Linking double pages LazReport to DataSets in RunTime
lazarus / 16-Databases

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szeti · 2011-09-13 09:58

Hello!. (Sorry for my english!) I'm trying to link a DS Dataset1 to a
tfrDBDataset1 object and a DS Dataset2 to a tfrDBDataSet2 object to
make a double pages report (Page1 and Page2) with lazreport. In design
time it's very easy because set the Data source of the Master Data
Band in the Page. When I try it in runtime it is wrong.

I try in the onBeginBand event, but is wrong: „Invalid type cast”

procedure MyObject.frPtjBeginBand(Band: TfrBand);
 var Band1,Band2,Band3: TfrBand;
begin
 Band1:=frPtj.FindObject('MasterData1') as TfrBand;
 Band1.DataSet:=frPtjDS;
 Band2:=frPtj.FindObject('MasterData2') as TfrBand;
 Band2.DataSet:=frPtjFkvDS;
end;

What is the good procedure and what is the good event in the
LazReport?

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jesusr · 2011-09-14 18:12

Try this:

Code: [Select]....
var
   b: TfrBandView;
   ...
begin
   b := TfrBandView(frPtj.FindObject('MasterData1'));
   b.DataSet := 'frPtjDS'; // Note this the name (a string) of frPtjDS
tfrDbDataset object
   ...
end;

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szeti · 2011-09-14 19:41

Hi!  Thanks a lot, so already it works.

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szeti · 2011-09-17 14:08

I have a question about the Lazreport. I to search for answer from the
net, but I didn’t  find it.
I made a double pages frPtj:TfrReport (Page1, Page2).  All the page
have a Master Data Band (frPtjDS->Master Data1 of Page1 , frPtjFkvDS->
Master Data of Page2). In design time it's very easy because I set the
Data source of the Master Data Band in the Pages. When I try it in
runtime it is wrong.


Example:

**********************************************************************
********************
unit tasks;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, Dialogs, Rutin, LR_Class, Reports, LR_DBSet,
LR_DSet, lr_e_pdf,
  FileUtil;

type
  MyObject=Class(TObject)
  procedure TaskPtjel(Show: Boolean; tmb: array of string);
  procedure frPtjGetValue(const ParName: String; var ParValue:
Variant);
  procedure frPtjDSFirst(Sender: TObject);
  procedure frPtjDSNext(Sender: TObject);
  procedure frPtjFkvDSCheckEOF(Sender: TObject; var VEof: Boolean);
  procedure frPtjFkvDSFirst(Sender: TObject);
  procedure frPtjFkvDSNext(Sender: TObject);

  private
    { private declarations }
  public
    { public declarations }
  end;


  var TaskObject: MyObject;
      Comp:TComponent;
      frOwner:TComponent;
      frPtjDS:TfrDBDataSet;
      frPtj:TfrReport;
      frPtjFkvDS: TfrUserDataSet;
...;

implementation        
Uses ...;

procedure MyObject.frPtjGetValue(const ParName: String; var ParValue:
Variant);
var...;
begin  ...;  end;
procedure MyObject.frPtjDSFirst(Sender: TObject);
var...;
begin  ...;  end;
procedure MyObject.frPtjDSNext(Sender: TObject);
var...;
begin  ...;  end;
procedure MyObject.frPtjFkvDSCheckEOF(Sender: TObject; var VEof:
Boolean);
var...;
begin  ...;  end;
procedure MyObject.frPtjFkvDSFirst(Sender: TObject);
var...;
begin  ...;  end;
procedure MyObject.frPtjFkvDSNext(Sender: TObject);

procedure MyObject.TaskPtjel(Show: Boolean; tmb: array of string);
var ...;
begin
 frOwner:=TComponent.Create(Comp);
 frPtj:=TfrReport.Create(frOwner);
 frPtjDS:=TfrDBDataSet.Create(frOwner);
 frPtjFkvDS:=TfrUserDataSet.Create(frOwner);
 frPtjDS.DataSet:=DataModule1.frZQPtjel;
 //frPtj.Dataset:=frPtjDs;

 frPtj.OnGetValue:=@frPtjGetValue;

 frPtjDS.OnFirst:=@frPtjDSFirst;
 frPtjDS.OnNext:=@frPtjDSNext;

 frPtjFkvDS.OnCheckEOF:=@frPtjFkvDSCheckEOF;
 frPtjFkvDS.OnFirst:=@frPtjFkvDSFirst;
 frPtjFkvDS.OnNext:=@frPtjFkvDSNext;

...;

frPtj.LoadFromFile('MyReport.lrf');
frPtj.ShowReport;
...
end;
end.

**********************************************************************
********************

If I don’t set the frPtj.DataSet then Page1 and Page2 include Report
Title and Page Header only, but no MasterData rows. If I do set the
frPtj:=frPtjDS then Page1 is OK, but Page2 is empty. If I do set the
frPtj:=frPtjFkvDS then Page2 is OK, but Page1 is empty.  How I do make
the correct  Lazreprt with Page1 and Page2, in runtime?

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antonioJOF · 2022-11-04 13:00

lazreport search datasets by name. (in LR_Class CreateDS)

You must asign the TfrDBDataSet name property for runtime created DS

frPtjDS.Name='frPtjDS';