[TinyOWS-users] fids in database views

[Rahkonen Jukka]

Hi,

Some more thoughts about fids and views.

- Views which include joins usually need several columns for building
something unique, typically PK_table1+PK_table2.
- Attribute used for a primary key and fid should normally not be
included as a normal attribute in the schema. Especially this is the
case with WFS-T, users should definitely not edit the fids!
- However, sometimes database is defined so that PK is made from
person-IDs or cadastrial IDs or something else that is also important as
a normal attribute. They are harder to handle with WFS-T inserts,
perhaps the only possibility is just to trust the user and accept what
comes in with the insert message. If it is not unique the database will
not take it but of course it can be unique but wrong it user makes an
error. For my mind it would not be a crime to decide that TinyOWS will
not support such tables for WFS-T at all.
- However, it should be possible to use those tables read-only in such a
way that both the fids are unique and correct and the PK field is
included as an attribute in the output GML.
- Most simple way to do this is to make a view and select the primary
key column two times like
 CREATE VIEW view as (SELECT person_id PK, person_id person_id...)

In the confifuration PK will be defined as a primary key. WFS server
uses that for creating fids and eats that column away from the output
just as usual. The same information is included also in the person_id
field and that is included as a normal attribute.

Would this be simple enough? It is not very hard to document "Primary
key columns are not included in the output GML. If that information is
needed, make a view and select PK column two times with different names.
Do not use this for WFS-T".

-Jukka Rahkonen-