[fpc-devel] Recent changes to TField.SetData

[michael.vancanneyt at wisa.be]

On Tue, 26 Apr 2011, LacaK wrote:

> Michael,
> do you plan do something else with this "OnValidate" problem ?

I thought I had done everything, or did I (again) forget something ?

Michael.

> Thanks
> -Laco.
>
>> Hi,
>> here are diffs with changes, I hope they will be good for all TDataSet 
>> descendants (those specific to FPC and also those which are also for use in 
>> Delphi)
>> Code which is general (and is used repeatedly) is placed in TField methods 
>> and only small code remains which must be placed into each TDataSet 
>> descendant.
>> (I patched only TBufDataSet, but later can be updated also other TDataSet 
>> descendants ... remove redundant code and add Field.Validate(...))
>> Thanks
>> -Laco.
>> 
>>> 
>>>>>> The whole code, which is repeated (and can be put in one place) is:
>>>>>> 
>>>>>> if not (State in [dsEdit, dsInsert, dsFilter, dsCalcFields]) then
>>>>>> begin
>>>>>>   DatabaseErrorFmt(SNotEditing,[Name],self);
>>>>>>   exit;
>>>>>> end;
>>>>>> if (Field.FieldNo>0) and not (State in [dsSetKey, dsFilter]) then
>>>>>> begin
>>>>>>   if Read 
>>>>>> OnlythenDatabaseErrorFmtSReadOnlyField,[Field.DisplayName],
>>>>>> Self);
>>>>>>   Field.Validate(Buffer);
>>>>>> end;
>>>>> 
>>>>> You are right in your dislike.
>>>>> 
>>>>> I will create a 'BeforeSetFieldData' in TDataset and put the code in 
>>>>> there,
>>>>> and the same for 'AfterSetFieldData' with the OnChange code.
>>>>> 
>>>> OK,
>>>> Then please do not forget commit necessary changes also in other 
>>>> descendants (not only in TCustomBufDataSet but also in TParadox, 
>>>> TMemDataset,  TFixedFormatDataSet,  TDbf) to completelly fix 'missing 
>>>> onvalidate call' problem.
>>>> Thanks
>>>> 
>>> I am still thinking about this.
>>> I have other solution, which is relative simple , puts base logic into 
>>> base TField methods (so all TDataSet descendants can benefit from it) and 
>>> does not negatively affect existing TDataSet descendants and does not 
>>> require introduce new methods (BeforeSetFieldData, AfterSetFieldData).
>>> Let's distributes repeating used code as follows:
>>> 
>>> 1. base checks "before" into procedure TField.SetData(Buffer: Pointer; 
>>> NativeFormat : Boolean);
>>>
>>>  820 begin
>>>  821   If Not Assigned(FDataset) then
>>>  822     DatabaseErrorFmt(SNoDataset,[FieldName]);
>>>
>>>        if not (State in [dsEdit, dsInsert, dsFilter, dsCalcFields]) then 
>>> //here should be IMO also dsNewValue
>>>          DatabaseErrorFmt(SNotEditing,[FDataSet.Name],FDataSet);
>>>
>>>        if ReadOnly and (FieldNo>0) and not (FDataSet.State in [dsSetKey, 
>>> dsFilter]) then
>>>          DatabaseErrorFmt(SReadOnlyField, [DisplayName], Self);
>>>
>>>  829   FDataSet.SetFieldData(Self,Buffer, NativeFormat);
>>> -------------------------------------------------------------------------- 
>>> 
>>> 2. into procedure TField.Validate(Buffer: Pointer);
>>>
>>>  892 begin
>>>        if FData     S      et.Statein[dsSetKey,dsFilter]thenExit893If
>>> assigned(OnValidate) Then
>>> 
>>> -------------------------------------------------------------------------- 
>>> 
>>> 3. "after call" into procedure TDataSet.SetFieldData(Field: TField; 
>>> Buffer: Pointer);
>>>     begin
>>>       if not (State in [dsCalcFields, dsFilter, dsNewValue]) then
>>>         DataEvent(deFieldChange, Ptrint(Field));
>>>     end;
>>> 
>>> -------------------------------------------------------------------------- 
>>> 
>>> And now all what we must do, is put into method SetFieldData in TDataSet 
>>> descendants one line:
>>> 
>>> Field.Validate(Buffer);
>>> and one line at end:
>>> 
>>> inherited; //calls "field change" ... this is done by all TDataSet 
>>> descendants in fcl-db as a last thing
>>> 
>>> 
>>> It is only draft, so some detils may be changed ... ;-)
>>> What do you think ?
>>> 
>>> Laco.
>>> 
>>> 
>> 
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>> 
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