Helen / Jason

Many thanks for the guidance.

I apologise for not having expressed our issues more clearly.
The problem comes from not being immersed in Firebird or IBO but focussed on
problem solving - once the head is buried in the problem, the wood becomes
too dense to see the trees.

Merely setting the GeneratorLinks solved everything, so we must have been
close or thereabouts already.
(and I did mean controls as opposed to components - IBO seems to include
different sets of controls, on the surface of it doing the same thing).

Please be kind to those of us who don't have your depth of knowledge of the
products and forgive a lack of understanding in the absence of readily
accessible documentation.

To a Firebird and IBO newbie, the combination is confusing. Helen's book is
a superb reference for Firebird but we have been unable to find anything
similar for IBO. (Deconstructing Delphi samples doesn't rank as accessable -
it's possible, but also an added overhead.)

This conversion exercise has been an evaluation of the Firebird / IBO
Component combination.
We have all found Firebird straighforward thanks to Helen's book. We have
all been equally confused by IBO and have reached a successful conversion
largely by trial and error, assisted by advice from yourselves. Our main
issue is with the lack of accessible documentation - especially for C++
users. This makes the development process a far longer and costly activity
than it needs to be.

Again, many thanks for your guidance.

George

----- Original Message -----
From: "Helen Borrie" <helebor@...>
To: <IBObjects@yahoogroups.com>
Sent: Monday, December 04, 2006 10:04 PM
Subject: Re: [IBO] Firebird Generated Keys as Master / Slave Links and IBO
Controls


> At 02:46 AM 5/12/2006, you wrote:
>> > > Our problem concerns generators - specifically, having gone to
>> > > primary keys having no logic in the real world but being
>>generated by
>> > > a Firebird Generator, we now have linking problems.
>> > >
>> > > From what we understand, for a field to be populated by a
>>generator
>> > > it must be left out of the IBO query SQL statement.
>
> No, quite wrong.
>
>>If this is so then the query doesn't have it and cannot use it as a
>>linking
>>field in a master/slave relationship.
>
> Jason wrote:
>
>> > The surrogate keys (that's what I call them) should still be
>> included in all
>> > your queries.
>> >
>> > > Can anyone point us to a document that will enlighten us on
>>Master /> Slave relationships using generator populated fields as the key?
>> >
>>[Jason] Is all you need to do is put a setting in the GeneratorLinks
>>property for the surrogate key column and IBO will take care of
>>providing values for your keys. Just be sure your triggers do not
>>overwrite the values IBO
>>retrieves.
>> > Check for NULL before applying a value in a trigger.
>> >
>>[Jason] You can make a setting at the TIB_Connection.GeneratorLinks level
>>and it will be applied for all datasets on that connection, or you can
>>isolate a setting in your dataset GeneratorLinks property.
>> >
>> > > The samples are in Delphi and we are using C++ so can't access
>>them.
>
> What you can do is inspect them in a text editor, particularly to
> look at the DFM file. Some text editors, e.g. CONText (free!!) will
> even format the Pascal files with the correct highlighting, to make
> it easier to read them.
>
>
>>Many thanks but what do you mean by 'settings' and should they be in
>>the master or slave? (Or if only in the transaction - what settings?).
>>
>>I tried including the generated field in the query and that produces
>>an error message, obviously the control checks the NOT NULL and
>>throws an exception before the trigger fires and the generator has a
>>chance to populate the field.
>
> You use a SELECT query to retrieve a dataset. You need to have the
> primary key in the set.
>
> The query component has built-in methods that internally create
> Insert, Update and Delete statements for when you call Insert, Edit
> and Delete in your app. Because the primary key is a compulsory field
> and, for a master-detail setup, a matching foreign key is compulsory,
> you will get an error on calling Insert on *either* set, if IBO
> doesn't have a value for the PK of the new master record.
>
> If you want IBO to have access to the new generator value *before* a
> new row is constructed, you use the GeneratorLinks property. The
> format is the same regardless of whether you're using Delphi or
> CPPB. If you want to set it globally for the whole application, set
> it in the TIB_connection object (no doubt the IBODatabase in your case):
>
> aTable.PrimaryKeyName=aGenerator
>
> Or you can set it at dataset level, in which case you don't qualify
> the fieldname and so it's just
>
> PrimaryKeyName=Generator
>
>>The trigger itself checks for NULL in accordance with the Bible
>>(Helen's book).
>
> Then setting GeneratorLinks is all you have to do. IBO does the
> rest. As soon as you call the Insert method, and before IBO puts the
> dataset into Insert mode, it calls a function called Gen_ID which
> returns the new value of the generator and writes it to the PK field
> of the (forthcoming) new record. That's it.
>
> Don't include any spaces between PrimaryKeyName and Generator.
>
>>What I suppose I am really after is a user guide so we don't have to
>>keep bothering you.
>
> I think GeneratorLinks is covered in the Getting Started
> Guide. However, the GSG is *not* a newbie tutorial about SQL,
> Firebird/InterBase or Delphi, rather it fills in the gap between your
> knowledge of Delphi and the way things are implemented in IBO. So,
> for example.-
>
> -- If you're using the TDataset-compatible (TIBO---) components, the
> ways of doing Master-Detail are covered in the Delphi help. Same
> rules, same limitations.
>
> Supporting generators, viz. GeneratorLinks and the underlying Gen_ID
> function, *is* available to "TIBO--" components, being one of a group
> of IBO-specific features that is wrapped into these components and
> published. It does behove you to understand how generators (more
> correctly called "sequences") work, since generators are a
> DBMS-specific feature of Firebird and InterBase.
>
> Also, seeing your Subject title makes me want to suggest that you
> also try to understand the difference between "components" and
> "controls". Controls are components, but they are the visual things
> that you use in your user interface - TDBEdit, TDBGrid, and so on.
>
> The data access components are linked to the controls via a
> datasource component.
>
> -- With the TIBO-- components you can ONLY use Delphi's TDatasource
> for this linking, and you can ONLY use controls that work with (are
> compatible with) the TDatasource.
>
> -- With the TIB_-- components you can ONLY use the native IBO
> TIB_Datasource and you can ONLY use the TIB_-- controls.
>
> Helen
>
>
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