Hi there,
I recently tried my luck with lazReports, but it seems that lazReports in lazarus version 1.2.2 is broken.
In my case i have a db application that connects to a MySQL db (5.5). I tried many times to design a single report with the designer from lazReports but all the time designer crashes with the
all time classic "Access violation" message (in cases like: delete a box, or band from report, trying to open the Variables, etc etc).
Recently i installed the trunk version of lazarus in order to check what (the heck) is happening in the latest version trunk and FPC 2.7.1.
There things look smoother now, but again i faced 2 problems, during the design of my reports.
Problem #1Line 71 in lr_dbrel.pasIn this line we have a call to the underlying dataset (which is my TSQLQuery) to update his field definitions, which results in a mystirious "
no data from query" like message.
I am already in the designer, while my app is running, query is open and definitions are already in place, so no need for this update.
So, in order to bypass this, i put a comment to the update for definitions call in line 71 and move fwd with the design process.
Problem #2:While i succeded with my first report which prints data from a single table, now i tried to make a report with 2 tables in a master-detail binding (2 TSQLQueries + 1 datasource that binds them in a master detail relation).
Here i faced (again) the
old time classic "Access Violation" from the
LR_Class file in method
TfrPage.FormPage.
There is a call to a
DoLoop(1) procedure, which aquires bookmarks from my queries and when
DoLoop(1) ends, then there is a call to a local proc with name
RestoreBookmarks which causes the "Aceess Violation" message.
The code from
RestoreBookmarks is listed below
procedure RestoreBookmarks;
var
n: Integer;
begin
for n:=0 to Length(BooksBkUp)-1 do
with BooksBkUp[n] do begin
Dataset.GotoBookMark(Bookmark); // <<< IS THIS BOOKMARKD VALID FOR THE DETAIL DATASET ????
Dataset.FreeBookMark(Bookmark);
if DetailCount=0 then
Dataset.EnableControls;
end;
SetLength(BooksBkUp, 0);
end;My conclusion is that the call to
Dataset.GotoBookMark(BookMark) causes the problem (when it refers to a bookmark for detail dataset), and when i comment this line report is working without problems.
The problem (from my point of view) is caused because in a master detail relation the bookmark for the detail is no longer valid, since master dataset is scrolled to another record.
Now, one question here is:
Is this line needed?
I am not sure for that, but i believe (or hope) it is not!
Normally RestoreBookmarks should work with
DataSet.GotoBookMark IF for every detail it had
PREVIOUSLY aquired a bookmark for master record and stored it in the BooksBkUp array, and later it restores them with
the same sequence (in order to avoid invalid bookmarks) but it seems that this is not happening and leads to our evidence .... "Access violation" which occurs deep inside when Dataset tries to copy a buffer to the current buffer, which is not valid! (how can this happen?)
Also, looks silly (2 me) to call all the GotoBookmarks in a series, for every bookmark the report has acquired, WITHOUT using them (i didn't notice any use, did anyone else notice some use for them?)
For the time i left this line out until i find that i need this...
But i need also the opinion from other, perhaps someone knows this unit better...
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