RefreshDetail is causing exception (Unidac 6.1.4)

[swierzbicki]

Hello,

RereshDetails is causing exception:
"Can not perform this operation on a closed dataset"

Here is a call stack

:7600812f KERNELBASE.RaiseException + 0x54
:005e0cbc DatabaseError + $64
:005f2f26 TDataSet.CheckActive + $36
:00b8fead TCustomDADataSet.CheckActive + $5
:00b94f3a TCustomDADataSet.RefreshDetail + $1E2

I'll try to make a simple reproducible project. Are you aware of the problem ?

[AlexP]

Hello,

This is a correct error, since it is raised in the TDataSet.CheckActive base method in the standard module DB if the DataSet is dsInactive.

[swierzbicki]

But I never call "CheckActive" ! This is a project that used to worked... and moving from one record to another one raise this error.

Was there any modification with details dataset handling ?

[swierzbicki]

I've stepped into the code and error appears in

Code: Select all

TCustomDADataSet.RefreshDetail(Sender: TObject);
...
              try
              DoBeforeOpen;
              DataReopen;
              if Length(FIRecordSet.IndexFields) > 0 then
                FIRecordSet.SortItems;
            finally
              Resync([]);
              First;  // <==== Exception because dataset is closed
              DoAfterOpen;
            end;
...

This behaviour was introduced in this version (First call is not present in previous release).
Removing it solves my problem. Is there a specific reason to call "First" ?

[AlexP]

Yes, we have added a call for this method, however, it mustn't cause an error. Please send a small sample reproducing the issue to alexp*devart*com .

[swierzbicki]

You can easily reproduce it :
Create a master/details relation.
On the OnBeforeOpen event of the detail dataset add something like that (in my case, i'm setting SQL script before opening any TUniQuery component) : TUniquery(Sender).Sql.Text := 'Select * from Table';

Demo sended to your email address

[AlexP]

You can't change the SQL text in the OnBeforeOpen event, since this leads to DataSet closing. You can use the BeforeRefresh event for this.

[swierzbicki]

I don't understand why I cannot use the "BeforeOpen" event. This event occurs before an application executes a request to open a dataset, a dataset that is *already* closed. "BeforeRefresh" occurs immediately before an application refreshes the data in the dataset.

Most of my TUniQuery does refresh before / after modifying data... Some of the data are automatically refreshed... Using the "BeforeRefresh" event will definitively not be the right event to choose !

I don't have such errors when working with Master/Details TClientDatasets for exemple. I didn't get these issues whit previous Unidac release and for years now...

I guess that detail dataset linked event in this special case should'nt be triggered at all... Please review your point of view.

Thank you

[AlexP]

We will add a global variable responsible for this behavior, i.e. the BeforeOpen event will be called one time by default (on "real" opening DataSet), as well as in other DataSets.

[swierzbicki]

That's nice. I suppose you will do the same for the other events ?

[AlexP]

No, we won't change behavior for other events.