('High');
 JSON_DS.Fields.Add('Low');
 JSON_DS.Fields.Add('Vol');
 JSON_DS.RangeEndCount := frxJSONArrayT.Count;
 end
 else StatusBar1.SimpleText :=StatusBar1.SimpleText +' /JSON is Invalid';
 finally
 end;
 finally
 end;
end;

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procedure TFormJSON.JSON_DSGetValue(const VarName: string; var Value: Variant);
var
 Item: string;
 Time : string;
begin
 Item := frxJSONArrayT.GetString(JSON_DS.RecNo);
 DateTimeToString(Time, 't', UnixToDateTime(StrToInt64(Item)));
 
 if VarName = 'Ticker' then
 begin
 Value := Symbol;
 exit;
 end
 else if VarName = 'Date' then
 begin
 Value := DateToStr(UnixToDateTime(StrToInt64(Item)))+' '+Time;
 exit;
 end
 else if VarName = 'Time' then
 begin
 Value := Time;
 exit;
 end
 else if VarName = 'Open' then
 Item := frxJSONArrayO.GetString(JSON_DS.RecNo)
 else if VarName = 'Close' then
 Item := frxJSONArrayC.GetString(JSON_DS.RecNo)
 else if VarName = 'High' then
 Item := frxJSONArrayH.GetString(JSON_DS.RecNo)
 else if VarName = 'Low' then
 Item := frxJSONArrayL.GetString(JSON_DS.RecNo)
 else if VarName = 'Vol' then
 Item := frxJSONArrayV.GetString(JSON_DS.RecNo);
 
 Value := Item;
end;

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procedure TFormJSON.ButtonDesignClick(Sender: TObject);
begin
 if (Res = '') then ButtonConnectToJSON.Click;
 frxReport1.DesignReport();
end;

procedure TFormJSON.ButtonShowReportClick(Sender: TObject);
begin
if (Res = '') then ButtonConnectToJSON.Click;
 frxReport1.ShowReport();
end;

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procedure TFormJSON.ComboBoxNameChange(Sender: TObject);
begin
 ButtonConnectToJSON.Click;
end;
 
procedure TFormJSON.DateTimePickerFromChange(Sender: TObject);
begin
 ButtonConnectToJSON.Click;
end;
 
procedure TFormJSON.DateTimePickerToChange(Sender: TObject);
begin
 ButtonConnectToJSON.Click;
end;

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procedure TFormJSON.FormClose(Sender: TObject; var Action: TCloseAction);
begin
 tHTTP.Free;
 frxJSON.Free;
 frxJSONArrayT.Free;
 frxJSONArrayC.Free;
 frxJSONArrayO.Free;
 frxJSONArrayH.Free;
 frxJSONArrayL.Free;
 frxJSONArrayV.Free;
end;