[fpc-devel] Should TAutoIncField be read only?

Luiz Americo Pereira Camara luizmed at oi.com.br
Wed May 19 19:10:11 CEST 2010

Michael Van Canneyt escreveu:
> On Wed, 19 May 2010, Luiz Americo Pereira Camara wrote:
>> Until a few moments ago i would say yes because it seems logical and 
>> fpc raises an exception when trying to set the value programatically.
>> But while investigating why TAutoIncField.ReadOnly always returns 
>> false, i found that, regardless of FReadOnly being set to true in the 
>> constructor, this value is overriden in TFieldDef.CreateField throung 
>> Attributes.faReadOnly flag.
>> So i tested in Delphi (TClientDatset and TDbf) and found that 
>> TAutoIncField.ReadOnly is false (like fpc).
>> So what should fpc do:
>> - Follow delphi behavior and let TAutoIncField.ReadOnly return False?
>> - Fix TAutoIncField.ReadOnly to return True?
> As far as I know, you can force a value for an autoinc field, so it
> is not always read-only. AutoInc means the engine will assign a value 
> if none is given at insert.

Trying to set value through TField.AsInteger or TField.Value raises an 
exception (autoinc fields are read only) both in Delphi and fpc.


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