Re: [Geotools-devel] Using native filters in queries

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Hi Nuno,
last time a new type of filter was in this commit:

https://github.com/geotools/geotools/commit/47e9259d74482b92244b4dd301363b434e382baf

Thankfully now there are default methods, allowing for quite a bit less
painful extension.
Overall I see where this need comes from and agree with it, a few
notes/questions off the top of my head:

   - Can you share how you intend to implement NativeFilter? Is it an
   interface with store specific implementations, or does it have a single
   one? Which stores will receive a sample implementation of the concept?
   - Make sure the functionality is open for programmers but not from the
   web (e.g., one cannot setup a XML or CQL filter using it
   - Properly document the intended usage of it including notion of
   pre/post filter splitting, e.g., if a NativeFilter is supported, but it's
   OR-ed with another bit using an unsupported filter function, it will end in
   the post, in memory evaluation, and will blow up.This is unavoidable, but
   should not be a surprise for users.

Cheers
Andrea

On Mon, Mar 19, 2018 at 11:07 PM, Nuno Oliveira <
nun...@ge...> wrote:

> Hi all,
>
> Recently I have been dealing with some use cases that require the ability
> to inject some native filters,
> specific for each feature type and non static over time, to the final
> native query build by GeoTools and
> send to the data store.
>
> For example, the content of a feature type is partially controlled by an
> external service who provides a non
> static native query (the request changes over time) that filters the
> content that should be show.
>
> Another use case is a complex authorization rules system where the
> authorization rules are SQL
> expressions that need to be append to the final SQL WHERE clause build by
> GeoTools, the system
> provides SQL expressions for different databases (Oracle, PostgreSQL,
> MySQL, etc ...).
>
> Most of the native filters of this use cases are quite complex and can't
> be translated to OGC filters.
>
> Since we have a pattern here that can be applied to several use cases and
> data stores I have think about
> an approach that would allow extensions, external code, etc ... to inject
> the necessary native filter(s)
> and allow data stores implementations to handle those native filters in an
> harmonized way.
>
> I have come up with the idea of a new filter named *NativeFilter*:
>
>    - this filter will NOT be directly usable by the final users, for
>    example in WFS requests
>
>
>    - if any code try to evaluate it in memory an exception will be throw
>
>
>    - it will not break any API and data stores will be free to implement
>    is support has needed
>
>
>    - it will have a method getNative() that will return a String
>    containing the native filter
>
> A new default method would need to be added to the *FilterVisitor*
> interface and a default
> implementation would need to be added to *AsbtractFilterVisitor and
> DuplicatingFilterVisitor *
> classes (like for any other filter).
>
> The data store who wants to supports this filter will need to extends it
> custom visitor, for example,
> for relational databases we only need to add a new visit method to
> *FilterToSQL* visitor.
>
> This gives the necessary flexibility for third party code (codes that use
> GeoTools) to inject native
> filters without any specific extension points or cumbersome handling. It
> is also worth notice unless
> some code is using native filters this will have no impact on other usages.
>
> Any thoughts on this ? Objections ?
>
> King regards,
>
> Nuno Oliveira
>
> --
> Regards,
> Nuno Oliveira
> ==
> GeoServer Professional Services from the experts! Visit http://goo.gl/it488V for more information.
> ==
>
> Nuno Miguel Carvalho Oliveira
> @nmcoliveira
> Software Engineer
>
> GeoSolutions S.A.S.
> Via di Montramito 3/A
> 55054  Massarosa (LU)
> Italy
> phone: +39 0584 962313 <+39%200584%20962313>
> fax:      +39 0584 1660272 <+39%200584%20166%200272>
> http://www.geo-solutions.ithttp://twitter.com/geosolutions_it
>
> -------------------------------------------------------
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-- 

Regards,

Andrea Aime

==
GeoServer Professional Services from the experts! Visit http://goo.gl/it488V
for more information.
==

Ing. Andrea Aime
@geowolf
Technical Lead

GeoSolutions S.A.S.
Via di Montramito 3/A
55054  Massarosa (LU)
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39  339 8844549

http://www.geo-solutions.it
http://twitter.com/geosolutions_it

AVVERTENZE AI SENSI DEL D.Lgs. 196/2003

Le informazioni contenute in questo messaggio di posta elettronica e/o
nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il
loro utilizzo è consentito esclusivamente al destinatario del messaggio,
per le finalità indicate nel messaggio stesso. Qualora riceviate questo
messaggio senza esserne il destinatario, Vi preghiamo cortesemente di
darcene notizia via e-mail e di procedere alla distruzione del messaggio
stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso,
divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od
utilizzarlo per finalità diverse, costituisce comportamento contrario ai
principi dettati dal D.Lgs. 196/2003.

The information in this message and/or attachments, is intended solely for
the attention and use of the named addressee(s) and may be confidential or
proprietary in nature or covered by the provisions of privacy act
(Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
Code).Any use not in accord with its purpose, any disclosure, reproduction,
copying, distribution, or either dissemination, either whole or partial, is
strictly forbidden except previous formal approval of the named
addressee(s). If you are not the intended recipient, please contact
immediately the sender by telephone, fax or e-mail and delete the
information in this message that has been received in error. The sender
does not give any warranty or accept liability as the content, accuracy or
completeness of sent messages and accepts no responsibility  for changes
made after they were sent or for other risks which arise as a result of
e-mail transmission, viruses, etc.

Re: [Geotools-devel] Using native filters in queries

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Re: [Geotools-devel] Using native filters in queries