Zeoslib Portal

CREATE TABLE TEST_CHAR_BOOL
(
  SOME_STRING Varchar(10),
  SOME_BOOL Char(1)
);

procedure TForm3.Button1Click(Sender: TObject);
begin
  ZTable1.Append;
  ZTable1['some_string'] := IntToStr(Random(999));
  ZTable1['some_bool'] := Random(2) = 1;
  ZTable1.Post;
end;

Project Project1.exe raised exception class EZSQLException with message 'SQL Error: Dynamic SQL ErrorSQL error code = -303arithmetic exception, numeric overflow, or string truncationstring right truncation. Error Code: -303. Incompatible column/host variable data type The SQL: INSERT INTO TEST_CHAR_BOOL (SOME_STRING,SOME_BOOL) VALUES (?,?); '.

:76a21812 KERNELBASE.RaiseException + 0x62
ZDbcInterbase6Utils.CheckInterbase6Error(???,???,$25E91A0,lcExecute,'INSERT INTO TEST_CHAR_BOOL (SOME_STRING,SOME_BOOL) VALUES (?,?)')
ZDbcInterbase6Statement.TZInterbase6PreparedStatement.ExecuteInternal
ZDbcInterbase6Statement.TZInterbase6PreparedStatement.ExecuteUpdatePrepared
ZDbcGenericResolver.TZGenericCachedResolver.PostUpdates(TZAbstractCachedResultSet($26468A0) as IZCachedResultSet,???,???,$263FEE0)
ZDbcCachedResultSet.TZAbstractCachedResultSet.PostRowUpdates(???,???)
ZDbcCachedResultSet.TZAbstractCachedResultSet.PostUpdates
ZDbcCachedResultSet.TZAbstractCachedResultSet.InsertRow
ZAbstractDataset.TZAbstractDataset.InternalAddRecord(???,False)
ZAbstractDataset.TZAbstractDataset.InternalPost
DB.TDataSet.CheckOperation((ZAbstractDataset.TZAbstractDataset.InternalPost,$2B6ED90),(nil,nil))
DB.TDataSet.Post
Unit1.TForm3.Button1Click(???)
Controls.TControl.Click
StdCtrls.TButton.Click
StdCtrls.TButton.CNCommand(???)
Controls.TControl.WndProc(???)
Controls.TWinControl.WndProc((48401, 3268, 6294724, 0, 3268, 0, 3268, 96, 0, 0))
StdCtrls.TButtonControl.WndProc(???)
Controls.TControl.Perform(???,???,6294724)
Controls.DoControlMsg(???,(no value))
Controls.TWinControl.WMCommand((273, 3268, 0, 6294724, 0))
Forms.TCustomForm.WMCommand(???)
Controls.TControl.WndProc(???)
Controls.TWinControl.WndProc((273, 3268, 6294724, 0, 3268, 0, 3268, 96, 0, 0))
Forms.TCustomForm.WndProc(???)
Controls.TWinControl.MainWndProc(???)

Revision: 3756
Author: egonhugeist
Date: Friday, 22 January 2016 21:17:08
Message:
finalize the FIELDSIZE story!

duzenko wrote:The expected behavior (and observed on 7.1) is that it would save either 'F' or 'T' to the char(1) column while I suspect 7.2 tries to push the entire "False" or "True" into it?

function MyBoolToStr(const x: Boolean): String;
begin
  case x of
    True: Result := 'T';
    False: Result := 'F';
  end;
end;

procedure TForm3.Button1Click(Sender: TObject);
begin
  ZTable1.Append;
  ZTable1['some_string'] := IntToStr(Random(999));
  ZTable1['some_bool'] := MyBoolToStr(Random(2) = 1);
  ZTable1.Post;
end;

Zeos 7.2 (correctly) forwards the whole string to Firebird

duzenko wrote:Sorry, do you understand that this is a backward incompatible, breaking change?

duzenko wrote:I just can't update literally hundreds of my customers' Firebird servers to 3.0.

duzenko wrote:Was it announced anywhere that starting from 7.2 Zeoslib no longer supports bool's as firebird 2.5 char's?

duzenko wrote:Was it discussed on this forum before the decision was made?

duzenko wrote:Did you read my comment above that the string value is truncated to 4 chars while the field itself is 1 char?

duzenko wrote:No offense intended, but It just sounds like you're trying to dress a bug as a feature.

duzenko wrote:You seem to be missing the point that Zeoslib is truncating the string to 4 char's while it should truncate to 1. It's not about truncate or not - it's about 4 or 1.

Zeos 7.2 (correctly) forwards the whole string to Firebird

Except it does not. It just truncates to more char's than 7.1 (and in no way that is 'correct')
You still need to truncate to real field length in character, but do that on a WideString rather than AnsiString

ZTable1['some_bool'] := Random(2) = 1;

• To me it seems that your connection character set is UTF8 while you use an ANSI Delphi. Why? This simply doesn't make sense. You might want to consider using the correct ANSI character set for your database connection. ZConnection.ClientCodepage='WIN1252' for example.
• Another option might be to use ClientCodepage=UTF8 and ControlsCodePage=cCP_UTF16. On the SVN version of Zeos 7.2 this will make Zeos generate TWideStingField instead of TStringField with the correct number of characters. I am not 100% sure if the release version Zeos 7.2.4 will behave in the same way. Watch out for type casts like TStringField(DataSet.FieldByName('somefield')) in your code in that case because they might be incorrect afterwards and cause access violations then.

Fr0sT wrote:So you rely on the following chain:
- having Boolean
- when assigned to string field, implicitly converted with BoolToStr
- string value copied to string field AND silently truncated to that field size
- value of 1st char in Delphi's boolean string representation is then written to DB
As for me, this bunch of implicit behaviors is apparently a bad practice not suitable for production. Moreover I would raise an exception like FB's 'string truncation' on field assignment but Delphi seems to be a forgiver.

I'd advice to not use char fields for booleans at all. Char fields bring many problems with encodings. Proper way of imitating booleans is a smallint domain with check that value is [0,1]. This way you won't have hidden string conversions and stuff. Or it might allow any value in the range implementing "everything <>0 is true" logic.

For your case might be an option to use:
- your own TField descendant with any conversions you wish
- or TField.OnSet/GetText handlers.

We did the decision that we support users pushing UTF8 directly to the database using TStringField in ANSI Delphis.

In this use case the user is responsible for making sure that not more than the allowed amount of characters gets pushed into the TString Field.

There is no such support as using bools as Firbird Char(1) fields. You relied on behaviour that worked but was not intentionally working. At least from a Zeos point of view.

Even if Zeos would do some kind of check here, it wouldn't be a truncation but raising an exception that there are too many characters stored in the field.

No - it wasn't. Do we need your approval before we make changes to the Zeos code? Do you want to step up and support or do Zeos development? If you don't want to do any of that then why do you demand that we discuss the development of Zeos with you before we do changes?

Too bad - the way you write here, I already did take offense.

You still need to truncate to real field length in character, but do that on a WideString rather than AnsiString

Again: Zeos does no intentional truncation. Delphi is doing the truncation in this example because it happens on this line of your example code:

Code: Select all

ZTable1['some_bool'] := Random(2) = 1;

During this assignment Delphi decides to truncate the string value of "False" to Fals or to F - depending on TStringField.Size.

Zeos (correctly) just sends the value that gets stored in the StringField to the database that in turn correctly raises an exception.

marsupilami wrote: Soo - to bring this to an end:

• To me it seems that your connection character set is UTF8 while you use an ANSI Delphi. Why? This simply doesn't make sense. You might want to consider using the correct ANSI character set for your database connection. ZConnection.ClientCodepage='WIN1252' for example.

[*]Another option might be to use ClientCodepage=UTF8 and ControlsCodePage=cCP_UTF16. On the SVN version of Zeos 7.2 this will make Zeos generate TWideStingField instead of TStringField with the correct number of characters. I am not 100% sure if the release version Zeos 7.2.4 will behave in the same way. Watch out for type casts like TStringField(DataSet.FieldByName('somefield')) in your code in that case because they might be incorrect afterwards and cause access violations then.[/list]

Soo - to bring this to an end:

• Consider one of the following
• Ban my forum account cause I'm not going to agree and call this bug an 'improvement'
• Agree to optionally return the ACTUAL field size
• Agree to optionally use TWideStringField's on unicode databases instead of TStringField