TMemDataset freeing memory
lazarus / 16-Databases

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brick08 · 2022-02-09 01:56

i use stable Lazarus 2.2.0, FPC 3.2.2 for Win32
when TMemDataset is destroyed, a memory leak error appears. I compile
with Use heaptrc (-gh).
Test project in attach. Does anyone reproduce this error?
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var  mds:
TMemDataSet;begin  mds := TMemDataSet.Create(Self);  try   
mds.Clear(True);    TFieldDef.Create(mds.FieldDefs, 'id', ftInteger,
0, False, 0);    TMemDataSet(mds).CreateTable;    mds.Open;   
mds.Append;    mds.FieldByName('id').AsInteger:=1;    mds.Post; 
finally    mds.Free;   //in this line error  end;

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Handoko · 2022-02-09 02:43

That should be:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.Button1Click(Sender: TObject);var  mds: TMemDataSet;begin  mds
:= TMemDataSet.Create(Self);  try    mds.Clear(True);   
mds.FieldDefs.Add('id', ftInteger, 0, False);    mds.CreateTable;   
mds.Open;    mds.Append;    mds.FieldByName('id').AsInteger:=1;   
mds.Post;  finally    mds.Free;  end;end;

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brick08 · 2022-02-09 03:30

ok, it's right
In module memds in procedure TMemDataset.CopyFromDataset(DataSet:
TDataSet; CopyData: Boolean); 
there is line:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i TFieldDef.C
reate(FieldDefs,F.FieldName,F.DataType,F.Size,F.Required,F.FieldNo);al
so lead to errors for me. Can you check it?

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Handoko · 2022-02-09 03:51

I do not use it, but I found this work for me:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    
TFieldDef.Create(mds.FieldDefs, 'id', ftInteger, 0, False, 1);
Maybe the last parameter should start from 1.

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brick08 · 2022-02-09 06:19

i think it would be better to change this line in the module memds,
because many TField.FieldNo started from 0, which leads to the error.
Am I right?